Consumption of galacto-oligosaccharides increases iron absorption from a micronutrient powder containing ferrous fumarate and sodium iron EDTA: a stable-isotope study in Kenyan infants

A review of the effect of iron supplementation on the gut microbiota of children in developing countries and the impact of prebiotics

Iron is essential for many physiological functions of the body, and it is required for normal growth and development. Iron deficiency (ID) is the most common form of micronutrient malnutrition and is particularly prevalent in infants and young children in developing countries. Iron supplementation is considered the most effective strategy to combat the risk of ID and ID anaemia (IDA) in infants, although iron supplements cause a range of deleterious gut-related problems in malnourished children. The purpose of this review is to assess the available evidence on the effect of iron supplementation on the gut microbiota during childhood ID and to further assess whether prebiotics offer any benefits for iron supplementation. Prebiotics are well known to improve gut-microbial health in children, and recent reports indicate that prebiotics can mitigate the adverse gut-related effects of iron supplementation in children with ID and IDA. Thus, provision of prebiotics alongside iron supplements has the potential for an enhanced strategy for combatting ID and IDA among children in the developing world. However, further understanding is required before the benefit of such combined treatments of ID in nutritionally deprived children across populations can be fully confirmed. Such enhanced understanding is of high relevance in resource-poor countries where ID, poor sanitation and hygiene, alongside inadequate access to good drinking water and poor health systems, are serious public health concerns.

A Systematic Review of Isotopically Measured Iron Absorption in Infants and Children Under 2 Years

BACKGROUND

Iron is an essential element for critical biological functions, with iron deficiency negatively affecting growth and brain development and iron excess associated with adverse effects. The goal of this review is to provide a comprehensive assessment of up-to-date evidence on iron absorption measured isotopically in children, preterm infants, and full-term infants, up to 24 months of age.

METHODS

Search databases included Pubmed, Cochrane, Web of Science, and Scopus from a date range of 1 January 1953 to 22 July 2024. The included articles were experimental studies with iron absorption outcomes measured by isotopic techniques. The risk of bias was assessed using the Cochrane Risk of Bias Tool.

RESULTS

A total of 1594 records were identified from databases, and 37 studies were included in the quality review with a total of 1531 participants. Article results were grouped by study commonality: absorption and red blood cell incorporation, type of milk feedings, additives to improve absorption, how and when to supplement with iron, and iron forms and complimentary foods.

CONCLUSIONS

The results from this review support the current recommendations of oral iron supplementation. Iron from breast milk has high bioavailability, and unmodified cow's milk reduces iron absorption. Supplemental iron is required at 4-6 months for healthy, full-term infants and sooner for preterm infants. Ascorbic acid increases iron absorption in full-term infants and children. Lactoferrin and prebiotics are promising candidates for enhancing iron absorption, but they require further investigation. Research evidence of iron absorption mechanisms and modulating factors in preterm infants is limited and should be a research priority.

Assessing Human Iron Kinetics Using Stable Iron Isotopic Techniques

Stable iron isotope techniques are critical for developing strategies to combat iron deficiency anemia, a leading cause of global disability. There are four primary stable iron isotope methods to assess ferrokinetics in humans. (i) The fecal recovery method applies the principles of a metabolic balance study but offers enhanced accuracy because the amount of iron isotope present in feces can be directly traced back to the labeled dose, distinguishing it from endogenous iron lost in stool from shed intestinal cells. (ii) In the plasma isotope appearance method, plasma samples are collected for several hours after oral dosing to evaluate the rate, quantity, and pattern of iron absorption. Key metrics include the time of peak isotope concentration and the area under the curve. (iii) The erythrocyte iron incorporation method measures iron bioavailability (absorption and erythrocyte iron utilization) from a whole blood sample collected 2 weeks after oral dosing. Simultaneous administration of oral and intravenous tracers allows for separate measurements of iron absorption and iron utilization. These three methods determine iron absorption by measuring tracer concentrations in feces, serum, or erythrocytes after administration of a tracer. In contrast, (iv) in iron isotope dilution, an innovative new approach, iron of natural composition acts as the tracer, diluting an ad hoc modified isotopic signature obtained via prior isotope administration and equilibration with body iron. This technique enables highly accurate long-term studies of iron absorption, loss, and gain. This review discusses the application of these kinetic methods and their potential to address important questions in hematology and iron biology.

Iron Absorption from an Iron-Fortified Follow-Up Formula with and without the Addition of a Synbiotic or a Human-Identical Milk Oligosaccharide: A Randomized Crossover Stable Isotope Study in Young Thai Children

BACKGROUND

Previous studies showed that pre- and probiotics may enhance iron absorption. Probiotics combined with prebiotics (synbiotics), including human-identical milk oligosaccharides (HiMOs), are commonly added to infant and follow-up formula (FUF). Whether these additions enhance iron absorption from iron-fortified commercial milk formula is uncertain.

OBJECTIVES

We determined the effect of adding 1) a synbiotic [galacto-oligosaccharide [GOS] + Limosilactobacillus reuteri (L. reuteri)] or 2) the HiMO 2'-fucosyllactose (2'FL) to iron-fortified FUF on iron absorption in young Thai children.

METHODS

In a randomized, controlled, single-blinded (participants) crossover study, 82 Thai children aged 8-14 mo were enrolled to consume single servings (235 mL) of FUF with isotopically labeled ferrous sulfate (2.2 mg iron) with 1) the synbiotic (400 mg/100 mL GOS and L. reuteri DSM 17938), 2) the HiMO 2'FL (100 mg/100 mL), and 3) without synbiotic and 2'FL (control) in random order and a 3-d washout period between administrations. Fractional iron absorption [FIA (%)] was assessed by measuring erythrocyte incorporation of isotopic labels 14 d (n = 26) and 28 d (n = 76) after consumption of the last test FUF.

RESULTS

Median (IQR) FIA from iron-fortified FUF with the synbiotic [8.2 (5.2, 12.9)%] and with 2'FL [8.4 (5.5, 14.1)%] did not differ from the control FUF [8.1 (4.8,14.7)%] (synbiotic compared with control, P = 0.24; 2'FL compared with control, P = 0.95). FIA from all FUF did not differ when measured after 14 and 28 d of erythrocyte incorporation (Time, P = 0.368; FUF, P = 0.435; Time × FUF, P = 0.937). Fecal pH and hemoglobin were negatively associated with FIA.

CONCLUSIONS

In young Thai children, the addition of a synbiotic (GOS + L. reuteri) or 2'FL to iron-fortified FUF did not impact FIA from a single serving. The study was registered at clinicaltrials.gov as NCT04774016.

The effect of iron absorption in ferrous gluconate form from enriched rice flour using an in vitro digestion model and a Caco-2 cell model

Iron deficiency can cause serious diseases in infants and young children such as indigestion, anemia, and nervous system dysplasia. Consumption of high-iron rice flour can prevent iron deficiency. The objective of this study was to evaluate the potential application of ferrous gluconate as an iron source in high-iron rice flour used as a type of accessory food for infants and young children. In this study, the differences in iron absorption ability between ferrous gluconate and ferrous fumarate in rice flour with the same ingredients in both high and low phytic acid systems were evaluated. The results showed that there was no significant difference in the bioaccessibility/bioavailability between ferrous gluconate and ferrous fumarate at both low and high phytic acid contents. In low phytic acid and high phytic acid systems, the iron absorption rate of ferrous gluconate is 11.53% and 13.45% higher than that of ferrous fumarate, respectively (p < 0.05). In summary, the iron absorption rate of ferrous gluconate was higher than that of ferrous fumarate in the rice flour system. Additionally, the low phytic acid environment is more conducive to iron uptake and utilization. Therefore, ferrous gluconate can be used as an alternative source of iron in accessory foods for infants and young children.

Gram-scale chemical synthesis of galactosyllactoses and their impact on infant gut microbiota in vitro

Galactooligosaccharides (GOS) are widely used as a supplement in infant nutrition to mimic the beneficial effects found in prebiotic human milk oligosaccharides (HMOs). However, the complexity of the GOS mixture makes it challenging to ascertain which of the GOS components contribute most to their health benefits. Galactosyllactoses (GLs) are lactose-based trisaccharides containing a β-galactopyranosyl residue at the 3'-position (3'galactosyllactose, 3'-GL), 4'-position (4'-galactosyllactose, 4'-GL), or the 6'-position (6'-galactosyllactose, 6'-GL). These GLs are of particular interest as they are present in both GOS mixtures and human milk at early stages of lactation. However, research on the potential health benefits of these individual GLs has been limited. Gram quantities are needed to assess their health benefits but these GLs are not readily available at this scale. In this study, we report the gram-scale chemical synthesis of 3'-GL, 4'-GL, and 6'-GL. All three galactosyllactoses were obtained on a gram scale in good purity from cheap and commercially available lactose. Furthermore, in vitro incubation of GLs with infant faecal microbiota demonstrates that the GLs were able to increase the abundance of Bifidobacterium and stimulate short chain fatty acid production.

Prebiotics increase iron absorption and reduce the adverse effects of iron on the gut microbiome and inflammation: a randomized controlled trial using iron stable isotopes in Kenyan infants

BACKGROUND

Iron fortificants tend to be poorly absorbed and may adversely affect the gut, especially in African children.

OBJECTIVE

We assessed the effects of prebiotic galacto-oligosaccharides/fructo-oligosaccharides (GOS/FOS) on iron absorption and gut health when added to iron-fortified infant cereal.

METHODS

We randomly assigned Kenyan infants (n = 191) to receive daily for 3 wk a cereal containing iron and 7.5 g GOS/FOS (7.5 g+iron group), 3 g (3-g+iron group) GOS/FOS, or no prebiotics (iron group). A subset of infants in the 2 prebiotic+iron groups (n = 66) consumed 4 stable iron isotope-labeled test meals without and with prebiotics, both before and after the intervention. Primary outcome was fractional iron absorption (FIA) from the cereal with or without prebiotics regardless of dose, before and after 3 wk of consumption. Secondary outcomes included fecal gut microbiota, iron and inflammation status, and effects of prebiotic dose.

RESULTS

Median (25th-75th percentiles) FIAs from meals before intervention were as follows: 16.3% (8.0%-27.6%) without prebiotics compared with 20.5% (10.4%-33.4%) with prebiotics (Cohen d = 0.53; P < 0.001). FIA from the meal consumed without prebiotics after intervention was 22.9% (8.5%-32.4%), 41% higher than from the meal without prebiotics before intervention (Cohen d = 0.36; P = 0.002). FIA from the meal consumed with prebiotics after intervention was 26.0% (12.2%-36.1%), 60% higher than from the meal without prebiotics before intervention (Cohen d = 0.45; P = 0.007). After 3 wk, compared with the iron group, the following results were observed: 1) Lactobacillus sp. abundances were higher in both prebiotic+iron groups (P < 0.05); 2) Enterobacteriaceae sp. abundances (P = 0.022) and the sum of pathogens (P < 0.001) were lower in the 7.5-g+iron group; 3) the abundance of bacterial toxin-encoding genes was lower in the 3-g+iron group (false discovery rate < 0.05); 4) fecal pH (P < 0.001) and calprotectin (P = 0.033) were lower in the 7.5-g+iron group.

CONCLUSIONS

Adding prebiotics to iron-fortified infant cereal increases iron absorption and reduces the adverse effects of iron on the gut microbiome and inflammation in Kenyan infants. This trial was registered at clinicaltrials.gov as NCT03894358.

Comparative prebiotic potential of galacto- and fructo-oligosaccharides, native inulin, and acacia gum in Kenyan infant gut microbiota during iron supplementation

Iron fortification to prevent anemia in African infants increases colonic iron levels, favoring the growth of enteropathogens. The use of prebiotics may be an effective strategy to reduce these detrimental effects. Using the African infant PolyFermS gut model, we compared the effect of the prebiotics short-chain galacto- with long-chain fructo-oligosaccharides (scGOS/lcFOS) and native inulin, and the emerging prebiotic acacia gum, a branched-polysaccharide-protein complex consisting of arabinose and galactose, during iron supplementation on four Kenyan infant gut microbiota. Iron supplementation did not alter the microbiota but promoted Clostridioides difficile in one microbiota. The prebiotic effect of scGOS/lcFOS and inulin was confirmed during iron supplementation in all investigated Kenyan infant gut microbiota, leading to higher abundance of bifidobacteria, increased production of acetate, propionate, and butyrate, and a significant shift in microbiota composition compared to non-supplemented microbiota. The abundance of the pathogens Clostridium difficile and Clostridium perfringens was also inhibited upon addition of the prebiotic fibers. Acacia gum had no effect on any of the microbiota. In conclusion, scGOS/lcFOS and inulin, but not acacia gum, showed a donor-independent strong prebiotic potential in Kenyan infant gut microbiota. This study demonstrates the relevance of comparing fibers in vitro prior to clinical studies.

Approaches to Address the Anemia Challenge

Anemia is a multifactorial condition; approaches to address it must recognize that the causal factors represent an ecology consisting of internal (biology, genetics, and health) and external (social/behavioral/demographic and physical) environments. In this paper, we present an approach for selecting interventions, followed by a description of key issues related to the multiple available interventions for prevention and reduction of anemia. We address interventions for anemia using the following 2 main categories: 1) those that address nutrients alone, and, 2) those that address nonnutritional causes of anemia. The emphasis will be on interventions of public health relevance, but we also consider the clinical context. We also focus on interventions at different stages of the life course, with a particular focus on women of reproductive age and preschool-age children, and present evidence on various factors to consider when selecting an intervention-inflammation, genetic mutations, nutrient delivery, bioavailability, and safety. Each section on an intervention domain concludes with a brief discussion of key research areas.

Long-term continuous cultivation of Kenyan infant fecal microbiota using the host adapted PolyFermS model

Appropriate in vitro models to investigate the impact of novel nutritional strategies on the gut microbiota of infants living in rural Africa are scarce. Here, we aimed to develop such a continuous gut fermentation model based on the PolyFermS platform, which allows controlled and stable long-term cultivation of colon microbiota in conditions akin the host. Nine immobilized Kenyan infant fecal microbiota were used as inoculum for continuous PolyFermS colon models fed with medium mimicking the weaning infant diet. Fructo-oligosaccharides (FOS) supplementation (1, 4 and 8 g/L) and cultivation pH (5.8 and 6.3) were investigated stepwise. Conditions providing a close match between fecal and in vitro microbiota (pH 5.8 with 1 g/L FOS) were selected for investigating long-term stability of four Kenyan infant PolyFermS microbiota. The shared fraction of top bacterial genera between fecal and in vitro microbiota was high (74-89%) and stable during 107 days of continuous cultivation. Community diversity was maintained and two distinct fermentation metabolite profiles of infant fecal microbiota were observed. Three propiogenic and one butyrogenic metabolite profile of infant fecal microbiota established from day 8 onwards and stayed stable. We present here the first rationally designed continuous cultivation model of African infant gut microbiota. This model will be important to assess the effect of dietary or environmental factors on the gut microbiota of African infants with high enteropathogen exposure.

Effects of Different Galacto-Oligosaccharide Supplementation on Growth Performance, Immune Function, Serum Nutrients, and Appetite-Related Hormones in Holstein Calves

Our previous study showed that early supplementation with 10 g/(d·head) of galacto-oligosaccharides (GOS) in newborn Holstein dairy calves reduced the incidence of diarrhea and improved growth performance and mineral absorption. Since the dose of 10 g/(d·head) was the lowest by dose screening in our previous study, the present study was designed to investigate whether a lower amount of GOS has similar effects on growth performance, immune function, serum nutrients in newborn Holstein heifer calves, and to further investigate its effect on appetite-related hormones. Twenty-eight healthy newborn (1 day of age) Holstein heifers with similar average body weight (41.18 ± 1.90 kg) were randomly divided into four groups (n = 7): the control group (CON group), which received heated raw milk, and three experimental groups, which received heated raw milk supplemented with 2.5 (GOS2.5 group), 5 (GOS5 group), and 10 g/(d·head) (GOS10 group) GOS. All heifer calves were fed the same starter for 28 d. Supplementation with GOS linearly increased the final body weight, average daily gain, and feed efficiency in heifer calves (p < 0.01). Compared with the control group, the average daily gain and feed efficiency of heifer calves were significantly higher in the GOS5 and GOS10 groups than in the control group (p < 0.05). Furthermore, supplementation with GOS quadratically enhanced the starter and total average daily feed intake of the heifers (p < 0.01), especially in the GOS2.5 and GOS5 groups, (p < 0.05 vs. CON). The serum concentration of immunoglobulin A was linearly increased by GOS supplementation (p < 0.05), and the levels in the GOS5 and GOS10 groups were significantly higher than those in the CON group. Meanwhile, GOS linearly decreased serum interleukin-1β and interleukin-6 concentrations (p < 0.05). The serum concentration of triglycerides was also linearly decreased (p < 0.05), whereas total protein and blood urea nitrogen were linearly increased (p < 0.05). Supplementation with GOS linearly decreased the serum concentration of leptin (p < 0.05) but increased cholecystokinin and glucagon-like peptide-1 (p < 0.05). Increasing doses of GOS linearly improved serum calcium and copper concentrations (p < 0.01) and quadratically enhanced the concentration of magnesium, which peaked in the GOS5 group (p < 0.05). In conclusion, GOS supplementation reduced the incidence of diarrhea and improved the growth performance and immune function of Holstein heifer calves.

Biofortified Yellow-Fleshed Potatoes Provide More Absorbable Zinc than a Commonly Consumed Variety: A Randomized Trial Using Stable Isotopes in Women in the Peruvian Highlands

BACKGROUND

Zinc-biofortified potatoes have considerable potential to reduce zinc deficiency because of their low levels of phytate, an inhibitor of zinc absorption, and their high consumption, especially in the Andean region of Peru.

OBJECTIVES

The purpose of this study was to measure fractional and total zinc absorption from a test meal of biofortified compared with regular potatoes.

METHODS

We undertook a single-blinded randomized crossover study (using 67Zn and 70Zn stable isotopes) in which 37 women consumed 500-g biofortified or regular potatoes twice a day. Urine samples were collected to determine fractional and total zinc absorption.

RESULTS

The zinc content of the biofortified potato and regular potato was 0.48 (standard deviation [SD]: 0.02) and 0.32 (SD: 0.03) mg/100 g fresh weight, respectively. Mean fractional zinc absorption (FZA) from the biofortified potatoes was lower than from the regular potatoes, 20.8% (SD: 5.4%) and 25.5% (SD: 7.0%), respectively (P < 0.01). However, total zinc absorbed was significantly higher (0.49; SD: 0.13 and 0.40; SD: 0.11 mg/500 g, P < 0.01, respectively).

CONCLUSIONS

The results of this study demonstrate that biofortified potatoes provide more absorbable zinc than regular potatoes. Zinc-biofortified potatoes could contribute toward reducing zinc deficiency in populations where potatoes are a staple food. This trial was registered at clinicaltrials.gov as NCT05154500.

Long-term continuous cultivation of Kenyan infant fecal microbiota using the host adapted PolyFermS model

Appropriate in vitro models to investigate the impact of novel nutritional strategies on the gut microbiota of infants living in rural Africa are scarce. Here, we aimed to develop such a continuous gut fermentation model based on the PolyFermS platform. Eight immobilized Kenyan infant fecal microbiota were used as inoculum for continuous PolyFermS colon models fed with medium mimicking the weaning infant diet. Fructo-oligosaccharides (FOS) supplementation (1, 4 and 8 g/L) and cultivation pH (5.8 and 6.3) were stepwise investigated. Conditions providing a close match between fecal and in vitro microbiota (pH 5.8 with 1 g/L FOS) were selected for investigating long-term stability of four Kenyan infant PolyFermS microbiota. The shared fraction of top bacterial genera between fecal and in vitro microbiota was high (74-89%) and stable during 107 days of continuous cultivation. Community diversity was maintained, and two distinct fermentation metabolite profiles, propiogenic and butyrogenic, of infant fecal microbiota established from day 8 onwards and stayed stable. We present here the first rationally designed and accurate continuous cultivation model of African infant gut microbiota. This model will be important to assess the effect of dietary or environmental factors on the gut microbiota of African infants with high enteropathogen exposure.

Validation of a batch cultivation protocol for fecal microbiota of Kenyan infants

BACKGROUND

The combination of cultivation studies with molecular analysis approaches allows characterization of the complex human gut microbiota in depth. In vitro cultivation studies of infants living in rural sub-Saharan Africa are scarce. In this study, a batch cultivation protocol for Kenyan infant fecal microbiota was validated.

METHODS

Fresh fecal samples were collected from 10 infants living in a rural area of Kenya. Samples were transported under protective conditions and subsequently prepared for inoculation within less than 30 h for batch cultivation. A diet-adapted cultivation medium was used that mimicked the daily intake of human milk and maize porridge in Kenyan infants during weaning. 16 S rRNA gene amplicon sequencing and HPLC analyses were performed to assess the composition and metabolic activity, respectively, of the fecal microbiota after 24 h of batch cultivation.

RESULTS

High abundance of Bifidobacterium (53.4 ± 11.1%) and high proportions of acetate (56 ± 11% of total metabolites) and lactate (24 ± 22% of total metabolites) were detected in the Kenyan infant fecal microbiota. After cultivation started at an initial pH 7.6, the fraction of top bacterial genera (≥ 1% abundant) shared between fermentation and fecal samples was high at 97 ± 5%. However, Escherichia-Shigella, Clostridium sensu stricto 1, Bacteroides and Enterococcus were enriched concomitant with decreased Bifidobacterium abundance. Decreasing the initial pH to 6.9 lead to higher abundance of Bifidobacterium after incubation and increased the compositional similarity of fermentation and fecal samples. Despite similar total metabolite production of all fecal microbiota after cultivation, inter-individual differences in metabolite profiles were apparent.

CONCLUSIONS

Protected transport and batch cultivation in host and diet adapted conditions allowed regrowth of the top abundant genera and reproduction of the metabolic activity of fresh Kenyan infant fecal microbiota. The validated batch cultivation protocol can be used to study the composition and functional potential of Kenyan infant fecal microbiota in vitro.

Total iron absorbed from iron-biofortified potatoes is higher than from non-biofortified potatoes: a randomized trial using stable iron isotopes in women from the Peruvian highlands

BACKGROUND

Yellow fleshed potatoes biofortified with iron have been developed through conventional breeding but the bioavailability of the iron is unknown.

OBJECTIVES

Our objective was to measure iron absorption from an iron-biofortified yellow fleshed potato clone in comparison with a non-biofortified yellow fleshed potato variety.

METHODS

We conducted a single-blinded, randomized, crossover, multiple-meal intervention study. Women (n = 28; mean±SD plasma ferritin 21.3±3.3 μg/L) consumed 10 meals (460 g) of both potatoes, each meal extrinsically labelled with either ⁵⁸Fe sulfate (biofortified) or ⁵⁷Fe sulfate (non-fortified) , on consecutive days. Iron absorption was estimated from the iron isotopic composition in erythrocytes 14 days after administration of the final meal.

RESULTS

Mean±SD iron, phytic acid and ascorbic acid concentrations in the the iron-biofortified and the non-fortified potato meals (mg/per 100 mg) were 0.63±0.01 and 0.31±0.01 , 39.34±3.04 and 3.10±1.72 , and 7.65±0.34 and 3.74±0.39 , respectively (P < 0.01) while chlorogenic acid concentrations were 15.14±1.72 and 22.52±3.98 , respectively (P <0.05). Geometric mean (95% CI) fractional iron absorption (FIA) from the iron-biofortified clone and the non-biofortified variety was 12.1% (10.3-14.2%) and 16.6% (14.0-19.6%), respectively (P <0.001). Total iron absorption (TIA) from the iron-biofortified clone and the non-biofortified variety was 0.35 mg (0.30-0.41mg) and 0.24 mg (0.20-0.28 mg) per 460 g meal, respectively (P <0.001).

CONCLUSIONS

TIA from the iron-biofortified potato meals was 45.8% higher than from the non-biofortified potato meals, suggesting iron biofortification of potatoes through conventional breeding is a promising approach to improve iron intakes in iron-deficient women (p<0.01). The study was registered at www.

CLINICALTRIALS

gov (Identifier number NCT05154500).

The effects of 2'-fucosyllactose and lacto-N-neotetraose, galacto-oligosaccharides, and maternal human milk oligosaccharide profile on iron absorption in Kenyan infants

BACKGROUND

Whether prebiotic human milk oligosaccharides (HMO), such as 2'-fucosyllactose (2'-FL) and lacto-N-neotetraose (LNnT), enhance iron absorption in infants is unknown. Moreover, whether maternal HMO profile affects absorption of iron fortificants or the effects of prebiotic galacto-oligosaccharides (GOS) and/or HMO on iron absorption is uncertain.

OBJECTIVES

The aim of this study was to test whether consumption of 3.0 g GOS or HMO enhances iron absorption from iron-fortified maize porridge in partially breastfed Kenyan infants and whether maternal HMO profile modulates these effects.

METHODS

In a randomized, prospective crossover study, 55 infants (aged 8-12 mo) were fed test meals fortified with 1 of the following: 1) 5.0 mg iron as ⁵⁴Fe-labeled ferrous fumarate (FeFum); 2) 5.0 mg iron as ⁵⁸FeFum and 3.0 g GOS (FeFum+GOS); and 3) 5.0 mg iron as ⁵⁷FeFum and 2.0 g 2'-FL and 1.0 g LNnT (FeFum+HMO). Fractional iron absorption (FIA) was assessed by erythrocyte incorporation of iron isotopes. HMO profiles were determined by capillary gel electrophoresis with laser-induced florescence detection. Data were analyzed with mixed-effect models, and iron dialyzability was measured in vitro.

RESULTS

Of the 55 infants included, 49 were fed as instructed. FIA from the FeFum+GOS group [median (IQR) 22.2% (16.5%-25.9%)] was higher than that from the FeFum group [12.5% (9.5%-20.9%)] (P = 0.005). FIA from the FeFum+HMO group was 13.3% (7.1%-24.4%) and did not differ from the FeFum group (P = 0.923). Maternal HMO profile did not predict FIA or modulate the effects of GOS or HMO on FIA. Iron dialyzability ratios at pH 2 of FeFum+GOS to FeFum and FeFum+HMO to FeFum were 2.1 and 0.9 (P = 0.001 and P = 0.322), respectively.

CONCLUSIONS

In Kenyan infants consuming FeFum-fortified maize porridge, co-provision of 3.0 g GOS increased FIA by 78%, whereas co-provision of 3.0 g HMO did not affect FIA. Variations in maternal HMO profile, including secretor and Lewis phenotype, did not predict FIA. These data argue against a physiologic role for 2'-FL and LNnT in facilitating iron absorption in infancy. The study was registered at clinicaltrials.gov as NCT04163406 (https://clinicaltrials.gov/ct2/show/NCT04163406).

The Effect of Prebiotics on Human Iron Absorption: A Review

Iron deficiency remains the most common nutritional deficiency. Oral iron supplementation is the recommended first-line treatment and used as a preventive measure as well. Enhancers of iron absorption are highly sought after to improve supplementation outcomes. Evidence from animal and human studies exists that prebiotics can enhance iron absorption. The purpose of this present narrative review of the literature is to summarize the existing evidence on the effects of prebiotics on human iron absorption. Relevant articles were identified from PUBMED, Scopus, and Web of Science from inception to November 2021. Only human trials investigating the effect of prebiotics on iron absorption were included. Eleven articles were identified and included for review. There are promising findings supporting an enhancing effect of certain prebiotics, but inconsistencies between the studies and results exist. The most convincing evidence exists for the prebiotics galacto-oligosaccharides and fructo-oligosaccharides combined with the commonly used iron compound ferrous fumarate, from studies in adult women with low iron stores and in anemic infants. Many factors seem to play a role in the enhancing effect of prebiotics on iron absorption such as type of prebiotic, dose, acute (single-dose) or chronic (long-term) prebiotic consumption, iron compound, iron status, inflammatory status, and age of the population studied. More research investigating the optimal combination of prebiotic, iron compound, and dose as well as the effect of long-term application on iron status outcomes is needed.

The prebiotic effects of soluble dietary fiber mixture on renal anemia and the gut microbiota in end-stage renal disease patients on maintenance hemodialysis: a prospective, randomized, placebo-controlled study

BACKGROUND

Renal anemia is caused by end-stage renal disease (ESRD) but has a complex etiology. The application of dietary fiber (DF) to regulate the gut microbiota has shown effective therapeutic effects in some diseases, but its role in renal anemia is not clear. The aim of this study was to explore the effect of DF on renal anemia by regulating the gut microbiota and its metabolite, short-chain fatty acids (SCFAs).

METHODS

A total of 162 ESRD patients were enrolled and randomly distributed into a DF or a control group (received oral DF or potato starch, 10 g/day for 8 weeks). Hemoglobin (Hb), serum iron (Fe²⁺), serum ferritin (SF), soluble transferrin receptor (sTfR), hepcidin and the dosage of recombinant human erythropoietin (rhEPO) before and after intervention in patients were analyzed. The gut microbiota and SCFAs in both groups were analyzed by 16S rDNA sequencing and gas chromatography-mass spectrometry, respectively. Spearman's correlation test was used to analyze the correlation between the gut microbiota, SCFAs and the hematological indicators.

RESULTS

Compared with the control group, (1) the patients in the DF group had higher Hb [117.0 (12.5) g/L vs. 94.0 (14.5) g/L, p < 0.001], Fe²⁺ [13.23 (4.83) μmol/L vs. 10.26 (5.55) μmol/L, p < 0.001], and SF levels [54.15 (86.66) ng/ml vs. 41.48 (36.60) ng/ml, p = 0.003]. (2) The rhEPO dosage in the DF group was not significantly decreased (p = 0.12). (3) Bifidobacterium adolescentis, Lactobacillus and Lactobacillaceae were increased in the DF group, and Lactobacillus and Lactobacillaceae were positively correlated with Hb (r = 0.44, p < 0.001; r = 0.44, p < 0.001) and Fe²⁺ levels (r = 0.26, p = 0.016; r = 0.26, p = 0.016) and negatively correlated with rhEPO dosage (r = - 0.45, p < 0.001; r = - 0.45, p < 0.001). (4) Patients in the DF group had elevated serum butyric acid (BA) levels [0.80 (1.65) vs. 0.05 (0.04), p < 0.001] and BA levels were positively correlated with Hb (r = 0.26, p = 0.019) and Fe²⁺ (r = 0.31, p = 0.005) and negatively correlated with rhEPO dosage (r = - 0.36, p = 0.001). Lactobacillus and Lactobacillaceae were positively correlated with BA levels (r = 0.78, p < 0.001; r = 0.78, p < 0.001).

CONCLUSION

DF may improve renal anemia in ESRD patients by regulating the gut microbiota and SCFAs. Trial registration This study was registered in the China Clinical Trial Registry ( www.chictr.org.cn ) on December 20, 2018 ( ChiCTR1800020232 ).

Fecal Iron Measurement in Studies of the Human Intestinal Microbiome

Iron is an essential micronutrient for humans and their intestinal microbiota. Host intestinal cells and iron-dependent bacteria compete for intraluminal iron, so the composition and functions of the gut microbiota may influence iron availability. Studies of the effects of the microbiota or probiotic interventions on host iron absorption may be particularly relevant to settings with high burdens of iron deficiency and gastrointestinal infections, since inflammation reduces iron bioavailability and unabsorbed intraluminal iron may modify the composition of the microbiota. The quantification of stool iron content may serve as an indicator of the amount of intraluminal iron to which the intestinal microbiota is exposed, which is particularly relevant for studies of the effect of iron on the intestinal microbiome, where fecal samples collected for purposes of microbiome characterization can be leveraged for stool iron analysis. However, few studies are available to guide researchers in the selection and implementation of stool iron assays, particularly because cross-comparison of available methods is limited in literature. This review aims to describe the available stool iron quantification methods and highlight their potential application in studies of iron-microbiome relationships, with a focus on pediatric research. MS-based methods offer high sensitivity and precision, but the need for expensive equipment and the high per-sample and maintenance costs may limit their widespread use. Conversely, colorimetric assays offer lower cost, ease of use, and rapid turnaround times but have thus far been optimized primarily for blood-derived matrices rather than stool. Further research efforts are needed to validate and standardize methods for stool iron assessment and to determine if the incorporation of such analyses in human microbiome studies 1) yields insights into the interactions between intestinal microbiota and iron and 2) contributes to the development of interventions that mitigate iron deficiency and promote a healthy microbiome.

Prebiotics, Probiotics, and Postbiotics in the Prevention and Treatment of Anemia

Iron deficiency anemia (IDA) is very common and affects approximately 1/3 of the world’s human population. There are strong research data that some probiotics, such as Lactobacillus acidophilus and Bifidobacterium longum improve iron absorption and influence the course of anemia. Furthermore, prebiotics, including galactooligosaccharides (GOS) and fructooligosaccharides (FOS), increase iron bioavailability and decrease its destructive effect on the intestinal microbiota. In addition, multiple postbiotics, which are probiotic metabolites, including vitamins, short-chain fatty acids (SCFA), and tryptophan, are involved in the regulation of intestinal absorption and may influence iron status in humans. This review presents the actual data from research studies on the influence of probiotics, prebiotics, and postbiotics on the prevention and therapy of IDA and the latest findings regarding their mechanisms of action. A comparison of the latest research data and theories regarding the role of pre-, post-, and probiotics and the mechanism of their action in anemias is also presented and discussed.

Ensuring the Efficacious Iron Fortification of Foods: A Tale of Two Barriers

Iron fortification of foods has always been a challenge. This is because iron fortification compounds vary widely in relative absorption; because many foods undergo unacceptable changes in color or flavor from the addition of iron; and because many of the iron-fortified foods contain potent inhibitors of iron absorption. These technical barriers have largely been overcome, and efficacious iron-fortified foods, that maintain or improve the iron status of women or children in long-term feeding studies, can be designed. Commercially fortified infant foods are efficacious, and other commercial iron-fortified foods targeted at women and children will provide a useful amount of iron provided the fortification level is adjusted according to the relative absorption of the iron compound. Technologies for the large-scale fortification of wheat and maize flour are also well established, and iron fortification of rice, using the recently developed extruded premix technique, is showing great promise. However, some important knowledge gaps still remain, and further research and development is needed in relation to iron (and iodine)-fortified salt and iron-fortified liquid milk. The usefulness of less-soluble iron compounds, such as ferrous fumarate, to fortify foods for infants and young children in low- and middle-income countries (LMICs) also needs further investigation. A more formidable barrier to efficacious iron-fortified food has been reported in recent years. This is the infection-initiated inflammation barrier, which inhibits iron absorption in response to infection. This barrier is particularly important in LMICs where infections such as malaria and HIV are widespread, and gastrointestinal infections are common due to poor quality water supplies and sanitation. Another source of inflammation in such countries is the high prevalence of obesity in women. Most countries in sub-Saharan Africa have high inflammation which not only decreases the efficacy of iron-fortified and iron-biofortified foods but complicates the monitoring of large-scale iron fortification programs. This is because iron deficiency anemia cannot be differentiated from the more prominent anemia of inflammation and because inflammation confounds the measurement of iron status. There is an urgent need to better quantify the impact of inflammation on the efficacy of iron-fortified foods. However, at present, in LMICs with high inflammation exposure, infection control, cleaner water, improved sanitation, and a decrease in obesity prevalence will undoubtedly have a greater impact on iron status and anemia than the iron fortification of foods.

Effects of dietary fiber on intestinal iron absorption, and physiological status: a systematic review of in vivo and clinical studies

The benefits of dietary fiber on intestinal health have been well established. However, there is no consensus on the dietary fiber effects on mineral absorption. The objective of this systematic review is to discuss the evidence on the dietary fiber effects on iron absorption and iron status-related biomarkers. A comprehensive search of 3 databases: PubMed, Scopus and Web of Science was carried out. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, and a total of 32 studies were included with 9 of them clinical studies and 23 in vivo. The studies included assessment of dietary fiber in the form of fructo-oligosaccharides, galacto-oligosaccharides, inulin, pectin, guar gum, oligofructose, xylo-oligosaccharides, and mannan-oligosaccharide. Hemoglobin (n = 21) and fractional iron absorption (n = 6) were the most frequently reported outcomes. The results showed no significant correlations between consumption of dietary fiber to iron absorption/status-related biomarkers. However, the current evidence may not be substantial to invalidate the recommendation of dietary fiber as an agent to improve dietary iron bioavailability, and absorption. In conclusion, there is a need to conduct further clinical trials with long dietary fiber intervention focusing on population at high risk for iron deficiency.

Modulation of the Epithelial-Immune Cell Crosstalk and Related Galectin Secretion by DP3-5 Galacto-Oligosaccharides and β-3′Galactosyllactose

Prebiotic galacto-oligosaccharides (GOS) were shown to support mucosal immune development by enhancing regulatory-type Th1 immune polarization induced by synthetic CpG oligodeoxynucleotides (TLR9 agonist mimicking a bacterial DNA trigger). Epithelial-derived galectin-9 was associated with these immunomodulatory effects. We aimed to identify the most active fractions within GOS based on the degree of polymerization (DP), and to study the immunomodulatory capacities of DP3-sized β-3′galactosyllactose (β-3′GL) using a transwell co-culture model of human intestinal epithelial cells (IEC) and activated peripheral blood mononuclear cells (PBMC). IEC were apically exposed to different DP fractions of GOS or β-3′GL in the presence of CpG, and basolaterally co-cultured with αCD3/CD28-activated PBMC, washed, and incubated in fresh medium for IEC-derived galectin analysis. Only DP3-5 in the presence of CpG enhanced galectin-9 secretion. DP3-sized β-3′GL promoted a regulatory-type Th1 response by increasing IFNγ and IL-10 or galectin-9 concentrations as compared to CpG alone. In addition, IEC-derived galectin-3, -4, and -9 secretion was increased by β-3′GL when combined with CpG. Therefore, the GOS DP3-5 and most effectively DP3-sized β-3′GL supported the immunomodulatory properties induced by CpG by enhancing epithelial-derived galectin secretion, which, in turn, could support mucosal immunity.

Comparative Effects between Oral Lactoferrin and Ferrous Sulfate Supplementation on Iron-Deficiency Anemia: A Comprehensive Review and Meta-Analysis of Clinical Trials

Ferrous sulfate is a commonly used iron supplement for the correction of iron-deficiency anemia but with frequent gastrointestinal side effects. Milk-derived iron-binding glycoprotein lactoferrin possesses well gastrointestinal tolerance and fewer side effects caused by the intake of high-dose iron. However, the underlying mechanism of the iron-enhancing effect of lactoferrin remains unclear. In addition, the comparative efficacies between lactoferrin and ferrous sulfate are also remained to be determined. We conducted a systematic review and meta-analysis on published intervention studies to investigate how lactoferrin modulate iron metabolism and evaluate the comparative effects between lactoferrin and ferrous sulfate supplementation on iron absorption, iron storage, erythropoiesis and inflammation. Lactoferrin supplementation had better effects on serum iron (WMD: 41.44 ug/dL; p < 0.00001), ferritin (WMD: 13.60 ng/mL; p = 0.003) and hemoglobin concentration (11.80 g/dL; p < 0.00001), but a reducing effect on fractional iron absorption (WMD: −2.08%; p = 0.02) and IL-6 levels (WMD: −45.59 pg/mL; p < 0.00001) compared with ferrous sulfate. In conclusion, this study supports lactoferrin as a superior supplement to ferrous sulfate regarding the improvement in serum iron parameters and hemoglobin levels. Considering the weak influence of lactoferrin on iron absorption, the anti-inflammation effect of lactoferrin may be the potential mechanism to explain its efficacy on iron status and erythropoiesis.

The effect of oral iron supplementation on the gut microbiota, gut inflammation, and iron status in iron-depleted South African school-age children with virally suppressed HIV and without HIV

PURPOSE

Both HIV and oral iron interventions may alter gut microbiota composition and increase gut inflammation. We determined the effect of oral iron supplementation on gut microbiota composition, gut inflammation, and iron status in iron-depleted South Africa school-aged children living with HIV (HIV+) but virally suppressed on antiretroviral therapy and children without HIV (HIV-ve).

METHODS

In this before-after intervention study with case-control comparisons, we provided 55 mg elemental iron from ferrous sulphate, once daily for 3 months, to 33 virally suppressed (< 50 HIV RNA copies/mL) HIV+ and 31 HIV-ve children. At baseline and endpoint, we assessed microbial composition of faecal samples (16S rRNA sequencing), and markers of gut inflammation (faecal calprotectin), anaemia (haemoglobin) and iron status (plasma ferritin, soluble transferrin receptor). This study was nested within a larger trial registered at clinicaltrials.gov as NCT03572010.

RESULTS

HIV+ (11.3y SD ± 1.8, 46% male) and HIV-ve (11.1y SD ± 1.7, 52% male) groups did not significantly differ in age or sex ratio. Following iron supplementation, improvements were observed in haemoglobin (HIV+ : 118 to 124 g/L, P = 0.003; HIV-ve: 120 to 124 g/L, P = 0.003), plasma ferritin (HIV+ : 15 to 34 µg/L, P < 0.001; HIV-ve: 18 to 37 µg/L, P < 0.001), and soluble transferrin receptor (HIV+ : 7.1 to 5.9 mg/L, P < 0.001; HIV-ve: 6.6 to 5.7 mg/L, P < 0.001), with no significant change in the relative abundance of any genera, alpha diversity of the gut microbiota (HIV+ : P = 0.37; HIV-ve: P = 0.77), or faecal calprotectin (HIV+ : P = 0.42; HIV-ve: P = 0.80).

CONCLUSION

Our findings suggest that oral iron supplementation can significantly improve haemoglobin and iron status without increasing pathogenic gut microbial taxa or gut inflammation in iron-depleted virally suppressed HIV+ and HIV-ve school-age children.

Prebiotic Galacto-oligosaccharides and Fructo-oligosaccharides, but not Acacia Gum, Increase Iron Absorption from a Single High-dose Ferrous Fumarate Supplement in Iron-depleted Women

BACKGROUND

Prebiotic galacto-oligosaccharides (GOS) increase iron absorption from fortification-level iron doses given as ferrous fumarate (FeFum) in women and children. Whether GOS or other fibers, such as prebiotic fructo-oligosaccharides (FOS) and acacia gum, increase iron absorption from higher supplemental doses of FeFum is unclear.

OBJECTIVES

In iron-depleted [serum ferritin (SF)< 25μg/L] women,  we tested if oral co-administration of 15g of GOS, FOS or acacia gum increases iron absorption from a 100mg iron supplement given as FeFum.

METHODS

In a randomized, single-blind cross-over study, 30 women (median age 26.2 years, median SF 12.9μg/L) consumed a 100mg iron tablet labelled with 4mg of 57Fe or 58Fe, given with either: a) 15g GOS; b) 15g FOS; c) 15g acacia gum; or d) 6.1g lactose and 1.5g sucrose (control; matching the amounts of sucrose and lactose present in the GOS powder providing 15 g GOS), dissolved in water. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte isotopic incorporation 14 days after administration. Data were analysed using a linear mixed-effect model. We also tested, in vitro, iron solubility at different pH and dialyzability from the different supplement combinations administered in vivo.

RESULTS

FIA from FeFum given with GOS and FOS was significantly higher (+45% and 51%, respectively; P < 0.001 for both) compared with control; total iron absorption [median (IQR)] was 34.6 (28.4; 49.1); 36.1 (29.0; 46.2) and 23.9 (20.5; 34.0) mg, respectively. Acacia gum did not significantly affect FIA from FeFum (P = 0.688). In vitro, iron dialyzability of FeFum + GOS was 46% higher than of FeFum alone (P = 0.003).

CONCLUSIONS

In iron-depleted women, both GOS and FOS co-administration with FeFum increase iron absorption by ∼50% from a 100mg oral iron dose, resulting in an additional 10-12mg of absorbed iron. Thus, GOS and FOS may be promising new enhancers of supplemental iron absorption.The study was registered at clinicaltrials.gov as NCT04194255 (https://clinicaltrials.gov/ct2/show/NCT04194255).

Iron Bioavailability from Infant Cereals Containing Whole Grains and Pulses: A Stable Isotope Study in Malawian Children

BACKGROUND

Compared with infant cereals based on refined grains, an infant cereal containing whole grains (WGs) and pulses with adequate amounts of ascorbic acid to protect against absorption inhibitors could be a healthier source of well-absorbed iron. However, iron absorption from such cereals is uncertain.

OBJECTIVE

We measured iron bioavailability from ferrous fumarate (Fefum) added to commercial infant cereals containing 1) refined wheat flour (reference meal), 2) WG wheat and lentil flour (WG-wheat-lentil), 3) WG wheat and chickpea flour (WG-wheat-chickpeas), and 4) WG oat flour (WG-oat) and from ferrous bisglycinate (FeBG) added to the same oat-based cereal (WG-oat-FeBG).

METHODS

In a prospective, single-blinded randomized crossover study, 6- to 14-mo-old Malawian children (n = 30) consumed 25-g servings of all 5 test meals containing 2.25 mg stable isotope-labeled iron and 13.5 mg ascorbic acid. Fractional iron absorption (FIA) was assessed by erythrocyte incorporation of isotopes after 14 d. Comparisons were made using linear mixed models.

RESULTS

Seventy percent of the children were anemic and 67% were iron deficient. Geometric mean FIA percentages (-SD, +SD) from the cereals were as follows: 1) refined wheat, 12.1 (4.8, 30.6); 2) WG-wheat-lentil, 15.8 (6.6, 37.6); 3) WG-wheat-chickpeas, 12.8 (5.5, 29.8); and 4) WG-oat, 9.2 (3.9, 21.5) and 7.4 (2.9, 18.9) from WG-oat-FeBG. Meal predicted FIA (P ≤ 0.001), whereas in pairwise comparisons, only WG-oat-FeBG was significantly different compared with the refined wheat meal (P = 0.02). In addition, FIAs from WG-wheat-lentil and WG-wheat-chickpeas were significantly higher than from WG-oat (P = 0.002 and P = 0.04, respectively) and WG-oat-FeBG (P < 0.001 and P = 0.004, respectively).

CONCLUSION

In Malawian children, when given with ascorbic acid at a molar ratio of 2:1, iron bioavailability from Fefum-fortified infant cereals containing WG wheat and pulses is ≈13-15%, whereas that from FeBG- and Fefum-fortified infant cereals based on WG oats is ≈7-9%.

Distinct fermentation of human milk oligosaccharides 3-FL and LNT2 and GOS/inulin by infant gut microbiota and impact on adhesion of Lactobacillus plantarum WCFS1 to gut epithelial cells

Human milk oligosaccharides (hMOs) are unique bioactive components in human milk. 3-Fucosyllactose (3-FL) is an abundantly present hMO that can be produced in sufficient amounts to allow application in infant formula. Lacto-N-triaose II (LNT2) can be obtained by acid hydrolysis of lacto-N-neotetraose (LNnT). Both 3-FL and LNT2 have been shown to have health benefits, but their impact on infant microbiota composition and microbial metabolic products such as short-chain fatty acids (SCFAs) is unknown. To gain more insight in fermentability, we performed in vitro fermentation studies of 3-FL and LNT2 using pooled fecal microbiota from 12-week-old infants. The commonly investigated galacto-oligosaccharides (GOS)/inulin (9 : 1) served as control. Compared to GOS/inulin, we observed a delayed utilization of 3-FL, which was utilized at 60.3% after 36 h of fermentation, and induced the gradual production of acetic acid and lactic acid. 3-FL specifically enriched bacteria of Bacteroides and Enterococcus genus. LNT2 was fermented much faster. After 14 h of fermentation, 90.1% was already utilized, and production of acetic acid, succinic acid, lactic acid and butyric acid was observed. LNT2 specifically increased the abundance of Collinsella, as well as Bifidobacterium. The GOS present in the GOS/inulin mixture was completely fermented after 14 h, while for inulin, only low DP was rapidly utilized after 14 h. To determine whether the fermentation might lead to enhanced colonization of commensal bacteria to gut epithelial cells, we investigated adhesion of the commensal Lactobacillus plantarum WCFS1 to Caco-2 cells. The fermentation digesta of LNT2 collected after 14 h, 24 h, and 36 h, and GOS/inulin after 24 h of fermentation significantly increased the adhesion of L. plantarum WCFS1 to Caco-2 cells, while 3-FL had no such effect. Our findings illustrate that fermentation of hMOs is very structure-dependent and different from the commonly applied GOS/inulin, which might lead to differential potencies to stimulate adhesion of commensal cells to gut epithelium and consequent microbial colonization. This knowledge might contribute to the design of tailored infant formulas containing specific hMO molecules to meet the need of infants during the transition from breastfeeding to formula.

Kinetics of iron absorption from ferrous fumarate with and without galacto-oligosaccharides determined from stable isotope appearance curves in women

BACKGROUND

Prebiotic galacto-oligosaccharides (GOS) are novel enhancers of iron absorption from ferrous fumarate (FeFum). However, the mechanism(s) of this effect, and whether it occurs in the proximal or distal gut, are uncertain.

OBJECTIVES

We studied: 1) in vitro, the effect of GOS on iron solubility and dialyzability from FeFum; 2) in volunteers, the absorption kinetics of FeFum given with and without GOS using stable isotope appearance curves (SIAC).

METHODS

We measured iron solubility at various pH and dialyzability from FeFum with and without GOS. In crossover design, iron-depleted women [n = 11; median serum ferritin (SF) 15.2; IQR: 12.6-21.2 µg/L] received 2 14-mg iron doses as labeled (57Fe,58Fe) FeFum 14 d apart with and without 15 g GOS in randomly assigned order. Multiple blood samples were collected over a time period of 24 h and 14 d later to determine SIAC and fractional iron absorption (FIA), respectively. SIAC data were fitted using nonlinear mixed effects modeling to a 1-compartment model with first-order absorption, and AUC and time of peak serum isotope concentration (tmax) were calculated.

RESULTS

Iron dialyzability was 75% higher with GOS (P < 0.001) and iron solubility was more than doubled at pH 4 and 6 with GOS [both P < 0.001]. Mean ± SD AUC (5830.9 ± 4717.3 μg/min with GOS, 4454.0 ± 3260.7 μg/min for control), and median (IQR) FIA (20.3% (8.6%-38.7%) with GOS, and 15.6% (10.6%-24.8% f)or control) were not different with compared to without GOS (P = 0.064; P = 0.080). Mean ±SD tmax was not altered with GOS (3.08 ± 0.47 h with GOS; 2.80 ±0.50 h for control; P = 0.096). Iron bioavailability significantly increased with decreasing SF and this effect was significantly enhanced by GOS (P = 0.037, interaction of GOS with SF).

CONCLUSIONS

GOS increases iron solubility from FeFum at physiological pH characteristic of the proximal duodenum. The absorption kinetics in vivo are consistent with effects on iron absorption in the proximal, rather than distal, parts of the gut. There was no overall effect of GOS on FIA in vivo, but the interaction of GOS and SF on FIA might benefit iron-deficient women, an effect potentially mediated by the higher solubility shown in vitro. This study was registered at clinicaltrials.gov as NCT03996421.

Galacto-oligosaccharides as infant prebiotics: production, application, bioactive activities and future perspectives

Galacto-oligosaccharides (GOS) are non-digestible oligosaccharides characterized by a mix of structures that vary in their degree of polymerization (DP) and glycosidic linkage between the galactose moieties or between galactose and glucose. They have enjoyed extensive scientific scrutiny, and their health-promoting effects are supported by a large number of scientific and clinical studies. A variety of GOS-associated health-promoting effects have been reported, such as growth promotion of beneficial bacteria, in particular bifidobacteria and lactobacilli, inhibition of pathogen adhesion and improvement of gut barrier function. GOS have attracted significant interest from food industries for their versatility as a bioactive ingredient and in particular as a functional component of infant formulations. These oligosaccharides are produced in a kinetically-controlled reaction involving lactose transgalactosylation, being catalyzed by particular β-galactosidases of bacterial or fungal origin. Despite the well-established technology applied for GOS production, this process may still meet with technological challenges when employed at an industrial scale. The current review will cover relevant scientific literature on the beneficial physiological properties of GOS as a prebiotic for the infant gut microbiota, details of GOS structures, the associated reaction mechanism of β-galactosidase, and its (large-scale) production.

Tea Consumption Reduces Iron Bioavailability from NaFeEDTA in Nonanemic Women and Women with Iron Deficiency Anemia: Stable Iron Isotope Studies in Morocco

BACKGROUND

Available data suggest that polyphenols from tea can inhibit iron absorption from ferric sodium EDTA (NaFeEDTA), but previous studies were done in small groups of mostly nonanemic adults. Morocco recently introduced national wheat flour fortification with NaFeEDTA, but tea is the national beverage and is consumed with most meals.

OBJECTIVES

Our objective was to quantify bioavailability of iron from NaFeEDTA when added to a wheat flour-based meal in both nonanemic women and women with iron deficiency anemia (IDA), when consumed with and without traditional Moroccan green tea.

METHODS

We recruited 2 groups of healthy Moroccan women (n = 46): women with IDA (n = 25; hemoglobin <12 g/dL,  serum ferritin <15 μg/L) and nonanemic women (n = 21). Each group received in random order 2 standardized test meals containing 6 mg Fe as isotopically labeled NaFeEDTA and either 300 mL of tea or water. Fractional iron absorption (FIA) was measured by the erythrocyte incorporation of stable iron isotopes after 14 d. We performed linear mixed-model analysis and post hoc sample t tests to assess the effects of group and tea on FIA.

RESULTS

The polyphenol content of the tea serving was 492 mg. Tea consumption reduced iron absorption from NaFeEDTA by >85% in both IDA and nonanemic women. There were group (P < 0.001) and tea (P < 0.001) effects on FIA, but no group by tea interaction (P = 0.312). Median (IQR) FIA (%) in women with IDA from test meals consumed without and with tea was 36.7 (24.2-39.8) and 4.1 (2.8-6.1), respectively (P < 0.001). Median (IQR) FIA (%) in nonanemic women from test meals consumed without and with tea was 16.7 (9.2-24.2) and 1.4 (0.8-2.9), respectively (P < 0.001).

CONCLUSIONS

FIA from wheat flour-based meals without and with tea was ∼2-fold higher in women with IDA than in nonanemic women. Providing fortificant iron as NaFeEDTA cannot overcome the inhibition of tea polyphenols on iron absorption, even in IDA, where iron absorption is strongly upregulated. This trial was registered at www.clinicaltrials.gov as NCT02175888.

Impact of dietary fibers in infant formulas on gut microbiota and the intestinal immune barrier

Human milk (HM) is the gold standard for the nutrition of infants. An important component of HM is human milk oligosaccharides (hMOs), which play an important role in gut microbiota colonization and gut immune barrier establishment, and thereby contribute to the maturation of the immune system in early life. Guiding these processes is important as disturbances have life-long health effects and can lead to the development of allergic diseases. Unfortunately, not all infants can be exclusively fed with HM. These infants are routinely fed with infant formulas that contain hMO analogs and other non-digestible carbohydrates (NDCs) to mimic the effects of hMOs. Currently, the hMO analogs 2'-fucosyllactose (2'-FL), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), and pectins are added to infant formulas; however, these NDCs cannot mimic all hMO functions and therefore new NDCs and NDC mixtures need to become available for specific groups of neonates like preterm and disease-prone neonates. In this review, we discuss human data on the beneficial effects of infant formula supplements such as the specific hMO analog 2'-FL and NDCs as well as their mechanism of effects like stimulation of microbiota development, maturation of different parts of the gut immune barrier and anti-pathogenic effects. Insights into the structure-specific mechanisms by which hMOs and NDCs exert their beneficial functions might contribute to the development of new tailored NDCs and NDC mixtures. We also describe the needs for new in vitro systems that can be used for research on hMOs and NDCs. The current data suggest that "tailored infant formulas" for infants of different ages and healthy statuses are needed to ensure a healthy development of the microbiota and the gut immune system of infants.

Consumption of a Single Dose of Prebiotic Galacto-Oligosaccharides Does Not Enhance Iron Absorption from Micronutrient Powders in Kenyan Infants: A Stable Iron Isotope Study

BACKGROUND

Long-term feeding of prebiotic galacto-oligosaccharides (GOS) increases iron absorption in African infants, but the underlying mechanism and how long GOS need to be fed to infants to achieve an increase in absorption is uncertain.

OBJECTIVES

In Kenyan infants, we tested whether the addition of GOS to a single test meal would affect iron absorption from a micronutrient powder (MNP) containing ferrous sulfate (FeSO4) and another MNP containing ferrous fumarate (FeFum) and sodium iron ethylenediaminetetraacetate (NaFeEDTA).

METHODS

In a randomized-entry, prospective crossover study, iron deficient (87%) and anemic (70%) Kenyan infants (n  = 23; mean ± SD age, 9.9 ± 2.1 months) consumed 4 stable iron isotope-labeled maize porridge meals fortified with MNPs containing 5 mg iron as FeFum + NaFeEDTA, or FeSO4, either without or with 7.5 g GOS. The primary outcome, fractional iron absorption (FIA), was assessed by erythrocyte incorporation of isotopic labels. Data were analyzed using a 2-way repeated-measures ANOVA.

RESULTS

There was no significant interaction between GOS and the iron compounds on FIA, and the addition of GOS did not have a significant effect on FIA. There was a statistically significant difference in FIA between the meals fortified with FeSO4 and with FeFum + NaFeEDTA (P  < 0.001).Given with GOS, FIA from FeSO4 was 40% higher than from FeFum + NaFeEDTA (P  < 0.001); given without GOS, it was 51% higher (P  < 0.01).

CONCLUSIONS

The addition of GOS to a single iron-fortified maize porridge test meal in Kenyan infants did not significantly increase iron absorption, suggesting long-term feeding of GOS may be needed to enhance iron absorption at this age. This study was registered at clinicaltrials.gov as NCT02666417.

Synbiotic Supplementation Improves Response to Iron Supplementation in Female Athletes during Training

OBJECTIVE

Iron deficiency (ID) affects ∼30% of female athletes, and its consequences are highly relevant to athletic performance. Poor iron (Fe) uptake remains a major factor in the development of ID. While studies suggest that consumption of either prebiotics or probiotics may improve Fe uptake, consumption of synbiotics has not been well-studied. The main objective of this study was to determine the effects of synbiotic supplementation on the Fe status of female athletes during Fe repletion.

METHODS

The Fe status of 32 female athletes was screened early in the season. Twenty eligible athletes (hemoglobin:12.3 ± 0.9g/dL; serum ferritin, sFer:18.1 ± 9.2 µg/L) were randomized to receive either a daily synbiotic supplement (5 g prebiotic fiber + 8 billion colony forming units, CFU probiotic B. lactis) or placebo, along with Fe supplementation (140 mg ferrous sulfate, FeSO4/d) for 8 weeks using a double-blind design. Fe status was assessed again at mid-point and after the trial.

RESULTS

Nineteen athletes (n = 9 supplement, 10 placebo) completed the trial and there were no differences in compliance or GI symptoms reported between groups. After controlling for baseline Fe status, regression analyses revealed improvements in log sFer in the supplement group after both 4 and 8 weeks (p = 0.01 and p = 0.05, respectively), compared to placebo.

CONCLUSIONS

Synbiotic supplementation along with FeSO4 improved athletes' Fe status over 8 weeks. This data is essential to advancing our understanding of how dietary and supplemental Fe uptake in active women can be enhanced by synbiotic supplementation, as well as by foods containing pre- and probiotics.

Tostes M, Costa NM. The Potential Prebiotic Effects of Yacon (Smallanthus sonchifolius) in Colorectal Cancer

Background:

Colorectal cancer is caused by genetic predisposition and lifestyle risk factors and is associated with altered homeostasis of the intestinal microbiota. Evidence suggests that chronic infection and inflammation contribute to carcinogenic mutagenesis and promote cancer initiation and progression. Food components with prebiotic properties, such as fructooligosaccharides (FOS), promote intestinal integrity and health benefits. Yacon (Smallanthus sonchifolius) is an abundant source of FOS, which are fermented by beneficial bacteria, improving the intestinal environment affected by colorectal cancer.

Objective:

In the current review, the aim was to discuss colorectal cancer and its inflammatory process of development. Also, some general aspects concerning yacon roots and its prebiotic properties are described. Finely, the beneficial effects of yacon to reduce intestinal parameters altered due to colorectal cancer are summarized.

Conclusion:

It was verified that yacon might improve immunological parameters, intestinal barrier, intestinal microbiota, and inflammation in induced colorectal cancer in animals, especially. Researches with humans must be further investigated to prove these positive effects.

Iron

Iron deficiency anemia affects approximately one-third of the world's population, and about half the cases are due to iron deficiency. The latest research on iron metabolism published in original articles and systematic reviews is described, and references to recent reviews provided. The topics include dietary sources and bioavailability, iron homeostasis, functions of iron in the body, and biomarkers of status. The consequences of iron deficiency and excess are discussed, with particular focus on vulnerable populations such as pregnant women, infants and the elderly. The newest dietary recommendations, including dietary reference values and food based dietary guidelines, are briefly summarized, followed by the latest developments in food fortification and iron supplementation.

Iron Absorption from Iron-Biofortified Sweetpotato Is Higher Than Regular Sweetpotato in Malawian Women while Iron Absorption from Regular and Iron-Biofortified Potatoes Is High in Peruvian Women

BACKGROUND

Sweetpotato and potato are fast-maturing staple crops and widely consumed in low- and middle-income countries. Conventional breeding to biofortify these crops with iron could improve iron intakes. To our knowledge, iron absorption from sweetpotato and potato has not been assessed.

OBJECTIVE

The aim was to assess iron absorption from regular and iron-biofortified orange-fleshed sweetpotato in Malawi and yellow-fleshed potato and iron-biofortified purple-fleshed potato in Peru.

METHODS

We conducted 2 randomized, multiple-meal studies in generally healthy, iron-depleted women of reproductive age. Malawian women (n = 24) received 400 g regular or biofortified sweetpotato test meals and Peruvian women (n = 35) received 500 g regular or biofortified potato test meals. Women consumed the meals at breakfast for 2 wk and were then crossed over to the other variety. We labeled the test meals with 57Fe or 58Fe and measured cumulative erythrocyte incorporation of the labels 14 d after completion of each test-meal sequence to calculate iron absorption. Iron absorption was compared by paired-sample t tests.

RESULTS

The regular and biofortified orange-fleshed sweetpotato test meals contained 0.55 and 0.97 mg Fe/100 g. Geometric mean (95% CI) fractional iron absorption (FIA) was 5.82% (3.79%, 8.95%) and 6.02% (4.51%, 8.05%), respectively (P = 0.81), resulting in 1.9-fold higher total iron absorption (TIA) from biofortified sweetpotato (P < 0.001). The regular and biofortified potato test meals contained 0.33 and 0.69 mg Fe/100 g. FIA was 28.4% (23.5%, 34.2%) from the regular yellow-fleshed and 13.3% (10.6%, 16.6%) from the biofortified purple-fleshed potato meals, respectively (P < 0.001), resulting in no significant difference in TIA (P = 0.88).

CONCLUSIONS

FIA from regular yellow-fleshed potato was remarkably high, at 28%. Iron absorbed from both potato test meals covered 33% of the daily absorbed iron requirement for women of reproductive age, while the biofortified orange-fleshed sweetpotato test meal covered 18% of this requirement. High polyphenol concentrations were likely the major inhibitors of iron absorption. These trials were registered at www.clinicaltrials.gov as NCT03840031 (Malawi) and NCT04216030 (Peru).

The battle for iron in enteric infections

Iron is an essential element for almost all living organisms, but can be extremely toxic in high concentrations. All organisms must therefore employ homeostatic mechanisms to finely regulate iron uptake, usage and storage in the face of dynamic environmental conditions. The critical step in mammalian systemic iron homeostasis is the fine regulation of dietary iron absorption. However, as the gastrointestinal system is also home to >1014 bacteria, all of which engage in their own programmes of iron homeostasis, the gut represents an anatomical location where the inter-kingdom fight for iron is never-ending. Here, we explore the molecular mechanisms of, and interactions between, host and bacterial iron homeostasis in the gastrointestinal tract. We first detail how mammalian systemic and cellular iron homeostasis influences gastrointestinal iron availability. We then focus on two important human pathogens, Salmonella and Clostridia; despite their differences, they exemplify how a bacterial pathogen must navigate and exploit this web of iron homeostasis interactions to avoid host nutritional immunity and replicate successfully. We then reciprocally explore how iron availability interacts with the gastrointestinal microbiota, and the consequences of this on mammalian physiology and pathogen iron acquisition. Finally, we address how understanding the battle for iron in the gastrointestinal tract might inform clinical practice and inspire new treatments for important diseases.

The effect of iron dosing schedules on plasma hepcidin and iron absorption in Kenyan infants

BACKGROUND

In adults, oral iron doses increase plasma hepcidin (PHep) for 24 h, but not for 48 h, and there is a circadian increase in PHep over the day. Because high PHep decreases fractional iron absorption (FIA), alternate day iron dosing in the morning may be preferable to consecutive day dosing. Whether these effects occur in infants is uncertain.

OBJECTIVE

Using stable iron isotopes in Kenyan infants, we compared FIA from morning and afternoon doses and from consecutive, alternate (every second day) and every third day iron doses.

METHODS

In prospective studies, we measured and compared FIA and the PHep response from 1) meals fortified with a 12-mg iron micronutrient powder given in the morning or afternoon (n = 22); 2) the same given on consecutive or alternate days (n = 21); and 3) a 12-mg iron supplement given on alternate days or every third day (n = 24).

RESULTS

In total, 65.7% of infants were anemic. In study 1, PHep did not differ between morning and afternoon (P = 0.072), and geometric mean FIA[-SD, +SD](%) did not differ between the morning and afternoon doses [15.9 (8.9, 28.6) and 16.1 (8.7, 29.8), P = 0.877]. In study 2, PHep was increased 24 h after oral iron (P = 0.014), and mean FIA [±SD](%) from the baseline dose [23.3 (10.9)] was greater than that from the consecutive day dose (at 24 h) [20.1 (10.4); P = 0.042] but did not differ from the alternate day dose (at 48 h) [20.9 (13.4); P = 0.145]. In study 3, PHep was not increased 48 and 72 h after oral iron (P = 0.384), and the geometric mean FIA[-SD, +SD](%) from doses given at baseline, alternate days, and every third day did not differ [12.7 (7.3, 21.9), 13.8 (7.8, 24.2), and 14.8 (8.8, 24.8), respectively; P = 0.080].

CONCLUSIONS

In Kenyan infants given 12 mg oral iron, morning and afternoon doses are comparably absorbed, dosing on consecutive days increases PHep and modestly decreases iron absorption compared with alternate day dosing, and dosing on alternate days or every third day does not increase PHep or decrease absorption. This trial was registered at clinicaltrials.gov as NCT02989311 and NCT03617575.

Acute Consumption of Prebiotic Galacto-Oligosaccharides Increases Iron Absorption from Ferrous Fumarate, but not from Ferrous Sulfate and Ferric Pyrophosphate: Stable Iron Isotope Studies in Iron-Depleted Young Women

BACKGROUND

Although acute consumption of high doses of prebiotic galacto-oligosaccharides (GOS) increases fractional iron absorption (FIA) from ferrous fumarate (FeFum), it is uncertain if low doses of GOS have this effect. Furthermore, whether GOS improve iron absorption from other commonly used iron compounds and whether ascorbic acid (AA) enhances the effect of GOS on iron absorption from FeFum is unclear.

OBJECTIVES

In iron-depleted women [serum ferritin (SF) <30 μg/L], we assessed: 1) whether the acute enhancing effect of GOS on FeFum is dose dependent; 2) if GOS would affect FIA from ferrous sulfate (FeSO4) or ferric pyrophosphate (FePP); and 3) if AA and GOS given together enhance FIA from FeFum to a greater extent compared with GOS alone.

METHODS

We recruited 46 women (mean age 22.0 y, mean BMI 21.3 kg/m2, median SF 17.1 μg/L), and measured FIA from 14 mg iron labeled with stable isotopes in the following conditions: 1) FIA from FeFum given with 3.5 g, 7 g GOS, and without GOS; 2) FIA from FeSO4 and FePP given with and without 15 g GOS; and 3) FIA from FeFum given with 7 g GOS with and without 93 mg AA. FIA was measured as erythrocyte incorporation of stable isotopes after 14 d. Comparisons were made using paired samples t-test or Wilcoxon rank sum test where appropriate.

RESULTS

Giving 7 g of GOS significantly increased FIA from FeFum (+26%; P = 0.039), whereas 3.5 g GOS did not (P = 0.130). GOS did not significantly increase FIA from FeSO4 (P = 0.998) or FePP (P = 0.059). FIA from FeFum given with GOS and AA was significantly higher compared with FeFum given with GOS alone (+30%; P <0.001).

CONCLUSIONS

In iron-depleted women, GOS does not increase FIA from FeSO4 or FePP, but it increases FIA from FeFum. Thus, a combination of FeFum and GOS may be a well-absorbed formula for iron supplements. The study was registered at clinicaltrials.gov as NCT03762148.

Oral iron supplementation in iron-deficient women: How much and how often?

Iron deficiency and iron deficiency anemia (IDA) are major public health problems worldwide, especially in young women. Oral iron supplementation can be an effective strategy to treat and prevent IDA, but guidelines vary. Some experts recommend doses of 150-200 mg elemental iron per day, with the dose split through the day. However, recent studies suggest this may not be an optimal regimen. The fraction of iron absorbed from high doses of oral iron is low, and unabsorbed iron can cause gut irritation, inflammation and dysbiosis, and these reduce compliance. In recent studies using serum hepcidin profiles and stable iron isotopes to quantify iron absorption in young women, we have shown that: (a) oral iron doses ≥60 mg in iron-deficient women, and doses ≥100 mg in women with IDA, stimulate an acute increase in hepcidin that persists 24 h after the dose, but subsides by 48 h; (b) therefore, to maximize fractional iron absorption, oral doses ≥60 mg should be given on alternate days; (c) the circadian increase in plasma hepcidin is augmented by a morning iron dose; therefore, iron doses should not be given in the afternoon or evening after a morning dose. If rate of Hb response is important, a pooled analysis of our data done for this review indicates that total iron absorption is also higher if twice the target daily iron dose is given on alternate days. In summary, these studies suggest changing from daily to alternate-day schedules and from divided to morning single doses increases iron absorption and may reduce side effects. Thus, providing morning doses of 60-120 mg iron as a ferrous salt given with ascorbic acid on alternate days may be an optimal oral dosing regimen for women with iron-deficiency and mild IDA.

Iron Supplementation Influence on the Gut Microbiota and Probiotic Intake Effect in Iron Deficiency-A Literature-Based Review

Iron deficiency in the human body is a global issue with an impact on more than two billion individuals worldwide. The most important functions ensured by adequate amounts of iron in the body are related to transport and storage of oxygen, electron transfer, mediation of oxidation-reduction reactions, synthesis of hormones, the replication of DNA, cell cycle restoration and control, fixation of nitrogen, and antioxidant effects. In the case of iron deficiency, even marginal insufficiencies may impair the proper functionality of the human body. On the other hand, an excess in iron concentration has a major impact on the gut microbiota composition. There are several non-genetic causes that lead to iron deficiencies, and thus, several approaches in their treatment. The most common methods are related to food fortifications and supplements. In this review, following a summary of iron metabolism and its health implications, we analyzed the scientific literature for the influence of iron fortification and supplementation on the gut microbiome and the effect of probiotics, prebiotics, and/or synbiotics in iron absorption and availability for the organism.

In Vitro Evaluation of the Effects of Commercial Prebiotic GOS and FOS Products on Human Colonic Caco-2 Cells

Prebiotic oligosaccharides are widely used as human and animal feed additives for their beneficial effects on the gut microbiota. However, there are limited data to assess the direct effect of such functional foods on the transcriptome of intestinal epithelial cells. The purpose of this study is to describe the differential transcriptomes and cellular pathways of colonic cells directly exposed to galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS). We have examined the differential gene expression of polarized Caco–2 cells treated with GOS or FOS products and their respective mock-treated cells using mRNA sequencing (RNA-seq). A total of 89 significant differentially expressed genes were identified between GOS and mock-treated groups. For FOS treatment, a reduced number of 12 significant genes were observed to be differentially expressed relative to the control group. KEGG and gene ontology functional analysis revealed that genes up-regulated in the presence of GOS were involved in digestion and absorption processes, fatty acids and steroids metabolism, potential antimicrobial proteins, energy-dependent and -independent transmembrane trafficking of solutes and amino acids. Using our data, we have established complementary non-prebiotic modes of action for these frequently used dietary fibers.

Comparison of different doses of daily iron supplementation for anemia prophylaxis in pregnancy: A systematic review

Different doses of iron are used for oral supplementation during pregnancy throughout the world. This objective of this review is to describe the effectiveness and side effect profile of different doses of oral iron supplementation for prophylaxis of anemia among pregnant women. Published literature was searched using keywords "iron," "pregnancy," and "supplementation" and related terms. Gray literature was searched in medical libraries including National Medical Library, Dr. B. B. Dikshit library, and library of ICMR. Intervention studies comparing different doses of oral iron given as prophylaxis for anemia during pregnancy, published till December 2017, were retrieved. Studies done only among anemic patients, and studies comparing oral iron with placebo were excluded. In total, 1588 studies were obtained and 11 of them met the objectives. In global studies, prophylactic dose of 30 mg and above is shown to maintain normal hemoglobin. Among the studies from India, prophylactic dose of 120 mg showed consistent results and 60 mg showed inconsistent results in increasing both hemoglobin and ferritin levels. No significant difference in side effects was reported up to 80 mg iron in global studies and the side effects were comparable with 60 to 240 mg doses in Indian studies. It was evident from the review that a state of clinical equipoise exists for the ideal dose of iron supplementation for the prevention of anemia in pregnancy in terms of efficacy and side effect profile. Robust clinical trial as well as technical consultation is required, especially in Indian setting to explore this question further.

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age

BACKGROUND

Vitamin and mineral deficiencies, particularly those of iron, vitamin A, and zinc, affect more than two billion people worldwide. Young children are highly vulnerable because of rapid growth and inadequate dietary practices. Multiple micronutrient powders (MNPs) are single-dose packets containing multiple vitamins and minerals in powder form, which are mixed into any semi-solid food for children six months of age or older. The use of MNPs for home or point-of-use fortification of complementary foods has been proposed as an intervention for improving micronutrient intake in children under two years of age. In 2014, MNP interventions were implemented in 43 countries and reached over three million children. This review updates a previous Cochrane Review, which has become out-of-date.

OBJECTIVES

To assess the effects and safety of home (point-of-use) fortification of foods with MNPs on nutrition, health, and developmental outcomes in children under two years of age. For the purposes of this review, home fortification with MNP refers to the addition of powders containing vitamins and minerals to semi-solid foods immediately before consumption. This can be done at home or at any other place that meals are consumed (e.g. schools, refugee camps). For this reason, MNPs are also referred to as point-of-use fortification.

SEARCH METHODS

We searched the following databases up to July 2019: CENTRAL, MEDLINE, Embase, and eight other databases. We also searched four trials registers, contacted relevant organisations and authors of included studies to identify any ongoing or unpublished studies, and searched the reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs with individual randomisation or cluster-randomisation. Participants were infants and young children aged 6 to 23 months at the time of intervention, with no identified specific health problems. The intervention consisted of consumption of food fortified at the point of use with MNP formulated with at least iron, zinc, and vitamin A, compared with placebo, no intervention, or use of iron-containing supplements, which is standard practice.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of studies against the inclusion criteria, extracted data from included studies, and assessed the risk of bias of included studies. We reported categorical outcomes as risk ratios (RRs) or odds ratios (ORs), with 95% confidence intervals (CIs), and continuous outcomes as mean differences (MDs) and 95% CIs. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included 29 studies (33,147 children) conducted in low- and middle-income countries in Asia, Africa, Latin America, and the Caribbean, where anaemia is a public health problem. Twenty-six studies with 27,051 children contributed data. The interventions lasted between 2 and 44 months, and the powder formulations contained between 5 and 22 nutrients. Among the 26 studies contributing data, 24 studies (26,486 children) compared the use of MNP versus no intervention or placebo; the two remaining studies compared the use of MNP versus an iron-only supplement (iron drops) given daily. The main outcomes of interest were related to anaemia and iron status. We assessed most of the included studies at low risk of selection and attrition bias. We considered some studies to be at high risk of performance and detection bias due to lack of blinding. Most studies were funded by government programmes or foundations; only two were funded by industry. Home fortification with MNP, compared with no intervention or placebo, reduced the risk of anaemia in infants and young children by 18% (RR 0.82, 95% CI 0.76 to 0.90; 16 studies; 9927 children; moderate-certainty evidence) and iron deficiency by 53% (RR 0.47, 95% CI 0.39 to 0.56; 7 studies; 1634 children; high-certainty evidence). Children receiving MNP had higher haemoglobin concentrations (MD 2.74 g/L, 95% CI 1.95 to 3.53; 20 studies; 10,509 children; low-certainty evidence) and higher iron status (MD 12.93 μg/L, 95% CI 7.41 to 18.45; 7 studies; 2612 children; moderate-certainty evidence) at follow-up compared with children receiving the control intervention. We did not find an effect on weight-for-age (MD 0.02, 95% CI -0.03 to 0.07; 10 studies; 9287 children; moderate-certainty evidence). Few studies reported morbidity outcomes (three to five studies each outcome) and definitions varied, but MNP did not increase diarrhoea, upper respiratory infection, malaria, or all-cause morbidity. In comparison with daily iron supplementation, the use of MNP produced similar results for anaemia (RR 0.89, 95% CI 0.58 to 1.39; 1 study; 145 children; low-certainty evidence) and haemoglobin concentrations (MD -2.81 g/L, 95% CI -10.84 to 5.22; 2 studies; 278 children; very low-certainty evidence) but less diarrhoea (RR 0.52, 95% CI 0.38 to 0.72; 1 study; 262 children; low-certainty of evidence). However, given the limited quantity of data, these results should be interpreted cautiously. Reporting of death was infrequent, although no trials reported deaths attributable to the intervention. Information on side effects and morbidity, including malaria and diarrhoea, was scarce. It appears that use of MNP is efficacious among infants and young children aged 6 to 23 months who are living in settings with different prevalences of anaemia and malaria endemicity, regardless of intervention duration. MNP intake adherence was variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

AUTHORS' CONCLUSIONS

Home fortification of foods with MNP is an effective intervention for reducing anaemia and iron deficiency in children younger than two years of age. Providing MNP is better than providing no intervention or placebo and may be comparable to using daily iron supplementation. The benefits of this intervention as a child survival strategy or for developmental outcomes are unclear. Further investigation of morbidity outcomes, including malaria and diarrhoea, is needed. MNP intake adherence was variable and in some cases comparable to that achieved in infants and young children receiving standard iron supplements as drops or syrups.

Modular synthesis and immunological evaluation of suspected allergenic galactooligosaccharides

Galactooligosaccharides (GOS) are widely used in the food industry as prebiotics and in very rare cases, can lead to an allergic reaction. Due to the microheterogeneity of GOS it is very difficult to extract pure and well defined oligosaccharides to establish which component is responsible for the observed allergenicity. Herein, we report the chemical synthesis of a suspected allergen 4PX and three closely related oligosaccharides based on a modular approach. The fact that synthesized 4PX and a regioisomer did not cause basophil activation in subjects with confirmed GOS-allergy excludes both tetrasaccharides as key-epitopes in GOS-allergenicity in Singapore.