National nutrition and public health policies: issues related to bioavailability of nutrients when developing dietary reference intakes

Biofortification to avoid malnutrition in humans in a changing climate: Enhancing micronutrient bioavailability in seed, tuber, and storage roots

Malnutrition results in enormous socio-economic costs to the individual, their community, and the nation's economy. The evidence suggests an overall negative impact of climate change on the agricultural productivity and nutritional quality of food crops. Producing more food with better nutritional quality, which is feasible, should be prioritized in crop improvement programs. Biofortification refers to developing micronutrient -dense cultivars through crossbreeding or genetic engineering. This review provides updates on nutrient acquisition, transport, and storage in plant organs; the cross-talk between macro- and micronutrients transport and signaling; nutrient profiling and spatial and temporal distribution; the putative and functionally characterized genes/single-nucleotide polymorphisms associated with Fe, Zn, and β-carotene; and global efforts to breed nutrient-dense crops and map adoption of such crops globally. This article also includes an overview on the bioavailability, bioaccessibility, and bioactivity of nutrients as well as the molecular basis of nutrient transport and absorption in human. Over 400 minerals (Fe, Zn) and provitamin A-rich cultivars have been released in the Global South. Approximately 4.6 million households currently cultivate Zn-rich rice and wheat, while ~3 million households in sub-Saharan Africa and Latin America benefit from Fe-rich beans, and 2.6 million people in sub-Saharan Africa and Brazil eat provitamin A-rich cassava. Furthermore, nutrient profiles can be improved through genetic engineering in an agronomically acceptable genetic background. The development of "Golden Rice" and provitamin A-rich dessert bananas and subsequent transfer of this trait into locally adapted cultivars are evident, with no significant change in nutritional profile, except for the trait incorporated. A greater understanding of nutrient transport and absorption may lead to the development of diet therapy for the betterment of human health.

Dietary Intake of Folate and Assessment of the Folate Deficiency Prevalence in Slovenia Using Serum Biomarkers

Folate deficiency is associated with various health issues, including anemia, cardiovascular disease, and birth defects. Low folate intake and suboptimal folate status were found in several countries; however, this topic has not yet been investigated in Slovenia. Dietary folate intake and serum folate status were investigated through the nationally representative food consumption study SI.Menu/Nutrihealth. Folate intake was estimated using a sample of N = 1248 subjects aged 10–74 years, stratified in three age groups (adolescents, adults, elderly population), through two 24 h-dietary recalls and food propensity questionnaire. Data on serum folate and homocysteine was available for 280 participants. Very low folate intake (<300 µg/day) was observed in 59% of adolescents, 58% of adults and 68% of elderlies, and only about 12% achieved the WHO recommended level of 400 µg/day. Major dietary contributors were vegetables and fruit, and cereal products. Living environment, education, employment status and BMI were linked with low folate intake in adults; BMI, and sex in adolescents; and sex in elderlies. Considering low serum folate (<7 nmol/L) and high serum homocysteine (>15 nmol/L), folate deficiency was found in 7.6 and 10.5% in adults and elderlies, respectively. Additional public health strategies should be employed to promote the consumption of folate-rich foods. With current folate intakes, supplementation with folic acid is relevant especially in specific vulnerable populations, particularly in women planning and during pregnancy.

Global diversity of dietary intakes and standards for zinc, iron, and copper

BACKGROUND

The essentiality of trace elements in human diets is well recognized and adequate levels are a critical component of optimal health. To date, public health efforts have focused primarily on macronutrients or trace minerals that are easily analyzed. The goal of this research is to provide assessment of the dietary standards developed for Zn, Fe, and Cu in 100+ developed, marginal, and developing countries. We summarize the current recommendations and changes from the last decade, categorize and provide scientific basis for values established, factors that affect requirements, and current global challenges.

METHODS

The electronic databases of Google Scholar, PubMed, Embase, Web of Science and Cochrane Library were searched using the keywords "trace minerals," "micronutrients, ""zinc," "iron," "copper," "dietary standards" and "recommendations." A total of 123 studies published from 1965 to 2019 were included.

RESULTS

The World Health Organization (WHO) has established dietary standards to address nutrient deficiencies, prevent infections and ensure basic metabolic functions; these are utilized by most developing countries. Developed countries or their alliances have established values similar to or higher than the WHO, primarily for promotion of optimal health and well-being. Transitional countries are more concerned with issues of bioavailability, food security and undernutrition. Globally, Zn and Cu recommendations are lower in women than in men; Fe requirements are higher to compensate for menstrual losses. Important considerations in establishing guidelines for these minerals include bioaccessibility, dietary practices and restrictions, food processing, interactions, and chemical forms. The global challenges of the triple burden of malnutrition, hidden hunger, increased consumption of ultra-processed foods and obesity have been associated with Zn, Fe, and Cu deficiencies.

CONCLUSION

This research provides public policy and health professionals evidenced-based information useful for the establishment of dietary standards world-wide.

The Goal of Adequate Nutrition: Can It Be Made Affordable, Sustainable, and Universal?

Until about 1900, large proportions of the world population endured hunger and poverty. The 20th century saw world population increase from 1.6 to 6.1 billion, accompanied and to some extent made possible by rapid improvements in health standards and food supply, with associated advances in agricultural and nutrition sciences. In this paper, I use the application of linear programming (LP) in preparation of rations for farm animals to illustrate a method of calculating the lowest cost of a human diet selected from locally available food items, constrained to provide recommended levels of food energy and nutrients; then, to find a realistic minimum cost, I apply the further constraint that the main sources of food energy in the costed diet are weighted in proportion to the actual reported consumption of food items in that area. Worldwide variations in dietary preferences raise the issue as to the sustainability of popular dietary regimes, and the paper reviews the factors associated with satisfying requirements for adequate nutrition within those regimes. The ultimate physical constraints on food supply are described, together with the ways in which climate change may affect those constraints. During the 20th century, food supply increased sufficiently in most areas to keep pace with the rapid increase in world population. Many challenges will need to be overcome if food supply is to continue to meet demand, and those challenges are made more severe by rising expectations of quality of life in the developing world, as well as by the impacts of climate change on agriculture and aquaculture.

Is achlorhydria a cause of iron deficiency anemia?

We re-evaluated the old hypothesis that gastritis-induced achlorhydria is a cause of iron deficiency anemia (IDA) in humans. First, we analyzed the currently available research on the association between achlorhydria and IDA. When gastric acid secretion was measured after maximal stimulation, the frequency of achlorhydria (or severe hypochlorhydria) was 44% in patients with idiopathic IDA and 1.8% in healthy controls. In some patients with pernicious anemia, presumed achlorhydria preceded the development of IDA in time. However, we found no credible evidence that IDA caused gastritis or that IDA preceded the development of achlorhydria. Thus, correlational results favor achlorhydria as the causal factor in the association between achlorhydria and IDA. Second, we sought to determine whether gastritis and achlorhydria cause negative iron balance. When biosynthetic methods were used to isotopically label iron in food, achlorhydric patients were found to have severe malabsorption of nonheme iron, which persisted after the development of IDA. In 1 study, achlorhydria reduced the normal increase in heme-iron absorption from hemoglobin in response to iron deficiency. After an injection of isotopic iron into normal men, the physiologic loss of iron from the body was found to be 1 mg/d. Patients with chronic gastritis had excess fecal loss of isotopically tagged plasma iron. Calculations based on these results indicate that the absorption of iron from a typical Western diet by achlorhydric patients would be less than physiologic iron losses, creating a negative iron balance that could not be overcome by the adaptive increase in duodenal iron absorptive capacity that occurs in response to iron deficiency. The combination of results from these correlational and pathophysiologic studies supports the hypothesis that gastritis-induced achlorhydria can be an independent cause of IDA.

Explaining the variability in recommended intakes of folate, vitamin B12, iron and zinc for adults and elderly people

Objective

To signal key issues for harmonising approaches for establishing micronutrient recommendations by explaining observed variation in recommended intakes of folate, vitamin B12, Fe and Zn for adults and elderly people.

Design

We explored differences in recommended intakes of folate, vitamin B12, Fe and Zn for adults between nine reports on micronutrient recommendations. Approaches used for setting recommendations were compared as well as eminence-based decisions regarding the selection of health indicators indicating adequacy of intakes and the consulted evidence base.

Results

In nearly all reports, recommendations were based on the average nutrient requirement. Variation in recommended folate intakes (200–400 μg/d) was related to differences in the consulted evidence base, whereas variation in vitamin B12recommendations (1·4–3·0 μg/d) was due to the selection of different CV (10–20 %) and health indicators (maintenance of haematological status or basal losses). Variation in recommended Fe intakes (men 8–10 mg/d, premenopausal women 14·8–19·6 mg/d, postmenopausal women 7·5–10·0 mg/d) was explained by different assumed reference weights and bioavailability factors (10–18 %). Variation in Zn recommendations (men 7–14 mg/d, women 4·9–9·0 mg/d) was also explained by different bioavailability factors (24–48 %) as well as differences in the consulted evidence base.

Conclusions

For the harmonisation of approaches for setting recommended intakes of folate, vitamin B12, Fe and Zn across European countries, standardised methods are needed to (i) select health indicators and define adequate biomarker concentrations, (ii) make assumptions about inter-individual variation in requirements, (iii) derive bioavailability factors and (iv) collate, select, interpret and integrate evidence on requirements.

Optimal management of iron deficiency anemia due to poor dietary intake

Iron is necessary for the normal development of multiple vital processes. Iron deficiency (ID) may be caused by several diseases, even by physiological situations that increase requirements for this mineral. One of its possible causes is a poor dietary iron intake, which is infrequent in developed countries, but quite common in developing areas. In these countries, dietary ID is highly prevalent and comprises a real public health problem and a challenge for health authorities. ID, with or without anemia, can cause important symptoms that are not only physical, but can also include a decreased intellectual performance. All this, together with a high prevalence, can even have negative implications for a community’s economic and social development. Treatment consists of iron supplements. Prevention of ID obviously lies in increasing the dietary intake of iron, which can be difficult in developing countries. In these regions, foods with greater iron content are scarce, and attempts are made to compensate this by fortifying staple foods with iron. The effectiveness of this strategy is endorsed by multiple studies. On the other hand, in developed countries, ID with or without anemia is nearly always associated with diseases that trigger a negative balance between iron absorption and loss. Its management will be based on the treatment of underlying diseases, as well as on oral iron supplements, although these latter are limited by their tolerance and low potency, which on occasions may compel a change to intravenous administration. Iron deficiency has a series of peculiarities in pediatric patients, in the elderly, in pregnant women, and in patients with dietary restrictions, such as celiac disease.

Essentiality and toxicity in copper health risk assessment: overview, update and regulatory considerations

Copper (Cu), an essential element required as a cofactor and/or structural component of numerous metalloenzymes, is uniquely positioned as a case study for issues associated with the essential metals health risk assessment, because of its extensive database. Essential elements pose distinct challenges when establishing regulatory guidelines because too little as well as too much intake can produce adverse health consequences and the dose-response curve is roughly U-shaped. Thus, conventional health risk assessment paradigms do not apply to essential elements; the dose-response assessment needs to define an acceptable range of oral intake (AROI) which prevents deficiency by meeting nutritional requirements while avoiding toxicity due to high intakes. The conceptual framework for this type of risk assessment includes consideration of biological processes that are unique to essential elements-homeostasis, basal and normative nutritional requirements, bioavailability, and nutrient-nutrient interactions. In this paper, the Cu database on physiology, deficiency, and excess is briefly reviewed in order to establish the range of potential health hazards associated with varying levels of intake. Issues discussed include the (1) development of suitable dose-response methodologies, including appropriate dose and response metrics, for Cu; (2) categorization of severity of response and functional significance; (3) use of endpoints of similar severity and functionality for deficiency and excess in dose-response assessment; (4) development of valid biomarkers for subclinical effects, exposures and susceptibilities. Guideline values for Cu intake have been established by nutritional and toxicologic regulatory or advisory boards. Although regulators are more concerned with the potential human toxicity arising from excessive Cu intake, the preponderance of evidence suggests that deficiency is more of a public health concern than excess.

Proposed Recommended Nutrient Densities for Moderately Malnourished Children

Recommended Nutrient Intakes (RNIs) are set for healthy individuals living in clean environments. There are no generally accepted RNIs for those with moderate malnutrition, wasting, and stunting, who live in poor environments. Two sets of recommendations are made for the dietary intake of 30 essential nutrients in children with moderate malnutrition who require accelerated growth to regain normality: first, for those moderately malnourished children who will receive specially formulated foods and diets; and second, for those who are to take mixtures of locally available foods over a longer term to treat or prevent moderate stunting and wasting. Because of the change in definition of severe malnutrition, much of the older literature is pertinent to the moderately wasted or stunted child. A factorial approach has been used in deriving the recommendations for both functional, protective nutrients (type I) and growth nutrients (type II).

Multivitamin and multimineral dietary supplements: definitions, characterization, bioavailability, and drug interactions

Although multivitamins, multiminerals, and similar terms (eg, multis or multiples) are commonly used, they have no standard scientific, regulatory, or marketplace definitions. Thus, multivitamins-multiminerals refers to products with widely varied compositions and characteristics. Multivitamin-multimineral composition databases use label values as surrogates for analyzed values. However, actual vitamin and mineral amounts often deviate from label values. Vitamin and mineral bioavailability for dietary supplements also lacks a standard scientific and regulatory definition and validated in vitro and animal models that accurately reflect human bioavailabilities. Systematic information on the bioavailability and bioequivalence of vitamins and minerals in marketed products and on potential drug interactions is scarce. Because of limited information on product characteristics, our ability to directly compare results across studies, estimate changes in usage patterns or intakes over time, and generalize from published results to marketed products is problematic.

How different is the dietary pattern in non-alcoholic steatohepatitis patients?

BACKGROUND/AIMS

This study aimed at evaluating whether patients with non-alcoholic steatohepatitis (NASH) had a specific dietary pattern and how it compared with data representative from the same geographical region individuals.

SUBJECTS AND METHODS

Clinical, biochemical and anthropometrics: weight, height, body mass index (BMI) and waist circumference were collected in 45 NASH patients. Diet history was assessed using a validated semi-quantitative food frequency questionnaire, analysed with the Food Processor Plus, and was compared, after adjustment for BMI, with data from a sample of 856 free-living individuals, frequency matched for sex and age.

RESULTS

Patients' mean age was 49.6+/-10.6 years, 26 F: 19 M, BMI: 31.2+/-5.0 kg/m2. Comparison of their diet history with control data (C) revealed that carbohydrate consumption was lower in patients (P): P-243.6+/-5.7 g vs. C-261.5+/-1.6 g, P<0.05, and most patients had very low fibre intake. Conversely, total fat consumption was higher in patients: P-79.7+/-1.7 g vs. 73.0+/-0.4, P<0.01. A significantly higher intake of n-6 fatty acids (P=0.003) and n-6/n-3 ratio was found in patients, P<0.001.

CONCLUSIONS

Our results suggest that the quality and combination of carbohydrates and fat intake may be more relevant than their isolated amount; an increased fat intake with an excessive amount of n-6 fatty acids can be implicated in promoting necro-inflammation, and provides further grounds for individualized dietary therapy.

A long-term controlled folate feeding study in young women supports the validity of the 1.7 multiplier in the dietary folate equivalency equation

The presence of folic acid in enriched cereal grain products and the higher bioavailability of folic acid than food folate led to the expression of the 1998 folate RDA, 400 microg/d, as dietary folate equivalents (DFE). DFE are defined as: mug natural food folate + 1.7 x microg synthetic folic acid. The 1.7 multiplier was based on assumptions that added folic acid was 85% available and food folate was 50% available. The 85/50 ratio also inferred that the bioavailability of food folate was approximately 60% relative to added folic acid. The objective of this long-term controlled feeding study was to assess the dietary folate equivalency of folic acid. After a 2-wk period of folate restriction, women (n = 42, 18-45 y old) consumed either 400 or 800 microg DFE/d derived from various combinations of food folate and folic acid for 12 wk. Folic acid was converted to DFE using the 1.7 multiplier from the DFE calculation and was consumed with a meal throughout the treatment period. Folate status response to the various treatments was assessed during wk 12-14. Serum folate, RBC folate, and plasma total homocysteine did not differ among the 400 microg DFE/d groups or among the 800 microg DFE/d groups. In contrast, consumption of 800 microg DFE/d led to higher (P </= 0.05) serum and RBC folate than consumption of 400 microg DFE/d. These data support the validity of the 1.7 multiplier in the DFE equation and suggest that food folate bioavailability is approximately 60% that of added folic acid when consumed as part of a mixed diet.