Vitamin A-fortified rice increases total body vitamin A stores in lactating Thai women measured by retinol isotope dilution: a double-blind, randomized, controlled trial

A systematic review of post-harvest rice fortification: Technologies, sensory characteristics, consumer acceptance, and bioavailability

Fortifying rice with micronutrients is an effective strategy for addressing nutritional imbalances in post-harvest rice. This article systematically reviews technologies currently available for fortifying rice with vitamins, minerals, and other micronutrients. Fortification parameters, retention, stability, sensory perception, bioavailability of nutrients, and cost elements were covered. The effects of the fortified rice on cognitive and physiological outcomes were elaborated. Some nutrients are more stable in extruded rice. Coated kernels are endowed with distinctive colors and flavors that some consumers dislike. Dusted kernels loosen the micronutrient-premix on surface with rinsing. Ultrasonically fortified rice is suitable for long-term preservation. Compared with the parboiling method, high-pressure processing provides shorter processing time and closer grain shape. A combination of multiple methods has a better fortification effect. This review provides further information in understanding the effects of diverse fortification procedures, facilitating to promote their utilization and innovation in rice fortification.

Use of Population-Based Compartmental Modeling and Retinol Isotope Dilution to Study Vitamin A Kinetics and Total Body Stores among Ghanaian Women of Reproductive Age

Background

Limited data are available on vitamin A kinetics and total body stores (TBS) in women. Such information can be obtained using compartmental modeling and retinol isotope dilution (RID).

Objectives

Objectives were to apply population-based ("super-subject") modeling to determine retinol kinetics in nonpregnant Ghanaian women of reproductive age and to use RID to predict TBS in the group and its individuals.

Methods

Women (n = 89) ingested a dose of [2H6]retinyl acetate and blood samples (3/woman) were collected from 6 h to 91 d, with all participants sampled at 14 d, about half at either 21 or 28 d, and each at one other time. Composite data (plasma retinol fraction of dose; FDp) were analyzed using Simulation, Analysis and Modeling software to obtain kinetic parameters, TBS, and other state variables as well as model-derived values for the RID composite coefficient FaS. The latter were used in the RID equation TBS (μmol) = FaS × 1/SAp (where SAp is plasma retinol specific activity) to predict TBS at various times.

Results

Model-predicted TBS was 973 μmol (n = 87). Geometric mean RID-predicted TBS was 965, 926, and 1006 μmol at 14, 21, and 28 d, respectively, with wide ranges [for example, 252-3848 μmol on day 14 (n = 86)]; TBS predictions were similar at later times. Participants had a mean 2 y of vitamin A in stores and estimated liver vitamin A concentrations in the normal range. Model-predicted vitamin A disposal rate was 1.3 μmol/d and plasma recycling number was 37.

Conclusions

Super-subject modeling provides an estimate of group mean TBS as well as group-specific values for the RID coefficient FaS; the latter can be used to confidently predict TBS by RID for individual participants in the group under study or in similar individuals at 14 d or more after isotope ingestion.

Trial registration number

Trial is registered (NCT04632771) at https://clinicaltrials.gov.

Use of Theoretical Women and Model-Based Compartmental Analysis to Evaluate the Impact of Vitamin A Intake with or without a Daily Vitamin A Supplement on Vitamin A Total Body Stores and Balance During Lactation

BACKGROUND

Inadequate vitamin A (VA) intake is common among lactating women in many communities worldwide, but high-dose VA supplementation for postpartum women is not recommended by the World Health Organization as an effective intervention.

OBJECTIVES

To simulate the impact of VA intake via diet and daily VA supplements on VA total body stores (TBS) and balance in theoretical lactating women with low/moderate TBS.

METHODS

We studied 6 theoretical subjects with assigned values for TBS from 219-624 μmol. Using Simulation, Analysis, and Modeling software and a previously published compartmental model for whole-body VA metabolism, we simulated TBS over 6 mo of established lactation for each subject under 4 conditions: 1) prelactation VA intake was increased to maintain VA balance (LSS); 2) prelactation VA intake was maintained (NLSS); 3) VA intake was the same as 2) but a daily VA supplement (2.8 μmol/d) was added (NLSS+S); and 4) VA intake was as 1) and the daily VA supplement was included (LSS+S).

RESULTS

To compensate for the loss of VA via milk while VA balance was maintained (LSS) over 6 mo of lactation, VA intake had to increase by 0.8-1.87 μmol/d (n = 6) compared with NLSS. Over 6 mo of NLSS treatment, VA balance was negative (geometric mean, -0.77 μmol/d) compared with LSS, whereas balance was positive under NLSS+S and LSS+S conditions (0.75 and 1.5 μmol/d, respectively). For LSS, the proportion of total VA disposal was 37% via breastmilk, 32% from VA stores, and 32% from nonstorage tissues.

CONCLUSIONS

Adding a daily VA supplement (2.8 μmol/d) to the diet of lactating women with suboptimal VA intake may effectively counterbalance the negative VA balance resulting from the output of VA via breastmilk and thus benefit both mother and infant by maintaining or increasing VA stores and breastmilk VA concentration.

Effects of Food-Based Approaches on Vitamin A Status of Women and Children: A Systematic Review

Vitamin A deficiency (VAD) increases risk for morbidity and mortality. Food-based approaches offer one strategy to improve vitamin A status. This systematic review assessed evidence of the effects of food-based approaches on the vitamin A status of women and children under 5 y. VAD was defined as clinical ocular symptoms, such as loss of vision, and/or retinol plasma or serum concentration <0.70 μmol/L. Searches on food-based approaches to improve vitamin A status were conducted for the period 2011-2022 on PubMed, CINHAL, Web of Science, and Google Scholar using PRISMA guidelines. English-language publications were included. Case studies, unpublished dissertations, and non-peer-reviewed studies were excluded. This review comprises 24 of 27,322 identified studies; 23 included studies focused on provitamin A carotenoids. There were 17,214 participants across the 24 studies with sample sizes ranging from 8 to 3571 individuals. Intervention studies spanned from 3 wk to 2 y. Fifteen (63%) studies were randomized control trials, 7 were cross-sectional, and 2 were longitudinal studies. Most studies (N = 21) used biochemical measurements, for example, serum retinol, to assess vitamin A status; other studies used clinical symptoms (for example, xerophtalmia) or dietary intake. Thirteen (54%) studies reported a statistically significant effect of food-based interventions (N = 8) or an association of diet (N = 5) on vitamin A status. This systematic review indicated that some food-based interventions improved vitamin A status, thus offering a safe and effective delivery mechanism for vitamin A. There appeared to be significant association between vitamin A status and consumption of foods with high concentrations of preformed vitamin A and provitamin A carotenoids. Differences across studies in regard to the period of evaluation, food approaches used, and statistical power may explain the lack of effectiveness of food-based approaches on vitamin A status in some studies.

Use of Compartmental Modeling and Retinol Isotope Dilution to Determine Vitamin A Stores in Young People with Sickle Cell Disease Before and After Vitamin A Supplementation

BACKGROUND

Suboptimal plasma retinol concentrations have been documented in US children with sickle cell disease (SCD) hemoglobin SS type (SCD-HbSS), but little is known about vitamin A kinetics and stores in SCD.

OBJECTIVES

The objectives were to quantify vitamin A total body stores (TBS) and whole-body retinol kinetics in young people with SCD-HbSS and use retinol isotope dilution (RID) to predict TBS in SCD-HbSS and healthy peers as well as after vitamin A supplementation in SCD-HbSS subjects.

METHODS

Composite plasma [13C10]retinol response data collected from 22 subjects with SCD-HbSS for 28 d after isotope ingestion were analyzed using population-based compartmental modeling ("super-subject" approach); TBS and retinol kinetics were quantified for the group. TBS was also calculated for the same individuals using RID, as well as for healthy peers (n = 20) and for the subjects with SCD-HbSS after 8 wk of daily vitamin A supplements (3.15 or 6.29 μmol retinol/d [900 or 1800 μg retinol activity equivalents/d]).

RESULTS

Model-predicted group mean TBS for subjects with SCD-HbSS was 428 μmol, equivalent to ∼11 mo of stored vitamin A; vitamin A disposal rate was 1.3 μmol/d. Model-predicted TBS was similar to that predicted by RID at 3 d postdosing (mean, 389 μmol; ∼0.3 μmol/g liver); TBS predictions at 3 compared with 28 d were not significantly different. Mean TBS in healthy peers was similar (406 μmol). RID-predicted TBS for subjects with SCD-HbSS was not significantly affected by vitamin A supplementation at either dose.

CONCLUSIONS

Despite differences in plasma retinol concentrations, TBS was the same in subjects with SCD-HbSS compared with healthy peers. Because 56 d of vitamin A supplementation at levels 1.2 to 2.6 times the Recommended Dietary Allowance did not increase TBS in these subjects with SCD-HbSS, further work will be needed to understand the effects of SCD on retinol metabolism. This trial was registered as NCT03632876 at clinicaltrials.gov.

Total Liver Vitamin A Reserves, Determined With 13C2-Retinol Isotope Dilution, are Similar Among Tanzanian Preschool Children in Areas With Low and High Vitamin A Exposure

BACKGROUND

In Tanzania, some districts have single vitamin A (VA) interventions and others have multiple interventions. There is limited information on total liver VA reserves (TLRs) among preschool children (PSC) in Tanzania.

OBJECTIVES

We assessed total body VA stores (TBSs) and TLRs among PSC living in 2 districts with low and high exposures to VA interventions using 13C-retinol isotope dilution.

METHODS

A cross-sectional, health facility-based study was conducted in 2 districts with access to VA supplementation only (low exposure to VA interventions) or multiple interventions (high exposure to VA interventions) to determine TLRs in 120 PSC aged 36-59 months. A questionnaire was used to collect data. Height and weight were measured, and the prevalence of undernutrition was based on z-scores. Blood samples were collected for measurement of TBSs, TLRs, retinol, biomarkers of infection and inflammation, and hemoglobin. 13C2-retinyl acetate (1.0 μmol) was administered to each child after blood collection, and the second sample was taken 14 days later. Serum was analyzed with HPLC and gas chromatography-combustion-isotope ratio mass spectrometry. Mann-Whitney U test was used to compare medians of nonnormally distributed variables. Pearson χ2 test was used to assess associations between 2 categorical variables.

RESULTS

Median TBSs differed between PSC from low-exposure (196 μmol; IQR, 120 μmol) and high-exposure (231 μmol; IQR, 162 μmol) intervention areas (P = 0.015). Median TLRs were 0.23 μmol/g liver (IQR, 0.14 μmol/g liver) and 0.26 μmol/g liver (IQR, 0.16 μmol/g liver) from low- and high-exposure areas, respectively, which did not significantly differ (P = 0.12). Prevalences of VA deficiency (VAD; ≤0.1 μmol/g liver) were 6.3% and 1.7% for PSC from low- and high-exposure areas, respectively. There was no significant difference in VAD (P = 0.25). No child had hypervitaminosis A (≥1.0 μmol/g liver).

CONCLUSIONS

TLRs in Tanzanian PSC from 2 districts did not differ between low and high exposures to VA interventions. The majority had adequate VA stores. VAD in the study area presented a mild public health problem.

Breast Milk Retinol Concentrations Reflect Total Liver Vitamin A Reserves and Dietary Exposure in Thai Lactating Women from Urban and Rural Areas

BACKGROUND

Measuring vitamin A (VA) status during lactation is required to inform dietary recommendations. Limited data exist on VA stores in women.

OBJECTIVES

Our objective was to assess VA status in lactating Thai women by measuring total body VA stores (TBSs), serum and breast milk retinol concentrations, and dietary intake.

METHODS

Lactating women (n = 94), 6-8 wk postpartum, were enrolled from rural (Ayutthaya) and urban (Bangkok) areas. TBSs were measured by the 13C-retinol isotope dilution (RID) technique using 2.0 μmol 13C-retinyl acetate and a single blood sample 14 d post-dose. Natural 13C-enrichment was determined in nonenrolled women (n = 11). Estimated total liver VA reserves (TLRs) were determined using assumptions for lactation. Serum, foremilk, and hindmilk samples were analyzed for retinol by HPLC. Dietary VA intake was assessed by FFQ and 24-h dietary recalls for 3 d. Multiple regression and Pearson correlation were used to evaluate relations.

RESULTS

Median VA intakes were 51.8% of 2003 Thai daily recommendations for lactating women, with the majority from animal-source foods. Many women in Ayutthaya consumed liver weekly. Considering TLRs as 50% TBS, 20% and 11% of mothers in Ayutthaya and Bangkok, respectively, showed deficient reserves (≤0.10 μmol retinol/g). Median (quartile 1, quartile 3) serum [1.58 (1.34, 1.91) and 1.52 (1.30, 1.70) μmol/L] and milk [1.88 (1.29, 2.95) and 1.74 (0.96, 2.26) μmol/L] retinol in Ayutthaya and Bangkok, respectively, were normal. Women with deficient TLRs showed low milk retinol concentrations (≤1.0 μmol/L) and consumed less dietary VA, especially from animal-source foods. Breast milk retinol concentrations, especially hindmilk, demonstrated strong correlation with TBSs and TLRs estimated from the RID test.

CONCLUSIONS

Approximately 15% of Thai lactating women had deficient TLRs. Breast milk retinol concentrations in conjunction with dietary intake records show potential to screen mothers at risk of VA deficiency to guide interventions.The Thai Clinical Trials Registry number is TCTR20160824001 for the work in Thailand.

Compartmental Modeling of Vitamin A Stable Isotope Data from Milk or Plasma Provides Comparable Predictions of Vitamin A Stores in Theoretical Lactating Women

BACKGROUND

Previous compartmental models describing and quantifying whole-body vitamin A (VA) metabolism have been developed from plasma retinol kinetic data after human subjects ingest stable isotope-labeled VA. For humans, models based on data obtained from other sampling sites (e.g., excreta or milk) have not been proposed.

OBJECTIVES

Our objective was to determine whether comparable model predictions of VA total body stores (TBS) in theoretical lactating women were obtained using tracer data from only retinol in plasma or VA in milk.

METHODS

We used Simulation, Analysis and Modeling software to simulate values for TBS and the coefficients used in the retinol isotope dilution (RID) equation TBS = FaS/SAp (Fa, fraction of dose in stores; S, retinol specific activity (SA) in plasma/SA in stores; SAp, specific activity in plasma). We compared individual subject predictions of TBS and FaS based on modeling only plasma or only milk tracer data to previous results ("assigned values") for 12 theoretical lactating women when modeling was done based on tracer data for chylomicron retinyl esters, plasma retinol, and milk VA.

RESULTS

For subjects with a wide range of TBS, model-predicted TBS based on only plasma data were comparable with assigned values (range: 94%-106%). Using only milk data, predictions ranged from 72% to 178%, but when VA intake was included in modeling, predictions were improved (97%-102%). Similar results were obtained for simulated FaS.

CONCLUSIONS

If confirmed in free-living lactating women, results indicate that, similar to models based on serial plasma sampling, a model for whole-body VA kinetics, including predictions of TBS and FaS, can be identified based on tracer data for VA in milk when VA intake is included as a modeling constraint. Milk data have not been previously used for compartmental modeling of VA in humans.

Vitamin A Nutritional Status of Urban Lactating Chinese Women and Its Associated Factors

We aimed to investigate dietary vitamin A (DVA) intake, serum vitamin A (SVA) concentrations, and breast milk vitamin A (BMVA) concentrations of urban lactating Chinese women and explore the associated factors. We recruited 326 lactating women from ten cities in China and collected their dietary information, blood samples, and breast milk samples. SVA and BMVA were assessed with high-performance liquid chromatography. Mann–Whitney U tests, Kruskal–Wallis H tests, Chi-square tests, Spearman correlation tests, and multiple regression analyses were conducted. The median (25th, 75th) of DVA, SVA and BMVA were 372.36 (209.12, 619.78) μg RAE/day, 1.99 (1.71, 2.35) μmol/L, and 1.67 (1.13, 2.15) μmol/L, respectively. Only 3.1% of lactating women met the recommended nutrient intake of Vitamin A (VA), and 20.6% had a BMVA level below 1.05 μmol/L. Compared to underweight or normal weight women, overweight or obese lactating women had lower DVA and BMVA but higher SVA (p = 0.022; p = 0.030; p = 0.003). Multiparous women had a higher risk of inadequate BMVA (p = 0.023) than primiparous women. SVA and BMVA were positively associated with DVA, especially for lactating women not using VA supplements (β = 0.174, 95%CI = 0.025, 0.324, p = 0.022; β = 0.501, 95%CI = 0.208, 0.795, p = 0.001). There was no association between SVA and BMVA (β = 0.165, 95%CI = −0.037, 0.366, p = 0.109). In conclusion, VA nutritional status among Chinese urban lactating women needs more attention, especially for those who are obese, overweight, or higher parity. Increased DVA may contribute to increased BMVA.

Development of a Compartmental Model for Studying Vitamin A Kinetics and Status in Theoretical Lactating Women

BACKGROUND

Low vitamin A status and suboptimal milk vitamin A concentrations are problems in many populations worldwide. However, limited research has been done on whole-body vitamin A kinetics in women of reproductive age, especially during lactation.

OBJECTIVES

Goals were to develop compartmental models describing retinol kinetics in theoretical nonlactating (NL) and lactating (L) women and to determine whether the retinol isotope dilution (RID) method accurately predicted vitamin A total body stores (TBS) in the groups and individuals.

METHODS

We adapted 12 previously-used theoretical females with assigned values for retinol kinetic parameters and TBS (225-1348 μmol); subjects were NL or L (nursing one 3- to 6-mo-old infant) during 49-d kinetic studies after isotope dosing. We used an established compartmental model, adding a compartment for chylomicrons and, for L, another for mammary gland milk with inputs from holo-retinol-binding protein and chylomicron retinyl esters and output to milk. Using compartmental analysis, we simulated tracer responses in compartments of interest and calculated TBS using the RID equation TBS =   FaS/SAp [Fa, fraction of dose in stores; S, retinol specific activity in plasma/specific activity in stores; SAp, specific activity of retinol in plasma].

RESULTS

Models for both groups were well identified. Simulated plasma tracer responses were similar for NL and L, with L always below NL; milk tracer paralleled plasma from 10 d postdosing. Geometric mean FaS ratios (L/NL) were ∼0.75 during days 2-30. Using appropriate group FaS, RID provided accurate TBS predictions for >80% of NL and L subjects after day 18 when CV% for FaS was ∼10%.

CONCLUSIONS

These new physiologically-based models for vitamin A kinetics may be useful for future research in women of reproductive age. Results indicate that, in groups like these, RID to assess an individual's vitamin A status should be done at 21-28 d after isotope dosing.

Use of Compartmental Modeling and Datasets for Theoretical Lactating Women to Determine Conditions under Which Vitamin A-Specific Activity in Breast Milk Provides Accurate Estimates of Vitamin A Total Body Stores by Retinol Isotope Dilution

BACKGROUND

Vitamin A concentrations in breast milk are related to maternal vitamin A intake and status.

OBJECTIVES

Our objective was to identify conditions under which vitamin A specific activity in breast milk (SAm) could be used instead of retinol specific activity in plasma (SAp) to predict vitamin A total body stores (TBS) by retinol isotope dilution (RID).

METHODS

We used 12 previously-studied theoretical lactating women with assigned values for TBS (219-1348 μmol) and retinol kinetic parameters; we assumed subjects ingested a dose of stable isotope-labeled vitamin A. We expanded a 9-compartment steady state tracer model to include a parallel model for tracee (unlabeled retinol) and then adapted that model so vitamin A intake entered the system in 3 meals each day. Using compartmental analysis, we first simulated SAm and SAp after an overnight fast (as in actual RID experiments) and then with vitamin A intake also restricted in sequential meals on the day before sampling for RID.

RESULTS

After an overnight fast, SAm at day 21 postdosing was lower than SAp. However, if vitamin A intake was also restricted in 1, 2, or 3 meals before sampling, SAm/SAp (mean ± SD) was 0.92 ± 0.042,  0.96 ± 0.016,  or 0.99 ± 0.004,  respectively; results for days 14 and 28 were similar. When either SAp or SAm was used to predict TBS by RID on day 21 after 1-d restriction, predictions for all subjects were within 25% of assigned TBS.

CONCLUSIONS

Results indicate that, for theoretical lactating women with a wide range of vitamin A status, SAm will accurately predict TBS by RID at 2-4 wk postdosing if vitamin A intake is restricted for 1 d before sampling. If confirmed in community settings, results suggest that vitamin A status in lactating women can be determined without collecting blood.

Geographic and socio-demographic determinants of plasma retinol concentrations in Chinese pregnant and lactating women

PURPOSE

To examine plasma retinol status and its determinants in Chinese pregnant or lactating women.

METHODS

A cross-sectional study involving 1211 healthy women in mid-pregnancy, late pregnancy, or lactation was conducted in northern, central, and southern China. Plasma retinol concentration was determined by high-performance liquid chromatography. Multivariate quantile regression or modified Poisson regression was used to estimate adjusted medians, or to examine the associations of suboptimal retinol concentration (< 1.05 µmol/L) with various factors.

RESULTS

The overall median (interquartile range) retinol concentration was 1.25 (1.06-1.46) µmol/L. The adjusted concentration was higher in women at lactation (1.39 [1.20-1.63] µmol/L) and mid-pregnancy (1.26 [1.10-1.44] µmol/L) than late pregnancy (1.07 [0.92-1.28] µmol/L), and higher in women in the central area (1.34 [1.18-1.49] µmol/L) and the north (1.26 [1.10-1.43] µmol/L) than the south (1.19 [1.07-1.31] µmol/L). The retinol concentration was more likely to be low in women with lower pre-pregnancy BMI, younger age, less education, and in lactating women who had a caesarean birth or were breastfeeding exclusively. A total of 290 (24.0%) women had a suboptimal retinol concentration, and the prevalence was higher in women at late pregnancy, residing in the south, with younger age, and having underweight pre-pregnancy.

CONCLUSION

About one-fourth of pregnant or lactating women in China had suboptimal retinol concentrations that varied with phases of pregnancy and lactation, region of residence, and socio-demographic characteristics, indicating a need for population-specific public health strategies to optimize vitamin A status.

Biological evidence to define a vitamin A deficiency cutoff using total liver vitamin A reserves

Vitamin A is a fat-soluble vitamin involved in essential functions including growth, immunity, reproduction, and vision. The vitamin A Dietary Reference Intakes (DRIs) for North Americans suggested that a minimally acceptable total liver vitamin A reserve (TLR) is 0.07 µmol/g, which is not explicitly expressed as a vitamin A deficiency cutoff. The Biomarkers of Nutrition for Development panel set the TLR cutoff for vitamin A deficiency at 0.1 µmol/g based on changes in biological response of several physiological parameters at or above this cutoff. The criteria used to formulate the DRIs include clinical ophthalmic signs of vitamin A deficiency, circulating plasma retinol concentrations, excretion of vitamin A metabolites in the bile, and long-term storage of vitamin A as protection against vitamin A deficiency during times of low dietary intake. This review examines the biological responses that occur as TLRs are depleted. In consideration of all of the DRI criteria, the review concludes that induced biliary excretion and long-term vitamin A storage do not occur until TLRs are >0.10 µmol/g. If long-term storage is to continue to be part of the DRI criteria, vitamin A deficiency should be set at a minimum cutoff of 0.10 µmol/g and should be set higher during times of enhanced requirements where TLRs can be rapidly depleted, such as during lactation or in areas with high infection burden. In population-based surveys, cutoffs are important when using biomarkers of micronutrient status to define the prevalence of deficiency and sufficiency to inform public health interventions. Considering the increasing use of quantitative biomarkers of vitamin A status that indirectly assess TLRs, i.e. the modified-relative-dose response and retinol-isotope dilution tests, setting a TLR as a vitamin A deficiency cutoff is important for users of these techniques to estimate vitamin A deficiency prevalence. Future researchers and policymakers may suggest that DRIs should be set with regard to optimal health and not merely to prevent a micronutrient deficiency.