Vitamin A deficiency has declined in Malawi, but with evidence of elevated vitamin A in children

Prevalence and Determinants of Stunting-Anemia and Wasting-Anemia Comorbidities and Micronutrient Deficiencies in Children Under 5 in the Least-Developed Countries: A Systematic Review and Meta-analysis

CONTEXT

Despite shifting from addressing isolated forms of malnutrition to recognizing its multifaceted nature, evidence on the prevalence and determinants of micronutrient deficiencies, and their coexistence with undernutrition in children under 5, remains insufficient, unsystematic, and incohesive.

OBJECTIVE

The aim of this systematic review and meta-analysis was to assess the prevalence and determinants of stunting-anemia and wasting-anemia comorbidities and micronutrient deficiencies in children under 5 in the least-developed countries (LDCs).

DATA SOURCES

Electronic searches took place from January 15, 2023, to February 14, 2024, across multiple databases, including PubMed, Embase, Web of Science, SCOPUS, African Index Medicus (AIM), World Health Organization's Institutional Repository for Information Sharing (IRIS), and African Journals Online. The search spanned the years 2000 to 2024, yet it yielded eligible full-text English research articles from only 2005 to 2021 conducted in LDCs. Studies lacking quantitative data on malnutrition types and their determinants were excluded.

DATA EXTRACTION

Two independent authors assessed articles for bias and quality using Hoy et al's 10-item scale and Newcastle-Ottawa Scale (NOS) criteria. Prevalence and other details were extracted using a Joanna Briggs Institute Excel template. Authors extracted adjusted odds ratios (aORs) for determinant factors such as sex and vitamin A and iron supplementation.

DATA ANALYSIS

The search yielded 6248 articles from 46 LDCs. Sixty-nine articles, with a total sample size of 181 605, met inclusion criteria for the final meta-analysis. Vitamin A deficiency affected 16.32% of children, and iodine deficiency affected 43.41% of children. The pooled prevalence of wasting-anemia and stunting-anemia comorbidity was 5.44% and 19.47%, respectively. Stunting was associated with vitamin A deficiency (aOR: 1.54; 95% CI: 1.01-2.37), and not taking vitamin A supplementation was associated with iron-deficiency anemia (aOR: 1.37; 95% CI: 1.21-1.55).

CONCLUSION

A significant proportion of children under 5 in LDCs experienced stunting-anemia and wasting-anemia comorbidities and micronutrient deficiencies. This study underscores the urgent need to address factors driving these burdens.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023409483.

Repeated High-Dose Vitamin A Supplements, Standard of Care for Treating Xerophthalmia, Leads to Hypervitaminosis A in Piglets

BACKGROUND

Vitamin A (VA) deficiency and excess negatively affect development, growth, and bone health. The World Health Organization's standard of care for xerophthalmia due to VA deficiency, is 3 high-dose VA supplements of 50,000-200,000 IU, based on age, which may cause hypervitaminosis A in some individuals.

OBJECTIVES

This study measured VA status following 3 VA doses in 2 piglet studies.

METHODS

In Study 1, 5 groups of piglets (n = 10/group) were weaned 10 d postbirth to VA-free feed and orally administered 0; 25,000; 50,000; 100,000; or 200,000 IU VA ester on days 0, 1, and 7. On days 14 and 15, the piglets underwent the modified relative dose-response (MRDR) test for VA deficiency, and were killed. Tissues were collected for high-pressure liquid chromatography analysis. Study 2 used the same design in 3 groups (n = 13/group) weaned at 16 d and administered 0; 25,000; and 200,000 IU doses.

RESULTS

In Study 1 (final weight: 3.6 ± 0.7 kg), liver VA concentration was hypervitaminotic in 40%, 90%, and 100% of 50,000; 100,000; and 200,000 IU groups, respectively. The 25,000 IU group was 100% adequate, and the placebo group was 40% deficient. In Study 2 (final weight: 8.7 ± 0.8 kg), where 200,000 IU could be prescribed to infants with a similar body weight, 31% of the piglets were hypervitaminotic, the 25,000 IU group was 100% VA adequate, and the placebo group was 100% deficient. The MRDR test measured deficiency in 50% and 70% of the placebo group in each study but had 3 false positives among hypervitaminotic piglets in Study 1.

CONCLUSIONS

Repeated high-dose VA may cause hypervitaminosis, indicating dose sizes may need reduction. The MRDR resulted in false positives in a hypervitaminotic state during malnutrition and should be paired with serum retinyl ester evaluation to enhance VA status assessment in populations with overlapping interventions.

Respiratory syncytial virus-associated pneumonia in primary care in Malawi

OBJECTIVE

To identify the prevalence of respiratory syncytial virus (RSV) in a cohort of children under 5 years of age with World Health Organization (WHO)-defined pneumonia and the factors associated with developing severe RSV-associated community-acquired pneumonia (CAP) in primary care in a single centre in Northern Malawi.

METHODS

The BIOmarkers TO diagnose PnEumonia (BIOTOPE) study was a prospective cohort study conducted from March to June 2016 that took place in a primary care centre in Northern Malawi. Data from this study was used to identify the characteristics of children under 5 years of age who presented with RSV and WHO-defined CAP. Means, standard deviations, medians and ranges were calculated for continuous variables. A univariate logistic regression was performed to examine the potential predictor variables.

RESULTS

Four hundred and ninety-four infants presented with CAP and were eligible for inclusion in the study; RSV infection was detected in 205 (41.6%) of the infants. Eight factors were associated with increased risk for RSV CAP in the univariate model: age, born at term, presenting for care in June, crowded living environment, not being exclusively breastfed, not having received zinc or vitamin A supplementation in the last six months. Infants with RSV were more likely to have an oxygen saturation ≤92% compared to infants with other causes of pneumonia and more likely to have severe pneumonia as defined by the WHO.

CONCLUSION

This study supports that RSV-associated CAP is linked to modifiable and non-modifiable risk factors; further research is indicated to determine which interventions would be most impactful. Developing and implementing an infant or maternal vaccine could be a cost-effective way to prevent RSV-associated CAP and mortality in developing nations. More research is needed to understand seasonal patterns of CAP and research over extended periods can offer valuable insights on host, environmental and pathogen-specific factors that contribute to RSV-associated CAP.

Vitamin D Maintains Growth and Bone Mineral Density against a Background of Severe Vitamin A Deficiency and Moderate Toxicity in a Swine Model

Excessive vitamin A (VA) negatively impacts bone. Interactions between VA and vitamin D (VD) in bone health are not well-understood. This study used a traditional two-by-two factorial design. Pigs were weaned and randomized to four treatments (n = 13/group): -A-D, -A+D, +A-D, and +A+D for 3 and 5 wk. Serum, liver, kidney, adrenal glands, spleen, and lung were analyzed by ultra-performance LC. Growth was evaluated by weight measured weekly and BMD by DXA. Weights were higher in -A+D (18.1 ± 1.0 kg) and +A+D (18.2 ± 2.3 kg) at 5 wk than in -A-D (15.5 ± 2.1 kg) and +A-D (15.8 ± 1.5 kg). Serum retinol concentrations were 0.25 ± 0.023, 0.22 ± 0.10, 0.77 ± 0.12, and 0.84 ± 0.28 µmol/L; and liver VA concentrations were 0.016 ± 0.015, 0.0065 ± 0.0035, 2.97 ± 0.43, 3.05 ± 0.68 µmol/g in -A-D, -A+D, +A-D, and +A+D, respectively. Serum 25(OH)D3 concentrations were 1.5 ± 1.11, 1.8 ± 0.43, 27.7 ± 8.91, and 23.9 ± 6.67 ng/mL in -A-D, +A-D, -A+D, +A+D, respectively, indicating a deficiency in -D and adequacy in +D. BMD was highest in +D (p < 0.001). VA and the interaction had no effect on BMD. Dietary VD influenced weight gain, BMD, and health despite VA status.

Scientific opinion on the tolerable upper intake level for preformed vitamin A and β-carotene

Following two requests from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the revision of the tolerable upper intake level (UL) for preformed vitamin A and β-carotene. Systematic reviews of the literature were conducted for priority adverse health effects of excess vitamin A intake, namely teratogenicity, hepatotoxicity and endpoints related to bone health. Available data did not allow to address whether β-carotene could potentiate preformed vitamin A toxicity. Teratogenicity was selected as the critical effect on which to base the UL for preformed vitamin A. The Panel proposes to retain the UL for preformed vitamin A of 3000 μg RE/day for adults. This UL applies to men and women, including women of child-bearing age, pregnant and lactating women and post-menopausal women. This value was scaled down to other population groups using allometric scaling (body weight0.75), leading to ULs between 600 μg RE/day (infants 4-11 months) and 2600 μg RE/day (adolescents 15-17 years). Based on available intake data, European populations are unlikely to exceed the UL for preformed vitamin A if consumption of liver, offal and products thereof is limited to once per month or less. Women who are planning to become pregnant or who are pregnant are advised not to consume liver products. Lung cancer risk was selected as the critical effect of excess supplemental β-carotene. The available data were not sufficient and suitable to characterise a dose-response relationship and identify a reference point; therefore, no UL could be established. There is no indication that β-carotene intake from the background diet is associated with adverse health effects. Smokers should avoid consuming food supplements containing β-carotene. The use of supplemental β-carotene by the general population should be limited to the purpose of meeting vitamin A requirements.

Effects of primary or secondary prevention with vitamin A supplementation on clinically important outcomes: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis

OBJECTIVES

This systematic review with meta-analyses of randomised trials evaluated the preventive effects of vitamin A supplements versus placebo or no intervention on clinically important outcomes, in people of any age.

METHODS

We searched different electronic databases and other resources for randomised clinical trials that had compared vitamin A supplements versus placebo or no intervention (last search 16 April 2024). We used Cochrane methodology. We used the random-effects model to calculate risk ratios (RRs), with 95% CIs. We analysed individually and cluster randomised trials separately. Our primary outcomes were mortality, adverse events and quality of life. We assessed risks of bias in the trials and used Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) to assess the certainty of the evidence.

RESULTS

We included 120 randomised trials (1 671 672 participants); 105 trials allocated individuals and 15 allocated clusters. 92 trials included children (78 individually; 14 cluster randomised) and 28 adults (27 individually; 1 cluster randomised). 14/105 individually randomised trials (13%) and none of the cluster randomised trials were at overall low risk of bias. Vitamin A did not reduce mortality in individually randomised trials (RR 0.99, 95% CI 0.93 to 1.05; I²=32%; p=0.19; 105 trials; moderate certainty), and this effect was not affected by the risk of bias. In individually randomised trials, vitamin A had no effect on mortality in children (RR 0.96, 95% CI 0.88 to 1.04; I²=24%; p=0.28; 78 trials, 178 094 participants) nor in adults (RR 1.04, 95% CI 0.97 to 1.13; I²=24%; p=0.27; 27 trials, 61 880 participants). Vitamin A reduced mortality in the cluster randomised trials (0.84, 95% CI 0.76 to 0.93; I²=66%; p=0.0008; 15 trials, 14 in children and 1 in adults; 364 343 participants; very low certainty). No trial reported serious adverse events or quality of life. Vitamin A slightly increased bulging fontanelle of neonates and infants. We are uncertain whether vitamin A influences blindness under the conditions examined.

CONCLUSIONS

Based on moderate certainty of evidence, vitamin A had no effect on mortality in the individually randomised trials. Very low certainty evidence obtained from cluster randomised trials suggested a beneficial effect of vitamin A on mortality. If preventive vitamin A programmes are to be continued, supporting evidence should come from randomised trials allocating individuals and assessing patient-meaningful outcomes.

PROSPERO REGISTRATION NUMBER

CRD42018104347.

Vitamin A biomarkers were associated with α(1)-acid glycoprotein and C-reactive protein over the course of a human norovirus challenge infection

Retinol binding protein (RBP) is used as a proxy for retinol in population-based assessments of vitamin A deficiency (VAD) for cost-effectiveness and feasibility. When the cut-off of < 0·7 μmol/l for retinol is applied to RBP to define VAD, an equivalence of the two biomarkers is assumed. Evidence suggests that the relationship between retinol and RBP is not 1:1, particularly in populations with a high burden of infection or inflammation. The goal of this analysis was to longitudinally evaluate the retinol:RBP ratio over 1 month of follow-up among fifty-two individuals exposed to norovirus (n 26 infected, n 26 uninfected), test whether inflammation (measured as α-1-acid glycoprotein (AGP) and C-reactive protein (CRP)) affects retinol, RBP and the ratio between the two and assess whether adjusting vitamin A biomarkers for AGP or CRP improves the equivalence of retinol and RBP. We found that the median molar ratio between retinol and RBP was the same among infected (0·68) and uninfected (0·68) individuals. AGP was associated with the ratio and RBP individually, controlling for CRP, and CRP was associated with both retinol and RBP individually, controlling for AGP over 1 month of follow-up. Adjusting for inflammation led to a slight increase in the ratio among infected individuals (0·71) but remained significantly different from the expected value of one. These findings highlight the need for updated recommendations from the WHO on a cut-off value for RBP and an appropriate method for measuring and adjusting for inflammation when using RBP in population assessments of VAD.

Hepatic Vitamin A Concentrations and Association with Infectious Causes of Child Death

OBJECTIVES

To assess postmortem vitamin A (VA) concentrations in children under 5 years of age and evaluate the association between VA deficiency (VAD) and infectious causes of death (CoD).

STUDY DESIGN

In this cross-sectional study from the Child Health and Mortality Prevention Surveillance (CHAMPS) Network, liver biopsies collected within 72 hours of death were analyzed from 405 stillbirths and children under 5 years in Kenya and South Africa. Total liver VA (TLVA) concentrations were quantified using ultra-performance liquid chromatography, and cutoffs of ≤0.1 μmol/g, >0.1 to <0.7 μmol/g, ≥0.7 to <1.0 μmol/g, and ≥1.0 μmol/g were used to define VAD, adequate VA status, high VA, and hypervitaminosis A, respectively. CoD were determined by expert panel review.

RESULTS

Among 366 liver samples with viable extraction, pooled prevalences of VAD, adequacy, high VA, and hypervitaminosis were 34.2%, 51.1%, 6.0%, and 8.7%, respectively. VAD was more common among neonates compared with stillbirths, infants, or children, and among those with low birthweight (LBW), underweight, or stunting (P < .05). When adjusting for site, age, and sex, there was no significant association of VAD with increased infectious CoD (OR 1.9, 95% confidence interval [CI] 0.9, 3.8, P = .073). In stratified analyses, VA deficient boys, but not girls, had an increased risk of infectious CoD (OR 3.4, 95% CI 1.3, 10.3, P = .013).

CONCLUSIONS

Definitive postmortem assessment of VA status identified both VAD and VA excess among children under 5 years of age in Kenya and South Africa. VAD in boys was associated with increased risk of infectious mortality. Our findings may inform a transition from universal VA supplementation (VAS) to targeted strategies in certain countries.

Aligning the Epidemiology of Malnutrition with Food Fortification: Grasp Versus Reach

Large-scale food fortification (LSFF) has been recognized as one of the most cost-effective interventions to improve the intake of vitamins and minerals and decrease the burden of micronutrient deficiency. Indeed, the simple addition of micronutrients to staple foods, such as wheat, maize and rice, or condiments, including salt and bouillon, has tremendous potential to impact malnutrition. However, most LSFF programs have been poorly designed and have not taken into consideration critical inputs, including current levels of nutrient inadequacy and per capita consumption of different food vehicles when deciding which nutrients to add and at what concentrations. LSFF programs, like some other nutrition interventions, also tend to have low coverage and reach and lack monitoring to measure this and course correct. These program design flaws have resulted in limited effectiveness and have made it difficult to determine how best to harmonize LSFF with other interventions to reduce micronutrient deficiencies, including efforts to enhance dietary diversity, biofortification and supplementation. Furthermore, LSFF has often been touted as a population-based intervention, but in fact has heterogenous effects among sub-groups, particularly those with limited access to or inability to afford fortified foods, as well as those with higher physiological requirements, such as pregnant and lactating women. This article focuses on these limitations and the concerted efforts underway to improve the collection, analysis, and use of data to better plan LSFF programs, track implementation, and monitor coverage and impact. This includes a more sophisticated secondary analysis of existing data, innovations to increase the frequency of primary data collection and programmatically relevant visualizations of data of sub-national estimates. These improvements will enable better use of data to target resources and programmatic efforts to reach those who stand to benefit most from fortification.

The Effects of One Egg Per Day on Vitamin A Status Among Young Malawian Children: A Secondary Analysis of a Randomized Controlled Trial

Background

Vitamin A deficiency (VAD) is common in populations with limited dietary diversity and access to vitamin A-rich foods.

Objectives

This analysis aimed to determine the impact of supplementing children's diets with 1 egg/d on the concentration of plasma retinol and RBP and the prevalence of VAD.

Methods

Children age 6-9 mo living in the Mangochi district of Malawi were individually randomly assigned to receive 1 egg/d for 6 mo (n = 331) or continue their usual diet (n = 329) in the Mazira trial (clinicaltrials.gov; NCT03385252). This secondary analysis measured plasma retinol by HPLC and RBP, CRP, and α-1-acid glycoprotein (AGP) by ELISA techniques at enrollment and 6 mo follow-up. Retinol and RBP were adjusted for inflammation, and mean concentrations were compared between groups using linear regression models. In addition, prevalence ratios of VAD (retinol <0.7 μmol/L) were compared between groups using log-binomial or modified Poisson regression models.

Results

After 6 mo of study participation, 489 were assessed for retinol (egg: n = 238; control: n = 251), and 575 (egg: n = 281; control: n = 294) were assessed for RBP. Prevalence of inflammation (CRP >5 mg/L or AGP >1 g/L: 62%) and inflammation-adjusted VAD (7%) at enrollment did not differ between groups. At follow-up, the egg intervention group did not differ from the control in inflammation-adjusted retinol [geometric mean (95% CI); egg: 1.10 μmol/L (1.07, 1.13); control: 1.08 (1.05, 1.12)], RBP [egg: 0.99 μmol/L (0.96, 1.02); control: 0.97 (0.94, 1.00)], or prevalence of VAD [egg: 6%; control: 3%; prevalence ratio: 1.87 (0.83, 4.24)].

Conclusions

Provision of 1 egg/d did not impact VAD, plasma retinol, or RBP among young children in rural Malawi, where the prevalence of VAD was low. Curr Dev Nutr 2023;x:xx.This trial was registered at [clinicaltrials.gov] as [NCT03385252].

Estimates of child mortality reductions attributed to vitamin A supplementation in sub-Saharan Africa: scale up, scale back, or refocus?

BACKGROUND

Vitamin A supplementation (VAS) has been implemented in over 82 countries globally, primarily because of its beneficial effect in preventing child mortality. Secular reductions in child mortality and the implementation of alternative programs to promote vitamin A intake have led to questions on the need for national VAS programs.

OBJECTIVES

This study aimed to estimate child mortality changes related to VAS using current, scale-back, and scale-up coverage scenarios.

METHODS

Data related to demographic characteristics, fertility, intervention coverage, anthropometry, child mortality and cause-of-death structure were integrated into the Lives Saved Tool (LiST). We estimated the cause-specific (LiST model) and all-cause mortality reductions related to VAS based on evidence from recent meta-analyses.

RESULTS

Between 2008 and 2018, VAS coverage declined in most sub-Saharan African (SSA) countries. In 2019 alone, 12% and 24% reductions in all-cause mortality related to VAS were expected to avert from 105,332 to 234,704 child deaths, respectively, in SSA; whereas the cause-specific mortality model (LiST) estimated that 141,670 child deaths were averted in 2019. Estimates of VAS-related child mortality reductions were highly variable among countries. Our scaling-back scenario led to highly variable country-level results, with expected increases in mortality rates, from a low of 0.04/1000 live births to as high as 49.3/1000 live births, suggesting that some countries could start considering scaling back, while others need to scale up.

CONCLUSIONS

Excess child mortality that would be preventable by VAS has declined, but is still significant in many SSA countries. While scale-up of VAS is needed for most of the countries, scaling back can also be considered in some countries. Policy decisions, however, should be guided by more recent data on food consumption, vitamin A statuses, child health, and vitamin A fortification coverage.

Vitamin A supplementation among 9-59 month old children in India: geospatial perspectives and implications for targeted coverage

Introduction

Vitamin A supplementation (VAS) is yet to reach all Indian children aged 9–59 months, despite guidelines for universal coverage. This study mapped geospatial patterns underlying VAS coverage across two policy-relevant administrative unit levels (states and districts) in India. The relationship between spatial distribution of VAS coverage and vitamin A deficiency (VAD) prevalence was also investigated.

Methods

The study draws on nationally representative cross-sectional data collected during National Family and Health Survey 4 (NFHS-4) and Comprehensive National Nutritional Survey (CNNS). VAS coverage was estimated using information obtained during NFHS-4 from mothers about whether their children (n=204 645) had received VAS within 6 months of the survey. VAD prevalence estimates were based on serum retinol measurements during CNNS in under-five children (n=9563). State-level and district-level choropleth maps of VAS coverage were constructed. Spatial patterns were probed using Moran’s statistics, scatter plots and local indicators of spatial association (LISA). Relationship between VAS coverage (as an explanatory variable) and VAD prevalence was explored using spatial autoregressive models.

Results

VAS coverage in India (overall 60.5%) ranged from 29.5% (Nagaland) to 89.5% (Goa) across the various states/union territories. Among districts, it ranged from 12.8% (Longleng district, Nagaland) to 94.5% (Kolar district, Karnataka). The coverage exhibited positive spatial autocorrelation, more prominently at the district-level (univariate Moran’s I=0.638, z-value=25.614, pseudo p value=0.001). LISA maps identified spatial clusters of high coverage and low coverage districts. No significant spatial association was observed between VAS coverage and VAD prevalence in the states during spatial error (R²=0.07, λ=0.30, p value=0.14) and spatial lag (R²=0.05, ρ=0.25, p value=0.23) regression.

Conclusion

Two out of every five eligible Indian children were not supplemented with vitamin A. The coverage was geographically heterogeneous with discernible spatial patterns. Their consequences on vitamin A status and associated health effects in the community deserve close monitoring.

Time Since Dose and Dietary Vitamin A Intake Affect Tracer Mixing in the 13C-Retinol Isotope Dilution Test in Male Rats

BACKGROUND

Retinol isotope dilution (RID) estimates total liver vitamin A reserves (TLRs), the gold-standard vitamin A (VA) biomarker. RID equation assumptions are based on limited data.

OBJECTIVES

We measured the impact of tracer choice, mixing period, and VA intake on tracer mixing [ratio of tracer enrichment in serum to that in liver stores (S)] in VA-deficient, -adequate, and hypervitaminotic rats.

METHODS

Study 1 was a 3 × 2 × 3 design (18 groups, n = 5/group). Male Sprague-Dawley rats (21 d old) received 50, 100, or 3500 nmol VA/d for 21 d, were administered 52 nmol 13C2- or 13C10-retinyl acetate orally, and killed 5, 10, or 15 d later. Unlabeled VA (50 nmol/d) was given on days 11-14. Study 2 used 100 nmol VA/d for 21 d with 3 groups (n = 6-7): 52 nmol 13C2- or 13C10-retinyl acetate and 100 nmol VA/d throughout 14-d mixing, or 13C2-retinyl acetate without VA. Repeated-measures, 1-factor, and 3-factor ANOVAs were used for analysis.

RESULTS

Mean ± SD TLRs (μmol/g liver) reflected intake: 0.11 ± 0.04 (50 nmol VA/d), 0.16 ± 0.04 (100 nmol VA/d), and 5.07 ± 1.58 (3500 nmol VA/d) in Study 1 and 0.24 ± 0.08 (100 nmol VA/d) in Study 2. In Study 1, mean ± SD S was 1.65 ± 0.26 (5 d), 1.16 ± 0.09 (10 d), and 0.92 ± 0.08 (15 d). The interactions tracer*VA intake and time*VA intake were significant between days 10 and 15 (P < 0.05). In Study 2, mean ± SD S was 1.07 ± 0.02 without VA during mixing, and 0.81 ± 0.04 (13C2) and 0.79 ± 0.03 (13C10) with VA intake throughout. Estimated:measured TLRs varied by VA intake and time in Study 1 but not between groups in Study 2.

CONCLUSIONS

The 13C-content effect on RID through S is inconsistent. S is highly variable at 5 d, contraindicating early-time point RID. VA intake effects on S vary with timing and quantity. Assuming S = 0.8 at 14 d with consistent VA intake in human studies is likely appropriate.

Barriers to and Enablers of the Inclusion of Micronutrient Biomarkers in National Surveys and Surveillance Systems in Low- and Middle-Income Countries

Including biomarkers of micronutrient status in existing or planned national surveys or surveillance systems is a critical step in improving capacity to promote, design, monitor, and evaluate micronutrient policies and programs. We aimed to identify the barriers to and enablers of the inclusion of micronutrient biomarker assessment in national surveys and surveillance systems, to identify the main challenges faced during the survey process, and to review experiences using existing platforms for micronutrient surveys. We conducted a series of key informant interviews with in-country and external representatives from six countries where national-level data on micronutrient status were collected in the past 5 years: Cambodia, Pakistan, Malawi, Uganda, Ghana, and Uzbekistan. Micronutrients associated with specific public health programs were always prioritized for inclusion in the survey. If funding, time, and/or logistics allowed, other considered micronutrients were also included. The most important and frequently reported barrier to inclusion of a more comprehensive panel of micronutrient biomarkers was inadequate funding to cover the laboratory analysis cost for all micronutrients considered at the planning stage. Government support and commitment was stressed as the most important enabling factor by all key informants. Advocacy for funding for micronutrient status assessment is needed.

Modeling food fortification contributions to micronutrient requirements in Malawi using Household Consumption and Expenditure Surveys

Large-scale food fortification may be a cost-effective intervention to increase micronutrient supplies in the food system when implemented under appropriate conditions, yet it is unclear if current strategies can equitably benefit populations with the greatest micronutrient needs. This study developed a mathematical modeling framework for comparing fortification scenarios across different contexts. It was applied to model the potential contributions of three fortification vehicles (oil, sugar, and wheat flour) toward meeting dietary micronutrient requirements in Malawi through secondary data analyses of a Household Consumption and Expenditure Survey. We estimated fortification vehicle coverage, micronutrient density of the diet, and apparent intake of nonpregnant, nonlactating women for nine different micronutrients, under three food fortification scenarios and stratified by subpopulations across seasons. Oil and sugar had high coverage and apparent consumption that, when combined, were predicted to improve the vitamin A adequacy of the diet. Wheat flour contributed little to estimated dietary micronutrient supplies due to low apparent consumption. Potential contributions of all fortification vehicles were low in rural populations of the lowest socioeconomic position. While the model predicted large-scale food fortification would contribute to reducing vitamin A inadequacies, other interventions are necessary to meet other micronutrient requirements, especially for the rural poor.

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.