Estimates of the components of nutrient intake variation are needed for modelling distributions of usual intake or predicting the usual intake of individuals. Season is a potential source of ...variation in nutrient intakes in addition to within- and between-person variation, particularly in low- or middle-income countries. We aimed to describe seasonal variation in nutrient intakes and estimate within-person, between-person and other major components of intake variance among Zambian children. Children from rural villages and peri-urban towns in Mkushi District, Zambia aged 4-8 years were enrolled in the non-intervened arm of a randomised controlled trial of pro-vitamin A carotenoid biofortified maize (n 200). Up to seven 24-h dietary recalls per child were obtained at monthly intervals over a 6-month period covering the late post-harvest (August-October), early lean (November-January) and late lean (February-April) seasons (2012-2013). Nutrient intakes varied significantly by season. For energy and most nutrients, intakes were highest in the early lean season and lower in the late post-harvest and late lean seasons. Season and recall on a market day had the strongest effects on nutrient intakes among covariates examined. Unadjusted within- to between-person variance ratios ranged from 4·5 to 31·3. In components of variance models, season accounted for 3-20 % of nutrient intake variance. Particularly in rural settings in low- and middle-income countries, where availability of locally grown, nutrient-rich foods may vary seasonally, studies should include replicates across seasons to more precisely estimate long-term usual intakes.
Dietary diversity scores and dichotomous indicators derived from them are widely used to assess dietary quality, and specific scoring methods have been recommended for women and 6- to 23-mo-old ...children. However, there is no specific score recommended for older children and the effect of seasonal dietary changes on score performance is not well documented.
We assessed performance of 2 recommended dietary diversity scores as indicators of dietary quality over 3 seasons.
We conducted 7 repeat 24-h dietary recalls among 4- to 8-y-old rural Zambian children (n = 200) over 6 mo. Dietary diversity was assessed using a 7-food group score for assessing infant and young child feeding (DDS-IYCF) and a 10-food group score for use among women of reproductive age (DDS-W). Micronutrient intake adequacy was described by mean probability of adequacy (MPA) over 11 micronutrients. Longitudinal models were fit to test the association between each score and MPA overall and by season. Receiver operating characteristic (ROC) curves were used to describe indicator performance of each score.
Mean ± SE scores were 4.11 ± 0.03 for DDS-IYCF and 4.39 ± 0.03 for DDS-W. Both scores varied by season, but DDS-W better reflected seasonal dietary changes. Across seasons, MPA increased 1–6 percentage points/unit increase in DDS-IYCF or 1–10 percentage points for DDS-W (P < 0.05). Score performance as a predictor of MPA > 0.75 was moderate, with area under the ROC curve values by season ranging from 0.63 to 0.77 for DDS-IYCF and from 0.66 to 0.72 for DDS-W.
DDS-W performed better than DDS-IYCF in characterizing seasonal variability and micronutrient adequacy among rural Zambian children.
Biofortified maize, designed as an intervention strategy to prevent vitamin A deficiency, can provide upwards of 15 μg β-carotene per g dry weight. Some varieties also have elevated concentrations of ...other carotenoids. We conducted a cluster randomized, controlled feeding trial in rural Zambia to test the impact of daily consumption of biofortified maize over a 6-month period on vitamin A status. Serum concentrations of retinol and carotenoids were assessed by high-performance liquid chromatography. Data on circulating carotenoids by intervention group in 679 children are reported here. As previously shown, consumption of this β-carotene-rich maize significantly improved serum β-carotene concentrations (0.273 vs. 0.147 μmol/L, p < 0.001, in this subset of children). Here we show significant increases in α-carotene, β-cryptoxanthin, and zeaxanthin (p < 0.001). There was no impact on lutein or lycopene concentrations. Consumption of biofortified maize can have broader implications beyond the control of vitamin A deficiency (Trial registration: NCT01695148).
Background
Malaria causes anemia by destruction of red blood cells and inhibition of erythropoiesis.
Objective
We assessed whether the magnitude of the malaria‐specific effect on anemia differs by ...age, during low and high malaria seasons.
Method
In rural Zambian children participating in a pro‐vitamin A efficacy trial, we estimated differences in the prevalence of anemia (defined as hemoglobin < 110 g/L for children < 60 months. and < 115 g/L in older children) by malaria status and assessed malaria‐age interactions. Regression models (with anemia as the outcome) were used to model malaria‐age interaction in both the low and high malaria seasons, controlling for potential confounders.
Results
Average age was 68 months at baseline (n = 820 children). In the low malaria season, anemia prevalence was 29% in malaria‐negative children and 54% in malaria‐positive children (p < 0.001), with no malaria‐age interactions (p = 0.44). In the high malaria season, anemia prevalence was 41% in malaria‐negative children and 54% in malaria‐positive children (p < 0.001), with significant malaria‐age interactions (p = 0.02 for anemia). Age‐stratified prevalence of anemia in malaria positive versus negative children was 67.0% versus 37.1% (in children < 60 months); 57.0% versus 37.2% (in 60–69 months.); 46.8% versus 37.2% (in 70–79 months.); 37.0% versus 37.3% (in 80–89 months) and 28.0% versus 37.4% (in 90+ months).
Conclusions
Malarial anemia is most severe in younger children, especially when transmission is intense. Anemia control programs must prioritize this vulnerable group.
To determine the prevalence of vitamin A deficiency, infection and adequacy of vitamin A intakes among Zambian children, and the contribution of dietary vitamin A and infection to vitamin A status.
A ...cross-sectional survey of vitamin A intakes by the 24 h recall method, vitamin A status by plasma retinol and the modified relative dose-response test, and infection by acute-phase proteins.
Rural communities in Central and Eastern Provinces of Zambia.
Children 2-5 years of age.
The prevalence of vitamin A deficiency was 56 % by plasma retinol, 48 % with infection-adjusted plasma retinol and 22 % by the modified relative dose-response test. The majority of children (61 %) had a current infection. Vitamin A intakes were relatively high (331 to 585 μg retinol activity equivalents/d in the harvest/early post-harvest and late post-harvest seasons, respectively) and the prevalence of inadequate intakes was <1 % when compared with the Estimated Average Requirement (210 and 275 μg retinol activity equivalents/d for children aged 1-3 and 4-8 years, respectively). Elevated α-1-acid glycoprotein was negatively associated with plasma retinol (P < 0·0 0 1) and vitamin A intake was positively associated with plasma retinol (P < 0·05), but only when estimated assuming a 26:1 retinol equivalence for provitamin A from green and yellow vegetables.
Infection and vitamin A intakes were significant determinants of plasma retinol. We cannot conclude which indicator more accurately represents the true vitamin A status of the population. Reasons for the persistent high prevalence of vitamin A deficiency in the presence of adequate vitamin A intakes are unclear, but the high rates of infection may play a role.
Impaired dark adaptation is an early functional indicator of vitamin A deficiency that may be prevented by regular dietary intake of foods containing provitamin A carotenoids.
We tested the impact of ...provitamin A carotenoid-biofortified maize consumption (∼15 μg β-carotene/g) on dark adaptation in Zambian children.
We used a cluster-randomized trial of children aged 4-8 y (n = 1024) in Mkushi District, Zambia, and compared the regular consumption (2 meals/d, 6 d/wk for 6 mo) of biofortified orange maize (OM) to white maize (WM). The primary outcome was the serum retinol response. In a random sample (n = 542), we used a digital pupillometer to test pre- and postintervention responses to graded light stimuli (-2.9 to 0.1 log cd/m
) in a dark-adapted state.
At baseline, 11.7% of the children had serum retinol <0.7 μmol/L, 14.4% had impaired dark adaptation (pupillary threshold ≥ -1.11 log cd/m
), and 2.3% had night blindness. The mean ± SD pupillary responsiveness to light stimuli was poorer at baseline in the OM group (16.1% ± 6.6%) than the WM group (18.1% ± 6.4%) (P = 0.02) but did not differ at follow-up (OM: 17.6% ± 6.5%; WM: 18.3% ± 6.5%). Among children with serum retinol <1.05 μmol/L at baseline, there was greater improvement in pupillary responsiveness in the OM group (2.2%; 95% CI: 0.1%, 4.3%) than the WM group (0.2%; 95% CI: -1.1%, 1.5%; P = 0.01), but there were no differences in children with adequate baseline status. We found no effect of treatment on pupillary threshold or night blindness.
The regular consumption of provitamin A carotenoid-biofortified maize increased pupillary responsiveness among children with marginal or deficient vitamin A status, providing evidence of a functional benefit to consuming this biofortified crop. This trial was registered at clinicaltrials.gov as NCT01695148.
Vitamin A deficiency remains a nutritional concern in sub-Saharan Africa. Conventionally bred maize hybrids with high provitamin A carotenoid concentrations may have the potential to improve vitamin ...A status in maize-consuming populations.
We evaluated the efficacy of regular provitamin A carotenoid-biofortified "orange" maizemeal (∼15 μg β-carotene/g) consumption in improving vitamin A status and reducing vitamin A deficiency in children.
This was a cluster-randomized controlled trial in the rural farming district of Mkushi, Zambia. All 4- to 8-y-old children in an ∼400-km(2) area were identified and grouped by proximity into clusters of ∼15-25 children. We randomly assigned clusters to 1) orange maizemeal (n = 25), 2) white maizemeal (n = 25), or 3) a parallel, nonintervention group (n = 14). Children in intervention clusters (n = 1024) received 200 g maizemeal for 6 d/wk over 6 mo; the maizemeal was prepared according to standardized recipes and served in cluster-level kitchens. Staff recorded attendance and leftovers. We collected venous blood before and after the intervention to measure serum retinol, β-carotene, C-reactive protein, and α1-acid glycoprotein.
Intervention groups were comparable at baseline, and vitamin A status was better than anticipated (12.1% deficient on the basis of serum retinol <0.7 μmol/L). Although attendance at meals did not differ (85%), median daily maize intake was higher in white (154 g/d) than in orange (142 g/d) maizemeal clusters. At follow-up, mean serum β-carotene was 0.14 μmol/L (95% CI: 0.09, 0.20 μmol/L) higher in orange maizemeal clusters (P < 0.001), but mean serum retinol (1.00 ± 0.33 μmol/L overall) and deficiency prevalence (17.1% overall) did not differ between arms.
In this marginally nourished population, regular biofortified maizemeal consumption increased serum β-carotene concentrations but did not improve serum retinol. This trial was registered at clinicaltrials.gov as NCT01695148.
Abstract only
Objectives
Provitamin A carotenoid biofortified “orange” maize has been developed as a vitamin A deficiency control strategy using selective breeding for the β‐carotene hydroxylase‐1 ...gene, which increases β‐carotene, β‐cryptoxanthin, and zeaxanthin in the endosperm. We conducted a cluster‐randomized trial to test the impact of orange maize consumption (a predominantly β‐carotene‐rich variety) on serum retinol concentration in rural Zambian children (4–8 y). In the present analysis, we tested the intervention's impact on circulating carotenoids.
Methods
Children (n=1024, 4–8 y) were cluster‐randomized to receive 200 g dry weight/d orange or conventional “white” maize prepared with standardized low‐vitamin A relishes, 6 d/w for 6 m. The carotenoid profile was assessed in baseline and follow‐up serum samples in a subset (n=321 white, n=358 orange) of children. We assessed differences in log‐transformed carotenoids, expressed as geometric means and 95% confidence limits, accounting for cluster randomization.
Results
Baseline carotenoids did not differ between groups. There were no differences in lycopene and lutein between groups at follow‐up. Other carotenoids increased significantly (p<0.001) in orange vs white groups following the six‐month intervention: β‐carotene 273 (254,292) vs 147 (135,160) nmol/L, α‐carotene 19.7 (18.4,21.1) vs 10.6 (9.9,11.3) nmol/L, β‐cryptoxanthin 36.1 (33.6,38.8) vs 12.6 (11.8,13.5) nmol/L, α‐cryptoxanthin 18.7 (17.4,20.1) vs 8.9 (8.4,9.4) nmol/L, zeaxanthin 127 (119,135) vs 81 (75,88) nmol/L.
Conclusions
Children regularly consuming a biofortified maize variety bred primarily for β‐carotene had higher concentrations of other provitamin A carotenoids and zeaxanthin, suggesting the potential for health benefits beyond vitamin A deficiency control.
Support or Funding Information
Supported by HarvestPlus.
To estimate the burden of anemia attributable to malaria, inflammation, and deficiency of iron or vitamin A during low and high malaria seasons among Zambian children.
From a cohort of children ...(n = 820), 4-8 years of age participating in a randomized controlled trial of pro-vitamin A, we estimated attributable fractions for anemia (hemoglobin of <110 or 115 g/L, by age) owing to current malaria or inflammation (C-reactive protein of >5 mg/L, or α-1 acid glycoprotein of >1 g/L, or both), and current or prior iron deficiency (ID; defined as low ferritin <12 or 15 μg/L for age <5 or >5 years or functional ID soluble transferrin receptor of >8.3 mg/L or both) and vitamin A deficiency (retinol of <0.7 μmol/L), during low and high malaria seasons, using multivariate logistic regression. Serum ferritin, soluble transferrin receptor, and retinol were adjusted for inflammation.
The burden of anemia independently associated with current malaria, inflammation, ID, and vitamin A deficiency in the low malaria season were 12% (P < .001), 6% (P = .005), 14% (P = .001), and 2% (P = .07), respectively, and 32% (P < .001), 15% (P < .001), 10% (P = .06), and 2% (P = .06), respectively, in the high malaria season. In both seasons, functional ID was independently associated with more anemia (approximately 11%) than low ferritin (approximately 4%). Anemia and ID in the low malaria season, accounted for 20% (P < .001) and 4% (P = .095) of the anemia in the subsequent high malaria season.
Anemia in this population is strongly linked to malaria, inflammation, and functional ID, and to a lesser extent, low iron stores. Integrated control strategies are needed.
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