Age-specific differences in the magnitude of malaria-related anemia during low and high malaria seasons in rural Zambian children.

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.

Within-person, between-person and seasonal variance in nutrient intakes among 4- to 8-year-old rural Zambian children.

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.

Relative Contributions of Malaria, Inflammation, and Deficiencies of Iron and Vitamin A to the Burden of Anemia during Low and High Malaria Seasons in Rural Zambian Children.

OBJECTIVE: 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. STUDY DESIGN: 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. RESULTS: 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. CONCLUSIONS: 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.

Nutritional Status Measures Are Correlated with Pupillary Responsiveness in Zambian Children.

Background: Impairments in visual function have been well characterized in vitamin A deficiency. However, eye function may also be sensitive to other nutrient deficiencies. Objective: We examined associations between visual function-characterized by pupillary threshold or pupillary responsiveness-and nutritional status in Zambian children. Methods: We used digital pupillometry to measure visual responses to calibrated light stimuli (-2.9 to 0.1 log cd/m2) among dark-adapted children aged 4-8 y (n = 542). We defined pupillary threshold as the first light stimulus at which pupil diameter decreased by ≥10% and considered a pupillary threshold ≥-0.9 log cd/m2 as impaired. Pupillary responsiveness was defined by absolute percentage of change in pupil diameter from pre- to poststimulus. We tested associations between these measures and serum concentrations of retinol, ß-carotene, ferritin, soluble transferrin receptor, and hemoglobin (Hb <11.0 or 11.5 g/dL were used to define anemia, depending on age), as well as anthropometric indexes, with the use multilevel mixed-effects models. Results: Pupillary threshold was correlated only with serum retinol (r = 0.12, P < 0.05). The strongest correlates of pupillary responsiveness were Hb (r = -0.16, P < 0.01), height-for-age z score (r = 0.14, P < 0.05), weight-for-age z score (r = 0.14, P < 0.05), and soluble transferrin receptor (r = 0.12, P < 0.05). In multivariate models, anemia was positively associated with pupillary responsiveness (ß = 2.99; 95% CI: 1.26, 4.72). Conclusions: In this marginally nourished population, we found positive correlations between vitamin A status, iron status, or anthropometric indexes and visual function. Hb was negatively associated with visual function, with greater pupillary responsiveness among anemic children. We posit that this may signal altered parasympathetic activity, possibly driven by infection. Future studies should consider a broader range of indicators to better characterize the relation between nutrition and visual function. This trial was registered at clinicaltrials.gov as NCT01695148.

Usual nutrient intake adequacy among young, rural Zambian children.

Inadequate nutrient intakes put children at risk for impaired growth and development. We described diet, usual intakes of energy and macro- and micronutrients and prevalence of nutrient intake adequacies among 4-8-year-old Zambian children. Children not yet in school and living in Mkushi District, Central Province, Zambia were enrolled into an efficacy trial of pro-vitamin A biofortified maize. Children in the non-intervened arm were included in this analysis (n 202). Dietary intake data were collected by tablet-based 24-h recall on a monthly basis over the 6-month trial. Observed nutrient intakes were derived from reported food quantities, standard recipes and food composition tables. Usual nutrient intake distributions were modelled based on observed intakes. Prevalence of inadequacy was estimated by comparing the usual nutrient intake distribution to the nutrient requirement distribution. Frequency and quantity of consumption of commonly reported foods were described and key sources of energy and nutrients were identified. Median usual energy intake was 6422 kJ/d (1535 kcal/d). Most childrens' macronutrient intakes fell within recommended ranges (74-98 %). Estimated prevalences of inadequate intakes of Fe, folate, vitamin B12 and Ca were 25, 57, 76 and >99 %, respectively. Estimated prevalences of inadequacy for other micronutrients were low (0·1-2·2 %). Commonly consumed foods included maize, vegetable oil, tomatoes, rape leaves and small fish (>0·6 servings/d), whereas meat, eggs or dairy were rarely eaten (<0·2 servings/d). These findings suggest that the heavily plant-based diet of rural Zambian children provides inadequate Ca, folate, vitamin B12 and Fe to meet recommended nutrient intakes.

A 10-Food Group Dietary Diversity Score Outperforms a 7-Food Group Score in Characterizing Seasonal Variability and Micronutrient Adequacy in Rural Zambian Children.

Background: 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. Objective: We assessed performance of 2 recommended dietary diversity scores as indicators of dietary quality over 3 seasons. Methods: 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. Results: 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. Conclusions: DDS-W performed better than DDS-IYCF in characterizing seasonal variability and micronutrient adequacy among rural Zambian children.

Impact of biofortified maize consumption on serum carotenoid concentrations in Zambian children.

Biofortified maize, designed as an intervention strategy to prevent vitamin A deficiency, can provide upwards of 15 µg ß-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 ß-carotene-rich maize significantly improved serum ß-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, ß-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).

Comparability of Inflammation-Adjusted Vitamin A Deficiency Estimates and Variance in Retinol Explained by C-Reactive Protein and α1-Acid Glycoprotein during Low and High Malaria Transmission Seasons in Rural Zambian Children.

Inflammation-induced hyporetinolemia (IIH), a reduction in serum retinol (SR) during inflammation, may bias population estimates of vitamin A deficiency (VAD). The optimal adjustment for IIH depends on the type and extent of inflammation. In rural Zambian children (4-8 years, N = 886), we compared three models for defining inflammation: α-1-acid glycoprotein (AGP) only (inflammation present if > 1 g/L or normal if otherwise), C-reactive protein (CRP) only (moderate inflammation, 5-15 mg/L; high inflammation, > 15 mg/L; or normal if otherwise) and a combined model using both AGP and CRP to delineate stages of infectious episode. Models were compared with respect to 1) the variance in SR explained and 2) comparability of inflammation-adjusted VAD estimated in low and high malaria seasons. Linear regression was used to estimate the variance in SR explained by each model and in estimating the adjustment factors used in generating adjusted VAD (retinol < 0.7 µmol/L). The variance in SR explained were 2% (AGP-only), 11% (CRP-only), and 11% (AGP-CRP) in the low malaria season; and 2% (AGP-only), 15% (CRP-only), and 12% (AGP-CRP) in the high malaria season. Adjusted VAD estimates in the low and high malaria seasons differed significantly for the AGP (8.2 versus 13.1%) and combined (5.5 versus 9.1%) models but not the CRP-only model (6.1 versus 6.3%). In the multivariate regression, a decline in SR was observed with rising CRP (but not AGP), in both malaria seasons (slope = -0.06; P < 0.001). In this malaria endemic setting, CRP alone, as opposed to CRP and AGP, emerged as the most appropriate model for quantifying IIH.

Malaria exacerbates inflammation-associated elevation in ferritin and soluble transferrin receptor with only modest effects on iron deficiency and iron deficiency anaemia among rural Zambian children.

OBJECTIVE: In 4- to 8-year-old Zambian children (n = 744), we evaluated the effects of adjusting for inflammation (α1-acid glycoprotein >1 g/l), with or without additional adjustment for malaria, on prevalence estimates of iron deficiency (ID) and iron deficiency anaemia (IDA) during low malaria (LowM) and high malaria (HighM) transmission seasons. METHODS: To estimate adjustment factors, children were classified as: (i) reference (malaria negative without inflammation), (ii) inflammation without malaria (I), (iii) malaria without inflammation (M) and (iv) inflammation with malaria (IM). We estimated the unadjusted ID or IDA prevalence, and then adjusted for inflammation alone (IDI or IDAI ) or inflammation and malaria (IDIM or IDAIM ). RESULTS: Mean ferritin was 38 (reference), 45 (I), 43 (M) and 54 µg/l (IM) in LowM, increasing to 44, 56, 96 and 167 µg/l, respectively, in HighM. Corresponding mean sTfR was 6.4, 6.9, 7.9 and 8.4 mg/l in LowM, increasing to 8.2, 9.2. 8.7 and 9.7 mg/l in HighM. Ferritin-based ID, IDI and IDIM were 7.8%, 8.7% or 9.1%, respectively, in LowM and 4.6%, 10.0% or 11.7%, respectively, in HighM. Corresponding soluble transferrin receptor (sTfR)-based estimates were 27.0%, 24.1% and 19.1%, respectively, in LowM, increasing to 53.6%, 46.5% and 45.3%, respectively, in HighM. Additional adjustment for malaria resulted in a ~1- to 2-percentage point change in IDA, depending on biomarker and season. CONCLUSIONS: In this population, malaria substantially increased ferritin and sTfR concentrations, with modest effects on ID and IDA prevalence estimates.

High Iron Stores in the Low Malaria Season Increase Malaria Risk in the High Transmission Season in a Prospective Cohort of Rural Zambian Children.

Background: Higher iron stores, defined by serum ferritin (SF) concentration, may increase malaria risk.Objective: We evaluated the association between SF assessed during low malaria season and the risk of malaria during high malaria season, controlling for inflammation.Methods: Data for this prospective study were collected from children aged 4-8 y (n = 745) participating in a biofortified maize efficacy trial in rural Zambia. All malaria cases were treated at baseline (September 2012). We used baseline SF and malaria status indicated by positive microscopy at endline (March 2013) to define exposure and outcome, respectively. Iron status was defined as deficient (corrected or uncorrected SF <12 or <15 µg/L, depending on age <5 or ≥5 y, respectively), moderate (<75 µg/L, excluding deficient), or high (≥75 µg/L). We used a modified Poisson regression to model the risk of malaria in the high transmission seasons (endline) as a function of iron status assessed in the low malaria seasons (baseline).Results: We observed an age-dependent, positive dose-response association between ferritin in the low malaria season and malaria incidence during the high malaria season in younger children. In children aged <6 y (but not older children), we observed a relative increase in malaria risk in the moderate iron status [incidence rate ratio (IRR) with SF: 1.56; 95% CI: 0.64, 3.86; IRR with inflammation-corrected SF: 1.92; 95% CI: 0.75, 4.93] and high iron status (IRR with SF: 2.66; 95% CI: 1.10, 6.43; or IRR with corrected SF: 2.93; 95% CI: 1.17, 7.33) categories compared with the deficient iron status category. The relative increase in malaria risk for children with high iron status was statistically significant only among those with a concurrently normal serum soluble transferrin receptor concentration (<8.3 mg/L; IRR: 1.97; 95% CI: 1.20, 7.37).Conclusions: Iron adequacy in 4- to 8-y-old children in rural Zambia was associated with increased malaria risk. Our findings underscore the need to integrate iron interventions with malaria control programs. This trial was registered at clinicaltrials.gov as NCT01695148.

Provitamin A Carotenoid-Biofortified Maize Consumption Increases Pupillary Responsiveness among Zambian Children in a Randomized Controlled Trial.

BACKGROUND: 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. OBJECTIVE: We tested the impact of provitamin A carotenoid-biofortified maize consumption (∼15 µg ß-carotene/g) on dark adaptation in Zambian children. METHODS: 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/m2) in a dark-adapted state. RESULTS: 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/m2), 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. CONCLUSIONS: 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.

Provitamin A-biofortified maize increases serum ß-carotene, but not retinol, in marginally nourished children: a cluster-randomized trial in rural Zambia.

BACKGROUND: 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. OBJECTIVE: We evaluated the efficacy of regular provitamin A carotenoid-biofortified "orange" maizemeal (∼15 µg ß-carotene/g) consumption in improving vitamin A status and reducing vitamin A deficiency in children. DESIGN: 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, ß-carotene, C-reactive protein, and α1-acid glycoprotein. RESULTS: 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 ß-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. CONCLUSION: In this marginally nourished population, regular biofortified maizemeal consumption increased serum ß-carotene concentrations but did not improve serum retinol. This trial was registered at clinicaltrials.gov as NCT01695148.

Assessing Child Nutrient Intakes Using a Tablet-Based 24-Hour Recall Tool in Rural Zambia.

BACKGROUND: Detailed dietary intake data in low-income populations are needed for research and program evaluation. However, collection of such data by paper-based 24-hour recall imposes substantial demands for staff time and expertise, training, materials, and data entry. OBJECTIVE: To describe our development and use of a tablet-based 24-hour recall tool for conducting dietary intake surveys in remote settings. METHODS: We designed a 24-hour recall tool using Open Data Kit software on an Android tablet platform. The tool contains a list of local foods, questions on portion size, cooking method, ingredients, and food source and prompts to guide interviewers. We used this tool to interview caregivers on dietary intakes of children participating in an efficacy trial of provitamin A-biofortified maize conducted in Mkushi, a rural district in central Zambia. Participants were children aged 4 to 8 years not yet enrolled in school (n = 938). Dietary intake data were converted to nutrient intakes using local food composition and recipe tables. RESULTS: We developed a tablet-based 24-hour recall tool and used it to collect dietary data among 928 children. The majority of foods consumed were maize, leafy vegetable, or small fish dishes. Median daily energy intake was 6416 kJ (1469 kcal). CONCLUSIONS: Food and nutrient intakes assessed using the tablet-based tool were consistent with those reported in prior research. The tool was easily used by interviewers without prior nutrition training or computing experience. Challenges remain to improve programming, but the tool is an innovation that enables efficient collection of 24-hour recall data in remote settings.

Child Health Week in Zambia: costs, efficiency, coverage and a reassessment of need.

Child Health Weeks (CHWs) are semi-annual, campaign-style, facility- and outreach-based events that provide a package of high-impact nutrition and health services to under-five children. Since 1999, 30% of the 85 countries that regularly implement campaign-style vitamin A supplementation programmes have transformed their programmes into CHW. Using data drawn from districts' budget, expenditures and salary documents, UNICEF's CHW planning and budgeting tool and a special purposive survey, an economic analysis of the June 2010 CHW's provision of measles, vitamin A and deworming was conducted using activity-based costing combined with an ingredients approach. Total CHW costs were estimated to be US$5.7 million per round. Measles accounted for 57%, deworming 22% and vitamin A 21% of total costs. The cost per child was US$0.46. The additional supplies and personnel required to include measles increased total costs by 42%, but reduced the average costs of providing vitamin A and deworming alone, manifesting economies of scope. The average costs of covering larger, more urban populations was less than the cost of covering smaller, more dispersed populations. Provincial-level costs per child served were determined primarily by the number of service sites, not the number of children treated. Reliance on volunteers to provide 60% of CHW manpower enables expanding coverage, shortening the duration of CHWs and reduces costs by one-third. With costs of $1093 per life saved and $45 per disability-adjusted life-year saved, WHO criteria classify Zambia's CHWs as 'very cost-effective'. The continued need for CHWs is discussed.

Comparative intake of white- versus orange-colored maize by Zambian children in the context of promotion of biofortified maize.

BACKGROUND: Vitamin A deficiency is associated with poor health outcomes related to reproduction, growth, vision, and immunity. Biofortification of staple crops is a novel strategy for combating vitamin A deficiency in high-risk populations where staple food intakes are high. African populations are proposed beneficiaries of maize (Zea mays) biofortified with provitamin A carotenoids, often called "orange maize" because of its distinctive deep yellow-orange kernels. The color facilitates ready recognition but presents a cultural challenge to maize-consuming populations, including those in much of Africa, who traditionally eat white varieties. OBJECTIVE: This study explores the intake patterns of, as well as adaptation to, traditional foods made with provitamin A-biofortified maize compared with white maize in rural Zambian children 3 to 5 years of age (n = 189) during a 3-month feeding trial. METHODS: The subjects were fed a breakfast of maize porridge (sweet mush), a lunch of maize nshima (stiff mush) with various side dishes, and an afternoon snack based on a 6-day rotating menu. The trial was conducted in 2010. The orange maize used in the trial came from three different sources. O1 maize was from the 2009 harvest and was stored in a freezer until use in 2010. O2 maize was also from the 2009 harvest and was stored in a cold room until 2010. O3 ("fresh") maize was from the 2010 harvest and was fed immediately after harvest in week 9 of the study and then stored in a freezer until milling for the final four weeks. RESULTS: Consumption of menu items, except snacks, was influenced by week (p < .0084). The intakes of porridge and nshima made with orange maize equaled those of porridge and nshima made with white maize from week 2 onward. The intakes of porridge and nshima prepared from O1 and O2 did not differ, but intakes became significantly higher when meals made from O3 were introduced (p < .014 for porridge and p < or = .013 for nshima). CONCLUSIONS: These results demonstrate quick adaptation to orange maize, a preference for recently harvested maize, and an optimistic outlook for similar adaptation patterns in other biofortified-maize target countries.

Vitamin A intake and infection are associated with plasma retinol among pre-school children in rural Zambia.

OBJECTIVE: 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. DESIGN: 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. SETTING: Rural communities in Central and Eastern Provinces of Zambia. SUBJECTS: Children 2-5 years of age. RESULTS: 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. CONCLUSIONS: 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.