Identification of a Hemolysis Threshold That Increases Plasma and Serum Zinc Concentration.

Background: Plasma or serum zinc concentration (PZC or SZC) is the primary measure of zinc status, but accurate sampling requires controlling for hemolysis to prevent leakage of zinc from erythrocytes. It is not established how much hemolysis can occur without changing PZC/SZC concentrations.Objective: This study determines a guideline for the level of hemolysis that can significantly elevate PZC/SZC.Methods: The effect of hemolysis on PZC/SZC was estimated by using standard hematologic variables and mineral content. The calculated hemolysis threshold was then compared with results from an in vitro study and a population survey. Hemolysis was assessed by hemoglobin and iron concentrations, direct spectrophotometry, and visual assessment of the plasma or serum. Zinc and iron concentrations were determined by inductively coupled plasma spectrometry.Results: A 5% increase in PZC/SZC was calculated to result from the lysis of 1.15% of the erythrocytes in whole blood, corresponding to ∼1 g hemoglobin/L added into the plasma or serum. Similarly, the addition of simulated hemolysate to control plasma in vitro caused a 5% increase in PZC when hemoglobin concentrations reached 1.18 ± 0.10 g/L. In addition, serum samples from a population nutritional survey were scored for hemolysis and analyzed for changes in SZC; samples with hemolysis in the range of 1-2.5 g hemoglobin/L showed an estimated increase in SZC of 6% compared with nonhemolyzed samples. Each approach indicated that a 5% increase in PZC/SZC occurs at ∼1 g hemoglobin/L in plasma or serum. This concentration of hemoglobin can be readily identified directly by chemical hemoglobin assays or indirectly by direct spectrophotometry or matching to a color scale.Conclusions: A threshold of 1 g hemoglobin/L is recommended for PZC/SZC measurements to avoid increases in zinc caused by hemolysis. The use of this threshold may improve zinc assessment for monitoring zinc status and nutritional interventions.

Biomarkers of Nutrition for Development (BOND)-Zinc Review.

Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole-body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND (Biomarkers of Nutrition for Development) Zinc Expert Panel recommends 3 measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole-body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using the PZC to assess zinc status. PZCs respond less to additional zinc provided in food than to a supplement administered between meals, there is considerable interindividual variability in PZCs with changes in dietary zinc, and PZCs are influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one that is recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information are the activity or amounts of zinc-dependent enzymes and proteins and biomarkers of oxidative stress, inflammation, or DNA damage.

Meat supplementation increases arm muscle area in Kenyan schoolchildren.

The present study examines the effect of animal-source-food (ASF) intake on arm muscle area growth as part of a larger study examining causal links between ASF intake, growth rate, physical activity, cognitive function and micronutrient status in Kenyan schoolchildren. This randomised, controlled feeding intervention study was designed with three isoenergetic feeding interventions of meat, milk, and plain traditional vegetable stew (githeri), and a control group receiving no snack. A total of twelve elementary schools were randomly assigned to interventions, with three schools per group, and two cohorts of 518 and 392 schoolchildren were enrolled 1 year apart. Children in each cohort were given feedings at school and studied for three school terms per year over 2 years, a total of 9 months per year: cohort I from 1998 to 2000 and cohort II from 1999 to 2001. Food intake was assessed by 24 h recall every 1-2 months and biochemical analysis for micronutrient status conducted annually (in cohort I only). Anthropometric measurements included height, weight, triceps skinfold (TSF) and mid-upper-arm circumference (MUAC). Mid-upper-arm muscle area (MAMA) and mid-upper-arm fat area (MAFA) were calculated. The two cohorts were combined for analyses. The meat group showed the steepest rates of gain in MUAC and MAMA over time, and the milk group showed the next largest significant MUAC and MAMA gain compared with the plain githeri and control groups (P< 0.05). The meat group showed the least increase in TSF and MAFA of all groups. These findings have implications for increasing micronutrient intake and lean body mass in primary schoolchildren consuming vegetarian diets.

The focused ethnographic study 'assessing the behavioral and local market environment for improving the diets of infants and young children 6 to 23 months old' and its use in three countries.

The concept of a focused ethnographic study (FES) emerged as a new methodology to answer specific sets of questions that are required by agencies, policymakers, programme planners or by project implementation teams in order to make decisions about future actions with respect to social, public health or nutrition interventions, and for public-private partnership activities. This paper describes the FES on complementary feeding that was commissioned by the Global Alliance for Improved Nutrition and highlights findings from studies conducted in three very different country contexts (Ghana, South Africa and Afghanistan) burdened by high levels of malnutrition in older infants and young children (IYC). The findings are analysed from the perspective of decision-making for future interventions. In Ghana, a primary finding was that in urban areas the fortified, but not instant cereal, which was being proposed, would not be an appropriate intervention, given the complex balancing of time, costs and health concerns of caregivers. In both urban and rural South Africa, home fortification products such as micronutrient powders and small quantity, lipid-based nutrient supplements (LNS) are potentially feasible interventions, and would require thoughtful behaviour change communication programmes to support their adoption. Among the important results for future decision-making for interventions in Afghanistan are the findings that there is little cultural recognition of the concept of special foods for infants, and that within households food procurement for IYC are in the hands of men, whereas food preparation and feeding are women's responsibilities.

Fortifying complementary foods with NaFeEDTA--considerations for developing countries.

As a highly bioavailable iron compound, sodium iron (iii) ethylenediaminetetraacetate (NaFeEDTA) has been recommended as a food additive for fortification. The amount of a food additive that can be ingested daily over a lifetime without appreciable health risk is termed the acceptable daily intake (ADI). The ADI for NaFeEDTA is based on body weight. For complementary foods and food supplements for infants and young children in low-income countries, where prevalence of underweight is high yet nutrient needs are also high, it is not clear which doses might be appropriate. The objective is to calculate the dosage of NaFeEDTA for fortifying complementary foods assuming different population prevalences of underweight. Mathematical models were used to simulate the dosage of NaFeEDTA for 6- to 8-month-old infants under different prevalences of underweight ranging from 5% to 40%. In order to keep NaFeEDTA intake below the ADI for ethylenediaminetetraacetate (EDTA) recommended by the Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) Expert Committee on Food Additives for 95% of 6- to 8-month-old infants, the daily iron dose from NaFeEDTA in fortified complementary foods should be set between 2.2 mg and 1.8 mg in countries with a prevalence of underweight among 6- to 8-month-old infants between 5% and 40%, respectively. If 2 mg of iron is given to all 6- to 8-month-old infants, the percentage exceeding the ADI for EDTA would be <10% for populations with <30% of children who are underweight, which is the case for many countries. In conclusion, 2 mg of iron from NaFeEDTA could be used for fortifying one daily serving of complementary food to ensure EDTA levels are below the ADI for infants 6-8 months of age. An additional source of iron (such as ferrous sulfate) should be included to increase the iron dose to desired fortification levels.

The role of the Codex Alimentarius process in support of new products to enhance the nutritional health of infants and young children.

The Codex Alimentarius is a collection of internationally recognized standards, codes of practice, guidelines, and other recommendations relating to foods, food production, and food safety. Among other functions, it is responsible for setting international standards for safety and hygiene. Codex food standards and guidelines directed at foods produced primarily for young infants and children have important implications for maintaining nutritional status and health, especially given the positioning of these products as components of established World Health Organization (WHO)/UNICEF-recommended feeding strategies. Recently, new products targeted at this age group (e.g., lipid-based nutrient supplements and micronutrient powders) have been produced and used, but these are not totally covered under existing Codex guidelines or standards. The objective of this paper is to review the role of the Codex process and specifically to suggest revisions to existing Codex guidelines on formulated complementary foods (Guidelines for Formulated Supplementary Foods for Older Infants and Young Children, CAC/GL 08-1991) to encompass this new category of fortified complementary foods and home fortificants. In reviewing the existing guidelines, potential areas for revision included the sections on the recommended nutrients in these foods and their intended use. Updating the Codex guidelines provides the opportunity to encourage production and use of new products for children and help ensure that such foods, when used as directed, do not interfere with breastfeeding. The revised guidelines would help governments develop national regulations covering all forms of formulated complementary foods. They would also lessen impediments to international trade by providing clear guidance for foods used in feeding programs and for young children, particularly in developing countries.

Development of a WHO growth reference for school-aged children and adolescents.

OBJECTIVE: To construct growth curves for school-aged children and adolescents that accord with the WHO Child Growth Standards for preschool children and the body mass index (BMI) cut-offs for adults. METHODS: Data from the 1977 National Center for Health Statistics (NCHS)/WHO growth reference (1-24 years) were merged with data from the under-fives growth standards' cross-sectional sample (18-71 months) to smooth the transition between the two samples. State-of-the-art statistical methods used to construct the WHO Child Growth Standards (0-5 years), i.e. the Box-Cox power exponential (BCPE) method with appropriate diagnostic tools for the selection of best models, were applied to this combined sample. FINDINGS: The merged data sets resulted in a smooth transition at 5 years for height-for-age, weight-for-age and BMI-for-age. For BMI-for-age across all centiles the magnitude of the difference between the two curves at age 5 years is mostly 0.0 kg/m(2) to 0.1 kg/m(2). At 19 years, the new BMI values at +1 standard deviation (SD) are 25.4 kg/m(2) for boys and 25.0 kg/m(2) for girls. These values are equivalent to the overweight cut-off for adults (> or = 25.0 kg/m(2)). Similarly, the +2 SD value (29.7 kg/m(2) for both sexes) compares closely with the cut-off for obesity (> or = 30.0 kg/m(2)). CONCLUSION: The new curves are closely aligned with the WHO Child Growth Standards at 5 years, and the recommended adult cut-offs for overweight and obesity at 19 years. They fill the gap in growth curves and provide an appropriate reference for the 5 to 19 years age group.

Low plasma vitamin B-12 in Kenyan school children is highly prevalent and improved by supplemental animal source foods.

The high prevalence of vitamin B-12 deficiency in many regions of the world is becoming recognized as a widespread public health problem, but it is not known to what extent this deficiency results from a low intake of the vitamin or from its malabsorption from food. In rural Kenya, where a previous study identified a high prevalence of inadequate vitamin B-12 intakes, this study examined whether plasma vitamin B-12 concentrations were associated with dietary sources of the vitamin at baseline and could be increased by supplementation with animal source foods (ASF). The 4 experimental groups in 503 school children were: 1) control (no food provided); 2) githeri (a maize and bean staple with added oil); 3) githeri + meat (githeri + minced beef); or 4) githeri + milk (githeri + milk). Feedings were isocaloric. Dietary data were collected at baseline, and biochemical data at baseline and after 1 and 2 y of feeding. Baseline plasma vitamin B-12 concentration was 193.6 +/- 105.3 pmol/L and correlated with % energy from ASF (r = 0.308, P < 0.001). The odds ratio for low plasma vitamin B-12 (<148 pmol/L), which occurred in 40% of children, was 6.28 [95% CI: 3.07-12.82] for the lowest vs. highest ASF intake tertile (P < 0.001). Feeding ASF (meat or milk) greatly reduced the prevalence of low plasma vitamin B-12 (P < 0.001). The high prevalence of low plasma vitamin B-12 concentrations in these children is predicted by a low intake of ASF, and supplemental ASF improves vitamin B-12 status.

Kenyan school children have multiple micronutrient deficiencies, but increased plasma vitamin B-12 is the only detectable micronutrient response to meat or milk supplementation.

Animal source foods (ASF) can provide micronutrients in greater amounts and more bioavailable forms compared to plant source foods, but their intake is low in many poor populations. However, the impact of ASF on micronutrient status of undernourished populations has not been assessed. Supplemental meat (60-85 g/d), milk (200-250 mL/d) or energy (isocaloric with the meat and milk, 240-300 kcal/d) were randomly assigned to 555 undernourished school children aged 5-14 y in a rural malaria-endemic area of Kenya, at one school meal daily for one school year. Blood and stool samples were collected at baseline and after 1 y to assess stool parasites, malaria, hemoglobin, serum or plasma C-reactive protein, ferritin, iron, zinc, copper, vitamin B-12, folate and retinol, and erythrocyte riboflavin. At baseline, there was a high prevalence of micronutrient deficiencies (iron, zinc, vitamins A and B-12 and riboflavin), yet plasma ferritin was low in few children, and none had low serum copper. At the end of the year of supplementation, plasma vitamin B-12 concentrations were significantly increased in children fed the Meat or Milk meal; prevalence of severe plus moderate deficiency fell from 80.7% at baseline to 64.1% in the Meat group and from 71.6 to 45.1% in the Milk group, respectively. No significant improvement was observed in the status of other micronutrients compared to the Energy and Control groups, although malaria and other infections may have obscured effects. Supplementation with small amounts of meat or milk reduced the high prevalence of vitamin B-12 deficiency in these children.

Titers of antibody to common pathogens: relation to food-based interventions in rural Kenyan schoolchildren.

BACKGROUND: Undernutrition is widely perceived to affect the development of an effective immune system. OBJECTIVE: We used a mini-analysis system to quantitate antibody titers and evaluate the sera of 200 Kenyan schoolchildren for antibodies to Helicobacter pylori [isotypes of immunoglobulins A (IgA), G (IgG), and M (IgM)], hepatitis A virus, rotavirus, tetanus toxoid (IgG), and a panel of recombinant malarial antigens (MSP1(19), MSP2, Ag512, MSP4, and MSP5). DESIGN: Children participated in a school-based feeding intervention with meat, milk, or nonanimal-source foods or in a nonintervention control group. Microvolumes (200 mL) of sera were analyzed at baseline and after 1 y. RESULTS: Nearly all children had elevated titers of antibody to H. pylori, hepatitis A virus, rotavirus, and malaria at the outset, despite a high prevalence of apparent biochemical micronutrient deficiencies and stunting, but many had titers of tetanus toxoid IgG antibodies below the protective concentration. Children with low hemoglobin had a greater proportion of elevated H. pylori IgM antibody titers at baseline, which suggests that current infection with H. pylori may be associated with anemia. Compared with the control subjects, only the group eating meat had a significant increase in H. pylori IgM antibodies during the intervention (P = 0.019). No other group comparisons with the control subjects were statistically significant. The additional finding that the sera of some children showed inadequate tetanus-protective antibodies, despite immunization, suggests that the vaccination program was suboptimal. CONCLUSIONS: A large battery of immune assays can be performed on microvolumes of sera. Furthermore, despite evidence of malnutrition, children do develop significant antibody-mediated responses to common pathogens.