Objectives To compare iron status in breastfed infants randomized to complementary feeding regimens that provided iron from fortified infant cereals or meats, and examined the development of the enteric microbiota among groups. Study design Forty-five exclusively breastfed 5 month old infants were randomized to commercially available pureed meats, iron- and zinc-fortified infant cereals, or iron-only fortified infant cereals as the first and primary complementary food through 9–10 months of age. Dietary iron was determined by monthly 3-d diet records. Iron status was assessed at end of the study by hemoglobin (Hb), serum ferritin (SF), and soluble transferrin receptor (STfR) measurements. In a subsample 14 infants, enteric microbiota were profiled in monthly stool samples (5–9 mo) by 16S rRNA gene pyrosequencing. Results Infants in cereal groups had 2–3 fold greater daily iron intakes vs the meat group (P < 0.0001). 27% of participants had low SF, and 36% were mildly anemic, without significant differences by feeding group; more infants in meat group had high STfR (p=0.03). Sequence analysis identified differences by time and feeding group in the abundances of several bacterial groups, including significantly more abundant butyrate producing Clostridium Group XIVa in the meat group (P=0.01) Conclusions A high percentage of healthy infants who were breastfed-only were iron deficient, and complementary feeding, including iron exposure, influenced the development of the enteric microbiota. If these findings are confirmed, reconsideration of strategies to both meet infants’ iron requirements and optimize the developing microbiome may be warranted.

Zinc requirements for older breastfed-only infants are unlikely to be met without the regular consumption of either meats or zinc-fortified foods.

Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP − Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.

Objective: To assess the effectiveness of outpatient management with ready-to-use and supplementary foods for infants under 6 months (u6m) of age who were unable to be treated as inpatients due to social and economic barriers. Design: Review of operational acute malnutrition treatment records. Setting: 21 outpatient therapeutic feeding clinics in rural Malawi. Participants: Infants u6m with acute malnutrition treated as outpatients because of barriers to inpatient treatment. The comparison group consisted of acutely malnourished children 6-9 months of age who were being treated at the same time in the same location in the context of two different randomized clinical trials. Results: A total of 323 infants u6m were treated for acute malnutrition (130 severe and 193 moderate). A total of 357 infants 6-9 months old with acute malnutrition (74 severe and 283 moderate) were included as contemporaneous controls. Among infants u6m with severe acute malnutrition, 98 (75.4%) achieved nutritional recovery; in comparison, 56 (75.7%) of those with SAM 6-9 months old recovered. Among infants u6m with moderate acute malnutrition, 157 (81.3%) recovered; in comparison 241 (85.2%) of those aged 6-9 months recovered. Conclusions: In a rural Malawian population of infants u6m who had generally already stopped exclusive breastfeeding and were now acutely malnourished, treatment with therapeutic or supplementary foods under the community management of acute malnutrition model was safe and effective. In settings where social and financial factors make hospital admission challenging, consideration should be given to lowering the recommended age of ready-to-use therapeutic and supplementary foods to infants u6m.