A comparison of the bioavailability of ferrous fumarate and ferrous sulfate in non-anemic Mexican women and children consuming a sweetened maize and milk drink.

BACKGROUND/OBJECTIVES: Ferrous fumarate is recommended for the fortification of complementary foods based on similar iron absorption to ferrous sulfate in adults. Two recent studies in young children have reported that it is only 30% as well absorbed as ferrous sulfate. The objective of this study was to compare iron absorption from ferrous fumarate and ferrous sulfate in infants, young children and mothers. SUBJECTS/METHODS: Non-anemic Mexican infants (6-24 months), young children (2-5 years) and adult women were randomly assigned to receive either 4 mg Fe (women) or 2.5 mg Fe (infants and young children) as either [(57)Fe]-ferrous fumarate or [(58)Fe]-ferrous sulfate added to a sweetened drink based on degermed maize flour and milk powder. Iron absorption was calculated based on incorporation of isotopes into erythrocytes after 14 days. RESULTS: Within each population group, no significant differences (P > 0.05) in iron absorption were found between ferrous fumarate and ferrous sulfate. Mean iron absorption from ferrous fumarate vs ferrous sulfate was 17.5 vs 20.5% in women (relative bioavailability (RBV) =86), 7.0 vs 7.2% in infants (RBV = 97) and 6.3 vs 5.9% in young children (RBV = 106). CONCLUSIONS: Ferrous fumarate is as well absorbed as ferrous sulfate in non-anemic, iron sufficient infants and young children, and can be recommended as a useful fortification compound for complementary foods designed to prevent iron deficiency. Further studies are needed to clarify its usefulness in foods designed to treat iron deficiency.

Participatory nutrition education and adoption of new feeding practices are associated with improved adequacy of complementary diets among rural Malawian children: a pilot study.

OBJECTIVE: To introduce practices for improving complementary feeding and evaluate their adoption and association with improved dietary intakes. DESIGN: A quasiexperimental pilot study comparing dietary intakes from complementary foods among three intervention communities and one control community before and after the intervention, and adoption of new complementary feeding practices among intervention communities following the intervention. SETTING: Rural subsistence communities in southern Malawi, Central Africa. SUBJECTS: Mothers and their children aged 6 to 23 months receiving complementary foods. INTERVENTIONS: A participatory, nutrition education intervention based on four locally adapted lessons for complementary feeding practices designed to increase: (i) total complementary food intake; (ii) energy and nutrient density of the complementary diet, and; (iii) iron and zinc bioavailability of the complementary diet. RESULTS: Adoption rates for the four practices ranged from 25% for preparation of enriched porridges, to 10% for preparing soaked, pounded maize. The amount of complementary foods (g/day) and intakes of energy, animal protein, niacin, riboflavin, calcium, iron, and zinc, but not vitamin A, were significantly greater (P<0.05) in the intervention compared to control group, as were the energy, iron, and riboflavin density, and the estimated amount of bioavailable iron and zinc. CONCLUSIONS: Several intervention practices were well accepted and adopted and were associated with improved adequacy of energy and nutrient intakes from the complementary diet. Such improvements were attributed mainly to greater total intakes and, to a lesser extent, enhanced dietary quality of the complementary foods.

Complementary feeding practices and dietary intakes from complementary foods amongst weanlings in rural Malawi.

OBJECTIVE: The objectives of this study were to estimate the quantity and nutritive quality of the complementary diet in rural Malawi, and to identify feeding practices, nutrients and dietary modifiers of iron and zinc bioavailability that may limit the quality of the diet. DESIGN: This cross-sectional study design included an anthropometric survey, a feeding practices questionnaire, and an interactive, 24 h recall dietary data survey. SETTING: Four rural villages in Balaka district, southern Malawi. SUBJECTS: Mothers resident in the study communities with breastfed children aged up to 24 months were eligible. RESULTS: Stunting was prevalent among these weanlings. Maize was the predominant food source, with limited contribution of animal foods. Deficits in dietary energy and several nutrients were found when compared to estimated needs. When expressed per kg body weight, energy intakes appeared adequate. The bioavailability of zinc was low due to a high phytate:zinc molar ratio. Iron bioavailability was also low due to low intake of absorption enhancers such as meat/fish/poultry protein and ascorbic acid. Dietary quality was poorest for 6 to 8-month-old infants. CONCLUSIONS: Iron, zinc and calcium were the most limiting nutrients to the quality of the diet, partly exacerbated by the poor bioavailability of iron and zinc. Increased total intake and bioavailability of iron and zinc would improve the complementary diets. SPONSORSHIP: This study was funded by the Thrasher Research Fund, Salt Lake City, Utah, USA.

Dietary diversification/modification strategies to enhance micronutrient content and bioavailability of diets in developing countries.

Both cereal staples and household diets can be manipulated to enhance the content of micronutrients and/or alter the levels of absorption modifiers to improve micronutrient bioavailability. Strategies described range from plant breeding, use of fertilizers and genetic engineering to changes in food preparation and processing methods at the household level involving soaking, fermentation and germination. The impact of five household strategies designed to enhance the content and bioavailability of iron, zinc and calcium in a representative daily menu for rural Malawian preschool children has been calculated using food composition data. In the five strategies, relishes based on small dried fish replaced plant-based relishes, maize-based porridges prepared with maize flour soaked to reduce its hexa (IP-6)- and penta (IP-5)-inositol phosphate content replaced conventional porridges; and a pumpkin-leaf relish replaced sweet potato to increase the retinol content of the daily menu. Comparison of the calculated energy, nutrient, and phytate content, and [phytate]:[zinc] molar ratios of the five modified menus compared with the unmodified menu emphasizes that to ensure that the estimated requirements for iron and zinc are met, the optimal strategy includes dried fish relish twice daily together with porridges prepared using soaked (or fermented) maize flour to reduce their hexa- and penta-inositol phosphate content. Implementation of these household strategies has the potential to increase the bioavailability of iron and zinc in rural Malawian diets from low to high.

Identifying populations at risk of zinc deficiency: the use of supplementation trials.

Zinc supplementation trials assessing the response of growth and immunity have assisted in identifying populations at risk of zinc deficiency and the factors that contribute. A recent trial in Ethiopia demonstrated a high risk of zinc deficiency among young children, particularly among those who were stunted.

A home-based method to reduce phytate content and increase zinc bioavailability in maize-based complementary diets.

This study aimed to develop and assess the feasibility of a home-based method to reduce the phytate content of maize and improve zinc bioavailability from maize-based complementary diets in rural Malawi. A method of extracting phytate through the soaking of pounded maize was developed, and found to reduce phytate content to 49% of unrefined maize. An educational program was used to teach the processing method to mothers of children receiving complementary foods in rural Malawian communities. Samples of maize flour prepared by this process by participants were collected and analysed for phytate and zinc content. Of these, 70% of samples were found to be adequately prepared; mean phytate content of these samples was 48% of unprocessed, unrefined maize flour controls. Most participants found the cooked product to have an acceptable taste (99%) and texture (68%), and felt the processing method took little or no extra time (86%) and was culturally acceptable (96%). The phytate and zinc content of the processed maize flour samples analysed from community prepared samples was substituted into the dietary analysis of complementary foods for 9- to 11-month-old children (n = 31). The bioavailability of zinc from the complementary diet would predict an increase from low (24%) to moderate (33%) levels.

Dietary Iodine and selenium interact to affect thyroid hormone metabolism of rats.

The interaction of dietary selenium and iodine on the activities of the selenoenzymes, selenium-dependent glutathione peroxidase (GSH-Px), and type I deiodinase (DI-I), and the thyroid hormones thyroxine (T4) and triiodothyronine (T3) were studied. Male weanling Sprague-Dawley rats were fed an AIN-93G diet for 6 wk with modified selenium and iodine concentration as follows: three levels each of iodine and selenium (0.03, 0.2 added and 1.0 added mg iodine/kg diet, and 0.05, 0.18 added and 1.0 added mg selenium/kg diet) were used in a 3 x 3 factorial design. Renal, but not hepatic, DI-I activity was lower in rats with low selenium intake than in controls. Circulating T3 concentration was not affected by the dietary levels of iodine or selenium. Unlike in liver, kidney and erythrocytes, thyroidal GSH-Px activity was not lower than in controls in rats with low selenium intake, but was significantly higher when iodine intake was low. Significant interactions of iodine and selenium on serum T4 and thyroidal GSH-Px activity were observed. Serum T4 was maintained at control levels when both dietary iodine and selenium were low, but not when iodine alone, or selenium alone, was low. Activity of thyroidal GSH-Px was lowest in rats fed a diet containing high iodine and low selenium. The results suggest that high iodine intake, when selenium is deficient, may permit thyroid tissue damage as a result of low thyroidal GSH-Px activity during thyroid stimulation. A moderately low selenium intake normalized circulating T4 concentration in the presence of iodine deficiency.