The high prevalence of micronutrient deficiencies, in particular deficiencies of iron, zinc and vitamin A, is contributing significantly to the unacceptably high childhood morbidity and mortality observed in developing countries. Food fortification and biofortification are potentially useful strategies to prevent and control these deficiencies, however, limited data are available on the efficacy of these public health interventions in infants and children. Stable isotope techniques can be used in the development and evaluation of nutritional strategies by the assessment of bioavailability of iron, zinc and pro-vitamin A carotenoids as well as by monitoring changes in body pools of vitamin A to evaluate efficacy. This CRP will generate new information on the usefulness of food fortification and biofortification to improve micronutrient status in infants and children. The project will build on an ongoing CRP, in close collaboration with HarvestPlus, generating data on biofortification as a strategy to combat micronutrient deficiencies in adults.
To generate new information on the efficacy of food fortification and/or biofortification interventions to improve micronutrient status in children
To assess the change in vitamin A pool size in children consuming 140 g/d rice triple-fortified with Fe, Zn and Vitamin A for 60 days, and compare the results between assessment by the isotopic method to assessment by serum retinol concentration (THA 15426).
To assess the vitamin A status and body pool size in children using the modified relative dose response tests and stable 13C2 retinyl acetate as a tracer among children who receive Sprinkles with or without vitamin A through home fortification of complementary foods (GHA 15199).
To determine absorption of Fe and Zn from Fe & Zn-biofortfied and Zn-fortified pearl millet in young Indian children (IND 15205).
To estimate the amount of zinc absorbed (bioavailability) from zinc biofortified rice and compare that with absorption from conventional rice and zinc-fortified conventional rice using the triple stable isotope tracer ratio technique in children (BGD 15197).
To evaluate the impact of daily consumption of vitamin A fortified oil on vitamin A consumption from breast milk vitamin A during the first 6 months post-partum in breastfed babies from low-income communities (MOR 15815).
To investigate a) if the effect of bean polyphenols previously seen in a single meal study can be confirmed with multiple bean meals as part of a complex diet; b) human iron absorption from different bean varieties consumed with other meal components; c) if phytic acid in beans is the inhibitor responsible for equal iron bioavailability from high iron and normal iron beans observed in the multiple meal study (RWA 16152).
To investigate the impact of daily consumption of vitamin A-fortified milk on vitamin A status in preschool-children (MEX 15198).
Observations from this CRP will influence fortification and biofortification nutrition interventions in areas where the knowledge can be applied to promote adequate nutrition and prevent nutrient deficiencies using foods indigenous to the local diets. For example, the demonstration that phytic acid content is a primary factor in the iron absorption from beans should redirect research to concentrate on this factor for improvement of iron bioavailability from foods. The demonstrated effectiveness of both iron and zinc fortification of pearl millet has the potential to provide a sustainable source of these nutrients where this food is a staple, namely, semi-arid regions of India and Africa, and according to HarvestPlus, "more than 30,000 Indian farmers have purchased and planted this new variety marketed as Dhanshakti (meaning prosperity and strength)".
The demonstration that isotope dilution methods provided a much more sensitive measure than serum retinol of the effectiveness of vitamin A fortification in both Thailand and Mexico serves as a foundation for further work with this method to evaluate the effectiveness of multiple vitamin A interventions around the world. However, in the study in Mexican children, even though 50% of children may be considered vitamin A deficient by serum retinol concentrations <0.7 µmol/L, liver vitamin A reserves were more than adequate when assessed by stable isotope retinol methods. This raises concerns about the possible over-use of some nutrition interventions, and the need to use sensitive assessment methods to evaluate public health nutrition programs to prevent deficiencies while avoiding excessive levels of vitamin A. At the International Congress of Nutrition where the Mexico results were reported, our IAEA section head was approached by a representative of the Bill and Melinda Gates foundation to organize a further meeting and research on "Assessing the risk of vitamin A toxicity due to large scale intervention programmes".
The long-term impact of the CRP will be most evident in future years, as the peer-reviewed publications increase in number and influence further scientific effort.
The enthusiastic acceptance of the results of these studies, including publication in top peer-reviewed nutrition journals, and results that serve as the basis for additional work that has already begun (see impact above) demonstrates that this topic remains highly relevant in applying stable isotope techniques in human nutritional assessment, to help solve world food and nutrition problems.