Evaluating iron and zinc bioavailability from biofortified potatoes to reduce malnutrition in the Andean highlands.

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Iron and zinc deficiency are global problems, with high prevalence in Asia, Sub-Saharan Africa and South America. While iron and zinc supplementation and food fortification programmes have been shown to be efficacious in certain situations, their implementation requires good infrastructure, significant investment and safe delivery systems. The development of crops with enhanced levels of bioavailable iron and zinc - so called biofortification - is a sustainable and cost-effective complementary strategy that has the potential to provide sufficient iron and zinc for resource poor rural and urban communities, such as those in the Andean highlands. There has been significant effort within the international community to breed new varieties of staple crops that have enhanced levels of iron and/or zinc. It is however difficult to predict whether the additional iron and zinc in biofortified crops would be bioavailable - that is effectively absorbed from the diet into the body to improve iron and zinc status. The risk in breeding these biofortified crops is that the investment in crop development will have limited impact if the iron and zinc is not bioavailable. Iron and zinc biofortified potato are an ideal crop to contribute to a reduction in iron and zinc deficiencies in the Andean highlands for two major reasons. Firstly, unlike cereals and legumes, potatoes have very low levels of phytates which inhibit iron bioavailability, and this is combined with a relatively high concentration of vitamin C which promotes iron absorption - an ideal combination to maximize bioavailability. Secondly, potatoes are the major staple in the diet amongst the iron and zinc-deficient Andean population, and are largely consumed without other foods. Thus, while various strategies including agricultural diversification have potential to alleviate micronutrient deficiencies and should be considered in an integrated approach, biological, cultural and economic factors suggest that the introduction of iron and zinc biofortified potatoes may be an effective approach to have a significant contribution to reducing iron and zinc deficiencies. Quantifying the bioavailability of iron and zinc at this time is critical.The bioavailability of iron and zinc from biofortified crops can only be meaningfully quantified through human dietary intervention studies in which foods made from the biofortified crops are labelled with stable isotopes of iron or zinc, which are subsequently quantified human tissues to provide a measure of bioavailability. These studies are technically challenging, but of the utmost importance for the success of biofortification strategies.To quantify the potential impact of the introduction of biofortified potatoes, data from the human studies will be used within a Disability Adjusted Life Year (DALY) modelling approach. This method has been successfully applied to assess the potential impact of other biofortified crops to alleviate micronutrients deficiencies. Furthermore, we will use data from the proposed research along with that from other studies to develop iron dietary intake guidelines for low and middle-income countries. If we find compelling evidence through the human intervention studies and the subsequent DALY modeling that iron and zinc biofortified potatoes can contribute to alleviation of iron and zinc deficiencies in low and middle income countries, it will provide the justification for investment from the international donor community and national research programmes for further development and selection of clones of diploid and tetraploid potatoes that have enhanced iron and zinc content, and their transfer to national agricultural research programmes in south America, Asia and Africa. Subsequently, these programmes and their associated extension programmes and NGOs will ensure the introduction of biofortified potatoes to small scale farmers in regions of high iron and zinc deficiencies.