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

缺铁缺锌是全球性问题，在亚洲、撒哈拉以南非洲和南美洲发病率很高。虽然补充铁和锌方案和粮食强化方案已被证明在某些情况下是有效的，但它们的实施需要良好的基础设施、大量投资和安全的运送系统。发展生物可利用铁和锌水平更高的作物--即所谓的生物强化--是一种可持续和具有成本效益的补充战略，有可能为资源贫乏的农村和城市社区提供足够的铁和锌，例如安第斯高地的社区。国际社会在培育提高铁和/或锌水平的主食作物新品种方面作出了重大努力。然而，很难预测生物强化作物中额外的铁和锌是否会被生物利用--即有效地从饮食中吸收到身体中，以改善铁和锌的状况。培育这些生物强化作物的风险是，如果铁和锌无法生物利用，作物发展投资的影响将是有限的。铁和锌生物强化马铃薯是有助于减少安第斯高原铁和锌缺乏的理想作物，主要原因有两个。首先，与谷物和豆类不同，土豆含有非常低水平的植酸盐，这会抑制铁的生物利用率，这与相对高浓度的维生素C相结合，维生素C促进铁的吸收--这是最大限度地提高生物利用率的理想组合。其次，土豆是缺乏铁和锌的安第斯人的主食，大部分人在没有其他食物的情况下消费土豆。因此，尽管包括农业多样化在内的各种战略有可能缓解微量营养素缺乏，应综合考虑，但生物、文化和经济因素表明，引进铁锌生物强化土豆可能是一种有效的方法，可对减少铁锌缺乏作出重大贡献。目前，量化铁和锌的生物利用率是至关重要的。只有通过人类饮食干预研究，才能有意义地量化生物强化作物中铁和锌的生物利用率。在这些研究中，由生物强化作物制成的食品被标记上稳定的铁或锌同位素，然后将其量化，以提供生物有效性的衡量标准。这些研究在技术上具有挑战性，但对于生物强化策略的成功至关重要。为了量化引入生物强化土豆的潜在影响，来自人体研究的数据将在残疾调整生命年(DALY)建模方法中使用。该方法已成功地应用于评估其他生物强化作物缓解微量营养素缺乏的潜在影响。此外，我们将使用拟议研究的数据以及其他研究的数据来制定低收入和中等收入国家的铁饮食摄入量指南。如果我们通过人类干预研究和随后的DALY模型找到令人信服的证据，证明铁和锌生物强化土豆有助于缓解中低收入国家的铁和锌缺乏，这将为国际捐助界的投资和国家研究方案提供理由，以进一步开发和选择铁和锌含量更高的二倍体和四倍体土豆无性系，并将其转移到南美洲、亚洲和非洲的国家农业研究方案。随后，这些方案及其相关的推广方案和非政府组织将确保向铁和锌高度缺乏地区的小规模农民推广生物强化土豆。

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.