Assessment of nutrient uptake from biofortified crops in populations from developing countries

Background:

This CRP proposal was developed together with the Nutritional and Health-Related Environmental Studies Section and HarvestPlus, a global alliance of research institutions and implementing agencies that have come together to breed and disseminate crops for better nutrition. The main objective of this project is to determine the bioavailability and bioefficacy of micronutrients from improved crop varieties in humans using stable isotope techniques. At this stage, HarvestPlus institutions have prepared five nutritionally improved crop varieties. High beta carotene orange sweet potato, high-beta carotene maize, high beta carotene cassava, high iron-zinc beans and high iron beans. On the other hand, through regional TC project RAS/7/014, mutant rice with reduced phytic acid content has been developed, which is theoretically expected to be of higher iron and zinc bioavailability and it is expected that some participants of this regional project will be involved in the proposed CRP. Bioavailability has been defined as the proportion of the ingested nutrient that is absorbed and available for physiological processes in human body. Iron and zinc, once absorbed in the human body, are bound in blood to proteins for transport to sites where they can directly fulfil their functions. However, provitamin A carotenoids must be converted in the intestine or other sites in the body to retinol to exert vitamin A activity. Bioefficacy refers to the proportion of the ingested nutrient that is absorbed and converted to its active form.

Biofortification is the process of breeding staple food crops that are rich in micronutrients. The ultimate goal of the biofortification strategy is to reduce mortality and morbidity rates related to micronutrient malnutrition and to increase food security, productivity, and quality of life for poor populations of developing countries by breeding staple crops that provide, at low cost, improved levels of bioavailable micronutrients in a sustainable manner. Indeed, the effective supply of micronutrients in the human body not only depends on micronutrient concentrations in the ingested food, but also on the amount of food consumed and many factors that influence bioavailability and bioefficacy of these nutrients.

Quantitative estimates of bioavailability of iron and zinc and bioefficacy of provitamin A carotenoids are lacking for many crops. Thus crucial step in the development of improved crop varieties is to conduct studies to determine the bioavailability and bioefficacy. This should also guide plant breeders on the target concentrations of micronutrient to be eventually achieved in edible parts of the crops, so consumption of normal amounts of these foods results in the supply of a substantial proportion of the daily recommended intake.

Overall objectives:

To evaluate nutrition impact of consumption of biofortified crops using stable isotopic technique.

Specific objectives:

  • To determine the bioavailability of iron and zinc from improved crop varieties
  • To determine the bioefficacy of provitamin A carotenoids from improved crop varieties

Participants:

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Project Officer:

P.J.L. Lagoda