Carotenoids in staple foods: their potential to improve human nutrition

As part of the Consultative Group on International Agricultural Research (CGIAR) Micronutrients Project, we have investigated the content of carotenoids in staple foods, particularly wheat. Wheat varies widely in carotenoid content, depending on the variety and type. Durum (pasta) wheat is generally higher in carotenoid content, because the market has continued to demand strong pigment in pasta and noodle products, whereas in bread wheat the market demands flour as white as possible. Consequently, twentieth-century wheat breeders have consciously selected wheat varieties low in carotenoid content, although older, high-carotenoid bread wheats are still available and the trait is not lost. The entire carotenoid biosynthetic pathway exists in wheat grains, so varieties high in β-carotene and/or other carotenoids can be reintroduced if and when education in nutrition creates the demand. Numerous high-yielding maize varieties high in β-carotene already exist and have been used to eliminate vitamin A deficiency in livestock. A β-carotene–rich rice has been genetically engineered recently. Although the carotenoid content of beans has not yet been explored, high–β-carotene lines of cassava exist, and the trait is easily handled in a breeding programme. Yellow types of most staples are known, for example, sorghum, potatoes, and sweet potatoes. The amounts present are such that we can assert that vitamin A deficiency could easily be eliminated globally by delivering the required amounts via food staples. Moreover, there are strong signs that other benefits in eye health, enhanced absorption of iron from non-haem sources, anticarcinogenic effects, enhanced aroma, and better storage life may also result.