Content of zinc, iron, calcium and their absorption inhibitors in foods commonly consumed in Ethiopia

The zinc, iron, calcium, phosphorus, phytate, tannin and moisture content of 36 foods consumed in rural Ethiopia were analysed. The foods analysed included those based on cereals, starchy tubers and roots, and legumes and vegetables as well as some fruits. Although many foods were relatively rich in zinc and iron, many also contained high levels of phytic acid and tannins, which impair bioavailability of zinc and iron. The phytate:zinc molar ratios were >20 for non-fermented cereal foods, >15 for legumes, and <12 for fermented cereals, starchy tubers and roots. Ratios >15 are associated with low bioavailability of zinc. Given the high iron content and the relatively favourable phytate:iron molar ratio, tef enjera was the best source of bioavailable iron of all foods analysed. Foods prepared from tef, enset and kale are rich sources of calcium. The consumption of diets based on cereals and legumes but poor in animal products can lead to deficiencies of zinc and iron. However, since fermentation can decrease the phytate content by a factor of 3-4, traditional household practices such as fermentation need to be encouraged to address the problem of zinc deficiency, which is particularly prevalent in Ethiopia.