Bioavailability of Micronutrients from Plant Foods: An Update

Deficiencies of iron, zinc, iodine and vitamin A are widespread in the developing countries, poor bioavailability of these
micronutrients from plant-based foods being the major reason for their wide prevalence. Diets predominantly vegetarian
are composed of components that enhance as well as inhibit mineral bioavailability, the latter being predominant.
However, prudent cooking practices and use of ideal combinations of food components can significantly improve
micronutrient bioavailability. Household processing such as heat treatment, sprouting, fermentation and malting have
been evidenced to enhance the bioavailability of iron and b-carotene from plant foods. Food acidulants amchur and lime
are also shown to enhance the bioavailability of not only iron and zinc, but also of b-carotene. Recently indentified newer
enhancers of micronutrient bioaccessibility include sulphur compound-rich Allium spices—onion and garlic, which also
possess antioxidant properties, b-carotene-rich vegetables—carrot and amaranth, and pungent spices—pepper (both red
and black) as well as ginger. Information on the beneficial effect of these dietary compounds on micronutrient
bioaccessibility is novel. These food components evidenced to improve the bioavailability of micronutrients are common
ingredients of Indian culinary, and probably of other tropical countries. Fruits such as mango and papaya, when
consumed in combination with milk, provide significantly higher amounts of bioavailable b-carotene. Awareness of the
beneficial influence of these common dietary ingredients on the bioavailability of micronutrients would help in devising
dietary strategies to improve the bioavailability of these vital nutrients.