Millets are small-seeded grasses that are hardy and grow well in dry zones as rain-fed crops, under marginal conditions of soil fertility and moisture. So these grains are more sustainable than rice and wheat (which are heavily dependant on irrigation). Millets are one of the oldest foods known to humans and possibly the first cereal grain to be used for domestic purposes.
They are highly nutritious, non-glutinous and not acid forming foods. Hence they are soothing and easy to digest. They are considered to be the least allergenic and most digestible grains available. Compared to rice, especially polished rice, millets release lesser percentage of glucose and over a longer period of time. This lowers the risk of diabetes.
Millets are particularly high in minerals like iron, magnesium, phosphorous and potassium. Finger millet (Ragi) is the richest in calcium content, about 10 times that of rice or wheat. Click here for the nutrient composition of millets as compared to wheat and rice.