The product sold as "black lentil" is usually the whole urad bean or urad dal. The product sold as "white lentil" is the same lentil with the black skin removed.
Vigna mungo is used in traditional Indian(Ayurveda) medicine. Pharmacologically extracts have demonstrated immunostimolatory activity.
Vigna mungo, known as Urad, urad dal, udad dal, urd bean, urd, urid, black matpe bean, black gram, black lentil (not to be confused with the much smaller true black lentil (Lens culinaris)), maas (in Nepali), d?u den (Vietnamese, literally: black bean) or white lentil, is a bean grown in southern Asia. It is largely used to make dal from the whole or split, dehusked seeds. It, along with the mung bean, was placed in Phaseolus but has been transferred to Vigna. It was at one point considered to belong to the same species as the mung bean.