Brassica juncea includes the group known as mustard. In the southern United States, the foliage of B. juncea is often eaten as mustard greens . The distinctive flavor of mustard, present to some extent in all the brassicas, is strongest in the various types of B. juncea .
Most people use mustard as a condiment or spice.
Mustard contains oils called glucosinolates, which are activated by saliva and release the strong mustard flavor. These glucosinolates are a help to both plants and humans. Certain pests are repelled and others attracted by glucosinolates. The strong flavor also helps to discourage deer and rabbits from eating brassica crops. In mammals, certain glucosinolates have been found to help detoxify cancer-causing nitrosamine chemicals in the liver.