Flax is a North American plant, Linum usitatissimum, which probably originated in America, although it has been studied mainly in Europe. The oil it yields is called linseed and it is rich in linoleic acids. Some human studies suggest it is helpful in arthritis and similar diseases. Its main use is as a poor substitute for more effective cholesterol-lowering drugs. The fibrous plant is used to treat constipation and is popular for this purpose. Some animal research suggests it may have an anti-cancer effect, but this claim is made for numerous herbs and there is no reason at this time to believe any of them are of any practical value in cancer therapy. The cost of such studies is enormous, and it is very unlikely that either science or popular folk belief will establish any flax plant or linseed oil as a reliable agent for any form of human cancer.