Doctors have known that low levels of vitamin D are linked to certain kinds of cancers as well as to diabetes and asthma, but new research also shows that the vitamin can kill human cancer cells.

The results fall short of an immediate cancer cure, but they are encouraging, medical professionals say. JoEllen Welsh, a researcher with the State University of New York at Albany, has studied the effects of vitamin D for 25 years. Part of her research involves taking human breast cancer cells and treating them with a potent form of vitamin D.