Vitamin B-17 comes in 100-milligram tablets on the Web, according to CytoPharmaOnline.com. However, there is no evidence that it functions as a vitamin in either humans or animals, says Cancer.gov. The term is a misnomer for the compound laetrile which derives from amygdalin found in some fruits and nuts.
Laetrile is a popular anti-cancer treatment, notes WebMD.com. Various theories exist behind claims that cancer patients benefit from using laetrile, explains Cancer.gov. One such theory states that cancer is due to a vitamin deficiency and that supplementing the body with Vitamin B-17 works against cancer. However, laetrile lacks Food and Drug Administration approval as a treatment for cancer or other medical conditions.