There are claims that vitamin B-17, commonly called laetrile, kills cancerous cells without harming normal cells, but no scientific evidence supports this. In fact, laetrile does not even fit the scientific definition of a vitamin, as it has no proven benefit for health, notes the American Cancer Society.
Laetrile is a chemically altered form of amygdalin, a substance occurring naturally in almond, peach and apricot kernels. Its supporters claimed that cultures with amygdalin-rich diets, such as the Karakorum and Hunza people in south Asia, are free of cancer. According to this theory, cancer cells have an enzyme that divides the laetrile molecule, releasing cyanide inside, and the cyanide kills the cancer cell. Because non-cancerous cells lack that enzyme, the laetrile molecules leave them alone. Other supporters claim that laetrile is really the missing vitamin B-17, and that cancer is nothing more than a deficiency of this vitamin, according to the American Cancer Society.
Animal testing for the effectiveness of laetrile began in 1957, but no studies found any effectiveness against tumor cells, and the FDA instituted sanctions against the sale of laetrile. Because laetrile does contain cyanide and people who have used laetrile have been poisoned as a result, the FDA has banned bringing laetrile into the United States or over state lines, and the federal government has banned laetrile use in states that have not expressly authorized it, as stated by the American Cancer Society.