evidence: The hype: Laetrile, first popularized as a cancer therapy in Russia and the United States more than a century ago, is the trade name for a purified form of amygdalin, an extract derived from apricot pits and some nuts and plants. Intestinal enzymes break down Laetrile to produce cyanide, which proponents claim kills cancer cells and leaves normal tissue unharmed. Some also claim that Laetrile is actually a vitamin called B-17 and that deficiencies can cause certain cancers. Banned in the United States, an oral form of Laetrile is available in other countries.