Laetrile, also known as B-17, isn't a vitamin at all, but rather a chemically-modified form of a substance called amygdalin. Laetrile does not occur naturally in any foods, although amygdalin does. Laetrile, used as a popular alternative cancer treatment, has shown no benefit for this in clinical studies. Amygdalin, a compound containing cyanide, is not a vitamin because it does not meet the accepted definition of an essential element which must be obtained from dietary sources. Amygdalin does exist naturally in some foods; it usually has a bitter taste. Do not increase your amygdalin intake without talking to your physician.
Seeds and pits may not be part of many people's diet, and there's good reason for them not to be. Seeds and pits high in amygdalin can cause cyanide poisoning if you eat enough of them. Eating as few as 10 kernels from the center of an apricot pit can cause cyanide poisoning, the American College of Health Science states. Other pits and seeds high in amygdalin, but also potentially high in cyanide, include apple, cherry, peach, pear and plum seeds. Flaxseed, millet seed and buckwheat contains medium amounts of amygdalin, according to Vitamin B17.org -- a site dedicated to the use of Laetrile in cancer treatment. Do not consume seeds without discussing it first with your medical practitioner; cyanide poisoning can kill you.
Fruit sources high in amygdalin include crabapples, wild blackberries and Swedish cranberries. A high amount of amygdalin is listed by Vitamin B17.org as containing more than 500 mg of nitriloside per 100 g serving. Nitriloside is a term coined by the founders of the Laetrile movement to describe water-soluble compounds called Beta-cyanophoric glycosides. Raspberries, elderberries, currants, mulberries, wild strawberries and huckleberries contain medium amounts, defined as more than 100 mg of nitriloside per 100 g.
Sprouts often contain amygdalin in medium to high amounts. Bamboo sprouts are listed as having high amounts, while alfalfa, fava, garbanzo and mung sprouts contain medium amounts.
Of the nuts that contain amygdalin, bitter almond contains the highest amounts, but macadamia nuts, cashews and pecans also supply amygdalin.
Beans that supply medium to high amounts of amygdalin include fava, mung, lentils and Burma lima beans.