Discuss several examples of naturally occurring toxicants in foods and appropriate methods to minimize exposure to them

Question

What will be an ideal response?

Answer 1

ANS:
Cabbage, bok choy, turnips, mustard greens, kale, brussels sprouts, cauliflower, broccoli, kohlrabi, and radishes contain small quantities of goitrogens—compounds that can enlarge the thyroid gland. Eating exceptionally large amounts of goitrogen-containing vegetables can aggravate a preexisting thyroid problem, but it usually does not initiate one. Problems may develop when exceptionally large amounts (2 to 3 pounds a day) of these vegetables are eaten raw; cooking deactivates the enzyme that normally inhibits the uptake of iodine in the thyroid.

Lima beans and fruit seeds such as apricot pits contain cyanogens—inactive compounds that produce the deadly poison cyanide upon activation by a specific plant enzyme. For this reason, many countries restrict commercially grown lima beans to those varieties with the lowest cyanogen contents. As for fruit seeds, they are seldom deliberately eaten. An occasional swallowed seed or two presents no danger, but a couple of dozen seeds can be fatal to a small child. Perhaps the most infamous cyanogen in seeds is laetrile—a compound erroneously rep- resented as a cancer cure. True, laetrile kills cancer, but only at doses that kill the person too. The combination of cyanide poisoning and lack of medical attention is life-threatening.

The humble potato contains many natural poisons, including solanine, a powerful narcotic-like substance. Most of a potato's solanine is found in the sprouts and in the green layer that develops just beneath the skin. Solanine poisoning is extremely rare, however, because the small amounts of solanine (8 milligrams per 100 grams of potato) normally found in potatoes are harmless—even when the potato skin is eaten. Solanine can be toxic, however, and presents a hazard when consumed in large quantities (20 to 25 milligrams per 100 grams of potato). Cooking does not destroy solanine, but it can be removed by peeling the potato. Symptoms of solanine poisoning include gastrointestinal disturbances and neurological disorders.