In recent months there's been a steady stream of news reports showing that antioxidant vitamins - which include C, E and beta-carotene - can protect against some types of cancer. Also, these vitamins may help prevent coronary heart disease and cataracts.
But as people pay more attention to taking vitamins, there is concern about certain ones doing more harm than good.
Fat soluble vitamins such as A,D, E, and K are stored in the body and vitamins A and D may become highly toxic. Megadoses of vitamin A can cause liver damage, bone and joint pain, headaches or dry, flaking skin. Too much vitamin C can cause the development of kidney stones. And pregnant women who take megadoses of vitamin C could have babies who develop rebound scurvy as a result of vitamin C withdrawal.
"You can have problems with fat soluble vitamins because they are stored in the body. Long-term use of megadoses of fat soluble could pose a health risk," says Mary Jo Sawicki, a dietician who teaches nutrition at St. Louis University School of Medicine.
On top of that, excessive vitamin B-6 has been associated with paralysis; too much iron can inhibit the absorption of zinc and other minerals.
"Some vitamins may interact with certain conditions or certain medications," says Becky Vedder, a pharmacist at Barnes West County. But many people don't realize that the vitamins they swallow may affect other medications they take. For example, Vedder says, "calcium supplements can interact with tetracycline, making the medication inactive."
While everyone is always looking for a magic pill, scientists caution that vitamins are no substitute for a balanced diet. Also, they suspect that the combination of trace elements in fruits and vegetables plays a key role in preventing disease. If that theory is true, then a diet rich in fruits and vegetables may be much more effective than a capsule. …