Scientists have long known that vitamins found in foods are essential to good health, but the jury's still out on vitamin supplements.
Yet such consumer zealousness has many scientists alarmed. Although scientists won't dispute that vitamins are essential to good health they say the jury's still out on the benefits of supplements.
Are consumers going overboard? Isn't a well-balanced diet the key to getting all the essential vitamins without having to stock up on supplements?
Because the topic of health and vitamins always seems to be in the public eye as we enter the 1990s Arthritis Today spoke with several scientists around the country to discuss studies done in this field and to extract their opinions on the subject. Here's what they had to say.
The Best Sellers
Right now it seems vitamins C and E and beta carotene--a pigment present in some vegetables that enables the body to make vitamin A--are the best-selling supplements. A number of articles in popular magazines call this trio ''super- youth vitamins" and credit them with fighting aging, cataracts, cancer, even heart disease. Medical authorities are hesitant to make such claims - they admit the data are encouraging but insist that nothing has been proved.
Some scientists speculate that vitamins might boost health and life expectancy by enhancing the immune system and reducing oxidation--a generic word representing many chemical reactions.
"In aging oxidation results in a weakening of cell membranes " explains M. Elizabeth Kunkel, Ph.D. of the Department of Food Science at Clemson University. Kunkel says vitamin E helps slow the oxidation process by becoming oxidized instead. "It also may stabilize an enzyme that stops oxidation " she says.
In the Nov. 26 1988 issue of Science News, writer Janet Raloff described a study of vitamin use and immunity in the elderly conducted at the USDA's Human Nutrition Research Center on Aging at Tufts University. Immunity is thought to decrease with age and vitamin E is believed to improve immune function. Researchers tested a group of elderly volunteers to observe whether large doses of vitamin E could enhance the immune function.
The results of the study were encouraging according to Simin Meydani, Ph.D. who gave the 32 volunteers daily doses of the vitamin for a month. All of the participants tolerated the large doses well and laboratory tests performed before and after the 30-day regimen showed significant increases in the disease-fighting capacity of white blood cells.
Good sources of beta carotene:
|Yellow and green
fruits and vegetables such as:
Provided by the "American Dietetic Association"
"This was a small study" Dr. Meydani says. "Vitamins improved some immune responses but it's too early to cite the health implications. Vitamin E seems to help."
One theory says aging is the result of progressive deterioration in cells from attacks by oxidants. If that's true E indeed may be a "super youth" vitamin but there are a lot of ifs here.
E is also a city dweller's vitamin. It seems to protect sensitive tissues such as eyes and lungs against air pollution but it does nothing for cholesterol. E's only role in heart disease seems to be in preventing blood clots. It has been used for years in the treatment of clots in the veins of the legs.
Beta carotene holds the most promise for reducing cancer risks. Because it keeps the tissues of the lungs, mouth, larynx, esophagus, breasts, urinary tract, vagina, bladder and skin healthy, vitamin A may reduce the cancer risk in these places. It also may diminish fat levels in the blood thus reducing the risk of heart disease.
For some people vitamin C, ascorbic acid, is the vitamin of choice. It has received the most controversial publicity of all essential vitamins primarily considering its effect on colds and flu. C is water soluble and is found in the juice of fruits and vegetables. It also leaches out into the water when fruits and vegetables are boiled.
Good sources of vitamin E:
Common vegetable oils such as:
Provided by the "American Dietetic Association"
In his book, Vitamin C, the Common Cold and the Flu, Dr. Linus Pauling, a proponent of this controversial vitamin, suggests that the vitamin is also effective against both heart disease and cancer. Yet other studies indicate that low doses may actually stimulate cancer.
Still other studies suggest that low doses of vitamin C may increase high density lipoproteins, or HDL, the good cholesterol in the blood. If this is true, C is important in lowering risk of heart disease, but again, the jury is out.
In fact, it's apparent that the jury is still out on all the alleged health benefits of beta carotene and vitamins E and C. New studies of them in all areas are increasing while old studies are being reevaluated, but right now no one is willing to say unequivocally, yes, they help or no, they don't.
Authorities concede that results are encouraging, then qualify this by insisting that any benefits are derived from eating vitamins in their natural state rather than as supplements. "There may be other things - minerals or chemical combinations - in fruits and vegetables that account for the benefits instead of just the isolated vitamin," says Dr. Waller Willett, professor of Epidemiology and Nutrition at Harvard School of Public Health. "Remember, the data in many of the experiments came from people eating food, not taking vitamin pills."
A Word of Caution
Indeed, although vitamins are essential for life, it's possible to get too much of a good thing.
Vitamin C presents the least risk of overdose because it is water soluble and quickly excreted from the body. Vitamins A and E, however, are fat soluble, which means they are not readily excreted and are stored in the liver and fatty tissues.
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