Vitamin megadoses, overdoses
The bear had the last laughBy Dr. Gifford Jones
It’s been aptly said that “Too much of a good thing is worse than none at all.” Today the easy availability of over-the-counter vitamins provides both benefits and perils to medical consumers. Those who decide to be their own doctor should never forget the legal maxim, “Let the buyer beware.” Every year people assume that, if a little vitamin is good for you, more must be better. They often get more than they bargained for.
A story goes that hunters who tracked down and killed a bear were celebrating their prowess. But the bear had the last laugh. After they consumed its liver they developed acute vitamin A poisoning. Bear liver contains massive amounts of vitamin A.
Vitamin A is not an innocuous nutrient. A little girl recently developed increasing fatigue, loss of appetite and finally kidney failure. Her loving grandmother, who owned a health food store was gradually killing her granddaughter with excessive amounts of vitamin A. Another child developed extreme irritability, fever and pains in the bones. The diagnosis? Vitamin D poisoning.
Some people are taking up to 500 times the recommended daily intake of some vitamins. In these large “megadoses” vitamins are no longer nutrients, but must be considered drugs which can have harmful side effects.
One best-selling health book touted the “Amazing Story of Niacin”. This vitamin B3, it claimed, was one means of lowering blood cholesterol. It wasn’t that the theory had no validity and that vitamin B3 should never be used for this purpose. But taken in magadoses, without medical supervision, vitamin B3 has proven to be hazardous for some people.
People who have diabetes are at particular risk. Researchers at the University of Texas South Western Medical Center at Dallas discovered that large amounts of niacin increases the blood sugar level. Taking 250 milligrams, 13 times the recommended daily allowance, has caused nausea, itching, flushing and blurred vision.
Johns Hopkins University also reports that two men and one woman who had consumed 2,000 to 4,000 milligrams daily developed inflammation of the liver. Another 32 year old Los Angeles man suffered liver failure after taking 500 milligrams daily for two months.
Pyridoxine, vitamin B6, provides another good example of self-medication triggering problems. The recommended daily intake for vitamin B6 is about 2 milligrams a day. But B6 has been promoted in popular books and health magazines as a remedy for the symptoms of premenstrual tension such as bloating, breast tenderness, irritability, and depression. It’s resulted in some women taking up to 1000 milligrams a day! The result has been damage to peripheral nerves, impaired coordination, loss of sensory touch and pain, numbness of the feet and hands, and unsteady gait.
Now let’s look at the other side of the coin. Megadoses of vitamins taken for short periods of time under medical supervision may be helpful. For instance, Dr. Clayton L. Natta of Columbia University found that asthmatic patients with low levels of vitamin B6 were dramatically helped by taking 100 milligrams of B6 daily.
The debate over the value of megadoses of vitamin C continues. Linus Pauling, the Nobel Prize winner, is convinced that C fights the common cold, high blood cholesterol and heart disease. Others contend high doses cause diarrhea and trigger kidney stones.
We should also be aware of some new research when the snow starts to fall. Researchers at Glasgow Southern Hospital in Scotland report the level of total cholesterol in the blood rises not exhibit this seasonal variation.
Vitamin C also appears to provide protection against death by stroke. Dr. S.E. Vollset at the University of Bergen in Norway studied 16,713 people. Over a 12 year period 483 died of a stroke. Those patients who consumed a diet high in vegetables and fruit were less likely to succumb to such brain hemorrhage.
Another study at Harvard and Boston University showed that a diet rich in vitamin A helps to protect against cancer. The investigators followed 1,271 elderly people for five years. The result? Those who consumed carrots and other yellow vegetables high in carotene, the vitamin A forming-pigment, had 30 per cent less chance of dying from cancer.
Today osteoporosis, a thinning of the bones, causes a huge amount of disability. We know that estrogen, calcium and exercise can keep the bones strong. But one report reveals a shocking fact. 40 per cent of patients admitted to a Boston hospital with fractured hips had little or no vitamin D in their blood. Dr. Gerald Brookes, at London Hospital in England, also discovered low vitamin D levels in 8 out of 20 women and 12 men with otosclerosis, a major cause of hearing loss. Vitamin D supplements along with calcium produced marked hearing improvement in 30 per cent of patients.
The message is clear. Too much of a good thing can damage your health. So don’t be your own doctor.(0) Reader Feedback | Email Article | Email Us | Print friendly
Dr. Gifford Jones Bio
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W. Gifford-Jones M.D is the pen name of Dr. Ken Walker graduate of The Harvard Medical School. He’s been a ship’s surgeon, hotel physician and family doctor and later trained in surgery at McGill in Montreal, University of Rochester N.Y. and Harvard. His medical column is published by 60 Canadian newspapers and several in the U.S. He is the author of seven books. Dr. Walker has a medical practice in Toronto. His Web site is: http://www.mydoctor.ca/gifford-jones