Don't Overdo Vitamins

Tuesday, February 10, 2004

ROCHESTER, Minn. — Too much of a good thing — vitamins — can be bad for you.

Vitamins are good for you. They promote chemical reactions so your body can process foods — proteins, carbohydrates and fats. But taking high doses of certain essential vitamins can be harmful. Vitamins A, D and B-6 in particular can be dangerous in large amounts. The February issue of Mayo Clinic Health Letter outlines the risks.

Vitamin A: This vitamin plays a part in healthy vision, bone growth, reproduction and regulation of the immune system. Taking excess vitamin A, more than 5,000 International units (IU) a day, can cause reduced bone mineral density leading to osteoporosis, liver abnormalities, hair loss and some neurologic problems.

The recommended daily amount is 3,000 IU for men and 2,330 IU for women.

Vitamin D: This vitamin is necessary for the effective absorption of dietary calcium. It also helps the body deposit calcium in bones and teeth. The amount you need depends on your age, the amount of sunlight exposure you get, liver and kidney function and medical conditions. In general, the recommended amount is 400 IU a day for people ages 51 to 70. For those over age 70, the recommendation is 600 IU a day. More than 2,000 IU a day can cause problems including excessive urination, high blood pressure, calcium deposits in soft tissues (kidney stones) and kidney damage.

When tallying up your daily dose, remember to add in the amounts found in fortified foods such as cereals, milk, energy bars and drinks. Calcium supplements often include Vitamin D, too.

Vitamin B-6: Excessive amounts can result in nerve damage with signs and symptoms such as numbness of feet and hands, unsteady gait and impaired reflexes. The recommended amount for men over age 50 is 1.7 milligrams (mg)/day; for women over age 50, the recommendation is 1.5 mg/day. More than 100 mg/day can pose health risks.

Unless your doctor prescribes vitamin supplements for a medical condition, it's generally not necessary or advisable to take more than a basic multivitamin with 100 percent Daily Value of vitamins.

Mayo Clinic in Rochester
Carol Lammers
507-284-5005 (days)
507-284-2511(evenings)
email: newsbureau@mayo.edu

Mayo Clinic in Jacksonville
Erik Kaldor
904-953-2300

Mayo Clinic in Scottsdale
Anne Tewksbury
480-301-4368

Mayo Clinic Health Letter is an eight-page monthly newsletter of reliable, accurate and practical information on today's health and medical news. To subscribe, please call toll free 800-333-9037, extension 9PR1.

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