Vitamins: Too Much of a Good Thing?

Feb. 23 -- Popping a vitamin pill seems like an easy cure-all. But this once-a-day health ritual might actually be the cause of what ails you.

Experts warn toxic doses of four common nutrients — iron and vitamins A, D and B6 — can be easily consumed through careless use of everyday vitamin pills.

Click for Recommended Amounts of Four Key Nutrients

"People think there can't be a downside to vitamin and mineral supplements. After all, they're sold over the counter and contain the same vitamins found in foods," says Dr. Lora Sporny, professor of nutrition at Columbia University in New York City.

Medical experts agree taking a daily vitamin pill is safe for most people. "But in concentrated doses some vitamins and minerals can have very different effects on the body," cautions Sporny. "They can have pharmacologic, drug-like effects."

Too Much of a Good Thing

The one mineral and three vitamins found to cause health problems in large doses — iron and vitamins A, D and B6 — are all essential to health. Diets lacking them can cause a host of health problems, including anemia, dermatitis, skeletal deformities and eye damage.

But if a little is good, more is not always better. Popular grocery items like breakfast cereals, bread, nutrition bars, fruit juices and milk are now fortified with high doses of vitamins and minerals.

"We're seeing an over-fortification of the food supply," says Sporny. "Some breakfast cereals offer 100 percent of the recommended doses of vitamins and minerals in one serving — about one cup. And people are eating servings two to three times that large, then pouring milk fortified with vitamins A and D over that cereal."

Sporny adds: "I fear that as we move forward we may see more nutrient toxicity. It's a prescription for some very serious problems."