The health consequences of going overboard.
By Cari Nierenberg
WebMD Feature
Nowadays, everything from bottled water to orange juice seems to have souped-up levels of vitamins and minerals in it. That may sound like a way to help cover your nutritional bases, especially if your diet is less than stellar. But routinely getting an overload of vitamins and minerals can hurt you.
Too much vitamin C or zinc could cause nausea, diarrhea, and stomach cramps. Too much selenium could lead to hair loss, gastrointestinal upset, fatigue, and mild nerve damage.
While most people aren't getting megadoses, if you eat a fortified cereal at breakfast, grab an energy bar between meals, have enriched pasta for dinner, and take a daily supplement, you could easily be over the recommended daily intake of a host of nutrients.
Here's what you need to know to avoid overdoing it.
Supplements: Check the Dose
Chances are, the unfortified foods you eat aren't a problem. "It's pretty hard to overdo it from food alone," says Johanna Dwyer, RD, a senior research scientist with the National Institutes of Health's Office of Dietary Supplements.
So you'll want to think about the supplements you take and fortified foods or drinks.
"Most people don't realize there's no real advantage to taking more than the recommended amounts of vitamins and minerals, and they don't recognize there may be disadvantages," Dwyer says.
"If you're taking a supplement, stick to one that's no more than the daily value," Dwyer says. (Daily value is the amount of a vitamin or nutrient that a person should get for optimum health.)
Talk with your doctor about any supplements you're taking, including vitamins and minerals, and the dose you're taking, too. That way, your doctor can help you keep doses in a safe range.
"If you're taking a basic multivitamin, there's no need to fear taking too much," says Andrew Shao, PhD, senior vice president of scientific and regulatory affairs for the Council for Responsible Nutrition, a trade group for the supplements industry.
"Most multivitamins have such a wide margin of safety that even when you're combining them with fortified foods, it's still not going to cause you to keel over," Shao says.
Subtle Signs You're Getting Too Much
"I have not seen someone off the street who was taking a toxic level of vitamin A or D -- those are very unusual," says David Katz, MD, director of the Yale University Prevention Research Center in New Haven, CT, whose medical practice specializes in nutrition. "What I'm more likely to see is a person with a dosing level of supplements that's higher than optimal."
Scientists don't yet know if routinely getting a little bit too much of a vitamin or mineral (as opposed to a megadose) is a problem, Katz says.
source : Taking Too Many Vitamins? Side Effects of Vitamin Overdosing
