Getting Too Much of Vitamins And Minerals
The health consequences of going overboard on vitamins and minerals.
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 are you in danger of getting too much of these important nutrients? And can these overloads hurt you?
Yes, if you're routinely taking megadoses. For instance, too much vitamin C or zinc could cause nausea, diarrhea, and stomach cramps. Too much selenium could lead to problems including hair loss, gastrointestinal upset, fatigue, and mild nerve damage.
Most people aren't getting megadoses. Still, if you eat a fortified cereal at breakfast, grab an energy bar between meals, have enriched pasta for dinner, and take a daily multivitamin, you could easily be over the recommended daily intake of a host of nutrients.
When it comes to vitamins and minerals, more is not necessarily better. Here's what you need to know to avoid overdoing it.
Look Beyond Your Plate
Chances are, the unfortified foods you eat aren't a problem. "It's pretty hard to overdo it from food alone," says Johanna Dwyer, DSc, RD, a senior research scientist with the National Institutes of Health's Office of Dietary Supplements.
A few rare cases in medical journals have described, for example, an overload of vitamin A in a person who ate polar bear liver, a meat with extremely high amounts of this vitamin. Signs of a surplus of vitamin A may include nausea, blurred vision, and dizziness.
And if you eat handfuls of Brazil nuts every day, you could be way over the Tolerable Upper Intake Limit (the maximum per day that is unlikely to cause harm, as determined by the Institute of Medicine) for selenium. Just one ounce of Brazil nuts contains 544 micrograms of selenium. The Tolerable Upper Intake Limit is 400 micrograms per day -- and less if you're younger than 14.
Since polar bear liver and sacks of Brazil nuts are probably not on your menu, you'll want to think about the supplements you take and fortified foods or drinks.
Supplements: Check the Dose
"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.
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.