Dietician Roberta Anding with Texas Children's Hospital explained, "A dose of vitamin C, under 500 milligrams, powerful antioxidant. When you start to creep above 500 milligrams, there are also studies suggesting it acts as a pro-oxidant."
Most of us think that because vitamins are sold over the counter that they're benign. But the experts say when you start taking vitamins in mega-doses, they start acting like a drug and they can have side effects just like drugs.
"They can end up doing more harm than good," Anding said. "More and more studies are coming out about the dangers of excess vitamins."
UT Health psychologist and researcher Dr. Ken Goodrick said, "Long term intakes of high vitamin A may weaken the bones of older adults."
Dr. Goodrick says mega-doses of vitamins can lead to inflammation, which can make arthritis worse. And it's easy to overdo it.
"(People think) I'm going to take a lot of vitamin A because I read in that magazine, and then they go and drink milk that has vitamin A added, they eat bread that has vitamin A added. Then they're going to get in trouble," Dr. Goodrick explained.
Here are some common vitamins and what can happen if you take too much.
- Overdosing on vitamin B1 can lead to drowsiness
- Overdosing on vitamin B3 can cause liver damage
- Too much vitamin B5 can cause diarrhea and possibly nausea
- Overdosing on vitamin B6 can cause nerve damage
- Overdosing on vitamin C, besides the increased cancer risk, can cause stomach aches
- Overdosing on vitamin E can cause possible congestive heart failure
- Folic acid is important for pregnant women and their babies, but mega-doses of folic acid can cause colon polyps to grow
Experts say you can get the most vitamins by eating foods with a variety of colors, such as the blue in blueberries, the red in strawberries, the red in grapes and the green in broccoli.