Whether it's calcuium, St. John's wort or fish oil, supplements are part of the diets of many people.
Nutritionist Dina Khader says the problem is that most users don't realize supplements can be dangerous.
"People start to take their own supplements without really checking if they really need it or if it's something that would benefit them in any way," she said.
A Consumer Reports investigation found many surprising dangers in vitamins and supplements, which are largely unregulated. And there's increasing evidence there may be few, if any, benefits.
"There was a study published in June that showed that calcium supplements increased the risk of heart attack by 86 percent, compared to the group who didn't get them,” said Nancy Metcalf of Consumer Reports. “On the other hand, that same study showed eating calcium-rich foods can protect your heart."
A different study of antioxidants shows that high doses of some "may increase cancer risk" and not reduce it.
"Even more troubling - some supplements have turned out to contain prescription drugs like Viagra and Cialis that were not on the label,” Metcalf said.
The FDA says supplements spiked with prescription drugs are "the largest threat" to consumer safety.
Since 2008, more than 400 products have been recalled - mostly those marketed for bodybuilding, sexual enhancement and weight loss.
"Even with uncontaminated vitamins and minerals, the labels don't tell the whole story because, generally, the FDA does not require manufacturers to include warning labels,” Metcalf said.
Consumer Reports checked out the labels on more than 200 supplements, they found one in three listed possible reactions.
“In some cases, the potential risks of supplements can outweigh the benefits,” Metcalf said. “We say if you're generally pretty healthy person, you can skip them."
What not to skip? A healthy diet. Experts say it’s the best way for most people to get all the nutrients they need.