Nutritional supplements claim to treat everything from arthritis to hair loss. But now, some studies are calling their safety and effectiveness into question.

A consumer report investigation says calcium, as well as omega-3s and antioxidant supplements, contributed to 115 deaths and more than 2,000 hospitalizations in the U.S. over the past five years.

"There was a study published in June that showed that calcium supplements increased the risk of heart attack by 86 per cent compared to the group who didn't get them," said Nancy Metcalf of Consumer Reports. "In some cases, the risk of supplements can outweigh the benefits."

Nathan Zassman, owner of Aviva Natural Health Solutions, disagrees. He said problems only arise when people take supplements improperly.

"In many cases, people go overboard, take more than they need or go for an individual nutrient that puts things out of balance," he said.

For example, Zassman said taking calcium on its own could be harmful to someone who has a mineral deficiency. The calcium could be absorbed in the blood vessels rather than the bones, causing the arteries to harden.

"So it's not only the calcium that people are taking, it's the fact there are co-factors involved to make sure the calcium goes where it's supposed to go," said Zassman.

Personal Trainer RJ Padua, whose fitness routine includes a protein shake twice a day, said he doesn't rely solely on supplements for nutrition.

"Any supplementation, it is a supplement first, so it's secondary to all the foods I take in naturally."

He said anyone considering taking supplements should consult a health expert first.

There have been no reported deaths associated with supplement use in Canada. Health Canada regulates the 36,000 natural health products on the market, and said since 2007 about 400 of them have been recalled.