Do Supplements Cause Cancer? Here's what a New Study Says

The researchers analyzed data on more than 27,000 adults in the U.S. to evaluate the link between dietary supplements and mortality. They found that the "lower risk of death associated with adequate nutrient intakes of vitamin K and magnesium was limited to nutrients from foods, not from supplements," a statement on the research says.

Additionally, the researchers found that getting enough vitamin K, vitamin A, and zinc via a balanced diet lowers your chances of having cardiovascular disease. Getting enough of those three via pills, though, doesn't have the same effect. On top of that, the researchers found that getting too much calcium from supplements—defined as at least 1,000 milligrams a day—increases your risk of dying of cancer. But that relationship doesn't exist if you're getting that much calcium from food, the study found.

Another interesting finding from the new research: If you take vitamin D without being vitamin D deficient, you could be increasing your chances of dying of cancer. However, more studies are needed to solidify this finding, the researchers warn.

To be clear, there are a handful of legitimate reasons to take supplements. For example, you might want to consider taking zinc, copper, and B vitamins if you have inflammatory bowel disease. If you have osteoporosis, it's possible that you'll benefit from taking vitamin D and calcium. But most of us can probably get the vitamins and nutrients we need from eating a variety of nutritious whole foods, Heather Caplan, RD, previously told ishonest.

If you are going to use a supplement, keep a few things in mind when shopping for vitamins from our buyer's guide: For starters, avoid buying supplements made in China, where relaxed regulations could lead to contaminated products. You should also avoid discounts when you're shopping for supplements; the recommended dosages of cheaper products are less likely to match established standards. Refrain from taking supplements that include kava, an ingredient linked to liver damage; chromium, which is associated with anemia; bitter orange, which is associated with heart attacks and strokes; and contaminated L- tryptophan, which is linked to neurotoxic reactions.

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