Is Food Supplements Harmful to Health? - An Expert's Perspective

Safety and risk of dietary supplements are more likely to have side effects if taken in high doses or instead of prescription drugs. Learn about seven popular supplements that experts recommend taking with care.

Is Food Supplements Harmful to Health? - An Expert's Perspective

Safety and risk of dietary supplements are more likely to have side effects if taken in high doses or instead of prescription drugs, or if multiple supplements are taken. Some may increase the risk of bleeding or, if taken before surgery, may change the response to anesthesia. Unlike drugs, the U. S.

Food and Drug Administration (FDA) is not authorized to review the safety and effectiveness of dietary supplements before they are marketed. It is up to manufacturers to ensure that their products do not contain contaminants or impurities, are properly labeled and contain what they claim. Used correctly, some supplements can improve your health, but others may be ineffective or even harmful. A systematic review that analyzes the possible effects of nutritional supplements on cardiovascular health, mainly heart attacks and strokes, suggests that few supplements help prevent heart disease; only omega-3 fatty acids and folic acid were effective.

The same was true with dietary changes, except for a low-salt diet. Other research on self-reported dietary habits by a group of Americans linked daily doses of more than 1000 milligrams (mg) of calcium with a higher risk of death from cancer (although other studies suggest otherwise). In addition, the data showed that people who consumed adequate amounts of magnesium, zinc, and vitamins A and K had a lower risk of death, but only if they got those nutrients from food rather than supplements. The National Institutes of Health (NIH) fact sheets can provide detailed information on the benefits and risks of individual vitamins and minerals, as well as herbal supplements.

If you're managing an underlying health condition (especially if you're taking medications) or are pregnant or breastfeeding, it is best to talk to your health care team before adding any new supplement to your regimen. Here are seven popular supplements that experts recommend taking with care, if at all.

Vitamin D

promotes the absorption of calcium in the body, and having enough is critical to health and well-being, as it offers the promise of protecting bones and preventing bone diseases such as osteoporosis, according to the NIH. Vitamin D supplements are popular because it's difficult (if not impossible for some) to get enough from food.

In addition, our bodies produce vitamin D when bare skin is exposed to direct sunlight, but the increase in time spent indoors and the widespread use of sunscreen have minimized the amount of vitamin D that many of us get from exposure to the sun. Vitamin D supplements may benefit certain people, including those at risk of a deficiency, such as people with darker skin, living with certain health conditions, and older adults. The most recent consensus statement from the American Geriatrics Society specifically suggests that people over 65 can help reduce the risk of fractures and falls if they supplement their diet with at least 1000 IU of vitamin D per day, in addition to taking calcium supplements and eating foods rich in vitamin D. Keep in mind that vitamin D supplements and medications can interact with each other.

Drugs that don't mix well with vitamin D include orlistat (Xenical, Alli), a weight-loss medication, several statins such as atorvastatin (Lipitor), thiazide diuretics (such as Hygroton, Lozol, and Microzide), and corticosteroids such as prednisone (Deltasone, Rayos, Sterapred), according to the NIH.

St. John's Wort

is a plant that is used as tea or in capsules with supposed benefits for depression, attention deficit hyperactivity disorder, menopausal symptoms, insomnia, kidney and lung problems, obsessive-compulsive disorder, wound healing and more. St.

John's Wort will be effective in treating mild depression. For example, a review of short-term studies analyzed 27 clinical trials with about 3800 patients and suggested that the herbal remedy worked as well as certain antidepressants in reducing the symptoms of mild to moderate depression. However, St. John's Wort may reduce the effectiveness of other medications such as birth control pills, chemotherapy drugs against HIV or AIDS, and medications to prevent organ rejection after a transplant.

It is important to learn about possible drug interactions and ask your doctor about the risks and benefits of this supplement before taking it.


is essential for a strong skeleton but too much can be harmful. More than 2500 mg per day for adults ages 19 to 50 and more than 2000 mg per day for people age 51 and older can cause problems. Calcium supplements carry risks such as hardening of the arteries or atherosclerosis and an increased risk of heart disease although research is conflicting according to the Cleveland Clinic.

The NIH recommends 1 000 mg of calcium a day for women ages 19 to 50.