Vitamins and supplements are often seen as a quick fix for health problems, but they can be just as dangerous as they are beneficial. High folate intake may hide vitamin B12 deficiencies, while too much vitamin C or zinc can cause nausea, diarrhea, and stomach cramps. Too much selenium can lead to hair loss, gastrointestinal discomfort, fatigue, and mild nerve damage. Dietary supplements can also interact with each other and with over-the-counter and prescription drugs.
Unlike drugs, dietary supplements in the United States are not reviewed by the Food and Drug Administration (FDA) for safety and efficacy before they are marketed. Manufacturers must ensure that their products do not contain contaminants or impurities, are properly labeled, and contain what they claim. This means that the regulation of dietary supplements is much less stringent than that of prescription or over-the-counter drugs. Some supplements can improve your health if used correctly, but others may be ineffective or even harmful.
A systematic review analyzing the potential effects of nutritional supplements on cardiovascular health found that only omega-3 fatty acids and folic acid were effective in preventing heart disease. Dietary changes were also found to be effective, with the exception of a low-salt diet. Other research involving self-reported dietary habits of a group of Americans linked daily doses of more than 1000 milligrams (mg) of calcium to an increased risk of death from cancer. However, people who ingested adequate amounts of magnesium, zinc, and vitamins A and K had a lower risk of death if they got them from food rather than supplements.
If you're considering taking any supplements, it's important to talk to your health care team first. 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. Here are seven popular supplements that experts recommend taking with care: Vitamin D: Vitamin D promotes the absorption of calcium in the body and is essential for health and well-being. It offers the promise of protecting bones and preventing bone diseases such as osteoporosis.
Vitamin D supplements are popular because it's difficult (if not impossible for some) to get enough from food. Our bodies produce vitamin D when bare skin is exposed to direct sunlight, but this has been minimized due to time spent indoors and the widespread use of sunscreens. Vitamin D supplements may benefit certain people, including those at risk of suffering from a deficiency, such as people with darker skin, those with certain health conditions, and older adults. The American Geriatric Society suggests that people over 65 can help reduce the risk of fractures and falls by supplementing 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.
However, taking high doses isn't a good option as it can trigger greater calcium absorption and cause muscle pain, mood disorders, abdominal pain, kidney stones, heart attack, stroke, and more.
St John's Wort: St John's Wort is a plant used as a tea or in capsules with purported benefits for depression, attention deficit hyperactivity disorder (ADHD), menopausal symptoms, insomnia, kidney and lung problems, obsessive-compulsive disorder (OCD), wound healing, and more. It is effective in treating mild depression but can interact with medications such as weight-loss drug orlistat (Xenical, Alli), statins such as atorvastatin (Lipitor), thiazide diuretics such as Hygroton, Lozol, and Microzide), corticosteroids such as prednisone (Deltasone, Rayos, Sterapred), birth control pills, chemotherapy medications for HIV or AIDS, medications to prevent organ rejection after a transplant, and more. Learn about potential drug interactions before taking St John's Wort.
Calcium: Calcium is essential for a strong skeleton but too much can be harmful.
The NIH recommends 1000 mg of calcium per day for women ages 19 to 50 and 1200 mg per day for women age 51 and older. Taking more than 2,500 mg per day for adults ages 19 to 50 or more than 2,000 mg per day for people age 51 and older can cause problems such as hardening of the arteries or atherosclerosis and an increased risk of heart disease. It's important to remember that enthusiasm for vitamin D supplements is outpacing the evidence. Guidelines and research may seem contradictory but it's important to talk to your doctor about the risks and benefits before taking any new supplement.