Taking more than you need costs more and may also increase the risk of side effects. For example, too much vitamin A can cause headaches and liver damage, reduce bone strength, and cause birth defects. Excess iron causes nausea and vomiting and can damage the liver and other organs. For one thing, dietary supplements can sometimes interact with each other, as well as with over-the-counter (OTC) and prescription drugs.
In addition, unlike drugs, the U. S. Food & 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.
In other words, the regulation of dietary supplements is much less stringent than that of prescription or over-the-counter drugs. Used correctly, some supplements can improve your health, but others may be ineffective or even harmful. For example, 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, as noted by the National Cancer Institute, 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. Confused? 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. And if you're managing an underlying health condition (especially if you're taking medications) or are pregnant or breastfeeding, play it safe and talk to your health care team before adding any new supplement to your regimen.
While supplement trends come and go, here are seven supplements that have historically been popular, and in all cases, experts recommend taking them 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, as noted by the Centers for Disease Control and Prevention, 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, as a necessary way to prevent skin aging and skin cancer, have minimized the amount of vitamin D that many of us get from exposure to the sun.
However, vitamin D supplements are a sensitive topic. Sometimes, guidelines and research may seem to contradict each other. The truth is that enthusiasm for vitamin D supplements is outpacing the evidence. And taking high doses isn't a good option.
In healthy people, vitamin D blood levels greater than 100 nanograms per milliliter can cause additional calcium absorption and cause muscle pain, mood disorders, abdominal pain and kidney stones, notes the Cleveland Clinic. It can also increase the risk of heart attack and stroke. That said, 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, according to MedlinePlus. 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 says the NIH. 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; says Dr Denise Millstine; internist in the integrative medicine department at Mayo Clinic in Phoenix; Arizona; “the biggest problem with St John's Wort is its interaction with medications” Taking St John's Wort may also 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; according to the NIH If you're considering taking St John's Wort; learn about possible drug interactions and ask your doctor about the risks and benefits of this supplement; as well as its comparison with other options Calcium is essential for a strong skeleton; but as with all nutrients; too much of this mineral can be harmful As noted by the NIH; 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 hardening of the arteries or atherosclerosis; an increased risk of heart disease; although research is conflicting according to the Cleveland Clinic The NIH recommends 1000 mg of calcium a day for women ages 19 to 50.