Q: I take a lot of vitamin and herbal supplements? Is that safe?
A: The sale of nutrient supplements is a billion dollar a year business. But whether you’re looking to ward off cancer, lose weight or make up for poor eating habits, you must be careful when taking supplements! In 1994, the U.S. Food & Drug Administration revised government regulation of dietary supplements, which include vitamins, minerals, amino acids, herbs, enzymes and many other substances. The new law determined that it is up to the manufacturer of the supplement to make sure that the product is safe, the label claims are substantiated by solid evidence and that the supplement’s content matches ingredients declared on the packaging. In short, supplements do not need approval from the FDA prior to marketing, nor does the FDA analyze the composition of these products. Manufacturers are required to investigate and alert the FDA of any reports of adverse health events associated with the product.
Supplements are indicated for certain groups of people: people with diagnosed nutrient deficiencies, pregnant women, infants, those who are lactose intolerant, perpetual dieters, those addicted to drugs or alcohol, strict vegetarians, and those suffering or recovering from illness, surgery or injury. While these may be valid reasons to be taking supplements, you should always notify your doctor of any over-the-counter products you’re consuming.
Taking supplements increases your risk of toxicities. High potency single nutrient supplements can cause accidental poisoning that can result in liver damage, shock and possible death. High doses can be very dangerous and labels can sometimes lure you with misleading or unproven claims. Certain nutrients, such as the fat-soluble vitamins A, D, E and K, can build up in your system over time. In fact, intakes of vitamin A just twice the recommended amount, taken over a few years, are associated with osteoporosis, while daily supplements of beta-carotene may increase lung cancer risk in smokers. Always adhere to government-set tolerable upper intake levels, unless your doctor suggests otherwise. (Click here for detailed information on daily recommendations and upper limits for vitamins and minerals, divided by age and gender.)
Supplements can also affect the absorption and metabolism of medicines you take and nutrients in the food you eat. For example, when taken in a pure form, zinc interferes with copper and calcium absorption and calcium hinders magnesium and iron absorption. In addition, the herbal product St. John’s Wort can severely limit the effectiveness of AIDS medications and is not recommended when simultaneously taking an antidepressant from the SSRI family. Clearly, taking multiple over-the-counter supplements increases your chance for harmful food-drug and drug-drug interactions.
My best advice is to try and get all your nutrients from food! Taking a multivitamin can help “cover your bases,” but any amount of certain vitamins or minerals consumed in excess of what your body needs will generally be excreted. While a banana and a tablet may both contain potassium, the fruit provides a balanced assortment of nutrients, fiber and phytochemicals (beneficial, active plant compounds) that can temper the effects of the mineral.