Most of us are aware of the important role that vitamins and minerals play in our overall safety and health. In fact, billions of dollars are spent each year on dietary supplements, presumably because people are concerned that they aren't getting enough of these important nutrients in their diets. Even if your diet meets the recommended dietary allowances (RDA), what's the harm in consuming higher amounts?
It turns out that in many instances you can get too much of a good thing when it comes to vitamin and mineral supplements. There is plenty of evidence that high doses can sometimes cause serious, negative health effects. Let's look at 3 common supplements in order to learn more.
Vitamin C: many of us probably learned that early maritime voyagers who didn't eat enough vitamin C-containing fruits and vegetables were afflicted with scurvy, a disease that causes lethargy, skin changes, and even death. While we've been told that vitamin C can ward off colds, numerous studies show that doses which exceed the RDA of 75-90 milligrams per day (the actual amount varies by age and gender, see http://ods.od.nih.gov/Health_Information/Dietary_Reference_Intakes.aspx) have either no effect or a modest effect at best in preventing the cold, reducing its symptoms, or its duration.
Vitamin E: deficiencies involving this vitamin can lead to vision problems as well as nerve and muscle damage. The boldest claims for vitamin E focus on its ability to reduce heart disease and the risk of cancer. Unfortunately, these benefits were not observed in research studies. In fact, some studies indicated that long-term use of vitamin E supplements can increase the risk of cardiovascular disease, some types of cancer, including prostate cancer, and overall mortality rates.
Calcium: the dairy industry correctly reminds us that milk and milk products contain significant amounts of calcium, a mineral which promotes bone health. In addition, it helps to maintain normal heart rhythm and muscle function. Many women take calcium supplements in hopes of reducing the risk of osteoporosis. Unfortunately, research into the effects of calcium supplements present a conflicting picture. Some studies indicate that calcium supplements have no effect on preventing bone fractures in healthy women. Others conclude that these supplements actually increase the risk of cardiovascular disease and heart attacks.
Dietary supplements play an important role in delivering necessary nutrients to people who otherwise aren't getting them. The elderly, pregnant women, and vegans are often good candidates for dietary supplements. The rest of us should focus on getting these nutrients from the foods we eat. Take some time to add up the milligrams (mg) or international units (IU) of each vitamin and mineral that you take in during a typical day. Compare those amounts to the RDAs. Pay attention to cereals, breads, and other fortified or enriched products - some of these contain 100% or more of the RDA of certain nutrients! Make sure your intake does not exceed the Tolerable Upper Intake Level (UL), the dose that is potentially harmful. Work with your medical provider and/or a nutritionist who can help you identify nutritional deficiencies and potential contraindications. When it comes to dietary supplements, a conscientious consumer is a healthy consumer!