Supplements are big business. Last year, sales of dietary supplements topped $20 billion, and the industry continues to grow as four out of every ten Americans regularly use supplements. The most popular supplements include vitamin C, calcium, multivitamins, iron, B vitamin complex, and vitamin E.

Some people consume a daily vitamin supplement just for nutritional insurance since they are afraid their diet may not provide everything they need. Others believe they need vitamin pills for extra pep and energy, or to combat the effects of stressful living.

But are supplements really necessary for optimal health? Do elderly persons need a daily vitamin supplement? Do supplements protect us against heart disease, cancer, the common cold, mental decline, and other physiological changes associated with aging? Can they boost the immune system and increase our vitality?

In certain conditions, supplements may be recommended. Both the elderly person who experiences diminished nutrient absorption and the overweight person on a calorie-reduced diet will benefit from a multivitamin/mineral supplement. In addition, iron supplements facilitate a healthy pregnancy outcome, while folic acid supplements lower the risk of giving birth to a child with birth defects. The total vegetarian who consumes no animal products must ensure they have an adequate intake of vitamin B12, either from fortified foods or through the use of a daily vitamin B12 supplement. But supplements are not for everyone.

Can you take too much of a supplement and experience side effects? Yes, it is possible. For example, large doses of vitamin B6, used to treat depression and carpel tunnel syndrome, can cause serious nerve damage. Excessive amounts of vitamin A can cause headaches, dizziness, and nausea. High intakes of zinc have been shown to compromise the immune system. While fish oils lower blood triglyceride levels, they are generally ineffective for lowering cholesterol levels. Large quantities of the omega-3 rich fish oils may increase the risk for bleeding.

Not all supplements do what the manufacturers claim. In recent trials, vitamin E tablets have proven quite disappointing for cardiovascular patients, while antioxidant supplements have failed in experiments to reduce the risk of various human cancers. Chromium picolinate supplements are promoted to help a person lose fat and gain muscle. Not only are these supplements ineffective for this purpose, but they can also cause liver dysfunction and renal failure. You may ask “Where can someone get information about whether a particular dietary supplement is safe and effective? And how does one know if they even need a dietary supplement?” For answers, check out the government website: http://dietary-supplements.info.nih.gov.

How can you know if the supplement you purchased actually contains the ingredients that it claims on the label, or if it is contaminated? For help, check out the website: www.consumerlab.com.

Winston Craig, Ph.D., R.D., is a professor of nutrition at Andrews University.

Some supplements may produce adverse side effects.

Dietary supplements may not always deliver what the label claims.

Too much of a good thing may actually be bad.