Q I am taking several different vitamins and herbal supplements. Do I need them? Are there any problems? — K.M., Seneca

A Most people receive ‘vitamins and minerals in their diet and supplements are not necessary. In fact, the most important things anyone can do to maintain their health is to eat vegetables and fruits every day, exercise regularly every week, get enough sleep and avoid smoking and alcohol.

Teenagers or the elderly with irregular or poor eating habits may not eat a balanced diet and may need a multivitamin with minerals to fill in the nutritional gaps. The choice is which multivitamin to take and when. It should contain no more than 100 percent of the daily recommended amount, unless your doctor suggests otherwise. Daily values can be found on the label.

People who are on diets or who avoid entire food groups are more likely to have vitamin and mineral deficiencies. Vegetarians who eat absolutely no animal products need to consider a multivitamin with iron and other minerals. Iron and B12 deficiency can occur in strict vegetarians.

Women may need extra calcium and iron. Women who bleed excessively during menstruation may need a multivitamin and mineral supplement that contains iron. Pregnant and lactating women have increased nutritional needs and are given supplements by their doctors. During pregnancy a prenatal vitamin and folic acid are recommended. Perimenopausal women may need extra calcium and Vitamin D to prevent osteoporosis.

Men may benefit from selenium to reduce the risk of prostate cancer. A clinical trial found that 200 micrograms a day seem to be beneficial. Iron supplements are not recommended for healthy men.

Niacin seems to be helpful in reducing high cholesterol but side effects can occur with high dosages.

Smoking and heavy alcohol consumption may lower vitamin C and folic acid levels. Vitamin B1 (thiamin), B6 (pyridoxine), and B2 (riboflavin) also are suggested for people who drink excessively.

Many vitamins once recommended have been found to have little to no effect. Dr. Harvey Simon of Harvard Medical School reports that antioxidants are no longer recommended as protection against heart disease. Research has shown that vitamin E may increase respiratory infections, moderate doses of vitamin A may increase fractures and beta-carotene may increase the risk of lung cancer in male smokers.

The biggest concern with herbal supplements is that their manufacture is not regulated. Let your physician know if you are taking any herbal supplements. If you’re scheduled for surgery, discontinue taking herbs 24 hours to a week before surgery.

Several supplements have been found ineffective in clinical trials: zinc (for colds); echinacea (for colds); saw palmetto (enlarged prostate); ginseng (fatigue); ginkgo (mental alertness). Yohimbine (erectile dysfunction) and DHEA (anti-aging, memory loss) may not provide any additional benefits, based on clinical trials.

Check with your doctor or pharmacist if you are want to use more than the daily recommended amount of any product. Some vitamins and supplements can interfere with prescription medications.

Send your health questions to Debbie Jackson, PhD, MN Clemson University, 209 Sikes Hall, Clemson, SC 29634-5155 or email dbj@clemson.edu