Q. Can taking too many vitamins negatively affect my health?

A. Vitamins are substances found in foods and in the body, and are vital nutrients needed for growth, development, and good health. Taking too much of a particular vitamin, however, or taking too many varieties of vitamins, can lead to health problems.

According to the Centers for Disease Control and Prevention (CDC), more than half of Americans take some type of over-the-counter supplement.

In addition to having a rather healthy diet, many people think taking vitamins increase the immune system and boosts overall health. This is a common misconception. Some combinations or doses of vitamins may even cause harm. If you are healthy and eat a nutrient-rich diet, you do not need OTC supplements.

If you do plan to take vitamins, you should first consult with your doctor, who can advise you on the benefits and possible risks. Vitamin A, for example, can increase the risk of cardiovascular disease as well as the risk of osteoporosis in some women.

Some prescription medications can cause you to become deficient in a particular vitamin or mineral. In those cases, your doctor will advise you which supplements you may need.

Take only the recommended daily value listed. High doses of certain vitamins can be toxic. You should aim to take between 50 percent and 200 percent of the recommended daily value of supplements to avoid overdosing.

Some supplements sold over the counter contain more than vitamins and minerals. Some may include herbals and botanicals, among other compounds, that can be harmful to your health. Check to see whether the vitamin is verified by an independent scientific authority that provides a seal of approval. Your doctor should also provide clear recommendations.

Omeche Idoko, MD, primary care physician, Mercy Family Health Care Associates