Vitamins are chemical compounds which the human body needs to grow and function normally. Of the eleven vitamins we know humans need, nine are abundant in plants. Your body makes vitamin D from sunshine. Vitamin B12 is found only in animals, and is often added to plant based foods such as cereals or soy milk.

Most of the vitamins humans need are synthesized by plants, so you get plenty when you eat a variety of fruit, vegetables, whole grains, beans and other seeds.

The B vitamins (thiamin, riboflavin, niacin, pyridoxine, folate, cyanocobalamin and biotin) are needed to convert carbohydrates into energy and for hundreds of other functions. They are found in whole grains, beans and many other plants, and in the animals that eat these plants.

Vitamins A, C and E are called the antioxidant vitamins because one of their important jobs is to prevent certain oxidizing chemical reactions that can be harmful to your body. The antioxidant vitamins help to prevent heart disease because LDL cholesterol must be oxidized before it can form plaques in your arteries. Brightly colored fruits and vegetables are particularly good sources of the antioxidant vitamins.

Our primary source of vitamin D is sunshine, not food. A person with light skin can get enough vitamin D from a few minutes spent in sunlight each day, but the darker your skin, the more sun exposure you need to meet your daily requirements. You can also get vitamin D from supplements, fish oils, fish, eggs and fortified foods.

You can get all the vitamins you need from the food you eat plus some sunshine. A daily multi-vitamin for extra "insurance" won't hurt you, but an unhealthful diet with vitamin pills is still an unhealthful diet. Dont be misled by high-priced supplements that make extravagant promises. You will probably be wasting your money, and mega-doses of vitamins can cause problems.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.