I know how important antioxidants are for my health. I would prefer to get as many as possible through food sources rather than supplementation. Can you suggest an easy way to choose the most beneficial foods?

A: Almost every biological function requires oxygen, which supplies electrons to run the machinery of the body. An oxygen molecule that has released its electron becomes a free radical or reactive oxygen species (ROS). When a free radical forms, it becomes irritable and immediately seeks to replace its missing electron. It will do this by stealing an electron from any local protein, fat or DNA molecule. The resulting damage from this free-radical attack contributes to a wide range of illnesses, including heart disease, arthritis, Alzheimer’s disease and cancer. These are all related to levels of antioxidants.

The sources of antioxidants can be natural or artificial. Certain plant-based foods are thought to be rich in in them. Plant-based antioxidants are a kind of phytonutrient, or plant-based nutrient. The body also produces some antioxidants, known as endogenous antioxidants. Antioxidants that come from outside the body are called exogenous.

Antioxidants are molecules that willingly donate their electrons to free radicals. Vitamin E, vitamin C and beta-carotene are the best known of these natural ROS neutralizers. Nutritional science is discovering that there are many other potent natural anti-oxidants present in a wide variety of vegetables and fruits.

Antioxidants can protect against the cell damage that free radicals cause, known as oxidative stress. The damage caused by oxidative stress has been linked to cancer, atherosclerosis, and vision loss. It is thought that the free radicals cause changes in the cells that lead to these and possibly other conditions. An intake of antioxidants is believed to reduce these risks. According to one study: Antioxidants act as radical scavenger, hydrogen donor, electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and metal-chelating agents.

For example, when you consume grapes, cherries, broccoli and tomatoes, you ingest flavonoids, whose antioxidant properties have been associated with reduced risks for heart disease and cancer. Polyphenols, found in nuts, berries and green tea, as well as sulfides, carried in onions, garlic and chives, also have been shown to be valuable free-radical scavengers. Anthocyanins, responsible for the deep red, purple and blue colors of cherries, grapes and berries are some of the most effective antioxidants in nature.

The best way to ensure optimal levels of this important food in your diet is to consume a wide variety of fresh colored fruits and vegetables. Red tomatoes, orange carrots, yellow peppers, green broccoli, blueberries and purple grapes will bring flavor and nutrition to your body.