What are Antioxidants?

Antioxidants are molecules that prevent oxygen molecules from interacting with other molecules in a process called oxidation. In the body, antioxidants combine with potentially damaging molecules called free radicals to prevent the free radicals from causing damage to cell membranes, DNA, and proteins in the cell. Common antioxidants important to human health are vitamins A, C, E, beta-carotene, and selenium. In the mid-2000s, about 20% of North Americans and Europeans were taking at least one antioxidant dietary supplement.

What is the Purpose of Antioxidants?

The role of antioxidants in the body is complex and not completely understood. Antioxidants combine with free radicals so that the free radicals cannot react with, or oxidize, other molecules. In this way, antioxidants help slow or prevent damage to cells. Damage caused by free radicals is thought to cause or contribute to cardiovascular disease, cancer,Alzheimer’s disease, age-related changes in vision, and other signs of aging. However, no direct cause and effect relationship between antioxidant intake and disease prevention has been proven. Antioxidants unrelated to those of importance in the body have commercial uses in the preservation of processed food and in many industrial processes.

Health benefits of antioxidants and their food sources

Antioxidant	Health benefits	Food sources
Selenium	Helps maintain healthy hair and nails, enhances immunity, works with vitamin E to protect cells from damage. Reduces the risk of cancer, particularly lung, prostate, and colorectal.	Garlic, seeds, Brazil nuts, meat, eggs, poultry, seafood, whole grains. The amount in plant sources varies according to the content of the soil.
Beta-carotene	Keeps skin healthy, helps prevent night blindness and infections, promotes growth and bone development.	Red, yellow-orange, and leafy green vegetables and fruits, including carrots, apricots, cantaloupe, peppers, tomatoes, spinach, broccoli, sweet potatoes, and pumpkin.
Vitamin E	Acts as the protector of essential fats in cell membranes and red blood cells. Reduces risk of cancer, heart disease, and other age-associated diseases.	Peanut butter, nuts, seeds, vegetable oils and margarine, wheat germ, avocado, whole grains, salad dressings.
Vitamin C	Destroys free radicals inside and outside cells. Helps in the formation of connective tissue, the healing of wounds, and iron absorption, and also helps to prevent bruising and keep gums healthy. May reduce risk of cataracts, heart disease, and cancer.	Peppers, tomatoes, citrus fruits and juices, berries, broccoli, spinach, cabbage, potatoes, mango, papaya.

The American Dietetic Association

KEY TERMS

Coenzyme—Also called a cofactor; a small non-protein molecule that binds to an enzyme and catalyzes (stimulates) enzyme-mediated reactions.
Dietary supplement—A product, such as a vitamin, mineral, herb, amino acid, or enzyme, intended to be consumed in addition to an individual’s diet with the expectation that it will improve health.
Enzyme—A protein that changes the rate of a chemical reaction within the body without themselves being used up in the reaction.
Free radical—A molecule with an unpaired electron that has a strong tendency to react with other molecules in deoxyribonucleic acid (DNA), proteins, and lipids (fats), resulting in damage to cells. Free radicals are neutralized by antioxidants.
Mineral—An inorganic substance found in the earth that is necessary in small quantities for the body to maintain a health. Examples: zinc, copper, iron.
Oxidation—Interaction in which one molecule removes an electron from another molecule to stabilize itself.
Retina—The layer of light-sensitive cells on the back of the eyeball that function in converting light into nerve impulses.
Vitamin—An essential nutrient the body needs in small amounts to remain healthy but that the body cannot manufacture for itself and must acquire through diet.