Antioxidants are compounds that protect healthy cells from damage by free radicals, the molecules that have the ability change your cells’ DNA structure and possibly lead to diseases. Thousands of antioxidants have been identified, but there are several that are most prevalent and familiar. Research on antioxidants has focused on their ability to protect cells from the damage that leads to heart disease, cancer and other diseases related to aging.
Vitamins C and E
The term antioxidant actually refers to a substance’s ability to donate an electron to a free radical, which is like a scavenger looking to steal an electron from a healthy cell. Two major vitamins, C and E, have been shown to have antioxidant activity. Vitamin C is found in many fruits and vegetables, especially citrus fruits like oranges and grapefruit, as well as strawberries, red peppers, tomatoes, broccoli and spinach. Vitamin E is found mainly in nuts, seeds and oils, including wheat germ oil, sunflower seeds and oil, almonds, and peanut butter. Both of these vitamins play a role in immune function, but research on disease prevention has not shown any clear benefit for taking higher than daily recommended amounts of either.
Zinc and Selenium
The minerals zinc and selenium, needed in just trace amounts in the human body, also have antioxidant properties. Among their many important roles, these minerals help the immune system fight off bacteria and viruses, and they’re essential in the reproduction of DNA. Fish, poultry and meat are good sources of zinc and selenium. Some research has shown that individuals with lower levels of selenium are at increased risk for cancer and heart disease; however, taking additional doses of the mineral has not shown to be beneficial.
Beta Carotene, Lycopene and Lutein
Carotenoids are compounds that give plants like tomatoes, carrots, peppers and watermelon their red, orange or yellow color. Carotenoids, including beta carotene, lycopene and lutein, also have antioxidant activity. A summary of research published by the Linus Pauling Institute states that while population studies suggest that diets high in carotenoid-rich fruits and vegetables are associated with reduced risk of cardiovascular disease and some cancers, high-dose supplements do not appear to have benefits.
Anthocyanins, Flavanols and Isoflavones
Many other compounds in plants have been identified as having antioxidant properties and possible health benefits. Compounds that are members of the flavonoid family include anthocyanins, which give berries their deep red and blue color; flavanols, found in tea, chocolate, grapes and red wine; and isoflavones, found in soybeans and legumes. Overall, most research on the role individual antioxidants might play in preventing chronic disease hasn’t been promising. However, much evidence has shown that eating a diet rich in food sources of these antioxidants does provide protection against many forms of cancer and heart disease, as well as other age-related diseases.
- Harvard School of Public Health: Antioxidants Beyond the Hype
- Oxidative Medicine and Cellular Longevity: Exogenous Antioxidants -- Double-Edged Swords in Cellular Redox State (Table 1)
- Harvard School of Public Health: Vitamin C
- Office of Dietary Supplements: Vitamin E
- Office of Dietary Supplements: Zinc
- Office of Dietary Supplements: Selenium
- University of Maryland Medical Center: Selenium
- Linus Pauling Institute: Carotenoids
- Linus Pauling Institute: Flavonoids