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What Are Antioxidants and Phytochemicals?

author image M. Gideon Hoyle
M. Gideon Hoyle is a writer living outside of Houston. Previously, he produced brochures and a wide variety of other materials for a nonprofit educational foundation. He now specializes in topics related to health, exercise and nutrition, publishing for various websites.
What Are Antioxidants and Phytochemicals?
Many vegetables contain antioxidants and phytochemicals. Photo Credit Ingram Publishing/Ingram Publishing/Getty Images

Antioxidants are substances that help fight the harmful effects of unstable molecules in your body called free radicals. Phytochemicals are substances derived from plants that have potential benefits for your health. In some cases, phytochemicals produce antioxidant effects. In other cases, they may act on your body in ways similar to hormones.


Antioxidants get their name because they combat oxidation, a body process that occurs naturally and when you are exposed to environmental factors such as radiation and tobacco smoke, according to the National Center for Complementary and Alternative Medicine, or NCCAM. Oxidation produces free radicals, which may help trigger a number of serious ailments, including rheumatoid arthritis, cancer, heart disease, Parkinson’s disease and Alzheimer’s disease. Examples of antioxidant substances include vitamins C and E, lutein, lycopene, beta-carotene, coenzyme Q10, flavonoids and lipoic acid.


Strictly speaking, phytochemicals are any chemicals found in plant materials such as fruits, vegetables, grains and beans, according to Oregon State University. In regard to human health, the term describes plant substances not specifically required for your well-being. Although scientists have uncovered thousands of phytochemicals, they have thoroughly examined only a small portion of them, the American Cancer Society, or ACS, reports. Examples of phytochemicals include groups of substances such as polyphenols, carotenoids, lignans and isoflavones, as well as folic acid and vitamins C and E.

Antioxidant Sources and Effects

Some antioxidant compounds are produced in your body, while you may obtain others from dietary sources and supplements, the NCCAM reports. Food sources of antioxidants include fruits and vegetables, cereal grains, nuts and legumes. Depending on the particular product you use, supplements may contain either man-made antioxidants or antioxidants derived from food sources. Individuals who eat diets high in antioxidant-containing vegetables and fruits appear to have lower risks for the development of chronic diseases.

Phytochemical Sources and Effects

Certain phytochemicals classified as isoflavones and lignans may have effects on your body similar to the hormone estrogen, according to the ACS. For that reason, they are also sometimes classified as phytoestrogens. Various forms of these substances occur in foods such as soybeans, licorice, garbanzo beans, red clover, whole grains and flaxseed. Some phytochemicals belonging to the flavonoid group have antioxidant properties, including substances found in cauliflower, Brussels sprouts, grapes, radishes and red cabbage. Carotenoid phytochemicals found in foods such as squash and carrots may have cancer-fighting properties.


Scientists cannot factually prove the links between antioxidant food intake and lower chronic disease risks because other factors may account for these effects, the NCCAM notes. Current available evidence also does not support the use of antioxidant supplements for disease prevention. Scientists have just begun researching the real-world effects of phytochemicals, the ACS notes. Because various foods contain so many different phytochemical compounds, it may be difficult to determine which substances or combinations of substances actually protect, improve or harm your health.

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