Antioxidants are chemicals that interact with and neutralizefreeradicals, thus preventing them from causing damage.Antioxidantsare also known as free radical scavengers. The bodymakes some ofthe antioxidants it uses to neutralize free radicals.Theseantioxidants are called endogenous antioxidants. However, thebodyrelies on external (exogenous) sources, primarily the diet,toobtain the rest of the antioxidants it needs. Theseexogenousantioxidants are commonly called dietary antioxidants.Fruits,vegetables, and grains are rich sources of dietaryantioxidants.Some dietary antioxidants are also available asdietarysupplements. Examples of dietary antioxidantsincludebeta-carotene, lycopene, and vitamins A, C, andE(alpha-tocopherol). The mineral element selenium is oftenthoughtto be a dietary antioxidant, but the antioxidant effectsofselenium are most likely due to the antioxidant activityofproteins that have this element as an essential component(i.e.,selenium-containing proteins), and not to selenium itself.Inlaboratory and animal studies, the presence of increased levelsofexogenous antioxidants has been shown to prevent the types offreeradical damage that have been associated with cancerdevelopment.Therefore, researchers have investigated whether takingdietaryantioxidant supplements can help lower the risk ofdeveloping ordying from cancer in humans. Many observationalstudies, includingcase control studies and cohort studies, havebeen conducted toinvestigate whether the use of dietary antioxidantsupplements isassociated with reduced risks of cancer in humans.Overall, thesestudies have yielded mixed results (5). Becauseobservationalstudies cannot adequately control for biases thatmight influencestudy outcomes, the results of any individualobservational studymust be viewed with caution. Randomizedcontrolled clinical trials,however, lack most of the biases thatlimit the reliability ofobservational studies. Therefore,randomized trials are consideredto provide the strongest and mostreliable evidence of the benefitand/or harm of a health-relatedintervention. To date, ninerandomized controlled trials of dietaryantioxidant supplements forcancer prevention have been conductedworldwide. Many of the trialswere sponsored by the National CancerInstitute. The results ofthese nine trials are summarizedfollowing. Antioxidants aresubstances that can help protect cellsfrom damage caused by freeradicals, or unstable molecules. Thatdamage, called oxidativestress, is linked to the kind of damage inDNA mutations that cancontribute to the risk of certain cancers, aswell as diabetes,Alzheimer's disease, and Parkinson's disease.Learn about thespecific health benefits of superfoods andsuperspices, includinganti-inflammatory, antifungal, andantibacterial properties. Thisapplication is for informationalpurposes only. Before you startusing any of these foods you shouldconsult a qualified healthprofessional.