What are Antioxidants?

Antioxidants, as the name suggests are the agents acting against oxidation or oxidation mediated process. They are regarded valuable for the human body as they are responsible in inhibiting the oxidative processes that are mediated by the free radicals in the body and therefore, guards the body. It is because of their direct action with the radicals that they are referred as the ‘free radical scavengers’. They protect vital biological structures like lipid membranes, DNA, and proteins.

Antioxidant vitamins are of two types. Water soluble ones exist in aqueous solutions (vitamin C) and the fat soluble ones exists in membranes and lipoproteins (vitamin E). Apart from these, other antioxidants are: 

  • Carotenoids such as beta-carotene found in dark red, green and yellow fruits and vegetables.
  • Some quinones such as ubiquinone (Coenzyme Q) also have antioxidant properties.
  • Flavonoids and other phenols, polyphenols found in green tea, red wine, olive oil, grapes and other fruits are also antioxidants.
  • Trace elements like copper, magnesium, zinc, and selenium are essential components of antioxidant enzymes.

ACE vitamins (Vitamin A, Vitamin C, Vitamin E) with selenium, alpha-lipoic acid, carnitine, carotenoids, coenzyme-Q, green tea extract and zinc are marketed as antioxidant supplements.

Before we discuss the health benefits of antioxidants, let us get to know briefly about the ill-effects of free radicals in our body.
Free-radicals are highly reactive molecules that are generated when the outer shell of the molecule in its orbital loses an electron and therefore becomes unpaired. Such unpaired molecules are called free-radical and they start reacting with the nearby stable ones and make them unstable. As a result, an endless chain of free radicals are produced that damages the living cells. Such an increased free radical formation in the body increases the body damage and such a state is referred as ‘oxidative-stress’. Severe oxidative-stress leads to cell injury and cell death.

In order to terminate this free radical effect, either the free radical must react with another free radical to form a covalent bond between them and loose its activity or the free radical must react with an antioxidant or an antioxidant enzyme or both. Hence an antioxidant gets itself oxidized by the free radical and indirectly protects the cells from getting damaged.

Such reactive oxygen species (ROS) are continuous and unavoidable. They are either produced by the electron removal as described earlier or also produced from food, pollutants, photosensitizing reaction or due to ionizations.

Health Benefits of Anti-oxidants

Antioxidants as nutrients – various antioxidants are responsible for various different actions. Carotenoids help in trapping away the free radicals and if they are inadequate they lead to risk of cancer of skin, stomach, colon, esophagus, lung, bladder and rectum. Vitamin A helps in guiding normal tissue development. Vitamin C destroys the water-soluble free radicals and hence protects from cancer. Vitamin c not only is regarded as good in wound healing but also needed for a healthy immune system. Vitamin E is a fat-soluble free radical trapper; it is responsible for normal functioning of smooth muscles and also in reducing the risk of atherosclerosis by preventing platelet aggregation. Selenium is also required for healthy immune system.antioxidant

In physical exercise – physical exercise is believed to produce free radicals and antioxidant supplementation shows a positive result in alleviating those free radicals. It was seen that supplementation markedly reduced the oxidative stress in basketball players, increased amount of antioxidant enzymes in athletes, enhancing neutrophil oxidative burst in trained runners, prevents exercise induced lipid peroxidation also.

Antioxidants as food additives – antioxidants are religiously added in small amounts in food items so as to avoid color changes in product or any sort of deterioration making the product less appetizing and less nutritious. Examples of antioxidants being applied in food industries are butylated hydroxyl anisole (BHA) and butylated hydroxyl toluene (BHT); ethylene diamine tetra acetic acid (EDTA); propyl gallate and Vitamin C. BHT and BHA efficiently avoid any chances of rancidity in fats and oils especially in baked confectionaries and cookies. EDTA is used in salads, mayonnaise, sandwich spreads, beer and soft drinks as antioxidant.

Miscellaneous use / benefits:

  • It is seen that antioxidant supplementation have shown to treat asthma and lung functions too. Though research is still required to be conducted in these areas.
  • Antioxidants are famous anti-cancer agents and anti-aging agents as well.

Probable use / benefits of antioxidants

Increasing evidences and trials have shown that antioxidants might be used to treat diseases like coronary heart disease (CHD) and cancer that are basically related to low plasma levels of antioxidant as well as low dietary intake. Antioxidant providing fruits and vegetables has shown to delay the incidence of these diseases. Supplementation of antioxidant nutrients in reducing the incidence of these diseases is still being researched.


Many clinical trials for effect in cardio-system have also been performed from many years but no strong basis has been achieved so far. There are contradictory results obtained varying from patient to patient. To conclude its effect so far, we can say that subjects with higher supplementation of vitamin C had a lower congestive heart disease (CHD) incidence whereas that of vitamin E had no significance associated with CHD risk.

Similar results were obtained for cancer trials. Not all of them showed positive results. It was found that no supplementation including vitamin A, C, E and beta-carotene showed any healing effect for gastrointestinal cancers but they seemed to increase the overall mortality. More clinical trials are required.

Trials are also going on for cataract treatment with the result that supplementation of antioxidants might reduce the risk of cataracts but there is no evidence yet to treat any sort of visual acuity loss or age related lens opacities. Research is also going on to study the effects of antioxidant supplementation in treating age related macular degeneration (ARMD) in which the central portion of retina degenerates so that only peripheral vision remains. Further research is still required in this field.

Research is also going on for Type-2 Diabetes and chronic obstructive pulmonary disease (COPD). These two diseases are also a cause of oxidative damage and hence antioxidant therapy is studied to reduce its incidence.

Adverse effects

Antioxidants are safe when used in low dose but may pose a danger when consumed above the level of Recommended Daily Allowance (RDA). Long term use of antioxidants has found to block the favorable effect of statins and niacin.

Interactions – no harmful interactions with antioxidants have been reported so far.


Thus, antioxidants have a wide scope of usefulness with negligible amount of negative points. Its use is abundant in many areas as discussed above and it is also under research for more discoveries.