What Are Antioxidants?

An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols or polyphenols.

Antioxidants are found in many fresh fruits and vegetables. Antioxidants can often be identified by their vibrant colors such as the yellow of saffron, mangos and corn, the purple blue of grapes, blackberries and blueberries. Foods that contain antioxidants typically have lycopene, selenium, beta-carotene and the vitamins E, C and A. It is thought that a diet rich in antioxidants can delay many diseases that often come upon us as we age.

When electrons are lost or the process of oxidation occurs, substances such as free radicals are produced. These free radicals are reactive and they can cause cell damage or stress to the cells. Antioxidants are said to stabilize those roaming free radicals before they react and do any harm. Oxidation is a natural process of the body so antioxidants are needed in order to sustain good health.

As we age, the body is less effective in producing defenses that can combat oxidative stress. Diseases such as cataracts, dysfunction of the immune system, Alzheimer’s, disease to the cardiovascular system and cancer are thought to be the result of free radicals. Chronic conditions can also allow the formation of free radicals and ill health is the result.

Although oxidation reactions are crucial for life, they can also be damaging; hence, plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, and vitamin E as well as enzymes such as catalase, superoxide dismutase and various peroxidases. Low levels of antioxidants, or inhibition of the antioxidant enzymes, causes oxidative stress and may damage or kill cells.

As oxidative stress might be an important part of many human diseases, the use of antioxidants in pharmacology is intensively studied, particularly as treatments for stroke and neurodegenerative diseases. However, it is unknown whether oxidative stress is the cause or the consequence of disease. Antioxidants are also widely used as ingredients in dietary supplements in the hope of maintaining health and preventing diseases such as cancer and coronary heart disease. Although some studies have suggested antioxidant supplements have health benefits, other large clinical trials did not detect any benefit for the formulations tested, and excess supplementation may be harmful. In addition to these uses in medicine, antioxidants have many industrial uses, such as preservatives in food and cosmetics and preventing the degradation of rubber and gasoline.