What is antioxidant?

In these few years, there are a lot of food products promoting antioxidant. Besides, there are some skin care products and supplements also promoting antioxidant. But actually what is antioxidant? I'm wondering what is the function of antioxidant? What effect does antioxidant bring to our body?

Space-filling model of the antioxidant
The yellow sphere is the redox-active sulfur atom that provides antioxidant activity, while the red, blue, white, and dark grey spheres represent oxygen, nitrogen, hydrogen, and carbon atoms, respectively.

Now I will find out what is antioxidant. You may have heard about the health benefits of antioxidants, but do you know what an antioxidant is? Antioxidants work by significantly slowing or preventing the oxidative or damage from oxygen(process caused by substances called free radicals that can lead to cell dysfunction). Antioxidants may also improve immune function and perhaps lower your risk for infection and cancer.

In chemistry, free radicals are atoms, molecules, or ions with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions.

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. Antioxidants that are reducing agents can also act as pro-oxidants. For example, vitamin C has antioxidant activity when it reduces oxidizing substances such as hydrogen peroxide,however, it will also reduce metal ions that generate free radicals through the Fenton reaction.

2 Fe3+ + Ascorbate → 2 Fe2+ + Dehydroascorbate
2 Fe2+ + 2 H2O2 → 2 Fe3+ + 2 OH· + 2 OH




Antioxidants are a diverse group of chemicals that can be naturally found in vegetables, fruits and plants. Antioxidants are also synthesized in our body. Examples of dietary antioxidants are vitamin E, C, A, phenolic acids, selenium, chlorophyll and cholorphyll derivatives, carotenoids, flavonoids, glutathione, coenzyme Q 10, melatonin, and lycopene. Synthetic dietary antioxidants include butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Chemicals with antioxidant activity produced in human body include uric acid, high density lipo-protein (HDL), and amino acids such as arginine.

Antioxidants protect the body from oxidative damage induced by free radicals and reactive oxygen species by
(1) suppressing their formation
(2) acting as scavengers
(3) acting as their substrate

Antioixdants are essential for proper function of the immune system. If the level of free radicals in the immune cells surpasses beyond the normal level, they negatively affect the immune system. On the other hand, antioxidants act as scavengers of the free radicals in cells and there fore promote our immunity.

Therefore, to have enough antioxidant to maintain good health we can uptake food that contain or produce antioxidant. A variety of fruits, vegetables, nuts, whole grain cereals and legumes, tea, red wine, and herbs such as rosemary extract are rich sources of natural antioxidants. The benefit of eating whole fruits, vegetables, and whole grain foods, in contrast to antioxidant supplements, is that they contain a variety of natural antioxidants. A combination of multiple antioxidants has greater health benefit than when an antioxidant is taken individually. Furthermore, the antioxidant content tends to be high on their outer layer of the plant products. For example, in cereals, the bran is richer in antioxidants such as phenolic acids, and phytic acid than the inner part of the grain.













Food high in antioxidants include fruits such as apple, grape, grapefruit, crane berry, black berry and blueberry. Even though, comprehensive studies on antioxidant content of foods are yet to come, among the best antioxidant sources are crane berry, black berry and blue berry. Vegetables are also rich antioxidant sources. Red bean, pinto bean, kidney bean, carrot, tomato, garlic and Russet potato are among the vegetables high in antioxidant content and categorized among the best antioxidant sources. Other important sources of antioxidants are green tea, black tea, herbal tea, spices, red wine, ginger, and garlic.







Antioxident can prevent 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 initial studies suggested that antioxidant supplements might promote health, later large clinical trials did not detect any benefit and suggested instead that excess supplementation may be harmful.In addition to these uses of natural antioxidants in medicine, these compounds have many industrial uses, such as preservatives in food and cosmetics.

To obtain antioxidant, the best way is to uptake diferent kind of fruits and vegatable, in contrast to antioxidant supplements. A combination of multiple antioxidants has greater health benefit than when an antioxidant is taken individually. Prevention is better than cure. To maintain good health, having a balanced diet is important!