What are Antioxidants?

aging Oct 28, 2018


A balanced diet is the main focus when we look for our healthy living, which also requires nutrients to fight against infections and diseases. There are certain foods that help to protect your cells, and these foods are packed with antioxidants.

What are Antioxidants?

Antioxidants are those substances that work both inside as well as outside of the body’s cells. They protect the cell membrane from the damaging effects of highly reactive molecules known as free radicals.


What are free radicals?

Free radicals are defined as any molecular species that is capable of an independent existence which has an unpaired electron in its atomic orbital. Many of the radicals are unstable and highly reactive. They can either donate their electron or accept an electron from any other molecule, hence they might behave either as oxidant or reductant.

The free radicals when not counteracted by antioxidant can cause irreparable damage to the cell membranes including cell structures.

Antioxidant and Free Radicals

Both antioxidants and free radicals are important as free radicals are formed constantly during metabolism. Without the presence of antioxidants, they will destroy our bodies fast. However, free radicals do have some important functions to serve in our body for our survival, such as the body’s immune cells use free radicals to kill the harmful bacteria.

Hence, we need a balance of the right amount of both antioxidants and free radicals as any imbalance will lead to the destruction of our body. The state when there is more free radicals or pro-oxidant compared to antioxidant is called oxidative stress. This condition leads to severe damage to our cells and it might lead to cell death.

Foods Rich in Antioxidants

Antioxidants being essential for the survival of all the living beings. Antioxidants can be water soluble or fat soluble, and our body needs both types of antioxidants to protect the cells. Water-soluble antioxidants include vitamin C, plant polyphenols, astaxanthin, and glutathione. The fat-soluble antioxidants are vitamin E, vitamin A, and carotenoids. Though the human body can generate its own antioxidants such as cellular antioxidant glutathione, getting antioxidants from food sources is also important. Our life is dependent on the intake of certain antioxidants such as vitamin C and vitamin E. Other examples of antioxidants include selenium, and carotenoids like beta-carotene, lycopene, zeaxanthin, and lutein.

Antioxidants are also categorized into enzymatic i.e. produced in the body and non-enzymatic which is found in foods. Although the enzymatic antioxidants are produced in the body they need co-factors such as trace minerals (copper, selenium, zinc, manganese, magnesium, iron) that have to be obtained through diet. The non-enzymatic antioxidants are found in foods supplements our internal antioxidant defense system and prevent possible depletion and onset of disease.

Let us discuss each antioxidant in detail


There are more than 600 carotenoids found in foods, out of which, beta-carotene, lutein, and lycopene are well-known antioxidants to reduce the damage from free radicals. Foods high in carotenoids are effective in preventing certain types of cancers and might decrease the risk of macular degeneration. The food sources high in carotenoids are orange, red, deep-yellow and some dark green leafy vegetables; these include carrots, tomatoes, spinach, Brussels sprouts, winter squash, sweet potatoes, and broccoli.

Vitamin E

Vitamin E main function is it acts as an antioxidant. It helps in protecting our body from cell damage that can lead to heart disease, cancers, and cataract as we age. Vitamin E works with vitamin C which is another antioxidant to offer protection from chronic diseases. Vitamin E is found in salad dressings, vegetable oils, margarine, whole grain products, wheat germ, seeds, peanut butter, and nuts.

Vitamin C

Vitamin C is among the best antioxidants which offer a wide variety of health benefits, such as, protecting our body from infection and damage to body cells, helping in the production of collagen and helps in absorption of nutrients such as iron and folate. Thus, include foods rich in vitamin C such as citrus fruits that include oranges, grapefruits, strawberries, sweet peppers, broccoli, tomatoes, and potatoes.


It is produced in the body and present in every cell. It is known as a master antioxidant. Glutathione maximizes the actions of other antioxidants. Glutathione combines with mineral selenium to form antioxidant enzyme glutathione peroxidase which is important for healthy liver function and longevity.

Uric Acid

It accounts for almost half the antioxidant ability of plasma. Uric acid might have been substituted for ascorbate in human evolution. Similar to ascorbate, uric acid can also mediate the production of active oxygen species.

Superoxide dismutase (SOD)

Another important antioxidant produced in the body. It is being assisted by trace minerals, manganese, zinc, and copper. SOD is present in aerobic cells and extracellular fluids.

N-acetyl cysteine (NAC)

Another antioxidant which enhances immune function and maintains normal lung function. It helps in boosting the levels of glutathione.

Health Benefits of Antioxidants

Antioxidants are known for fighting free radicals and inflammation. They boost heart health and improve cognitive function and enhances immunity and vision. Adequate intake of antioxidants can delay aging and also improve hair health

Prevention of Atherosclerosis

The most important stage for the development of atherosclerosis is lipoprotein oxidation. The oxidized LDL promotes atherogenesis through foam cell formation and inflammatory response. Free radicals have been involved in the oxidative modification of the LDL and studies suggests that the progression of the atherosclerotic lesions can be delayed by intervention with antioxidants. Studies state that intake of plant-based diets that are loaded with fresh fruits and vegetables can protect our heart and prevent cardiovascular issues. Fruits and vegetables are rich sources of antioxidants and hence might help to maintain normal health of the heart.

Prevention of Cancer

The main cause of cancer being damage to DNA, which is oxidative in nature. The intervention with antioxidants might interfere with the metabolic activation of chemical carcinogens, causing regression of pre-malignant lesions or inhibit their development into cancer. Studies suggest that individuals consuming high intakes of fruits and vegetables have lower risks of developing cancer.

Prevention of Ocular Disease

Development of cataract and age-related disorder of retina (maculopathy) is thought to be affected by the oxidative processes. Oxidation-induced by exposure to UV light is the major cause of damage to the protein of the lens. The oxidized protein will precipitate and causes cloudiness of the lens. The antioxidants and the antioxidant enzymes will inactivate the harmful free radicals and proteases and remove the damaged protein from the lens. Supplementation with antioxidant vitamins and minerals proved to prevent and delay cataract development. Individuals consuming higher intakes of fruits and vegetables or higher plasma levels of various antioxidant nutrients have a lower risk of cataract. Other important antioxidants for vision health are lutein and zeaxanthin which prevent age-related macular degeneration.

Prevention of Aging

Free radicals might cause signs of aging. They cause cell damage and inflammation leading to wrinkles and age spots. Antioxidants fight free radicals and hence they play a major role in delaying the signs of aging.


Hence, consuming right as well as the required amount of antioxidants is a key to good health. It is also important to remind that avoid the intake of oxidant sources such as alcohol, smoking, stress, etc. must be considered which is also important as taking a diet rich in antioxidants. Thus, our health depends on our choice of the lifestyle.

Stay Fit, Healthy, and Happy!!!


  1. https://medlineplus.gov/antioxidants.html
  2. https://www.hsph.harvard.edu/nutritionsource/antioxidants/
  3. https://nccih.nih.gov/health/antioxidants/introduction.htm
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614697/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249911/
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093095/
  7. https://www.ncbi.nlm.nih.gov/pubmed/24923567/



Neha Saini

Hi, I am Dr. Neha Lohia Saini. I am a nutritionist. Blogging is my passion as I love writing and share my knowledge about food and nutrition. I have completed my Ph.D. in Food Science and Nutrition f

Great! You've successfully subscribed.
Great! Next, complete checkout for full access.
Welcome back! You've successfully signed in.
Success! Your account is fully activated, you now have access to all content.