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Antioxidants and Cancer Prevention

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Antioxidants help in cancer prevention by neutralizing free radicals. Read this article to learn more about the role of antioxidants in cancer prevention.

Written by

Dr. Ramji. R. K

Medically reviewed by

Neha Suryawanshi

Published At September 16, 2022
Reviewed AtJanuary 8, 2024

What Are Free Radicals and How Do They Cause Cancer?

Free radicals are chemical molecules that are produced mainly by the oxidation process in the body, which happens during metabolism. Free radicals are also developed in the body through other sources like exposure to carcinogens, harmful environmental factors, etc. These highly reactive substances damage the genes in the body, thus resulting in cancer. Antioxidants play a major role in preventing cancer by neutralizing free radicals.

What Are Antioxidants?

Antioxidants are chemical compounds that neutralize free radicals and help in cancer prevention. They are also referred to as “ free radical scavengers.” Antioxidants inhibit the oxidation process, which produces free radicals in the body. Antioxidants not only prevent cancer but also help in preventing heart disease, aging, etc. It can be obtained either naturally or synthetically. Natural ways of obtaining antioxidants include:

  • Production of antioxidants by the cells in the body (for example, alpha-lipoic acid and glutathione are the different antioxidants produced by the body cells.)

  • Antioxidants can be highly obtained from dietary sources. The dietary sources include different fruits, herbs, spices, vegetables, etc.

Synthetic antioxidants are derived from chemical processes. Some of the common synthetic antioxidants are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), etc. They are safe to use, but certain studies reported some health issues seen in people taking them in the long term. Some studies even suggest that a high intake of these can damage DNA.

What Would Be the Impact Factor of Antioxidants?

Studies on the relationship between antioxidants and cancer are intricate and dynamic, with different results based on the type of cancer, the particular context, and individual factors. Free radicals are dangerous molecules that are generated in the body as a result of regular metabolic processes and exposure to certain environmental factors, such as radiation and tobacco smoke. Antioxidants are substances that can help neutralize these harmful molecules. Free radicals can harm DNA in cells, which may result in cancer.

What Are the Types of Antioxidants?

The two different types of antioxidants are:

  • Enzymatic Antioxidants: They can also be referred to as primary or natural antioxidants. The enzymatic antioxidants are:

  1. Glutathione peroxidase.

  2. Glutathione reductase.

  3. Catalase.

  4. Superoxide dismutase.

  • Non-Enzymatic Antioxidants: The non-enzymatic antioxidants include:

  1. Beta carotene.

  2. Alpha-tocopherol.

  3. Vitamin C.

  4. Vitamin E.

  5. Selenium.

  6. Zinc.

  7. Melatonin, etc.

What Are the Different Types of Dietary Antioxidants That Help in Cancer Prevention?

We all know that to prevent cancer, antioxidants are essential, and such antioxidants can be produced by our body cells to help fight against the free radicals that cause damage to health. Since free radicals are so ubiquitous, we need additional requirements for antioxidants through our dietary sources. Some of the antioxidant-rich dietary sources that help in cancer prevention include:

1) Vitamin C (Ascorbic Acid): Vitamin C, also known as ascorbic acid, is a water-soluble antioxidant. It helps in cancer prevention by improving immune function and protecting against oxidative stress. Vitamin C is effective in reducing the risk of developing cancers in the oral cavity, stomach, esophagus, rectum, pancreas, cervix, etc. Some of the rich sources of vitamin C include:

  • Fruits like lemon, oranges, guava, strawberry, kiwi, papaya, etc.

  • Leafy vegetables like spinach, broccoli, kale, etc.

  • Tomatoes, red bell peppers, etc

The daily requirement of vitamin C is around 75 mg for women and 90 mg for men.

2) Beta Carotene: It is also known as provitamin A. Beta carotene helps in cancer prevention by stimulating the immune system. The food rich in beta-carotene includes:

  • Vegetables like sweet potatoes, broccoli, green leafy vegetables, etc.

  • Fruits like oranges, bananas, etc.

However, recent studies found that high doses of beta-carotene supplementation are associated with an increased risk of developing lung cancer in smokers. Do have a word with the doctor before taking any beta-carotene supplements.

3) Vitamin D: Vitamin D deficiency is associated with an increased risk of cancer development. Vitamin D deficiency is most common among cancer patients. Some studies reported that it prevents colorectal cancer. It is a fat-soluble antioxidant, and it is rich in dietary sources like fish, red meat, egg yolk, dairy products, etc.

4) Vitamin E: Vitamin E is also known as alpha-tocopherol. It is also a fat-soluble antioxidant that helps in cancer prevention by protecting against oxidative stress in cells. The sources rich in vitamin E include:

  • Rich in nuts and seeds like sunflower seeds, almonds, hazelnuts, peanuts, pinenuts, etc.

  • Meat sources like salmon, fish, chicken, beef, etc.

  • Fruits like avocado, mango, berries, apricots, etc.

5) Polyphenolic Antioxidants: Many recent studies have reported that polyphenol antioxidants are beneficial to human health. It reduces the risk of developing diseases associated with ROS (reactive oxygen species) and also helps in cancer prevention. It is a water-soluble antioxidant, and its sources include natural plants and fruits. The sources rich in polyphenol antioxidants include:

  • Herbs and spices.

  • Beverages like coffee and tea.

  • Berries.

  • Cocoa.

  • Vegetables like yam, potato, tomato, etc.

  • Turmeric is one of the richest sources of polyphenols. It contains curcumin, which is a flavonoid polyphenol.

6) Foods Rich in Selenium and Zinc: Compounds like selenium and zinc help in cancer prevention by increasing the apoptosis (a form of cell death) of cancer cells in the body. Some studies reported the deficiency of selenium and zinc in developing prostate cancer. The foods rich in zinc and selenium include:

  • Meat sources like red meat, poultry, oysters, tuna, etc.

  • Nuts and seeds like Brazil nuts, cashews, and sunflower seeds.

  • Black beans, legumes, lentils.

  • Vegetables like green peas, asparagus, broccoli, etc.

Can A Person Take Antioxidants During Chemotherapy in Cancer Treatment?

Some studies suggest that antioxidants show no interference with chemotherapy and show increased cancer cell death, and help in cancer prevention. On the other hand, some recent studies reported that antioxidants do interfere with chemotherapy and should be avoided. Only a doctor can bring the patient out of this dilemma, so consulting the doctor before having any antioxidant supplements during chemotherapy is recommended.

Does a High Intake of Antioxidants Cause Any Problems?

An excess intake of antioxidants can also be harmful to health. High doses of antioxidants resulting in an increased risk of cancer are also reported in some cases. Consuming too many antioxidants increases oxidative stress and causes harm to the body. It will be a wise decision to have a word with the doctor before taking any additional antioxidant supplements in the diet. Having a healthy diet, including antioxidant-rich foods, is more than necessary. During chemotherapy, take caution when taking the following vitamins and supplements:

  • Vitamin C: Excessive vitamin C intake may cause certain chemotherapy medications to stop working.

  • Vitamin E: The efficacy of chemotherapy may be impacted by high doses of vitamin E supplements.

  • Beta-carotene: It may be best to stay away from supplements containing this antioxidant during chemotherapy, as the body transforms it into vitamin A.

  • Selenium: Certain chemotherapy medications may interact with an excessive selenium intake.

  • Coenzyme Q10: Some chemotherapy medications may not work as intended when this antioxidant is present.


Antioxidants are valuable in cancer prevention by inhibiting oxidative stress in the body. One can meet the daily requirement of antioxidants by taking antioxidant-rich foods. If they feel like adding additional antioxidant supplements to their diet, then do consult the doctor since the high dose of antioxidants can play a role as an antagonist to the body by increasing oxidative stress and inducing cancer.

Neha Suryawanshi
Neha Suryawanshi



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