Can antioxidants prevent cancer? What about antioxidant supplements, how effective are they? Read on to find out.

Normal body functions such as breathing or physical activity, as well as unhealthy lifestyle habits such as smoking and drinking alcohol, all produce free radicals that attack healthy cells. When your cells are weakened by free radicals, they are more susceptible to developing certain types of cancers.

Antioxidants are a broad range of compounds that destroy free radicals. Many of these compounds are present in the diet as vitamins. The best known antioxidants are vitamin A, vitamin C and vitamin E.

Natural antioxidants are the best

The best way to get antioxidant vitamins is through healthy eating habits.

Fruits and vegetables contain essential vitamins, minerals, fibre and other nutrients including antioxidants. A good start to optimal health is to eat two servings of fruits and two vegetables a day (you can think of a "serving" as about a fistful).

Individuals who have diets rich in fruits and vegetables may have a reduced risk of cancer compared with those who eat a much higher proportion of high-fat and processed foods.

To have an idea of what to put on your plate daily, click here.

How effective are antioxidant supplements in preventing cancer?

Numerous studies have examined the association between dietary antioxidant intake and the risk of cancer. The results of these studies are summarised below. Surprisingly, it has been found that antioxidant supplementation for some disease groups may increase cancer risk.

Antioxidant supplementation and cancer prevention: Results based on randomised trials

Experimental Intervention

Sample Size

Duration of Study

Characteristics of Participants

Study Outcome

B-carotene: 15mg/day Vit E: 30mg/day Selenium: 50mcg/day


6 years

Malnourished age:
40 - 69

Lowers cancer rate

B-carotene: 20mg/day compared to atocopherol: 50mg/day


5 - 8 years Average 6 years

Male smokers age:
50 - 69

B-carotene: 20mg/day associated with increased risk in lung cancer in people who smoke and/or are exposed to asbestos

B-carotene: 30mg/day and retinyl palmitate: 25 000IU/day


4 years

Male and female age: 45 - 74 Smoker and/or occupational exposure to asbestos

No clear evidence  of benefit

B-carotene: 50mg on alternate days


11.6 - 14.2 years, average 12 years

Male age: 40 - 84 Current/former or 

No clear evidence of benefit or harm related to cancer risk

B-carotene: 50mg on alternate days 


0.00-2.72 years, median 2.1 years

Female age: > = 45 

No significant difference in incidence of cancer

 B-carotene:  25mg/day Vit C: 1000mg/day Vit E: 400IU/day


4 years

Adenoma diagnosed Good health

Age: < 80

No clear evidence of benefit

B-carotene:  50mg/day 


5 years

Recent non-melanoma skin cancer

No clear evidence of benefit

Ref: U11

Check out our comprehensive list of cancer articles:

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Lymphoma Cancer: First Signs, Types, Treatment

Endometrial Cancer: Risk Factors, Symptoms, Treatment and Prevention

Ovarian Cancer: Causes, Symptoms, Treatment and Prevention

Cervical Cancer: Symptoms, Screening and How to Prevent

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Cancer Diet: Top Foods to Eat and Avoid When Undergoing Treatment