Can antioxidants prevent cancer or do they increase your risk of it? The Department of Oncology Pharmacy at Singapore General Hospital explains.
Can antioxidants prevent cancer or do they, to the contrary, promote it? What if you already have cancer? Here's what you should know
Normal body functions such as breathing or physical activity, as well as 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.
Getting the right amount of antioxidant vitamins
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 at least 5 servings of fruits and 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.
Antioxidant vitamins in cancer prevention studies
Numerous studies have examined the association between dietary antioxidant intake and the risk of cancer. The results of recent studies are summarised below. As shown, a major surprise of these studies has been that antioxidant supplementation actually appears to be harmful in some disease groups.
Antioxidant supplementation and cancer prevention: Randomised trials
|Experimental Intervention||Sample Size||Duration Of Study||Characteristics Of Participants||Study Outcome|
Vit E: 30mg/day
Selenium: 50mcg/day||29,584||6 years||Malnourished Age: 40 - 69||Lower cancer rate|
atocopherol: 50mg/day||29,133||5 - 8 years Average 6 years||Male smokers Age: 50 - 69|| B-carotene:
in lung cancer|
retinyl palmitate: 25 000IU/day||18,314||4 years||Male and female
Age: 45 - 74
occupational exposure to asbestos||No clear evidence of benefit. Associated with more death|
|B-carotene: 50mg on
11.6 - 14.2 years, average 12 years
Age: 40 - 84
Current/former or non-smokers||No clear evidence of benefit or harm related to cancer risk|
|B-carotene: 50mg on alternate days ||39,876 ||0.00-2.72 years,
median 2.1 years||Female Age: > = 45 ||No significance difference in
incidence of cancer|
Vit C: 1000mg/day
Adenoma diagnosed Good health
Age: < 80
|No clear evidence of benefit|
Recent non-melanoma skin cancer
| No clear evidence of benefit|