| |
Too much antioxidant supplementation actually appears to be harmful for cancer.
Antioxidants
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
B-carotene:
15mg/day
Vit E:
30mg/day
Selenium:
50mcg/day
|
29,584 |
6 years |
Malnourished
Age: 40 - 69 |
Lower cancer rate |
|
B-carotene:
20mg/day
compared to
atocopherol:
50mg/day
|
29,133 |
5 - 8 years
Average 6 years
|
Male smokers
Age: 50 - 69 |
B-carotene:
20mg/day
associated
with increase
in lung cancer
|
B-carotene:
30mg/day
and
retinyl palmitate:
25 000IU/day
|
18,314 |
4 years |
Male and female
Age: 45 - 74
Smoker and/or
occupational
exposure to
asbestos
|
No clear evidence
of benefit. Associated
with more death |
B-carotene:
50mg on
alternate days
|
22,071 |
11.6 - 14.2 years,
average 12 years |
Male
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
|
B-carotene:
25mg/day
Vit C:
1000mg/day
Vit E:
400IU/day
|
864 |
4 years |
Adenoma diagnosed
Good health
Age: < 80
|
No clear evidence
of benefit |
B-carotene:
50mg/day
|
1,805 |
5 years |
Recent
non-melanoma
skin cancer
|
No clear evidence
of benefit
|
Should I take antioxidants?
If you're being treated for cancer, it is not a good idea to take high doses of antioxidant nutrients as they may interfere with cancer treatment. Be sure to discuss them with your healthcare providers. If you decide to take antioxidant supplementation, here are some basic points to consider:
- Do I need to think first about my total diet plan?
- Should I check first with my doctors?
- How reliable is the source recommending those supplements?
- Does it sound too good to be true?
- Is it really likely to be worth the expense, or would I be better off spending my money in some other way?
|
|