Bjelakovic et al (2007) JAMA 297: 842-857
Mortality in randomized trials of antioxidant supplements for
primary and secondary prevention - Systematic review and metaanalysis.
- 47 low-bias trials with 180 938 participants,
- antioxidant supplements (BC, vit A, C, E, Se)
- significantly increased mortality (RR, 1.05; 95% CI, 1.02-1.08).
After exclusion of selenium trials:
beta carotene (RR, 1.07; 95% CI, 1.02-1.11),
vitamin A (RR, 1.16; 95% CI, 1.10-1.24), and
vitamin E (RR, 1.04; 95% CI, 1.01-1.07),
singly or combined, significantly increased mortality.
Vitamin C and selenium had no significant effect on mortality.
Conclusions: Treatment with beta carotene, vitamin A, and
vitamin E may increase mortality. The potential roles of vitamin C
and selenium on mortality need further study.
Beta-carotene supplements increase mortality risk
- Increased intake of vegetables and fruits rich in carotenoids
reduced the risk of lung cancer.
High levels of ß-carotene in the blood were consistently associated
with reduced incidence of lung cancer.
TOLERABLE UPPER INTAKE LEVELS FOR VITAMINS AND MINERALS
European Food Safety Authority, February 2006
Scientific Committee on Food and Scientific Panel on Dietetic Products,
Nutrition and Allergies
High natural intake: reduced risk.
Intervention with supplements: no confirmation, indications for
possible adverse effects
What is the difference between intake from food and intake from
- Modifying factors (smokers, timing, genes, age, sex, etc)
- Isolated components, while food is complex
HUMAN AND ANIMAL PHYSIOLOGY
We have to establish the window of benefit