Antioxidant supplements and mortality.
OBJECTIVE
Oxidative damage to cells and tissues is considered involved in the aging process and in the development of chronic diseases in humans, including cancer and cardiovascular diseases, the leading causes of death in high-income countries. This has stimulated interest in the preventive potential of antioxidant supplements. Today, more than one half of adults in high-income countries ingest antioxidant supplements hoping to improve their health, oppose unhealthy behaviors, and counteract the ravages of aging.


RESULTS
Older observational studies and some randomized clinical trials with high risks of systematic errors ('bias') have suggested that antioxidant supplements may improve health and prolong life. A number of randomized clinical trials with adequate methodologies observed neutral or negative results of antioxidant supplements. Recently completed large randomized clinical trials with low risks of bias and systematic reviews of randomized clinical trials taking systematic errors ('bias') and risks of random errors ('play of chance') into account have shown that antioxidant supplements do not seem to prevent cancer, cardiovascular diseases, or death. Even more, beta-carotene, vitamin A, and vitamin E may increase mortality. Some recent large observational studies now support these findings. According to recent dietary guidelines, there is no evidence to support the use of antioxidant supplements in the primary prevention of chronic diseases or mortality.


CONCLUSIONS
Antioxidant supplements do not possess preventive effects and may be harmful with unwanted consequences to our health, especially in well-nourished populations. The optimal source of antioxidants seems to come from our diet, not from antioxidant supplements in pills or tablets.
aThe Cochrane Hepato-Biliary Group, Copenhagen Trial Unit bThe Copenhagen Trial Unit, Centre for Clinical Intervention Research, Department 7812, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
Goran
G
Bjelakovic
Dimitrinka
D
Nikolova
Christian
C
Gluud
D000975:Antioxidants / Q000008:administration & dosage* / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000401:mortality* / Q000517:prevention & control; D002908:Chronic Disease; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015201:Meta-Analysis as Topic; D009369:Neoplasms / Q000401:mortality* / Q000517:prevention & control; D064887:Observational Studies as Topic; D016032:Randomized Controlled Trials as Topic; D014801:Vitamin A / Q000008:administration & dosage / Q000009:adverse effects; D014810:Vitamin E / Q000008:administration & dosage / Q000009:adverse effects; D019207:beta Carotene / Q000008:administration & dosage / Q000009:adverse effects
D000975:Antioxidants; D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E