‘Antioxidant’ supplements in general are harmful
And the evidence that when it comes to antioxidants, more isn’t necessarily better, keeps mounting. In 2007 a combined analysis of 68 randomized trials of any antioxidant supplements showed a statistically significant 5% increase in risk of death in the groups taking the supplements compared to the groups taking placebo pills.
When the outcome is total deaths, a 5% increase is huge. The findings were a shock and disconcerting to the research community; the first edict in medicine is to do no harm, yet these trials clearly did harm. The results showed that when individual antioxidant tablets were supplemented with beta-carotene, vitamin A and vitamin E, each significantly increased risk of death. In addition to their role as vitamins, A and E are also antioxidants. Vitamin C and selenium supplements had no effect one way or the other on risk of death.
For otherwise healthy persons, taking antioxidant supplements doesn’t seem to do good, but rather can do harm. However, there might be an exception to this rule.
What happens if you take a low dose?
But are all antioxidant supplements really bad?
A recent multivitamin study that was part of a large trial of physicians called the Physician’s Health Study II based at Harvard offers a clue.
The study began in 1997 with almost 15,000 male doctors who were randomly assigned to take one of four kinds of pills. One was a placebo and the others were either vitamin E, vitamin C or a multivitamin that contained some antioxidants such as a low dose of vitamin E. Because the researchers wanted to use a product available to the public, they decided to use Centrum Silver, a brand of multivitamin manufactured by Pfizer. Other than providing Centrum Silver, Pfizer evidently played no role in the study.
By 2011, about 2,700 of the 15,000 participants had been diagnosed with cancer. The vitamin E and C pills had no impact on risk of cancer in this trial, but the multivitamin group showed an 8% lower risk. The multivitamin contained no iron, which is a good thing. It also contained far less of the nutrients that you tend to find in supplements. For instance, Centrum Silver contains much less vitamin E than what you would find in a typical vitamin E supplement (45 International Units compared to 400 IU).