The largely unregulated supplement industry sells a variety of weird and sometimes dangerous stuff that it wink-nudge promises will cure what ails you, but even the most accurately labeled, evidence-based supplements can make sick people much, much sicker.
People who eat diets rich in antioxidants — plants, mostly — are at a lower risk of many illnesses, including cancer. There's good evidence to support the idea that the anti-oxidants in their diet are protecting them from cancer by attacking mutation-causing free radicals.
But when those anti-oxidants are extracted and turned into supplements, they have a very different effect from the foods in which they're found. In a new study published in Science Translational Medicine, researchers from the Karolinska Institute report on a study that found antioxidants were responsible for speeding up the growth of melanomas; last year they reported a similar finding for antioxidants and lung cancer.
The Karolinska Institute's Martin Bergö, a molecular biologist, hypothesizes that antioxidants are protecting cancer cells from free radicals. Cancer cells are particularly vulnerable to "oxidative stress" — the damage from free radicals, and this retards the spread of cancer, unless, that is, you're megadosing on anti-oxidants.
Though more work needs to be done, Morrison and Bergö expect the results to hold true for other types of cancers. And the findings are actually quite consistent with results from previous clinical trials, Morrison told Ars. Those previous data have just been largely overlooked, he said—probably because "the idea that antioxidants are good for you has been so strong in people's minds."
These results have been backed up by some studies in humans, too. In 1994, researchers published results from a double-blind, randomized clinical trail of more than 29,000 Finnish male smokers who were either given antioxidant supplements or placebo. After years of follow up, those given beta-carotene antioxidants had an 18 percent increased risk of lung cancer and an eighteen percent higher death rate. Another large clinical trial of men, published in 2011, similarly found that vitamin E increased the risk of prostate cancer.
But, Morrison cautions, much of those data relate to people who already have cancer or likely have precancerous conditions. They don't tell us much about risks for healthy people, he said.
Myths about antioxidant supplements need to die
[Beth Mole/Ars Technica]
Antioxidants can increase melanoma metastasis in mice
[Kristell Le Gal and co/Science Translational Medicine]
Oxidative stress inhibits distant metastasis by human melanoma cells
[Elena Piskounova/Nature]
