Antioxidants Boosting Lung Tumors in Mice Does Not Mean They Cause Cancer

The big health news of the day is that antioxidants, the cancer-fighting, free radical-busting superheroes of the nutrition world, may actually accelerate cancer. Sike—lemme just go dump my acai smoothie down the drain. The thing is though, that conclusion is not exactly true.

A study published today in Science Translational Medicine lended weight to a long-held suspicion that certain antioxidants may cause cancerous tumors to form and grow more rapidly when they are overconsumed by taking vitamin supplements. That’s a key distinction. What the researchers from Sweden’s University of Gothenburg discovered is yet more proof of the unpopular fact that vitamin supplements aren't a panacea for a nutrient-starved diet. Or a get out of cancer free card.

Even more to the point, thinking they are can be dangerous in itself, if it deters you from ingesting vitamins and minerals the old-fashioned, mother-approved way: eating fruits and vegetables. People's weakness for burgers and beer over kale and grapefruit is money in supplement companies' pockets.

As Motherboard’s Michael Byrne has pointed out, a large swatch of the supplement brands you’ll find in the eco-friendly section of the grocery store have no proven benefits at all, due in part due to loose regulations in the US that let the supplement industry evade FDA regulations and boom into a billion-dollar business.

But back to antioxidants. These chemical compounds, like vitamins A, C, and E, won their superstar reputation for protecting against free radicals that can damage DNA cells. However, the study published today found that when researchers fed supplements of the common antioxidants N-acetylcysteine and vitamin E to mice with lung cancer, it caused the cancer to progress more rapidly.

Of course, this doesn't mean that would be the case for humans. But the conclusion echoes previous studies of the effects of antioxidant overconsumption. Most notably, a 1994 National Cancer Institute study that found supplements of the antioxidant beta-carotene increased the rate of lung cancer in smokers.

Today, Reuters reported that “Last month, a review of dozens of studies found ‘no clear evidence of a beneficial effect of supplements’ on heart disease, cancer or mortality. An accompanying editorial in the Annals of Internal Medicine warned that ‘beta carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful,’ while other antioxidants ‘are ineffective.'"

Still, there are some caveats of the mouse study worth mentioning. One, researchers only tested animals that already had cancerous tumors, so suggesting that antioxidants increase the risk of developing cancer would be missing the mark. Two, researchers tested two specific antioxidants, vitamin E and NAC. Not all antioxidants are created equal, which is much of the point.

Health research is a very nuanced field, and as the authors of the latest study note, the "deeply rooted" belief in the general public that antioxidants fight cancer is a distortion of what's actually been proven. It's a problem that's plagued the supplement market for years. Combine unclear media reports with the temptation to believe in an easy fix for deep-rooted unhealthy habits, and you'll see why the more impressionable members of the public have been jumping on and off health bandwagons for years.

In the case of today's study, the motivation to research antioxidant overconsumption was a reaction to a reaction—the hype around the fact that certain vitamins found in nutritious foods can fight disease. It doesn't mean antioxidants don't have healthy properties, and it doesn't necessarily mean they accelerate disease. It's yet another reminder of why you should take any new health craze with a grain of salt. But not too much salt.