The marketing of antioxidants leads us to imagine them sweeping through the body like little white knights, ready to do battle with the myriad chemicals that assault our cells. This image goes back decades; Linus Pauling built an entire post-Nobel career on promoting the idea that we should bathe our inner workings in antioxidant supplements. The result was superhero status for antioxidant-rich blueberries, açai berries, pomegranate—and billions of dollars trading hands. Now, though, a growing body of research is rubbing away some of their luster.
To better understand antioxidants, you have to begin with the "oxidant" part. Free radicals are molecules that are a natural by-product of the body's metabolic processes. But they are missing an electron—and go looking to steal one from somewhere in the body. This theft creates what is known as oxidation, which speeds up the aging process of cells. "It's a bit like rust," explains Walter Willett, DrPH, MD, chair of the department of nutrition at the Harvard School of Public Health.
Antioxidants, in essence, are compounds with an electron to spare. If we have plenty of them, they can lend their extra electrons, stabilizing free radicals, counteracting oxidation.
So what's the problem with gobbling antioxidants? First of all, the body actually needs a few free radicals on hand. "One way the immune system works to kill bacteria is by releasing oxidative bursts," explains David C. Poole, PhD, DSc, FACSM a professor of kinesiology, anatomy, and physiology at Kansas State University. "If you have antioxidant levels too high, that process won't work as well as it should."
There's more, and it's ironic: "At superhigh doses, antioxidants turn into pro-oxidants and add to the body's load of oxidative stress," says Darlene McCord, PhD, an independent researcher in the field of cellular nutrition and biochemistry.
Here's another problem with antioxidants: There's no longer any reliable way to count them. In May, the USDA pulled the plug on their online nutrient database that measured foods' oxygen radical absorbance capacity (ORAC) scores, essentially leaving antioxidants without an agreed-upon unit of measure—or any way to recommend how much of them we should or shouldn't be getting.
Over the past decade, more and more ORAC tests produced an antioxidant arms race ("Blueberries are highest! No, goji berries are! No, wait, it's oregano!"), and the tests became less serious scientific inquiry than gimmick. Outrageous products followed—like one widely available "superjuice" that promises a 161,000 ORAC rating per bottle.
With each new ORAC ranking came the kinds of petri-dish studies where a single antioxidant, isolated from a food source, appeared to have a boffo health benefit.
But this is no model for the complexities of the human body. "Different kinds of antioxidants are absorbed and metabolized differently," Willett says. "Their function depends on being in the right place at the right time."
Or, as the USDA put it in the letter that occupies the space where their database of high-ORAC foods used to be: "There is no evidence that beneficial effects can be attributed to the antioxidant properties of these foods."
At a meeting of the Institute of Food Technologists earlier this year, Carl Keen, PhD, professor of nutrition and internal medicine at the University of California, Davis, suggested the term "antioxidants" be banished from labels because it's too vague to be meaningful. His reasoning: Antioxidants aren't one single nutrient like beta-carotene or zinc; it's an umbrella term, like "minerals." Calcium and magnesium are minerals. So is arsenic.
Food makers are already beginning to shift away from antioxidant claims. For example, Lipton Tea removed the word from packaging earlier this year. Instead, they are now touting tea's flavonoids, dietary compounds that may help maintain normal, healthy bodily functions.
The key to getting the benefits of any antioxidant is, as always, a diet that's sensible and balanced—both in content and approach. Pile blueberries on your morning cereal not because of their free-radical-fighting superfood reputation, but because you like them, because they add a bit of sweetness without a whole lot of sugar, or because a bowl full of bright color starts your day in a happy way.