Radical thinking on antioxidants
Antioxidant-rich products promise an easy way to stave off disease. Simply swallow two softgels daily or knock back a glass of goji-pomegranate juice and the “supercritical” compounds will neutralize those nasty free radicals that threaten your health.
Such bold claims seem logical. There’s evidence that free radicals, or oxidants, are involved in cancer, degenerative brain diseases and certain other illnesses.
And when oxidants turn up in our bodies — it happens when we turn food into energy or are exposed to infection, smoking and other triggers — we fight back by producing antioxidants that can soak them up like a sponge.
Thus a theory was born: Perhaps oxidation and disease can be prevented by eating fortified foods or taking dietary supplements containing plant-based antioxidants, which include vitamins C and E, beta carotene and polyphenols (flavonoids).
But researchers now say antioxidants have been overhyped and widely misunderstood. Scientists haven’t determined how antioxidants work in our bodies, and it’s unclear whether dietary supplements have any beneficial effect. In some cases, studies suggest antioxidants may cause more harm than good. While some dietary antioxidants may have a role in cancer prevention, excessive doses of vitamins can aggravate illness or even cause it, researchers say.
“People should be aware that there is little to no data supporting the use of antioxidants to protect against disease,” said cardiologist Toren Finkel, chief of the Center for Molecular Medicine at the National Heart, Lung, and Blood Institute in Bethesda, Md.
Yet “antioxidants” remains one of the hottest buzzwords in the health and wellness industry.
Manufacturers have emblazoned it on water, breakfast cereal and even alcoholic drinks. Hundreds of products with antioxidant claims were launched last year alone, and items containing the nutrients continue to be a strong area of development, said Carlotta Mast, editor in chief of Boulder, Colo.-based newhope360.com, which tracks the market in natural, organic and health products.
In the U.S., sales of top antioxidant supplements hit $5 billion last year, up 2.3% from 2009, according to Nutrition Business Journal.
“Consumers have made an association between antioxidants and health,” Mast said. “They have a general understanding that antioxidants help with free radicals, and they know free radicals are bad. So they see a functional beverage that’s ‘rich in antioxidants’ and think, ‘This will be healthy for me.’”
Free radicals are an unavoidable hazard of living, a natural byproduct of eating, drinking and breathing.
“Oxygen oxidizes our food to produce energy, and the oxygen is reduced, mostly to water,” said biochemist Barry Halliwell, a pioneering researcher in free radicals and disease who is now deputy president of the National University of Singapore.
But some oxygen winds up as free radicals, unstable molecules that are missing an electron. Desperate to regain their balance, free radicals will steal an electron from the nearest substance, whether it’s DNA, protein or fat. The theft alters the structure of the nearby victim, creating another unstable compound and triggering a chain reaction.
Our bodies naturally respond by producing antioxidants that defuse free radicals by donating electrons while staying in balance themselves — a system people can strengthen through regular exercise.
But aging and exposure to environmental stressors like sunburn and pollution make it harder to keep up with antioxidant production, said Amy Howell, an associate research scientist at the Marucci Center for Blueberry and Cranberry Research at Rutgers University in Chatsworth, N.J.
Researchers have known for decades that illnesses including heart disease, cancer, stroke and neurodegenerative disorders are linked to damage caused by free radicals. They also know that people who eat a diet rich in fruits and vegetables have lower rates of disease.
As a result, they hypothesized that taking antioxidants as supplements or in fortified foods could decrease oxidative damage. But when antioxidant compounds were tested, the results were largely disappointing.
Beta carotene supplements didn’t just fail to protect people against cancer, they increased the risk of lung cancer in smokers. Trials looking at cardiovascular disease, other cancers and strokes have been mixed, but most haven’t found the hoped-for benefits.
Complicating the picture is the fact that free radicals aren’t always bad. The oxidant hydrogen peroxide, for example, can help open blood vessels; removing it with antioxidant therapy can impair the body’s ability to get oxygen to muscles.
There’s also some evidence that what doesn’t kill you can make you stronger: A little short-term free radical damage may activate pathways in the body that are protective in the long run, Finkel said.
“The real debate is whether we should let the radicals do their thing and not get in the way,” said David Neiman, director of the Human Performance Lab at Appalachian State University in Kannapolis, N.C. His advice: To fight oxidative stress, exercise. And eat your fruits and vegetables.