Few medical remedies have a more sterling reputation than that assortment of foods, pills, and general life maneuvers known collectively as "antioxidants." At last, here's something that promises better heart health, improved immunity, a pellucid complexion as well as relief against cancer, arthritis, and the blahs—and it's all-natural! What's not to like?
Well, there is a wee small problem in our ongoing anti-oxidize-athon: As it turns out, we have no evidence that antioxidants are beneficial in humans. (Though if you're a Sprague-Dawley rat, there's hope.) In fact, as Emily Anthes wrote last year in Slate, the best available data demonstrate that antioxidants are bad for you—so long as you count an increased risk of death as "bad."
But, hey, who ever let a little evidence stand in the way of a good time? Especially in this case, when the charge toward lifestyle legitimacy has been led by willowy celebrities with karmic equipoise, ably supported by the Four Horsemen of the Alternative: Drs. Weil, Oz, Null, and Chopra. The seduction of this confederacy (sex! doctors! pills!) is immense; to appreciate its power, one need only consider the pomegranate. Once a rare fruit requiring a complicated eating strategy, its derivatives are now stationed on every grocery shelf based on their promise of an antioxidant punch.
The field of antioxidants is further buffeted by the fact that no one really understands much about them, so winning an argument is greatly simplified. (And never mind that the main commercial use of antioxidants is to act as food preservatives, placing them squarely on the axis of toxicity). Their story began in the 1940s when a physician-chemist named Denham Harman set out to determine the biochemical explanation for aging. As a young man, he had worked in the lubricating department of Shell—a place where the problems of a chemical spoilage caused by "free radicals" were well-known. By the mid-50s Harman hit upon the theory that the same free radicals that were cutting into petroleum industry profits could also simply and completely explain the phenomenon of aging. Better yet, he said, their effects could be ameliorated by something called antioxidants.
But first, what exactly is a free radical? Not a fiery Berkeley politico but rather a lonely unpaired electron lost and spinning around an atomic nucleus. Electrons are compelled to travel in pairs; an unpaired electron therefore will greedily grab the next electron it meets, regardless of pedigree or station. DNA, RNA, mitochondria—it's open season. Sometimes the miscegenation does serious damage to the cell, resulting (the theory goes) in a gradual and irreversible deterioration. For us this means wrinkles and sagging and creaking joints.
The role of antioxidants in this schema is simple: They are brought onboard to hook up with the vagrant electrons and prevent damage. Harman's observation was supported by then-novel insights into management of radiation exposure, a large concern in the 1950s. One known effect of radiation was tissue damage that looked to us like aging. Among the treatments that seemed to blunt this effect were antioxidants such as melatonin, Acetylcysteine, and pentoxiphylline. Presto: A star was born. Never mind how meager the slings and arrows of everyday life are compared with radiation from an atom bomb. If it (might) work for gamma rays, imagine what it can do for my tennis elbow.
If only reality would play along. As noted by Anthes, and Michael Specter in his book Denialism, the first clear crack in the façade was the 2007 revelation in JAMA that antioxidant vitamins were not merely useless but harmful. Building on this clinical observation, a German group has developed a plausible scientific explanation of the increased risk. The title of the group's most recent publication, " Extending life span by increasing oxidative stress," pretty much sums up their view: The human cell should toughen up. It can benefit from enduring something harsh like the insult caused by free radicals. This way, the organism is more prepared to fend off the inevitable Big One, be it cancer or a toxic fume or perhaps a bout of cholera. Practice makes perfect.