Where did we get the idea that antioxidants will help defy aging? Partly, we got them from studies on a diminutive worm called Caenorhabditis elegans, much-loved by developmental biologists because it is easy to rear and breed in little dishes and is complicated enough for the study of development yet simple enough -- it has just 959 cells -- to not utterly befuddle.
A study published in 2006, for example, found that the antioxidant alpha-lipoic acid extended average and maximal lifespan of C. elegans, and epigallocatechin gallate, an antioxidant in green tea, didn't extend lifespan but did "attenuate the rate of decline in pharyngeal pumping behavior." (You may not care much about that ability, but we'd guess that it matters for worms.) Both substances enhanced the ability of more elderly worms to slither toward chemicals that interested them. Studies have also shown that vitamin E exposure increases C. elegans lifespan; that mutant worms more capable of processing free radicals live longer lives; and more, much more. (A caveat: Aging is a complicated business, and the antioxidant theory is only one of a number, whether we're talking about worms or mice, rats, fruit flies or us.)
So does that mean you and I should go and dose ourselves with as many antioxidants as we can? Silly question! If consumer behavior and supplement marketers are any yardstick of what we should do, the answer is obviously yes.
A new study suggests that willy-nilly piling-on of any old antioxidant might not be entirely smart, however. And, furthermore, that we don't really know what we're doing. Conducted by researchers at the Buck Institute for Age Research and published in the online edition of Experimental Gerontology, it tested 40 different antioxidants for their effects upon the worm. Four extended lifespan. Just four. The rest did not -- some, in fact, harmed the worms. As a news release at the Buck Institute website put it (the study, alas, can't be accessed unless you pay):
"We've taken a careful look at the way antioxidants affect aging in simple animals and what we find is that it’s a hodge-podge of effects," said Gordon Lithgow, lead author of the study and a Buck faculty member. "We see antioxidants that appear to make simple invertebrates live healthier, longer lives and we also find antioxidants that have precisely the opposite effect, that compromise the animal’s survival."
The chemicals found effective in the study (extending lifespan by 15% to 20%) were lipoic acid, Trolox (a water-soluble vitamin E derivative), taxifolin (found in milk thistle) and propyl gallate. And it gets more complicated than that. Lipoic acid in high doses did extend worm lifespan, but it also reduced fertility. (Any parent will suspect that these factors are related: However wonderful raising a kid may be, think of the sleepless nights, the sapping of energy, the lines that form on the face, those interminable holiday season shows and recorder recitals.) But in low doses, lipoic acid did the opposite. Worms were less resistant to stress and lived less long.
The scientists don't understand this, but as Lithgow says, when it comes to people using antioxidants to extend their lives, "I think what we've got to do is be very careful. If consumers are looking at a product that makes an anti-aging claim, they need to investigate that claim and see where the evidence comes from."