ANTIOXIDANTS AND HEALTH
Although I would not go so far as to say Melinda Wenner Moyer's “The Myth of Antioxidants” established “myth” status for antioxidants, it was an eye-opening account of recent experimental evidence demonstrating that an increase in free radical levels in living systems does not consistently correlate with shorter life spans and that the aging process contains more uncharted territory than initially believed. More important, however, no reader should come away feeling that vitamins from food products are in any way overrated or are “killers.”
The studies that are mentioned in the article repeatedly made use of unnatural (and often unmeasured) vitamin sources, which of course will have the potential to do more harm than good to an organism. As a chemist in the pharmaceutical industry, I can state with considerable certainty that a drug product's formulation, inert substances and potency are equally as critical to its overall safety and efficacy as the active pharmaceutical ingredient, per se.
Case in point, a broccoli floret is a presentation of vitamin C and beta-carotene that the body digests and systemically disperses in a manner more natural and evolved than that of the exact same vitamins presented in tablets and capsules. Ingestion of supplements charges the body with concentrated vitamin doses lacking the beneficial delivery components that broccoli and other vegetables provide in well-received quantities. The generation and buildup of harmful oxidants is thus more likely to occur.
This may seem like a roundabout way of stating the obvious: a diet including foods rich in vitamins and other antioxidants is more beneficial than the routine consumption of vitamin supplements.
John J. Walsh
The article states that roundworms genetically engineered to not produce naturally occurring antioxidants lived as long as worms that produced them, implying that antioxidants are worthless at best. Yet length of life is not the only criterion we should go by. If it were, then you could say that my father-in-law, who never took antioxidants and subsisted almost entirely on candy bars, lived a good life. In fact, he lived to the same age as Jack LaLanne (97). But LaLanne was fit, active and in command of his faculties at the end of his life, whereas my father-in-law spent his declining years in a long, slow descent into the abyss of dementia.
Wenner Moyer correctly points out that some studies of the effects of high doses of antioxidant supplements such as beta-carotene or vitamin E have found that they are associated with increased mortality. She fails to mention, however, that those studies were inspired by many others showing that higher levels of such dietary antioxidants in the blood are strongly linked with lower overall mortality and lower death rates from cancer and cardiovascular disease. This is particularly true of the carotenoids, the family of antioxidants related to vitamin A.
Because humans lack the ability to synthesize carotenoids, those measured in the blood must come from diet—especially from fruits and vegetables. Thus, it appears that antioxidant carotenoids derived from natural sources in diet do increase life span, whereas individual carotenoids given in high doses do not.
University of Pittsburgh
“THE LEFT” AND SCIENCE
Michael Shermer appears to be reaching in his Skeptic column this month [“The Left's War on Science”]. He says that “there is more, and recent, antiscience fare from far-left progressives,” yet his examples aren't antiscience at all. “Liberals tend to be antinuclear because of the waste-disposal problem,” he says. So are most people—that's why Yucca Mountain hasn't been approved as a repository. “Anti–fossil fuels because of global warming.” Global warming is occurring, in large part, because of fossil fuels. “Antihydroelectric because dams disrupt river ecosystems.” Well, yes, they do (ask any ichthyologist how North American native fishes are doing; ask coastal cities why they are running out of beach sand). “Anti–wind power because of avian fatalities.” Again, is this antiscience? No, birds do die in wind turbines (and because of other unnatural structures like mirrored skyscrapers).[break]
Chino Hills, Calif.
SHERMER REPLIES: Each of these topics (nuclear energy, fossil fuels, and hydroelectric and wind power) involves complex webs of science, technology, economics and politics. The last two are where an “anti” bias can creep in from the far left. People in that camp tend to oppose anything “unnatural” and favor nature over humans if given the choice. Perhaps instead of “antiscience,” it is “antiprogress.” Whatever you call it, both the left and the right have their biases that go into influencing public policy relating to these energy technologies.
MELTING SPACE DUST
In “Secrets of Primitive Meteorites,” Alan E. Rubin mentions the search for a heating process in the early solar system that would partly melt dust to form the layered chondrules found in meteorites. He laments the problems with competing ideas for the cause, such as supernova shock waves. I am curious about the viability of the idea that nonaccreted grains were accelerated and heated by close encounters with protoplanetesimals, thereby generating the variable heating required.
RUBIN REPLIES: Protoplanetesimals may be only a few kilometers in size; dust grains flying by such bodies would not be noticeably heated. There was a suggestion in the 1970s that chondrules may have formed by frictional melting of dust grains in the nascent atmospheres of protoplanets. The problem with this scenario is that many chondrules contain silicate grains that are unrelated to their hosts (that is, they may differ in mineral chemistry and have a different oxygen-isotopic composition). These “relict” grains are not simply unmelted host chondrule material; they were derived from a preexisting earlier generation of chondrules.
It is more straightforward to assume that some early chondrules were broken by collisions with other chondrules in the solar nebula and that their fragments were incorporated into dust balls that were later partly remelted. An energy source capable of melting just the outer part of a chondrule and not an interior relict grain is required. That is why many researchers prefer flash-heating mechanisms such as lightning bolts.
“Brain Cells for Grandmother,” by Rodrigo Quian Quiroga, Itzhak Fried and Christof Koch, describes splendid research suggesting that small sets of neurons code for single concepts in humans. But an important caveat was not mentioned: much of the evidence comes from studies of brains of patients with epilepsy, and it is a leap to assume that epilepsy does not alter neuronal function of these neurons or of other cells and networks in the brain.
Martin J. Steinbach
Distinguished Research Professor Emeritus York University, Toronto