NATURALLY DANGEROUS: Surprising Facts About Food, Health, and the Environment.
By James P. Collman, Professor of Chemistry, Stanford University
Epilogue: There Is No Free Lunch!
© James P. Collman, 2003. All rights reserved
There is growing evidence in animal studies and a few human studies that exercise is not only good for one's physical health, it also improves mental health. This new research suggests that physical exercise encourages the subject's brain to function at an optimum level. Most of these studies have been done with trained mice, and one knows from many drug studies that: "mice are not humans", but there is some evidence that this might work on humans as well. When allowed to do so, mice will voluntarily run on exercise wheels (up to 4 km a night), so most studies simply amount to putting such wheels in the cages of selected mice, then studying their performance on mental tasks. The exercising mice always show superior performance. Moreover, those mice were then dissected and their brains were examined. Those mice who had been exercising had more new neurons and stronger connectivity, as well as large amounts of a brain-derived neurotrophic factor, BDNF, a protein which is thought to promote brain benefits. Because of its effect on brain cell cultures, BDMF has been referred to as a "brain fertilizer". Additional evidence indicated that BDNF is the primary source for the behavioral benefits from exercise. Some mice that have been genetically predisposed to develop Alzheimer's-like disease showed slower regression when they were allowed to exercise.
There is less evidence for the mental benefits that humans might gain from
exercise. Statistical surveys of lifestyle and health suggest that people
who exercise one hour a day (walking will do) are less likely to develop Parkinson's
disease than other sedentary individuals. Moreover, memory tests given to
1740 people over 65 over a 6-year period have associated a reduced risk of
dementia with moderate exercise. (Science News Online, February 25, 2006,
Vol. 169, No. 8)
Several times each week I run from Father Time and his companion, Entropy, which is the scientific word describing the inevitable increase in disorder which follows the arrow of time. Do supposedly healthful activities such as exercise and diet extend life or just improve the quality of life. The extension of the human life span is an important issue, which is being actively studied by both scientists and entrepreneurs. The internet is filled with quackery purporting to extend life. Anti-aging clinics and products abound. What is known and what are the prospects, if any for increasing the human life span? We do know that we can retard aging in other creatures. For example changing a single gene in a nematode dramatically increases that worm’s life. Another gene has been found that extends the life-span of a yeast. Humans are not worms or yeasts, but the lifetimes of fruit flies, spiders, mice, and even monkeys (animals that we do resemble) have been extended through a simple device: calorie restriction! Animals fed two-thirds of their normal diet live longer and put off t diseases of old age such as arthritis and cancer. That method is not appealing to most people and its unethical to carry on experiments of this sort on humans. One ethical approach is to study the diets, physiology and genes of centenarians, people who have lived over a hundred years. The oldest, well-documented person is a Frenchwoman, died at 122. So far nothing useful seems to have been discovered by exploring these relatively healthy old people. Another strategy is to explore the enzymes that control the length of telomers. These groups, which are at the end of DNA, shorten as cells age and lose the ability to divide. At least one company is studying the related enzymes, telomerases. Another therapy is discussed in Naturally Dangerous, page 82, injections of human growth hormone, HGH. Such treatment is expensive and seems to improve some things such as smoothed skin, increased muscle mass and loss of fat, but there are dangerous side effects such as raised blood glucose levels and there is no evidence that life is prolonged. The balance of living organisms, homeostasis may be upset. Still, if life can be extended for some creatures, a treatment may be found for wealthy old adults, but beware of hucksters and quackery. (Science, February 8, 2002, page 1033)