Source: The Saturday Mercury, 31 March, 2001, p.21
SCIENCE WATCH with STANLEY ROBERT HUMANS, especially in developed countries, are living longer than we ever have before. This can mostly be put down to better nutrition, vaccination, antibiotics, sewers and clean drinking water. In an apparent contradiction, we have also been hearing that people currently alive, especially children, are fatter than ever before. Are we at the crest of our achievement in regard to human lifespan? Will the current crop of chubby children bring down our life-expectancy averages in the next few decades? It will be interesting to see if medicine can keep up with our lifestyle diseases-usually caused by the overeating and underexercising parts of our lifestyle. Of course, the simplest way to reduce the risks of lifestyle disease is to modify one's lifestyle. Several studies published over the past week appear to report the blindingly obvious. However, given that humans in developed countries keep getting fatter, maybe we need more and more reminding of these obvious findings. The results of a large-scale US survey showed that there was a positive correlation in children between watching television and obesity. Children who watched more than four hours of television a day, aside from having hopeless parents, were 2.6 times more likely to be obese than those who watched less than one hour a day. Presumably there just isn't enough time in the day for such ravenous TV- watchers to also get some exercise. I guess that similar risks would apply to children spending hours on the computer or reading books. However, it seems to me that most bookworms have a better sense of balance than do TV addicts. A long-term study from Finland provides another example of what everyone expects. Fitter men have lower incidences of death by heart disease. In fact, in their observations of arbitrarily defined fit and unfit men over 10 years, the researchers found that unfit men had a three-fold increased risk of dying from heart disease and a 2.7-fold increased risk of dying by some other means. This is a very big difference! In case you're now worried that you're going to die because you're unfit, another American study suggested that you don't have to do all that much to start reducing your risk of death by heart disease. In women (that's all the researchers looked at here) the risks started dropping when only one hour of light walking a week was done. Of course more exercise is better. Another aspect of modern lifestyle that contributes to human disease is tobacco smoking. There's plenty of evidence that it's a good way to reduce lifespan. One more subtle aspect of cigarette smoking is the effect on the skin. Have you noticed that many smokers look more wrinkly and older than they actually are? Researchers from Germany and the UK analysed skin from the buttocks of smokers and nonsmokers for levels of an enzyme called MMP-1. It is known that MMP-1 destroys collagen in skin that has been exposed to UV radiation, which explains why sunbathers become wrinkly. The researchers looked at buttocks not because they were naughty but because most buttocks do not get exposed to UV radiation. They found that smokers' buttocks contained MMP-1 while nonsmokers' did not. This suggests that wrinkles from smoking are caused by the same mechanism as wrinkles from sunbathing, which, by the way, is a lot cheaper. · Stanley Robert has a PhD in genetics and gained a post-doctoral fellowship at the University of Washington, Seattle.
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