Friday, May 25, 2007


So if you have the sort of "olive" skin that predisposes to melanoma, should you throw away your pills? Not really. The sampling below is impressive but the effects noted were small and melanoma has a very low incidence in most populations anyway (Estimated lifetime risk of 1 in 75 for American Caucasians). The word "parity" below is used in a peculiar medical way -- meaning the number of kids you have had. It's sort of fun that having kids seems to protect men too! Perhaps that's another reason not to take the findings too seriously. If families tend to go out in the sun less than singles, it would make sense, though. That big ball in the sky is the main cause of melanoma. It's nice to see "may be" used in the conclusion to an epidemiological article. We would have got a lot more definiteness if the article had been about "obesity"

Reproductive History and Cutaneous Malignant Melanoma: A Comparison between Women and Men

By Jeanette Kaae et al.

To evaluate whether previously observed associations between parity and cutaneous malignant melanoma (CMM) risk in women reflected a biologic mechanism or resulted from uncontrolled confounding by lifestyle factors associated with parity (e.g., patterns of sun exposure), the authors investigated the effect of reproductive history (parenthood) on CMM risk in both women and men. Using information from Danish national registers (1968-2003), the authors established a population-based cohort of more than 3,500,000 persons with information on parenthood and CMM. Relative risks were estimated using Poisson regression models. Overall, number of children was significantly associated with a woman's risk of CMM (p = 0.004), with the lowest risk being seen among women with many births. Women aged 25 years or older at their first birth had a 24% (95% confidence interval: 16, 33) higher risk of CMM than younger women. Ten or more years after the birth of her youngest child, a woman had a 15% (95% confidence interval: 5, 27) higher risk of CMM than she did in the first 10 years. Similar results were observed in men. The similarity of effects for men and women suggests that lifestyle factors, rather than exposure to pregnancy hormones, may be responsible for the observed associations between reproductive history and CMM risk in women


Tall guys get more prostate cancer

More fun from The American Journal of Epidemiology. What would I do without it when I want a laugh? The findings below are quite a mixture but fatties come out pretty well. It is tall guys who had better watch out! The effect was small, however, and only found by looking at real shorties versus real tallies. Perhaps tall guys get more women and overwork their prostates that way. As is usual in epidemiology, nobody knows

Anthropometrics and Prostate Cancer Risk

By Alyson J. Littman et al.

Studies on obesity and prostate cancer risk are inconsistent, perhaps because of differential effects on aggressive and nonaggressive cancers. Participants included 34,754 men residing in Washington State (aged 50-76 years at baseline) in a prospective cohort study who were recruited between 2000 and 2002; 383 developed aggressive (regional/distant stage or Gleason sum 7-10) and 437 developed nonaggressive disease through December 2004. Compared with normal-weight men (body mass index (kg/m2) <25), obese men ~30 kg/m2) had a reduced risk of nonaggressive disease (hazard ratio = 0.69, 95% confidence interval: 0.52, 0.93; p for trend = 0.01). Overweight men (25-29.9 kg/m2) had an increased risk of aggressive disease (hazard ratio = 1.4, 95% confidence interval: 1.1, 1.8), but there was no increased risk for obese men (p for trend = 0.69). Body mass index of >25 at age 18 years was associated with increased risk of aggressive prostate cancer; obesity at ages 30 and 45, but not 18, years was associated with reduced risk of nonaggressive prostate cancer. Height (fourth vs. first quartile) was associated with an increased risk of total prostate cancer (hazard ratio = 1.3, 95% confidence interval: 1.1, 1.6), which did not differ by aggressiveness. There were no associations of prostate cancer with age at which maximum height was reached. Results from this study demonstrate the complexity of prostate cancer epidemiology and the importance of examining risk factors by tumor characteristics.


Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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