Saturday, March 08, 2008

Short people could live longer

And pigs might fly. Tall people are always shown as healthier in research

Evidence of a link between height and longevity has been found by scientists, suggesting that some short people will live longer than their taller peers. Normal variation in human height is due to a blend of environmental factors, notably diet, and genetic factors. Now one such inherited factor that could extend the human lifespan by as much as one third in theory has been uncovered, though it may come at the cost of a few inches in height.

The work also suggests that the [inappropriate] use of growth hormone as an anti-ageing medicine may actually be shortening lifespan. And it confirms the emerging view among scientists that rather than being a passive, haphazard process of wear and tear, some people may be blessed with genes that make them more likely to live to a ripe old age. [So that is new??]

Earlier work by a French team showed that mice lacking one copy of the gene IGF-1 live on average 26 per cent longer than normal, with females enjoying a bigger advantage (33 per cent increase in lifespan) than males (16 per cent increase). Damping down the same pathway of the metabolism also resulted in extension of lifespan in yeasts, worms, and flies too. And the same pathway is affected by diets low in calories, the only proven way to extend lifespan.

Now a study by Prof Nir Barzilai, Director, Institute for Aging Research, Albert Einstein College of Medicine, New York, reveals that the same gene is involved in the "oldest old" of people, revealing in the long run how to postpone the physiological ageing process.

Insulin-like growth factor (IGF-1) levels have previously been linked with both ageing and body size, with evidence showing that decreased levels of IGF-1 predispose the animals for short stature, but increased longevity. To determine if IGF-1 plays a role in human longevity, Prof Barzilai, Dr Yousin Suh and colleagues looked for variations in the gene within a group of Ashkenazi Jewish centenarians and their children.

The researchers used Ashkenazi individuals with no history of familial longevity, matched for age and sex as controls. Comparing the two groups, the researchers report in the Proceedings of the National Academy of Sciences that centenarians and their offspring were more likely to have a variety of mutations in the IGF-1 receptor which reduced the effects of the factor. As had been shown by the mouse work, the less active IGF-1 pathway had bigger effects on women than men and led to shorter stature.

The work shows that this pathway plays a role in human longevity, which provides new clues as to how to boost lifespan by damping down the action of IGF-1, and other molecules that play a part in this piece of metabolic machinery. "Practically, this discovery supports the notion that growth hormone, which is injected as anti-ageing medicine in the US (and other countries) maybe dangerous, because it is the people who have low growth hormone levels that are living longer," Prof Barzilai tells The Daily Telegraph. "So avoiding growth hormone may increase ones longevity."

The team does not yet know if longevity is assured by having low growth hormone action throughout life, or whether it is enough to have it decreased at a certain age. "The fact is that growth hormone levels and actions are decreased in old age," he adds.

His team has found other longevity genes - notably CETP and APOC3 - that are also under study to see if there is potential to make anti ageing drugs, though it is too early to speculate on when people will benefit from this understanding.


New 'thin pill' could replace surgery

A new generation of diet pills that could achieve the same dramatic weight loss as surgery could be available within a decade. A team at University College London is working towards developing a weight loss pill that makes people feel they are full after eating a small amount of food. The stomach has to expand to digest food, the basic process by which the body harvests calories from meals, but scientists have found a way of stopping this from happening.

The pill could offer an alternative to stomach stapling - gastroplasty - in which a band or surgery is used to reduce the size of the stomach. This can result in weight loss of up to 7st in a year. However, surgery can be risky with one in every 100 patients dying within 12 months. The potential new drug is described in the Journal of Pharmacology and Experimental Therapeutics by Dr Brian King and Dr Andrea Townsend-Nicholson. "It is chemical gastric banding," said Dr Townsend-Nicholson, adding that the pill could be available for use within five to 10 years.

The team found two proteins - P2Y1 and P2Y11 - which are receptors that pick up signals from nerves to control the size of the gut. These were identified in the guinea pig, but are also present in humans. Dr King said: "This would be a brand new approach to weight control." Dr Brian King says: "The mechanisms we have identified are important to the normal workings of the stomach - a hollow organ which actively relaxes to help accommodate the size of your meal.

The human stomach has a 'resting' internal volume of 75 millilitres (one tenth of a pint) but, by relaxing its muscular wall, can expand to an internal volume of two litres (3.5 pints) or more - a 25-fold increase in the volume it can accept. "This expansion is controlled by nerves inside the stomach wall and these release molecules that stimulate the P2Y1 and P2Y11 receptor proteins embedded in muscle cells in the gut wall. The mechanism of this slow relaxation of the stomach might represent a future drug target in the fight to control weight gain and reverse obesity. "We are looking to identify drugs that would block the P2Y11 receptor and, therefore, prevent slow relaxation of the stomach. As a result of blocking the P2Y11-based mechanism, meal size would be smaller, offering the person a better chance of regulating their food intake.

"This would be a brand new approach to weight control. At present, the most successful way to help obese patients lose weight is gastric banding or stomach stapling, both of which reduce the maximum volume of the stomach. "But these are also tricky surgical procedures, not without attendant risks. A pill that could replace this surgery, yet have the same effect, might be a useful alternative."

If the gastric bypass is anything to go by, there may be side effects. In the wake of stomach stapling, high fibre foods and foods with a more dense, natural consistency can become very difficult to eat relative to highly refined foods. There can be vomiting and severe discomfort if food is not properly chewed or if food is eaten too quickly. However, the UCL team believes that any possible side effects of chemical gastric banding are likely to outweigh the adverse health consequences of obesity.

Figures released in January showed that more than one million prescriptions for obesity drugs are now given to patients by GPs.



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].

9). And how odd it is that we never hear of the huge American study which showed that women who eat lots of veggies have an INCREASED risk of stomach cancer? So the official recommendation to eat five lots of veggies every day might just be creating lots of cancer for the future! It's as plausible (i.e. not very) as all the other dietary "wisdom" we read about fat etc.

10). And will "this generation of Western children be the first in history to lead shorter lives than their parents did"? This is another anti-fat scare that emanates from a much-cited editorial in a prominent medical journal that said so. Yet this editorial offered no statistical basis for its opinion -- an opinion that flies directly in the face of the available evidence.

Even statistical correlations far stronger than anything found in medical research may disappear if more data is used. A remarkable example from Sociology:
"The modern literature on hate crimes began with a remarkable 1933 book by Arthur Raper titled The Tragedy of Lynching. Raper assembled data on the number of lynchings each year in the South and on the price of an acre's yield of cotton. He calculated the correlation coefficient between the two series at -0.532. In other words, when the economy was doing well, the number of lynchings was lower.... In 2001, Donald Green, Laurence McFalls, and Jennifer Smith published a paper that demolished the alleged connection between economic conditions and lynchings in Raper's data. Raper had the misfortune of stopping his analysis in 1929. After the Great Depression hit, the price of cotton plummeted and economic conditions deteriorated, yet lynchings continued to fall. The correlation disappeared altogether when more years of data were added."
So we must be sure to base our conclusions on ALL the data. But in medical research, data selectivity and the "overlooking" of discordant research findings is epidemic.

"What we should be doing is monitoring children from birth so we can detect any deviations from the norm at an early stage and action can be taken". Who said that? Joe Stalin? Adolf Hitler? Orwell's "Big Brother"? The Spanish Inquisition? Generalissimo Francisco Franco Bahamonde? None of those. It was Dr Colin Waine, chairman of Britain's National Obesity Forum. What a fine fellow!


No comments: