Sunday, April 22, 2007

The anti-salt war jerks back into life

Another over-hyped finding of tiny differences -- and this time the differences are not even statistically significant. The article below appears to be a rewrite of a BMJ press release but at the time of writing this I could find no trace of the article in the current issue of BMJ -- which suggests extraordinary eagerness to publicize findings that are yet to be put up for detailed scrutiny -- not unexpected in the heavily politicized BMJ.

But working from the figures below we find that there were only 25 deaths out of a sample size totalling 769 and only a 25% difference between the two subgoups. Reconstructing from that information, it seems that around 10 controls died of heart attacks and 15 salt-eaters died of heart attacks. Given the differing subgroup sizes of 337 and 432, the expected frequencies would be 11 and 14 -- yielding a Chi-squared of 1.00! -- which is nowhere near statistical significance.

Note also that the findings concern hypertensives only. Among people in general those on salt-restricted diets die SOONER. And the Japanese eat heaps of salt -- soy sauce is VERY salty -- yet have exceptionally long lifespans. This is really crazy stuff below but the fact that it appeared in "The Times" of London will make it very influential nonetheless

Eating less salt reduces the chances of suffering a heart attack or stroke, the first long-term study of salt's impact on health confirms today. The findings, from a 15-year study, offer the clearest evidence yet that cutting salt consumption saves lives by reducing the risks of cardiovascular disease. People who ate less salty food were found to have a 25 per cent lower risk of cardiac arrest or stroke, and a 20 per cent lower risk of premature death. The results, published in the British Medical Journal, underline the need for population-wide salt reductions in the diet, the scientists conclude.

Despite campaigns to reduce salt intake, such as that run by the Food Standards Agency (FSA), actual evidence of any benefit has been limited. This has enabled the salt industry to contest vigorously the value of such campaigns. Both sides accept that cutting salt consumption reduces blood pressure, although not very dramatically. This ought to translate over the longer term into reductions in strokes and heart attacks, but no studies have been able to show this convincingly until now.

The new findings are the result of work by a US team led by Nancy Cook, of Harvard Medical School, which has followed up two trials originally conducted in the late 1980s and early 1990s. Both were designed to persuade people to cut their salt intake and to measure how far their blood pressure fell. By pursuing these trials, Dr Cook's team has shown that those who reduced their salt intake did have a lower risk of heart disease and stroke. "Our study provides unique evidence that sodium reduction might prevent cardiovascular disease and should dispel any residual concern that sodium reduction might be harmful," it concludes. The interventions had reduced sodium intake by about 25-35 per cent - roughly the same as is planned by the FSA, which is seeking to reduce daily intake in Britain from an average of 9.5g to 6g ( /3 oz to /5 oz) a day.

Ellen Mason, cardiac nurse at the British Heart Foundation, said: "Salt intake amongst many adults and children in Britain is way too high. Many people could lower the level of salt in their diet by reducing the amount of processed food they eat. Also, by simply checking the labels and switching to a lower salt option, you'll be doing your heart a favour."

But the Salt Manufacturers' Association questioned the quality and conclusions of the study. "The research only relates to subjects who already have high blood pressure. Most people have acknowledged for some time that such individuals may be advised to restrict their salt intake with their GP's advice. "What the evidence does not prove is that salt reduction will have any significant health benefits for the majority of us."

The original studies - called the trials of hypertension prevention (TOHP 1 and 2) - used counselling and advice to persuade participants to reduce intake. In the first trial, 327 healthy men and women aged 30-54 who took part in the intervention were compared with 417 controls who did not. Measurements of sodium in urine showed that a reduction of roughly one third in salt intake had been achieved in the 327 who took part- but blood pressure was found to fall only slightly.

The authors of the original study had no idea if this reduction would be sustained, but estimated that if it were it might reduce stroke deaths by 6 per cent, heart disease deaths by 4 per cent, and deaths from all causes by 3 per cent. However, the follow-up has shown much more marked health benefits. The actual numbers of heart attacks and strokes are small - 76 heart attacks, 19 strokes and 23 heart deaths without previous warning - in both TOPH 1 and 2. So it remains possible that chance, or incomplete follow-up, have distorted the findings.

Graham MacGregor, a professor at St George's University of London, said the size of the benefit was not surprising. "When there was a campaign in Finland to cut salt there was a very large reduction in stroke and heart attacks."

Exactly how salt increases blood pressure is still in dispute. The simplest explanation is that when salt intake is too high, the kidneys cannot pass it all into the urine and some ends up in the bloodstream. This then draws more water into the blood, increasing volume and pressure. But not everybody is equally sensitive to salt, and so not everybody will benefit equally from reducing intake.



Though anybody who knows of their absurd "600,000 Iraqi deaths" claim will not be surprised. The BMJ has also of course long been known for its frantic Leftism. This politicization does of course explain the very low intellectual standards in both journals that I have repeatedly noted on this blog. With their openly avowed contempt for the truth ("There is no such thing as right and wrong") and their failure to consider ALL the facts of most matters, Leftists corrupt everything they touch

A leading international medical journal has denounced the Prime Minister and urged its Australian readers to vote against him in the election. In an editorial titled "Australia: the politics of fear and neglect", The Lancet said John Howard had jeopardised Australia's enviable reputation in medical science with his suggested ban on HIV-positive migrants. It also censured the Health Minister, Tony Abbott, for saying those who spoke up for indigenous health were "simply establishing politically and morally correct credentials", and criticised the Environment Minister, Malcolm Turnbull, for his stance on climate change. It said Australian politicians were scoring below par on health.

The journal said Australian clinical and health research was "an emblem of excellence" in the Asia-Pacific: "That enviable position is being put at risk by Prime Minister John Howard's indifference to the academic medical community and his profound intolerance to those less secure than himself and his administration."

The latest example was his comment last week that HIV migrants should not be allowed, says the journal, whose editor, Dr Richard Horton, spoke at a conference on global health in Sydney this month. "To any visitor, Australian culture feels progressive and inclusive," The Lancet says. "This attractive exterior belies a strong undercurrent of political conservatism, which Howard is ruthlessly tapping into." The Lancet has a significant readership throughout the world and regularly takes a stand on key medical issues.



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.