Friday, July 20, 2007

Vitamin C myth blasted

The idea that vitamin C supplements can ward off colds is a myth, a major review of the evidence has concluded. The analysis of data from 30 studies involving more than 11,000 people found no evidence that high doses of the vitamin have any effect against colds for the average person.

The research, conducted by Australian and Finnish scientists, found that extra vitamin C is beneficial only for people under extreme physical stress, such as marathon runners and soldiers, who are 50 per cent less likely to catch a cold if they take daily supplements. For people living ordinary lives, any benefits conferred by vitamin C are so small that they would not be worth the effort or expense, the researchers said. Professor Harri Hemil„, of the University of Helsinki, who led the meta-analysis, said: "It doesn't make sense to take vitamin C 365 days a year to lessen the chance of a cold."

The analysis appears in the latest issue of The Cochrane Library, published by the research organisation, the Cochrane Collaboration, an international organisation that evaluates medical research. Scientists pooled information from studies, spanning several decades, that looked at the effect of taking daily supplements of at least 200 milligrams of vitamin C.

The belief that vitamin C can prevent or treat the common cold was championed in the 1970s by the Nobel prize-winning chemist Linus Pauling, who encouraged people to take 1,000 milligrams of the vitamin daily. This is more than 17 times the recommended daily amount of 60 milligrams, which can be obtained from a single glass of orange juice.


Veggies won't cure your cancer

But that is such a heresy that the researchers don't want to believe their own results

Eating very large amounts of fruit and vegetables does not improve the survival chances of women with breast cancer, scientists have found. A study of more than 3,000 women who had been treated for the disease showed that boosting fruit and vegetable consumption way beyond normal guidelines did not help them to live longer. Women who obeyed the super-strict eating rules imposed by scientists over seven years were just as likely to die or suffer a recurrence of breast cancer as those on a healthy "five-a-day" diet. In about 17 per cent of cases in both groups the cancer returned and 10 per cent of the women died.

Half the patients were placed on a low-fat diet which included five servings of fruit and vegetables a day. The other half were asked to make enormous changes to their diet. As well as limiting the fat they consumed to no more than 20 per cent of total calories, they were expected to eat five servings of vegetables, plus 470 millilitres of vegetable juice, three servings of fruit and 30 grams of fibre a day.

Many women in the intervention group found the regime tough - but after four years they were consuming on average 65 per cent more vegetables, 25 per cent more fruit, 30 per cent more fibre and 13 per cent less fat than their colleagues on the easier "control" diet.

However, the results published in the Journal of the American Medical Association showed that all the extra effort was in vain. Professor Marcia Stefanick, from Stanford University School of Medicine in California, who led the Women's Healthy Eating and Living (WHEL) study, said: "I was really surprised and, frankly, a little disappointed by the results. We expected the twofold increase in vegetables and fruits, plus the increased fibre and reduced fat, to make a difference in the recurrence rates."

However, she pointed out that rates for the recurrence of breast cancer in the control group were much lower than expected. At the start, the researchers had anticipated that 30 per cent of the "five-a-day" dieters would suffer a relapse. She said many of the women had already adopted a healthier diet than the average American. "I would certainly hope that people don't interpret these results as evidence that eating a lot of vegetables doesn't make a difference in breast cancer," she said. "What it shows is that getting more than the recommended amounts doesn't change the recurrence rate for women who have already had treatment for early-stage breast cancer."

Previous animal studies have shown that plant-derived foods contain anticancer agents. Research also suggests that high-fat diets might be linked to increased cancer risk.

The WHEL study was the largest trial ever undertaken to assess how diet affects breast cancer recurrence. Co-researcher Dr Cheryl Rock, from the John Moores Cancer Centre at the University of California, San Diego, said: "We recognise that several other studies have shown clearly that eating more than five fruits and vegetables a day can make major differences in disease risk, such as in lowering blood pressure and reducing risk of stroke and heart disease." Liz Baker, science information officer at Cancer Research UK, said: "This study certainly doesn't mean that women who have had breast cancer should stop eating fruit and veg."



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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