Thursday, September 21, 2006

Omega 3, probiotic and vitamin myths

Ever since Cleopatra bathed in milk to keep her skin radiant, people have sought short cuts to health and beauty. Alchemists chased the elixir of immortality, snake-oil salesmen touted dubious concoctions claimed to cure, as one brand had it, "all painful complaints and weaknesses". (It turned out to be 20% pure alcohol.). Government regulation of medicines and food stopped the more outlandish claims, but now a new phenomenon has emerged: the collision of science and nutrition.

Consumers have grown more health-conscious just as researchers are discovering more about how nutrients work. It has enabled the makers of smart foods, health supplements and other "nutraceuticals" to promote claims based on what, to consumers, may appear to be sound scientific grounds. Take fish oils. Scientists agree that omega-3 fatty acids known as DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are important constituents of our brains. The body cannot make the substances, so they are absorbed from food such as fish, nuts, seeds and to a lesser extent certain vegetables. Food manufacturers have latched onto this and started adding omega-3 to their products, as well as selling supplements. St Ivel, a large manufacturer, promotes milk with added omega-3 as "Clever Milk"...

But for the average child with a varied diet does extra omega-3 have any benefit? Last week an expert at a British Nutrition Foundation (BNF) conference in London said the science did not justify such hype. Professor Peter Rogers of Bristol University presented a review of studies into fish oils and behaviour. He concluded that there is no firm evidence that omega-3 improves cognitive function or mood. "A few years ago I was enthusiastic about this area because I thought it was very plausible that fatty acids could improve mood and cognitive function," he said. "But we haven't found striking effects in studies. Some research has shown benefits, but other studies have failed to find those effects. "We have to look at the totality, not cherry-pick - and more research needs to be done."

The Food Standards Agency agrees. "There is no clear evidence that increased intakes of omega-3 fatty acids improve cognition for the majority of children or adults," it says.

Other scientists believe that such fatty acids will eventually be shown to be beneficial in many ways, for the elderly as well as the young. A trial is now under way, for example, to study the effect of fish oils on Alzheimer's disease. But even these optimists have warnings about supplements. "The labelling is rubbish," said Dr Ann Walker, an expert in human nutrition at Reading University, who regards fish oils as potentially very beneficial - at the right dosage. "Many say `one a day', or something like that. But there's a huge difference between a capsule and a spoonful. You have to look at the actual quantities of EPA and DHA and do your own calculations." Two portions of oily fish a week - as the government recommends - equates to about 500mg of omega-3 a day.

Nor are all fatty acids free from risk. Oily fish can be contaminated with pollutants such as heavy metals. Omega-6, found in sunflower oil, is also an essential fatty acid, yet in large quantities it can cause inflammation.

What about probiotics? Supermarket shelves are now infested with yoghurts, drinks and other concoctions that claim to provide bacteria that promote good health. They are supposed to counter harmful bacteria, especially in the gut. But Professor Glenn Gibson, another expert at Reading University's renowned Food Biosciences department, recently reported that many probiotic products were useless. "They've got the wrong bacteria or the wrong numbers," he said. To be effective, he said, products had to have lactobacilli or bifidobacteria in minimum quantities of 10m per bottle.

Laboratory studies have also shown that the bacteria in some probiotic products are destroyed by the digestive system before they reach the part of the gut where they can take effect. Again, there's no clear benefit, let alone a panacea. Claire Williamson, a scientist at the BNF, said: "Not all products are effective, though my understanding is that in some the bacteria do survive the digestive system - and there are thought to be some health benefits. But that's not to say you're going to be dancing in the street or living another 20 years." ...

What about vitamins? Surely vitamin supplements are a no-brainer? But it's not that simple, said Williamson. Not all vitamins are well absorbed if taken as supplements. Nor may they be the ingredients that make fruit and vegetables so healthy for us. Trials with vitamin supplements have failed to show the same positive health effects as studies of fruit and vegetable consumption. This is probably because other compounds in foods, known as phytochemicals, play an important part in promoting good health. "It shows that it's hard to replace the benefits from food with supplements," said Williamson.

Phytochemicals include substances called polyphenols which are found in green tea and red wine. They may account for the reputation green tea and red wine (in moderation) now enjoy for preventing certain diseases. But these are no miracle elixirs either: polyphenols are also found, albeit at lower quantities, in ordinary English breakfast tea...

It's also difficult and time-consuming to follow all the twists and turns of health claims. Judith Wills, author of The Food Bible and other books on nutrition, said: "People must go barmy when they try to understand what is going on. They see all these claims but don't realise all the ins and outs. They see a big headline, but it's based on just one small study - and the next week there will be another study saying something completely different."

Consumers also have to contend with the law of unintended consequences. A recommendation for healthy action in one direction may turn out to be bad in another, unexpected way. "There's now a big debate on vitamin D, which is important against cancer," said Walker. "One group are saying you mustn't go in the sun because of the risk of skin cancer; but another is saying you need sunlight to make vitamin D to prevent other cancers. "We could be doing more harm than good by avoiding the sun."

Where does this leave parents and other consumers? Wills recommends a diet of healthy scepticism about fads and panaceas. Vitamins may be worth it if your food is dominated by processed junk; and the very young or elderly may benefit from fish oils, though there's no guarantee. But the best option, say most experts, is a good, varied, natural diet. And a cup of tea, green or otherwise, while you ponder reports of the next miracle cure.

More here

Fat switch dangerous

After a spate of bad publicity, large manufacturers of food are quietly dumping trans fats from their products, even at the cost of increasing saturated fats, which Federal Government policy regards as more dangerous. The food companies, including McDonald's, are reacting to increasing overseas evidence that there is no safe level of trans fat consumption. But Food Standards Australia New Zealand says saturated fats here are at a more dangerously high level of consumption than trans fats. While it is mandatory for manufacturers to list on the label the saturated fat content, the labelling of trans fat content is only needed if the product makes a nutritional claim, such as being low in fat or cholesterol.

McDonald's confirmed yesterday that it would switch from a partly hydrogenated canola oil to a blend significantly lower in trans fatty acids but only fractionally lower in saturated fat. And Ferrero, the maker of Nutella - which was singled out by Choice magazine last year for its high trans fat content - confirmed it had recently switched from vegetable oil to palm oil, thereby reducing trans fat content from 4 per cent to less than 0.1 per cent. But the new recipe raises the level of saturated fat from 6 per cent to 10 per cent.

A recent report by the Harvard School of Public Health found that at a conservative estimate replacing partially hydrogenated fat (trans fat) in the US diet with natural unhydrogenated vegetable oils would prevent between 30,000 and 100,0000 premature coronary deaths a year.

The moves by McDonald's and Ferrero contrast with the stance by Food Standards. Under instruction from the Federal Government, that stance is now being reviewed, but a report is not expected until early next year. At a forum on trans fats in state Parliament on Monday, the Greens spokesman John Kaye said that based on the Harvard study's figures, between 1000 and 3400 Australians would die of trans fat-related premature coronary heart disease while the Government waited for its report to be completed. Countries such as Denmark, the US and Canada had already legislated to ban or order the labelling of trans fat content, Dr Kaye said, and companies such as McDonald's and Ferrero could see the writing on the wall. "While maintaining a brave public face that everything is fine, some of the big operators are scurrying around reducing the trans fat content in their products," he said. "But FSANZ and the ministerial council are being left behind. They are waiting around until next year to complete a study of what Australians eat."

The parliamentary secretary to the federal Minister for Health, Christopher Pyne, who heads the ministerial council, said he expected to view the preliminary results of the study when the council met late next month, "but I won't respond to every wild claim by the Greens. A lot of people will die in the next six months for a whole host of reasons." Mr Pyne said the council would decide whether to ban trans fat as Denmark had, introduce mandatory labelling as the US had, or do nothing. The decision would be based on Food Standards' findings.

Source. See here for the other side of the trans fat story.


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.


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