February 19, 2007

The importance of fat

This is my translation of a commentary by Dr. Ralf Sundberg that appeared in our newspaper, Sydsvenskan, on Saturday February 17.

Recently Nils-Georg Asp, Professor of Industrial Food Science, wrote that it is too early to declare that milk fat is safe. Professor Asp believes that reduced heart-related mortality in recent years is due to reduced fat consumption.

There are other explanations for the trend, for example better heart surgery and heart attack care, but it is a common mistake in research to interpret parallel tendencies as if they were causally connected. How does the professor explain the violent increase in heart disease in the US between 1910 and 1960? During the same period consumption of margarine and vegetable oil increased dramatically, while the American's consumption of pork, eggs and milk products decreased.

And how does the professor explain the epidemic of obesity and diabetes that has arisen in parallel with reduced consumption of fat? Swedes eat less fat than ever but more calories, according to government statistics.

Professor Asp names a few recent studies that show some advantages of milk fat, but advises us not to put too much faith in these recent fashions. Asp's colleague Bengt Vessby at the National Food Agency doesn't even trust himself. He has shown that consumption of milk fat reduces risk factors for heart attacks including abdominal fat, but none of this appears in the Agency's dietary advice for the general public, diabetics or school children.

Neither are the American studies mentioned, studies showing that margarine-eaters have a greater risk of heart attack than those who choose butter. Or that studies of more than 400,000 individuals have shown that milk-drinkers have the lowest heart-related mortality rates.

The idea that saturated fat is dangerous originated with Ancel Keys, an American professor who in 1953 published a study from six countries that showed a correlation between the number of heart attacks and the consumption of fat. However it was revealed in 1957 that Keys had data from six more countries that he choose not to include in the publication because they did not support his conclusion. Pure scientific fraud.

Nobody reacted, but when his results could not be reproduced by other researchers, he chose instead to focus on saturated fats and chose seven new countries. Anyone who has read his study Seven countries will have a difficult time coming to the same conclusion, but the myth concerning the danger of saturated fat has unfortunately taken on a life of its own.

It is claimed that saturated fat increases cholesterol. However there are ten studies that have shown that cholesterol levels are unaffected by a diet that contains less carbohydrates and two to five times more saturated fat than what is recommended by the National Food Agency. Such a diet did however result in a dramatic decrease in triglyceride concentrations, which is another important risk factor.

Further, it is asserted that saturated fat can lead to diabetes. However all studies of diabetics in which the amount of carbohydrates in the diet was reduced and the amount of fat, especially saturated fat, was increased, have found a significant improvement of the condition of the patient.

That dietary fat makes you fat is a myth that has taken on a life of its own. A recent dissertation from the University of Gothenberg showed that four-year-olds who ate the least amount of fat had a higher risk of being overweight and contracting diabetes, while those that ate the most fat were thin and healthy. This may seem like a paradox but is actually completely in line with what biochemistry and physiology know about how the body's metabolism works.

The scientific studies that support the idea that milk fat is healthy are extremely well anchored.


At February 20, 2007 12:32 AM , Anonymous Tim said...

Interesting history re: Ancel Keys. I've never bought into the low fat thing. When I see a food package that says "low-fat" I tend to translate it as "do not eat". I always feel fine after a reasonable amount of fat. Fat free yogurt, though, can send me into a tailspin.

These myths are really entrenched in our thinking, though. Our kids are coming home with ideas about fat already and asking about how much fat is in food.

At February 20, 2007 3:44 PM , Anonymous Anonymous said...

Can Dr. Ralf Sundberg give some examples of peer-reviewed scientific work that recommends a diet high in saturated fat?

At February 23, 2007 2:50 PM , Blogger Matt_J said...

When I read his letter I found more than a few references to scientific studies. The examples exist and he refers to them, but this is of course a letter to the editor and not a scientific paper and so he has not written the specific details. I'm sure you could find them. Have you tried looking up the study he mentions by Bengt Vessby?

At February 24, 2007 8:38 PM , Blogger Matt_J said...

From an article in the New York Times:
Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health...is the de facto spokesman of the longest-running, most comprehensive diet and health studies ever performed, which have already cost upward of $100 million and include data on nearly 300,000 individuals. Those data, says Willett, clearly contradict the low-fat-is-good-health message ''and the idea that all fat is bad for you; the exclusive focus on adverse effects of fat may have contributed to the obesity epidemic.''


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