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28 April 08
re: more about healthy fats |
| chox: |
| Thanks for the info on healthy fats but I have more questions. |
| Why do weight management programs emphasize fat reduction? |
| m-c: |
| It generally takes at least 20 years for new scientific findings to trickle down to the level where everyday experts like nutritionists and dieticians and health magazines and personal trainers and newspapers incorporate the new message into their practice and the advice they offer. |
| People at that level aren't reading primary documents; they don't subscribe to the New England Journal of Medicine or the American Journal of Epidemiology or the American Society for Nutrition journal. They're reading each other's stuff, so the old message gets reiterated and reiterated until gradually the avant-garde among them start to get the word and then that group changes from the old story to the new one, and then gradually, gradually, the message starts to make its way into the mainstream. |
| Meanwhile, of course, at the primary level the scientists are doing more research, which may refine the message they put out before or contradict it. Science doesn't advance in a nice neat line, every step forward. It's hard to design good experiments in an area like nutrition, and most of the time the people who are good at experimental design are not good at making their results accessible. |
| Walter Willett is an exception to that rule. |
| chox: |
| I noticed that he was the author or co-author of all three passages you quoted in your earlier piece. |
| That seemed suspicious to me. |
| m-c: |
| There are lots of nutrition scientists and lots of lively writers who interpret nutrition science for the public, but Walter Willett is both. |
| He's the Fredrick John Stare Professor of Epidemiology and Nutrition in the Department of Nutrition and Epidemiology at Harvard School of Public Health, and is a Professor of Medicine at Harvard Medical School. |
| Most people in such positions rely on science journalists and educators to interpret their results to the general public. Willett felt that way of working was too slow; the findings of the second Nurses' Health Study, for which he is the principal investigator, had immediate implications for what people should be eating today, not twenty years from today. He's turned himself (and a number of his colleagues at Harvard) into a crusader for evidence-based nutritional advice. The first book came out in 2001, so we now know that 7 years is not enough to turn people's thinking around, but we can hope for less than 20. |
| I feel fortunate that I ran across the magazine article in Scientific American, which I don't read regularly. If I hadn't, I'd still be shunning fat in all its forms. |
| chox: |
| OK, one more question. What about butter? Is it monounsaturated? Polyunsaturated? Neither? |
| m-c: |
| You're kidding, right? |
According to the
US Department of Agriculture database
(on which all other nutritional information
is based), butter is roughly
|
| It's a treat food, not an everyday food. Olive oil is an everyday food. |
| If you'd like to see the USDA information set out in a much more entertaining way, take a look at how www.nutritiondata.com lays out the same facts about butter. Unfortunately, while the info is more entertaining, it's harder to interpret. 117 grams of saturated fat out of a serving of 227 grams is indeed the same 51% saturated fat as above, but how many people can calculate that in a flash? (Or, indeed, ever?) |
| Another way to approach this whole question is to go the Michael Pollan route and stop thinking of food as this nutritional bit and that nutritional bit. We don't know enough at this stage to separate food into its nutritional components. Even Walt Willett doesn't know enough. Pollan says, "Eat food. Mostly plants. Not too much." Words to live by, but remember, he's a journalist, however good; he's not a scientist. |
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