American Society For Nutrition

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“MADE WITH NO TRANS FAT”

Though I found the subtle application of a health claim to a deep fried Snickers bar amusing, the little yellow sign raised an interesting point. Candy bar innards notwithstanding, if we believe recent high profile epidemiological evidence (eg, Jakobsen et al), then the plant oils used to fry this puppy really might be good for me.

Now hold on, simmer down and step back down off those soap boxes. I am NOT actually suggesting a deep fried Snickers bar is health food. On questioning my nutritional conscience, “What would Walter Willett do?” (WWWWD for short, unless you pronounce ‘double u' four times, then it's actually longer…) I was promptly forced to acknowledge there were other problems with this fair fare.

All that aside, let's focus on the fat.

The tide of public health messaging is shifting from “fat = bad,” to, “saturated & trans fat = bad; unsaturated fat = good” Part of this counter-current has been criticism of some of Ancel Keys' early research. The argument usually goes something like this: Keys showed fat intakes strongly predict cardiovascular death rates in several countries. Data for other countries were available, but left out. If we add data for these countries, the trend is softened. In short, Keys “cherry picked” his countries.

After reading what Keys said about his own data, this is how I think he might respond: Adding more countries brings in different economies, medical establishments and leading causes of death. Fat intakes are high and cardiovascular deaths low in several regions where infectious diseases were primary causes of death, but to include these would be irresponsible epidemiology. Keys hand picked his countries for a fair comparison.

I was surprised that even 60 years ago Keys was teaching that polyunsaturated fat decreased serum cholesterol, that dietary cholesterol had very little effect on serum cholesterol and that the human-equivalent dose of dietary cholesterol inducing atherosclerosis in rabbits was far above what may be reasonably consumed by free living individuals. Some of these were concepts I had been given to understand were correct, but only recently resolved.

I cite here only one Keys review paper, a quick read for anyone interested in what he did and did not preach. The paper embodies what I believe was his core message: cut superfluous added fats out of the diet, but keep nutritious fats as part of a varied diet.

Whether we should target fats globally, of course, is  a debate in progress, and requires sorting out fat's influences on the related but not identical issues of obesity and cardiovascular risk. In the meantime, I'll try to keep the deep fried candy bars down to once a year.

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