Thursday, April 3, 2014

Some personal thoughts on the demonization of saturated fat

If I were to step outside AOCS headquarters here in Urbana, Illinois, USA, and ask the next 20 persons I encountered to give me one word to describe saturated fat, I would wager that at least 19 of the 20 would use some variant of the word “bad.” Seldom has received wisdom – knowledge that people generally believe is true but often is not – been so close to unanimous on any facet of nutrition as is the case with the idea that “saturated fat is bad for you.” (A close second would be the blind acceptance of the cholesterol/lipid hypothesis and, third, that dietary fat in general is suspect . . . even the so-called “good fats.”)

How saturated fat became so universally feared is a long and complicated story that is part politics, part US dietary policy based on preliminary findings, and part bad science. At the root, however, is what I find to be a false premise – the idea that the immensely complicated human metabolic system (that is still further complicated by variations among individuals) can be reduced to its individual working parts and that scientific research can tease out truths about what is “good” and what is “bad” in dietary terms. A corollary to this premise is that the effect of a whole food is merely the sum of its individual components; there is no synergistic (or, alternatively, antagonistic) relationship among all the individual components (and an individual’s personal biology and microbiome).

If you are interested in an alternative view of saturated fat, then by all means read articles and/or books by the noted science writer Gary P. Taubes. His 2002 article for The New York Times, “What If It’s All Been a Big, Fat Lie?,” was one of the first widely disseminated salvos in the war to reclaim an honorable position for dietary fat in general and saturated fat in particular.

A new book by investigative journalist Nina Teicholz, The Big Fat Surprise, will be released on May 13 by Simon & Shuster. Teicholz says the book, which I have yet to read, “traces the origins of the bias against saturated fats and how overzealous researchers – through a combination of ego, bias, and premature institutional consensus – have allowed dangerous misrepresentations to become dietary dogma.”

Michael Pollan, an award-winning author and journalism teacher at the University of California, Berkeley, has written extensively about “nutritionism” and the damage done by a reductive approach to food and eating. (Remember the “French paradox” wherein scientists puzzle over the fact that the French – a culture well known for indulging in long, leisurely, and often fat- and cholesterol-laden meals – have a low incidence of heart disease?) To reductionism can be added the difficulty of accurately assessing an individual’s diet over time outside of a research setting where intake is strictly controlled. (If you have ever taken a food frequency questionnaire, then you know just how flawed those instruments are.) Why not toss another log on the fire and raise the problems inherent with meta-analyses (the grouping together and analysis of data from a number of studies) as well as the limitations of observational studies (research wherein groups of people are observed and outcomes are noted minus intervention by the researchers)? A point that the popular press and lay public often forget about observational studies is that they are not randomized and cannot point to cause and effect.

So, where are we today, on the first day of April 2014, as I write this blog post? Official dietary guidelines such as the Dietary Guidelines for Americans 2010 (PDF) continue to call for reduced consumption: “Consume less than 10% of calories from saturated fatty acids by replacing them with monounsaturated and polyunsaturated fatty acids.” Most if not all diabetes groups advise against consumption of saturated fat despite the wealth of research showing benefit to both serum glucose and triglyceride levels as well as lipid profiles for diabetics on ketogenic (fat-burning) diets that include copious amounts of saturated fat.

The latest in a continuing series of epidemiological meta-analyses finding no association between ingestion of saturated fat and coronary heart disease (CHD) was released on March 17, 2014, and the popular press has had a grand time acting as if this were a new finding. (See the June 2009 issue of Inform (PDF) , the American Journal of Clinical Nutrition, or the British Medical Journal for proof that it is not a new idea.) However, having observed the fats and oils scene now for almost 15 years as associate editor of Inform, I think the current media brouhaha may signal that we are at a tipping point. Indeed, it is possible that we are witnessing the beginning of the end of the dogmatic demonization of saturated fat.

The new study in the Annals of Internal Medicine went beyond previous meta-analyses that found no association between dietary saturated fat and incidence of CHD or stroke. It also questioned whether polyunsaturated oils from plants and fish are inherently more healthful than saturated fats from animal or dairy sources. “Current evidence does not clearly support guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats,” the authors write.

Critics quickly pointed out errors in the data and data collection; some called for the paper’s retraction. After the study’s authors corrected those errors, lead author Rajiv Chowdhury of the University of Cambridge in the UK told Science Magazine that he feels the paper’s conclusions are valid even after the corrections.

So, what is a person concerned about things dietary to do? Here are my thoughts . . . not that anyone has asked for them. To be clear: I speak only for myself and not for AOCS. First off, I would suggest being less concerned about each bite of food, because a puritanical focus on “good” and “bad” foods sucks all the pleasure out of what should be a communal celebration of life (taking us back to the French paradox). Assuming you are eating plenty of fresh fruits, vegetables, and other foods that spent some time in the sun (including meat from grass-fed animals and fatty coldwater fish, if you are so inclined and able to afford them), you are likely to do well by yourself. (Michael Pollan’s pithy aphorism comes to mind: “Eat food. Not too much. Mainly plants.”)

Beyond that, here’s a thought: Don’t monitor reporting by the popular press on nutrition, which seldom puts incremental findings in context. Either read the papers yourself, which is why we have provided links in this post, or follow Ralph Waldo Emerson’s famous advice: “Moderation in all things, especially moderation.”

Catherine Watkins, Inform associate editor

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