Wednesday, April 8, 2015

The Nutrition Debate #303: Poor Dr. Walter Willett

The Nutrition Source, not to be confused with The Nutrition Debate (teehee), is the Harvard T. H. Chan School of Public Health’s website. Its aim is “to provide timely information on diet and nutrition for clinicians, allied health professionals, and the public.” I took a poke at their Alternate Healthy Eating Index last year in The Nutrition Debate #229 with “My Alternate Healthy Eating Index.” To their credit, they do bring to the table some gravitas, in my view, because they deign to criticize the USDA’s Dietary Guidelines, as the HSPH’s Alternate Healthy Eating Index amply demonstrates.
Much of that gravitas is attributable to Dr. Walter Willett, Professor of Epidemiology and Nutrition and chairman of the HSPH; he’s also professor of medicine at the Harvard Medical School’s teaching hospital, Brigham and Women’s. Willett is “the principal investigator of the second Nurses' Health Study, a compilation of studies regarding the health of older women and their risk factors for major chronic diseases. He has published more than 1,000 scientific articles regarding various aspects of diet and disease and is the second most cited author in clinical medicine,” according to Wiki.
Staying “King of the Hill” can be a rough game. Ancel Keys, despite numerous attempts to dethrone him, stayed King until long after he was smoldering in the grave. In fact, his ghost still casts a ghoulish pale. And Walter Willett has recently managed to do so too, using the same type of rough play as Keys used. This 2013 piece in Forbes tells the story of how the “Top Science Journal Rebukes Harvard’s Top Nutritionist.” The Nature story and accompanying editorial were both scathing. Willett’s offense was to say on NPR that a research piece in JAMA by Katherine Flegal, that showed people who were overweight (but not obese) lived longer than those deemed normal weight, was “a pile of rubbish, and no one should waste their time reading it.” He then organized a conference at Harvard expressly to discredit the JAMA piece.
More recently, Nina Teicholz, author of “The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet,” wrote a New York Times op-ed, “The Government's Bad Dietary Advice.” In it she says, “…the primary problem is that nutrition policy has long relied on a very weak kind of science: epidemiological, or “observational,” [i.e. “cohort”] studies in which researchers follow large groups of people over many years. But even the most rigorous epidemiological studies suffer from a fundamental limitation. At best, they can only show an association, not causation.”
“Epidemiological studies can be used to suggest hypotheses but not to prove them,” Teicholz said. “Instead of accepting that this evidence was inadequate to give sound advice, strong-willed scientists [ahem] overstated the significance of their studies.” Then, she zeros in: “Much of the epidemiological data underpinning the government’s dietary advice comes from studies run by Harvard’s school of public health.” Teicholz doesn’t pull punches. She also takes a hit at the Guideline’s advice on salt by citing a blistering and “authoritative Institute of Medicine study.” I cite it in #153: “Salt: Friend or Foe.” See also Medscape Medical News Editor-in-Chief Eric Topol’s report in #248, “Salt Warnings: Confusing and Contradictory.”
Now, Dr. Willett has used his quarterly, “Ask the Expert” interview to address the cholesterol issue. (Note: the draft 2015 Dietary Guidelines, for the first time since 1980, states that “cholesterol is not considered a nutrient for overconsumption.”) Largely responding to the Teicholz guest op-ed (that he inexplicably calls the NYT “story” or “article”), Willett says,
“The important point is to have the best possible evidence, and we shouldn’t be basing dietary guidance on just guesses or beliefs. In the case of both the egg issue and the total fat issue we were basically starting with virtually no direct evidence. When the evidence did start to come in – and there were different lines of evidence from our studies based on large cohorts and also short term studies investigating metabolic changes – it showed that people who consume more eggs did not have a higher risk of heart disease even after adjusting for any other factors, and that total fat in the diet was not related to heart disease risk or cancer risk. So it took those long term studies to show that those were not important factors, and that allowed us to modify the recommendations. We were really in a state 35 years ago in which we had very little direct evidence and we were basing guidelines on guesses and indirect evidence from very small, short term studies.”
Mea culpa? Mea culpa!!!!! But I think the best rebuke of Willett is from the Forbes piece. You have to read the story for context, but this sums it up well. This is “piling on,” of course, but sometimes that’s the best way with King of the Hill.

“Science is complex, and Willett’s message to his fellow scientists appears to be that the public can’t be trusted with this complexity (except, as noted, when it might be something that he thinks is worthy of research); the question, which the public might ask in turn, is whether Willett can be trusted with complexity given his apparent intolerance for it in other scientists?”

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