The PURE Study May Not Be So Pure: An Analysis Using the Method Nina Teicholz Applied to “What the Health”
All is fair in love and war but it seems that nothing is fair in the battle for the public mind, belly and budget when it comes to nutrition advice. Sadly, the unifying messages of groups like the True Health Initiative are lost in cries of more fats, less carbs, Paleo, Vegan and such. We know how to eat but in a world of 6 seconds headlines, Twitter, and multi-million dollar book sales, there is no peace.
Yesterday the headlines worldwide erupted with the news that carbs, not fats, were to blame for the excess of chronic diseases and deaths due to lifestyle factors. It is as if the media were ready and had their interviews set to go even before the presentation at the European Society of Cardiology in Barcelona and the simultaneous publication of the full data in The Lancet. The warriors had their spears sharpened.
The 3 reports of the PURE study are dense. Fortunately, experts are weighing in on the statistical findings, study design, strengths and major weakness. I recommend them as important but difficult reading.
At a higher plane, perhaps the PURE study should be disregarded without even reading it in detail. Why? If all is fair in love and war, this would be the reciprocal response to the biting review of the recent viral documentary What the Health authored by Nina Teicholz and widely reproduced over media outlets. Ms. Teicholz analyzed the claims made in that movie, a film that is motivating thousands if not millions of people to eat more fruits and vegetables and less dairy and meats. She introduced her analysis with comments on the science presented in the movie. Those comments would appear to pertain to the PURE study as well as PURE data was based on a single food frequency questionnaire obtained to describe the diet of individuals over more than 7 years. In a matter of tit for tat, her criticisms about the type of science presented in What the Health were:
1. The extreme unreliability of food frequency questionnaires
2. The impossibility of fully adjusting for confounding variables.
3. Epidemiologists cross-calculating hundreds of food and lifestyle variables against death rates from different ailments, resulting in a huge number of associations. Just as a matter of probability, some of the positive results will be spurious.
4. Scientists in most fields (except nutrition) agree that small associations — with “risk ratios” of less than 2 — are not reliable.
These 4 points she made were offered to invalidate the health claims of What the Health. They seem equally appropriate for an interpretation of the PURE study wherein all of the risk ratios in Table 2 of the paper on macronutrients and outcomes were <2.
Ms. Teicholz went on to invalidate 31 medical statements in the documentary as being offered by vegan doctors or proponents of a vegan menu such as myself along with Drs. Neal Barnard, Garth Davis, and Michael Greger. Although I would argue that one can choose to eat a diet free of animal products for reasons of personal health, animal rights, and environmental concerns while still being able to be objective about the larger body of health related medical research (e.g. if bacon were ever shown to reverse heart plaque I would inform my patients of the finding), she considered all statements made by vegans to be a “red” level finding that excluded them from being used to support the movie’s findings.
So what then of Dr. Salim Yusuf, the 2nd most quoted cardiovascular researcher in the world and senior author of the PURE studies? As I have written before, twice this year in public presentations that were videotaped and distributed worldwide, Dr. Yusuf indicated that in his opinion a deceased senior nutrition researcher Ancel Keys Ph.D. published research that was “fudged” (while offering no proof of that serious claim as there is no proof), and Dr. Yusuf praised the book written by Ms. Teicholz purporting that butter, meat and cheese belong in a healthy diet. These videos have been permanently removed but his bias was extreme and would seem to invalidate his ability to offer research that could be considered credible by the “Teicholz criteria”.
Overall, the PURE studies will continue to be analyzed, discussed and debated, hopefully in a civil manner. The Teicholz criteria, fairly applied to the new data from the PURE study of macronutrients, suggest that this new study has “scary images, compelling language, and the illusion of certainty and data, when in fact, there is none” (words used by Teicholz to slice and dice What the Health). In fact, it is likely that overall the PURE study does provide valid data about the harms of refined grains and added sugars (junk carbs) while supporting the health benefits of replacing animal saturated fats with PUFAs. I hope one day soon we can co-exist in a peaceful manner at the table and on the dinner plate honoring dietary patterns known to favor optimal health.