Once again experts are passionately disagreeing about the proper role of saturated fats and carbohydrates in the diet. The latest volley comes from a full-scale critique published in the BMJ of proposed new US dietary guidelines.
The author of the critique, Nina Teicholz, is the author of The Big Fat Surprise: Why Butter, Meat, & Cheese Belong in a Healthy Diet. In both the book and the BMJ article Teicholz maintains that the evidence against saturated fat and low carb diets is weak. The new guidelines, Teicholz claims, fail to fix old mistakes.
“Given the growing toll taken by these conditions and the failure of existing strategies to make meaningful progress in fighting obesity and diabetes to date, one might expect the guideline committee to welcome any new, promising dietary strategies,” said Teicholz, in a BMJ press release. Yet the committee largely sticks to the same advice it has given for decades – to eat less saturated fat (in meat and full-fat dairy products) and more plant foods for good health, she claims.
There’s an excellent summary of the article and the controversy in MedPage Today. Parker Brown interviews two experts, Marion Nestle and David Katz, who strongly defend the guidelines. I had previously asked several experts to comment on the study and ended up receiving responses from two, both of whom take the opposite position and are critical of the guidelines.
Arne Astrup (University of Copenhagen) wrote that “the committee seems to be completely dissociated from the top level scientific community, and unaware of the most updated evidence. There are now several new meta-analysis of both observational studies and also of randomized controlled trials clearly showing that there is no benefit of reducing saturated fat in the diet. All analyses and research can be criticized, but these meta-analyses have been published in leading scientific journals typically after critical reviews by 3-5 independent scientists (including a statistician), and by expert editors, so they cannot and should not be dismissed so easily.”
Equally important, writes Astrup, is “that the scientific studies that were the basis for the ‘cut down on saturated fat’ recommendations have been re-evaluated, and it is quite clear that today we would have concluded that there is no robust evidence to substantiate the advice.”
“The same,” he continues, “applies to the importance of carbohydrate amount and source. Reducing total carbs or selecting the low glycemic index carbohydrates are well documented tools to produce weight loss and treat type 2 diabetes, and there is quite good evidence for efficacy and safety.”
James DiNicolantonio (Saint Luke’s Mid America Heart Institute) wrote that “first and foremost, we shouldn’t be focusing on specific nutrients, we should be focusing on food. People eat food, not isolated food components (e.g., saturated fat), so telling them to restrict saturated fat to < 10% doesn’t tell them what they should/should not be eating. That’s probably the biggest problem with our Dietary Guidelines today.”
“The second problem is that when you demonize one nutrient (saturated fat), you end up replacing it with something else, and we know when fat was replaced with refined carbs/added sugars in the 80s and 90s, larger waistlines and more diabetes was the result for Americans.”
“Problem three is that there was never any evidence to demonize saturated fat per se back in 1977 in the original Dietary Goals…”
DiNicolantonio was also highly critical of the committee’s selective use of evidence to support the preferential use of polyunsaturated fats instead of saturated fats.
“What our dietary guidelines should be saying,” wrote DiNicolantonio, “is ‘eat real food as close to nature intended as possible’. Meaning we should be eating foods that are naturally available, not processed in an industrial factory.