Anyone who follows the U.S. nutritional guidelines has almost certainly been frustrated at some point or another by the conflicting advice and sometimes hopelessly outdated marketing material – think the Food Pyramid that still graces the walls of many elementary school classrooms.
The frustration has reached the point that cries of government corruption and inappropriate influence of big food industry lobbyists are frequently heard. Case in point, the February 2015 draft of the U.S. Dietary Guidelines,1 published every five years, prompted over 29,000 public comments compared to a couple thousand in 2010. The outcry has been so strong it has led to a Congressional review to start in October.
And just last week journalist Nina Teicholz published a scathing review of the guidelines in the high impact factor journal BMJ.2
Teicholz accused the Dietary Guidelines Advisory Committee (DGAC) of not listing their conflicts of interest, of using reviews from industry influenced professional associations, and of overall “weak scientific standards.” Which is scary considering the importance of the 2015 Dietary Guidelines can’t be understated.
According to Teicholz, “the guidelines have a big influence on diet in the U.S., determining nutrition education, food labeling, government research priorities at the National Institutes of Health (NIH) and public feeding programs.”
So what did the Committee recommend? The overall body of evidence examined by the 2015 DAC identifies that a healthy dietary pattern is higher in vegetables, fruits, whole grains, low- or non-fat dairy, seafood, legumes, and nuts; moderate in alcohol (among adults); lower in red and processed meats; and low in sugar-sweetened foods and drinks and refined grains.
Certainly not a win for the Paleo community, but also not anything we haven’t heard from these agencies for a long time.
Dr Barbara Millen, the Chair of the Committee, published an immediate response in BMJ claiming that “the procedures used to develop the DGAC scientific report are expansive, transparent, and thoughtful, with multiple opportunities for public input.”1
Millen pointed out that the committee was nominated by their peers and rigorously reviewed. She even fired back at Teicholz saying that she was just one individual with a clear bias herself having written the book The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet.
The biggest point of contention, however, was the methods for selecting the research the recommendations were based on.
In 2010, the US Department of Agriculture established the Nutrition Evidence Library (NEL) to help ensure the quality of nutritional recommendations by establishing standards for identifying and selecting research.3
Teicholz contends that the DGAC “did not use NEL reviews for more than 70 percent of the topics” and instead selected studies ad hoc often relying on reviews by external professional associations.
Millen defended the committee claiming that “you don’t simply answer these questions on the basis of the NEL. On topics where there were existing comprehensive guidelines, we didn’t do them.” Millen also contended that the bulk of their research came from the NIH and other federal agencies.
To her credit, the Guidelines detail four methods of research selection, most of which involved at the least consulting the NEL.
Ultimately, it is the recommendations themselves that will determine the integrity of the report and Teicholz had issues with several of them, all of which are highly relevant to those of us in the Paleo world:
THE CONTESTED RECOMMENDATIONS
Teicholz addressed the recommendation for lower dietary saturated fats first, pointing out that no NEL review of the research on saturated fat from the past five years was conducted. She claimed many conflicting studies were omitted, in particular a large controlled clinical trial known as the Women’s Health Initiative (WHI). No benefits of a lower saturated fat diet were observed in a cohort of 49,000 women over seven years.4
Millen responded that the report states “dietary advice should put the emphasis on optimizing the types of dietary fat and not reducing total fat.”
Next, Teicholz addressed the report’s failure to endorse a low carbohydrate diet claiming critical research was left out including a meta-analysis and a critical review demonstrating a benefit of low carb diets for type 2 diabetes.5, 6 Millen simply replied that there is limited evidence of the long-term health effects.
One of the biggest shifts in the new guidelines was a stronger emphasis on plant-based diets with the recommendation to reduce meat particularly red meat. The draft 2015 Guidelines added for the first time a “Healthy Vegetarian Pattern” to their three recommended diets that also include a “Healthy Mediterranean-Style Pattern” and a “Healthy U.S.-Style Pattern.”
Teicholz contends that there has been no review by the NEL of the health effects of red meat. While an NEL review of a vegetarian diet does exist and states that the evidence is limited for its disease fighting power.7 Yet, Teicholz holds that the report arbitrarily upgraded the rating of the evidence. She also claimed that the Guidelines left out three contradictory NIH studies including one from the WHI that found no significant advantage of a diet high in fruit, vegetables and grains for weight loss, diabetes, heart disease, or cancer.8-11 Even the Guideline’s sole diagram addressing red meat, according to Teicholz, showed that diets high in red meat were equivocal with diets lower in red meat.
Millen did not address the question of red meat in her response, but the report stated that the three recommended dietary patterns reaffirmed the 2010 DGAC recommendations and aligned with the American Institute for Cancer Research (AICR) and the American Health Association (AHA).1
A MORE MUNDANE EXPLANATION
A friend of mine, who by her own admission had a “cushy” well-paid job at a large government nutrition agency, once gave me her impression of government nutrition.
Her job was to follow the current research and take her findings to the higher-ups. She was quickly frustrated by the all-too-common response. They would thank her for bringing it to their attention, then tell her they already knew about it and they weren’t going to do anything. Did she experience, first hand, government corruption or industry influence at play?
My friend had a much more mundane answer. In a government nutrition agency, she said, there’s one unforgivable sin – to make a recommendation contrary to the decades old accepted cannon and end up being wrong. So was something this mundane going on with the DGAC?
The Report starts by asserting it was motivated by the current state of public health in the United States, a lot of which was a result of poor dietary patterns. Half of U.S. adults have a chronic disease and two-thirds are obese. It goes on to say these patterns “adversely affected the health of the U.S. public for decades and raise the urgency for immediate attention and bold action.”1
Yet that “bold action” consists of recommendations that by their own admission are consistent with past DGAC reports.
The few new recommendations they offer – replacing refined grain products with whole grain products and the reduction of refined sugar and sodium in the diet – are neither novel nor in any way controversial within the nutrition community.
Even in the Paleo world, while we would say to bypass the grains altogether, if you’re going to eat them, we’re still generally going to recommend whole grain products over refined empty-calorie snacks.
Perhaps Teicholz’s most poignant criticism of the report was her pointing out “a reluctance by the committee behind the report to consider any evidence that contradicts the last 35 years of nutritional advice.” She goes on to say that with the failure of existing intervention strategies, they should be welcoming new views.
Nowhere is the aging nature of the report potentially more obvious than in its handling of omega-3 fatty acids. As mentioned above, Millen responded to Teicholz by stating that the committee focused more on types of fats than absolute quantity. Which would imply that omega-3 fats were a focus.
Yet omega-3s are mentioned only three times in the 571-page report. Once in the context of wild vs farm raised fish. One paragraph under mental health where they briefly review the vast research showing the benefits of omega-3 for the brain and finally to point out the single study that found an association between nutrients in the diet and type 2 diabetes because it differentiated types of fats.12
The broad ranging health benefits of consuming omega-3 fatty acids, and the ratio of omega-3 to omega-6 fatty acids in the diet are some of the most heavily researched topics currently in nutrition.13 Yet the report made no recommendations about omega-3s. Instead it focused on a decades-old concept of “achieving better saturated fat to polyunsaturated fat ratios.”
IS MUNDANE ANY BETTER?
Teicholz herself concludes by admitting the mundane may be more at play than conflict of interest or industry pressure – “nearly all nutrition scientists accept funding from industry. Of far greater influence is likely to be bias in favor of institutionalized hypothesis.”
Nonetheless, does this really make the end result any better?
The report may very well answer that question itself. It has long been accepted that there is a big difference between refined sugar, refined grain products, and whole grain products despite all being grain-based. The report is careful and thorough in making this distinction and providing very different recommendations for each.
The report also admits to a difficulty in defining meat – “there was variability across the food groupings and this was particularly apparent in the meat group.” Red meats were clumped together with processed meat and chicken, fish was grouped with eggs and sausage.
Yet, after admitting to this issue, the report still stuck with traditional lines. Where it was careful to distinguish different categories of grains and plant foods it still ultimately lumped almost all meat together in its recommendation.
That is with the exception of a small footnote that ultimately contradicted its own recommendations:
As lean meats were not consistently defined or handled similarly between studies, they were not identified as a common characteristic across the reviews. However, as demonstrated in the food patterns modeling of the Healthy US-style and Healthy Mediterranean-style patterns, lean meats can be a part of a healthy dietary pattern.
Whether it was industry influence, conflict of interest, or simply mundane adherence to nutritional cannon, when it came to their final recommendations, they were unable to see the important implications of a distinction they themselves made.
- United States. Department of Agriculture., Dietary Guidelines Advisory Committee. Scientific Report. v.
- Teicholz, N., The scientific report guiding the US dietary guidelines: is it scientific? BMJ, 2015. 351: p. h4962.
- Library, N.E., Frequently Asked Questions. 2015.
- Howard, B.V., et al., Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 2006. 295(6): p. 655-66.
- Feinman, R.D., et al., Dietary carbohydrate restriction as the first approach in diabetes management: critical review and evidence base. Nutrition, 2015. 31(1): p. 1-13.
- Ajala, O., P. English, and J. Pinkney, Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr, 2013. 97(3): p. 505-16.
- Library, N.E., How do the health outcomes of a vegetarian diet compare to that of a diet which customarily includes animal products?
- Beresford, S.A., et al., Low-fat dietary pattern and risk of colorectal cancer: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 2006. 295(6): p. 643-54.
- Knopp, R.H., et al., Long-term cholesterol-lowering effects of 4 fat-restricted diets in hypercholesterolemic and combined hyperlipidemic men. The Dietary Alternatives Study. JAMA, 1997. 278(18): p. 1509-15.
- Prentice, R.L., et al., Low-fat dietary pattern and risk of invasive breast cancer: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 2006. 295(6): p. 629-42.
- Prentice, R.L., et al., Low-fat dietary pattern and cancer incidence in the Women’s Health Initiative Dietary Modification Randomized Controlled Trial. J Natl Cancer Inst, 2007. 99(20): p. 1534-43.
- Fung, T.T., et al., A prospective study of overall diet quality and risk of type 2 diabetes in women. Diabetes Care, 2007. 30(7): p. 1753-7.
- Gomez-Candela, C., et al., The Role of Omega-3 Fatty Acids in Diets. J Am Coll Nutr, 2015. 34 Suppl 1: p. 42-7.