BMJ Lambasts U.S. Dietary Group for Shoddy Research

I bet the doctors in your hospital aren't helping the nutritionist come up with the correct diet stroke protocol for survivors.
http://www.medpagetoday.com/PrimaryCare/DietNutrition/53701
A controversial expert report that was the basis for draft U.S. dietary guidelines failed to take into account relevant scientific evidence, and could be "misleading," according to an article in BMJ.
The report used "weak scientific standards," and the dietary committee that issued it did not use reviews from the Nutrition Evidence Library (NEL) -- set up by the U.S. Department of Agriculture (USDA) as a standardized process for finding and evaluating relevant studies -- in seven cases out of 10, according to a feature article, written by Nina Teicholz, a journalist based in the U.S.

The report in question, which was produced by a group of experts known as the Dietary Guidelines Advisory Committee (DGAC), was reviewed by the USDA which used the information to develop new dietary guidelines.
A draft of the guidelines was posted earlier this year and has received nearly 30,000 comments -- 15 times more than in 2010. Concern over the guidelines has also prompted Congress to get involved, with two cabinet secretaries scheduled to testify during a hearing in October.
The USDA is expected to issue the final guidelines by the end of this year.
'Stunned' by BMJ Take Down
Some experts have expressed approval that the proposed guidelines have been relatively free of outside influence from industry. David Katz, MD, of the Yale University School of Medicine in New Haven Conn., pointed out that the DGAC worked together to promote public health rather than favoring certain diets.

Katz told MedPage Today via email that he was "rather stunned" by the BMJ article.
"The DGAC report is excellent, and represents both the weight of evidence, and global consensus among experts," Katz wrote. "It is entirely in line with the persuasive experience of Blue Zone populations," referring to the areas of the world where people live measurably longer lives.
'Abandoned Established Methods'
Teicholz is the author of The Big Fat Surprise: Why Butter, Meat, & Cheese Belong in a Healthy Diet, which details how the low-fat diet rose to supremacy on the back of politics and shoddy science, leading to the consumption of more sugar and other unhealthy products.
She noted that in the 2015 report, the DGAC claimed that it "abandoned established methods for most of its analyses."
These methods include a 2010 overhaul of the review system to "implement systematic reviews of studies to bring scientific rigor and transparency to the review process," including the NEL, she wrote.
"However, in its 2015 report the committee stated that it did not use NEL reviews for more than 70% of the topics, including some of the most controversial issues in nutrition," she noted.
Instead, they relied on systematic reviews by professional groups, most notably the American Heart Association (AHA) and the American College of Cardiology (ACC). The DGAC also "relied on or conducted an hoc examination of the scientific literature without well defined systematic criteria for how studies or outside review papers were identified, selected, or evaluated," she charged.
Organization like the AHA and ACC take significant funds from industry, she said. For instance, these groups have relied on "decades of support from vegetable oil manufacturers, whose products the AHA has long promoted for cardiovascular health. This reliance on industry backed groups clearly undermines the credibility of the government report."
With regard to saturated fat, the DGAC failed to request a new NEL on this topic, and instead relied on old data, including a 2010 NEL review and an ad hoc selection of seven review papers, ultimately extending the current 10% cap on saturated fats.

Teicholz pointed out that when the DGAC began its work in 2012, several papers had been published that failed to confirm a link between between saturated fats and heart disease. Yet the current report concludes that the evidence linking consumption of saturated fats to cardiovascular disease is "strong," she wrote.
Teicholz pointed out similar patterns for low-carbohydrate diets, and questioned the strength of the evidence for the three diets recommended in the report: healthy vegetarian diet, Mediterranean-style diet, and healthy U.S.-style diet.
In other areas, like consumption of red meat, there is simply not enough evidence to know whether it is linked to higher risk of disease, but the report urged limits on its consumption, she said.
While Teicholz conceded that she is not trained as an expert in nutrition, she stated that "the field of nutrition science, however, has become entrenched in its mistakes, a situation that is now becoming obvious: sixty years of expert advice on dietary cholesterol have been overturned, as has the expert advice on the low-fat diet; sixty years of expert advice on saturated fats has been seriously challenged."
Doing a Disservice?

Marion Nestle, PhD, MPH, of New York University in New York City, noted in an email to MedPage Today that Teichart certainly isn't the first person to raise questions about the committee's approach to saturated fat.
"Teicholz is a journalist with a well-known viewpoint on the fat issue, but several respected scientists have also challenged the recommendations on total and saturated fat and the implications that follow -- to eat less red meat, dairy, and animal products," Nestle wrote. "I can't believe that the DGAC members were unaware of the scientific challenges, especially in light of the predictable reaction of the affected industries."
The report does take into account sustainability, something that the committee noted was not traditionally in their purview. "Ms. Teicholz seems inclined to ignore that altogether; perhaps she does not care whether there is anything for the next generation to eat or drink, but I suspect most of us do," Katz noted.
"The notion that the opinion of one journalist with a book to sell is any way a suitable counterpoint to the conclusions of a diverse, multidisciplinary, independent group of scientists who reviewed evidence for the better part of 2 years and relied upon knowledge and judgment cultivated over decades is nearly surreal," Katz added. "It is a disservice to the readership in both cases."
In the same BMJ article, DGAC Chair Barbara Millen, DrPH, RD, defended the committee's approach.
"The evidence base has never been stronger to guide solutions. You don't simply answer these questions on the basis of the NEL," she said. "Where we didn't feel we needed to, we didn't do them. On topics where there were existing comprehensive guidelines, we didn't do them."
Millen is the president of Millennium Prevention of Westwood, Mass., a company that sells mobile apps for self-health monitoring.
Nestle added that nutrition research is difficult to design, perform, and interpret. "Drawing recommendations out of this literature requires committee members to have broad knowledge of science and its implications," she wrote. "Teicholz suggests that this committee lacked these attributes."
Teicholz concluded that because obesity, diabetes, and heart disease are taking an increasingly serious toll, there's an "urgent need" for scientific-based nutritional advice.
"It may be time to ask our authorities to convene an unbiased and balanced panel of scientists to undertake a comprehensive review, in order to ensure that selection of the dietary guidelines committee becomes more transparent, with better disclosure of the conflicts of interest, and that the most rigorous scientific evidence is reliably used to produce the best possible nutrition policy," she wrote.

The article was funded by the Laura and John Arnold Foundation.
Teicholz disclosed relevant relationships with Simon & Schuster and the Nutrition Coalition.
Katz disclosed a relevant relationship with NuVal.

• Primary Source

  The BMJ

  Source Reference: Teicholz, N "The scientific report guiding the US dietary guidelines: is it scientific?" BMJ 2015; 351: h4962.