Are this year’s soon-to-be-issued dietary guidelines based on the most recent science? One author does not think so. (Photo: Getty Images)
The updated version of the U.S. dietary guidelines isn’t officially set to be issued until later this fall, but a new report in the British Medical Journal is claiming there’s already a major problem: The expert recommendations used to draw up the guidelines are flawed.
A new draft of the U.S. dietary guidelines comes out every five years and sets the standard both nationally and in much of the Western world. This year’s advice is seeking to make some key changes, notably to stop the demonization of eggs and dietary cholesterol and ease restrictions on salt intake, instead limiting sugar and meat intake — while also giving an OK to moderate coffee consumption. The draft guidelines came out to substantial fanfare earlier this year.
However, according to the report, the contributing experts failed to look closely at the most recent nutritional science, and thus got plenty wrong. Here are the significant criticisms:
Health journalist Nina Teicholz, author of The Big Fat Surprise, wrote the BMJ report, noting that the committee working on guideline recommendations did not use the best resources at its disposal: the Nutrition Evidence Library (NEL), established by the U.S. Department of Agriculture.
In 2010, when the last guidelines were released, the NEL was created to systematically review nutrition studies in order to be more rigorous in analyzing the science. However, the NEL was not consulted for about 70 percent of the topics discussed in 2015. Reviews conducted by the American Heart Association and American College of Cardiology were heavily used.
According to Teicholz, there are conflicts of interest with an external group’s reviews, based on the industries that fund them. “These groups conduct literature reviews according to different standards and are supported by food and drug companies,” she writes in her report. “The ACC reports receiving 38 percent of its revenue from industry in 2012, and the AHA reported 20 percent of revenue from industry in 2014.”
Teicholz criticizes the experts’ advice on saturated fats, which is to limit intake to no more than 10 percent of total calories. Citing several high-profile studies showing saturated fat isn’t necessarily linked to disease risk, she questions the experts’ assertion that there is “strong” reason to condemn this type of fat. In fact, she says the committee didn’t use the NEL to re-review saturated fat.
The author notes several “ambitious” studies of more than 25,000 people from the 1960s and ’70s that look at saturated fat but have never been reviewed by the guideline committee — and probably should be in light of more recent, more inconclusive research on the type of fat found in some forms of dairy and meat products.
“These studies showed mixed health outcomes for saturated fats, but early critical reviews, including one by the National Academy of Sciences, which cautioned against the inconclusive state of the evidence on saturated fats and heart disease, were dismissed by the USDA when it launched the first dietary guidelines in 1980,” writes Teicholz. “Subsequent guideline committees have never gone back to systematically review these early trials but instead relied on other government reports.”
The low-carb diet
Another major point of contention highlighted in the BMJ report was the low-carb diet, which wasn’t recommended by experts in their report. Although the guideline committee members said they were lacking evidence on regimens of this sort since 2000, Teicholz says there was actually a significant number of studies conducted since that year: 11 case studies, 19 observational studies, and 74 randomized controlled trials.
Low-carb diets showed potential results for controlling diabetes, improving heart disease risk, and, perhaps most notably, weight loss — results that seem more promising than low-fat regimens. “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,” Teicholz writes. “It is thus surprising that the studies listed above were considered insufficient to warrant a review.”
How to digest it all
Will the BMJ report make a difference in changing the guidelines? No one knows yet. Congress will be discussing the guidelines in October, including how the evidence was handled and reviewed by the expert panel.
Teicholz says she believes the transparency and review were weak enough that both the process and the science deserve another look before it’s approved to stand for five more years. If she were creating the guidelines, she’d favor an approach far similar to what the American diet looked like in the past, before the obesity epidemic swept the country.
“I believe that the literature shows that the low-fat, high-carbohydrate diet has not produced better health for Americans since it was first introduced as official government policy in 1980,” she tells Yahoo Health. “For healthy people, a reasonable recommendation would be simply to reverse out of the high-carb diet, to the balance that Americans ate in 1965 before the obesity and diabetes epidemics: roughly 40 percent carbs, 40 percent fat. The numbers now are more than 50 percent carbs and about 30 percent fat.”
For people struggling with metabolic disorders, especially the ever-prevalent obesity and diabetes, Teicholz believes that carbohydrate-restricted diets are a “safe and viable” option.
Perhaps this is so, says dietitian Keri Gans, RD, author of The Small Change Diet, but there are a couple things to keep in mind. “The dietary guidelines are tailored toward healthy individuals, not those with special dietary needs or restrictions — like someone with type 2 diabetes,” she tells Yahoo Health.
In addition, if we want to recommend only dietary strategies with “strong” track records, Gans is not convinced there is enough science yet on low-carb approaches or saturated fat to suggest either to the American public. “Now no one is saying you can’t have saturated fats at all or that a low-carb approach is wrong,” she explains. “But I like to stick to what I know for sure.”
What Gans knows for sure is that the fats we should be focusing on are the proven-healthy ones, like the polyunsaturated and monounsaturated fats found in olive oil, avocado, nuts, fish, and seeds.
“And overall, rather than pulling out individual nutrients, we should be encouraging everyone to eat a well-balanced diet of wholesome foods,” she says.