by Jason Block, MD, MPH
The overall body of evidence examined by the 2015 DGAC 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 meat; and low in sugar-sweetened foods and drinks and refined grains.
Fruits and vegetables were the clear winner, with authors recommending their intake to benefit all health outcomes examined. The Committee also described clear and consistent evidence of benefit from consumption of whole grains. The clear losers were red and processed meats, which were generally recognized as detrimental to health outcomes; while sugar-sweetened foods/drinks and refined grains were also typically viewed as harmful. These recommendations weren’t particularly novel. Prior reports have made largely the same recommendations. Only the caution regarding red and processed meat intake seems a bit stronger than prior.
Most of the novel 2015 recommendations were more liberating than in prior guidelines: no specific limitations are specified for cholesterol and overall fat consumption. Similar to prior recommendations, the report does call for limiting saturated fat to 10% of daily calories, salt to less than 2300 mg daily and added sugars to less than 10% of daily calories.
By itself, the guideline may not generate controversy. But, it seems, diet is never without controversy. Powerful food industries are already mobilizing to oppose these guidelines. Some authors and even 30 US Senators have lamented the report’s lack of support for meat, even though the report only really calls for limitations on red and processed meat. The report states that “lean meats can be a part of a healthy dietary pattern.”
Others have wondered whether the salt restrictions continue to ignore evidence demonstrating variability in the effect of salt on health, especially for patients with congestive heart failure, and whether saturated fat should be restricted at all. Dietary experts have fought back against these critiques, defending the guidelines as sensible and progressive.
In my opinion, the guidelines are strong, evidence-based and unbiased. The Committee, composed of nutrition experts, spent 2 years combing through the evidence. They threw out long-held beliefs that haven’t been supported by new evidence (such as limiting dietary cholesterol), and they pushed forward recommendations that changes are needed in all sectors of society, from physician-patient interactions to the environment. They began an important evolution toward recognition of the need for flexibility regarding diet.
Diet is complex and hard to change for many. In public health efforts and when counseling patients, we should try to work with people, governments, and the food industry, to make changes that are possible and sustainable. We must recognize great heterogeneity in preferences and culture. For individual patients, advocating for one particularly diet over another typically will not have much benefit. As long as the core components recognized by the Guideline Committee are considered, no diet is superior to others, especially for weight loss.
And, one last thing: This report isn’t even the final word. The Report goes to the US Department of Agriculture for consideration. Toward the end of 2015, the USDA will release the official guideline, based on this Scientific Report. The real controversy may come if the USDA goes against the evidence compiled by the Committee and makes recommendations that are friendlier to industry constituencies. This has happened before. We’ll be watching.