For nearly three decades, Americans have become accustomed to hearing about the latest dietary guidelines, which are required by federal regulation to be revised and reissued at five-year intervals. Mid-way to the drafting of the 2010 guidelines, researchers at Albert Einstein College of Medicine of Yeshiva University raise questions about the benefits of federal dietary guidelines, and urge that guideline writers be guided by explicit standards of evidence to ensure the public good. The researchers, led by Paul Marantz, M.D., MPH, associate dean for clinical research education at Einstein, outline their argument in the January 22 online edition of the American Journal of Preventive Medicine.
"When dietary guidelines were initially introduced in the late 1970s, their population-based approach was especially attractive since it was presumed to carry little risk," says Dr. Marantz, who also is professor of epidemiology and population health, and of medicine at Einstein. "However, the message delivered by these guidelines might actually have had a negative impact on health, including our current obesity epidemic. The possibility that these dietary guidelines might actually be endangering health is at the core of our concern about the way guidelines are currently developed and issued."
Dr. Marantz and colleagues argue that if guidelines can alter behavior, such alteration could have positive or negative effects. They cite how, in 2000, the Dietary Guideline Advisory Committee suggested that the recommendation to lower fat, advised in the 1995 guidelines, had perhaps been ill-advised and might actually have some potential harm. The committee noted concern that "the previous priority given to a 'low-fat intake' may lead people to believe that, as long as fat intake is low, the diet will be entirely healthful. This belief could engender an overconsumption of total calories in the form of carbohydrates, resulting in the adverse metabolic consequences of high-carbohydrate diets," the committee wrote, while also noting that "an increasing prevalence of obesity in the United States has corresponded roughly with an absolute increase in carbohydrate consumption."
Dr. Marantz and colleagues present data that support these trends; however, they are careful to note that this temporal association does not prove causation. Instead, says Dr. Marantz, "it raises the possibility of a net harmful effect of seemingly innocuous dietary advice. These dietary recommendations did not necessarily cause harm, but there is a realistic possibility that they may have."
"As doctors, our first call is to do no harm," he adds. "That's why we recommend that guidelines be generous in providing information, but more cautious in giving direction. Any directions should be based on the very highest standards of scientific evidence. After all, we expect that much from pharmaceutical companies before they bring a new drug to market."
In a commentary published in the same issue of the American Journal of Preventive Medicine, Steven H. Woolf, MD, MPH, from Virginia Commonwealth University and Marion Nestle, PhD, MPH, of New York University, maintain that the guidelines are supported by decades of research. While they agree with Dr. Marantz that people often compensate for low-fat intake by consuming more calories, they disagree that the guidelines were wrong to encourage low-fat diets. "The guidelines were not the culprit," said Dr. Woolf, who believes that the government was right to share what was known about the dietary causes of disease.
Woolf and Nestle do not dispute that guidelines can have unintended consequences. However, they write, "When the prevailing message fails to achieve its intended aims or achieves the wrong ends, the solution is not to abandon the enterprise but to reshape the message to achieve desired outcomes."
Other Einstein researchers contributing to the paper are Michael Alderman, M.D., professor of epidemiology and population health and of medicine, and Elizabeth Bird.
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