U.S. Secretary of Agriculture Tom Vilsack (L) and Secretary of Health and Human Services Sylvia Burwell (R) testify during a hearing before the House Agriculture Committee October 7, 2015 on Capitol Hill in Washington, DC. The committee held the hearing to review the development of the 2015 Dietary Guidelines for Americans. (Photo by Alex Wong/Getty Images)

Concerned about the integrity of the nation’s nutrition advice, Congress is calling for a comprehensive review of the way the influential Dietary Guidelines for Americans is compiled.

The measure, which passed the House and Senate as part of the massive budget bill, sets aside $1 million for the National Academy of Medicine to conduct the study.

“Questions have been raised about the scientific integrity of the process in developing the dietary guidelines and whether balanced nutritional information is reaching the public,” according to language that accompanying the bill. “The entire process used to formulate and establish the guidelines needs to be reviewed before future guidelines are issued.”

"I hope this will make sure that the Dietary Guidelines are science-based," said Rep. Collin C. Peterson (D-Minn.), ranking member of the House Agriculture Committee, one of the committees overseeing the Dietary Guidelines. "They keep changing so much I'm not sure how many of the American people pay attention to it anymore."

The Dietary Guidelines for Americans, updated every five years by the federal government, has far reaching effects on what Americans eat, shaping the contents of school meals and military rations and serving as the scientific basis for reams of diet claims published in newspapers, magazines, and advice books.

Nutrition science has been in turmoil in recent years, however, and this year, Post stories examined the scientific disagreements over the positions the Dietary Guidelines have taken on  salt, whole milk and saturated fat, cholesterol, as well as the health implications of skipping breakfast. The stories also explored the recommendations made by the Dietary Guidelines Advisory Committee, the expert group providing information to the government, regarding coffee and the environmental impacts of meat production.

The bill calls for the Department of Agriculture, within 30 days, to hire the National Academy of Medicine to conduct a comprehensive study that includes an analysis of how the Dietary Guidelines can better prevent chronic disease, how evidence is assembled and evaluated, and whether a full range of scientific viewpoints are considered.

"At a minimum, the process should include: full transparency, a lack of bias, and the inclusion and consideration of all of the latest available research and scientific evidence, even that which challenges current dietary recommendations," according to the language accompanying the measure.

A statement from a USDA spokesperson said "we look forward to furthering our work with the Institute of Medicine to continue to ensure that the guidelines help Americans make their own informed choices about their diets and create a road map for preventing diet-related health conditions, like obesity, diabetes and heart disease.”

"Since 1980, families, nutrition and health professionals across the nation have looked to the Departments of Health and Human Services and Agriculture for science-based dietary guidelines to serve as a framework for nutritious eating," the statement said.

The next Dietary Guidelines for Americans - they have come out every five years since 1980 - is scheduled to be released in January. Under the legislation,  Agriculture Secretary Tom Vilsack and Health and Human Services Secretary Sylvia Burwell are required to ensure that any revisions to the guidelines are "based on significant scientific agreement."

The Dietary Guidelines are largely the work of the federal bureaucracy and the Dietary Guidelines Advisory Committee, a 15-member panel of experts. Updating the guidelines every five years is a daunting task that falls to a relatively small group of people. Nutrition science evolves rapidly, and over the course of a year of meetings, the advisory committee is called upon to review hundreds of dense - and sometimes conflicting - scientific papers. Extracting sound diet recommendations from all the research information is both arduous and, arguably, confusing. Along the way, the Dietary Guidelines have grown more intricate, expanding from a pamphlet into a 112-page book.

While the guidelines have evolved as scientific understanding grows, critics charge that it has moved far too slowly, most notably with regard to saturated fats, which are the fats characteristic of meats and dairy products. They also note that during the existence of the Dietary Guidelines, rates of obesity have risen.

"This is important because it's the first time Congress has noted there is a problem with the Dietary Guidelines process," said David McCarron, research associate at the Department of Nutrition at the University of California-Davis. He is the incoming chair of the medical nutrition council at the American Society of Nutrition and sits on a scientific advisory board at ConAgra Foods. "There’s a lot of stuff in the guidelines that was right forty years ago but that science has disproved. Unfortunately, sometimes, the scientific community doesn’t like to backtrack."