The "Dietary Guidelines for Americans" have recommended for decades that people steer clear of whole milk, but recently the scientific support for that guidance has been eroding, and new research published Thursday underscored the idea that millions of people might have been been healthier had they ignored the government's advice.

The research, published in the Journal of Nutrition, finds that people who consume full-fat dairy products such as whole milk are less likely to be afflicted with so-called "metabolic syndrome," a set of related risk factors predicting heart disease and diabetes.

"Dietary recommendations to avoid full-fat dairy intake are not supported by our findings," the researchers conclude.

The study of more than 15,000 civil servants in Brazil examined the connection between the types of dairy products people consume and their likelihood to suffer from metabolic syndrome. The syndrome is characterized by high blood pressure, high blood sugar, belly fat, and risky levels of cholesterol and triglycerides in the blood.

What the researchers found is that consumption of full-fat dairy products such as whole milk, as well as butter and yogurt, was associated with lower likelihood of the risk factors that make up metabolic syndrome.  Consumption of low-fat dairy products, by contrast, was not associated with this health advantage, the researchers noted. The study was supported by the Brazilian Ministry of Health and the Brazilian Ministry of Science, Technology and Innovation.

The authors said that while past research on the topic has been "somewhat inconsistent," their new findings as well as their review of prior research undermine the advice in the Dietary Guidelines for Americans, which currently tell people to “replace whole milk and full-fat milk products with fat-free or low-fat choices.”

The study out of Brazil likely will add to the controversy around the Dietary Guidelines for Americans, which is being updated this year by the USDA and the Department of Health and Human Services.

In a statement, the USDA defended the current guidelines and their preference for low-fat milk.

“The Dietary Guidelines are based on the totality of scientific evidence found after poring through thousands of studies, not just one," the statement said.  "The body of evidence used for the current Dietary Guidelines for Americans demonstrated that diets which included low- and fat-free dairy products were associated with reduced risk of cardiovascular disease and overall mortality, and these dairy products contribute to an individual’s nutrient needs without the added calories associated with full-fat dairy products.”

Not everyone agrees on the virtues of low-fat milk, however, and some studies have suggested  that whole milk, not low-fat milk, best reduces the risk of heart disease. Some scientists have criticized the government guidelines for ignoring the new evidence.

At a hearing earlier this month, members of the House Agriculture Committee expressed doubts about the quality of the advice in the Dietary Guidelines, as Health and Human Services Secretary Sylvia Burwell and Agriculture Secretary Tom Vilsack defended the publication.

Vilsack noted that the evidence for the guidelines does not have to reach a standard of "beyond a reasonable doubt." Instead, the legislation creating the guidelines requires that the advice be based only on a "preponderance" of the evidence.

"This is really about well-informed opinion," Vilsack told the commiteee. "I wish there were scientific facts. But the reality is stuff changes, right? Stuff changes. The key here is taking a look at the preponderance, the greater weight of the evidence, and trying to make a judgment. "