When Americans hear about a health craze, they may turn to their physician for advice: Will that superfood really boost brain function? Is that supplement okay for me to take?
Or they may be interested in food choices because of obesity, malnutrition or the role of diet in chronic disease.
But a doctor may not be a reliable source. Experts say that while most physicians may recognize that diet is influential in health, they don't learn enough about nutrition in medical school or the training programs that follow.
An estimated 50 percent to 80 percent of chronic diseases, including heart disease and cancer, are partly related to or affected by nutrition, according to Martin Kohlmeier, a research professor in nutrition at the University of North Carolina at Chapel Hill.
For those experiencing risk factors early on, a change in diet is important.
"People are gaining a pound or two a year, and nobody says anything. But then by age 50 or 55, they've often gained 30 or 40 pounds, which has huge impacts on their health," said Walter Willett, an epidemiology and nutrition professor at the Harvard T.H. Chan School of Public Health. "In the younger years, middle age, people are acquiring the risk factors that often don't show up as major diseases until later in life."
"You can practice only what you know," Kohlmeier said. According to the Journal of the Academy of Nutrition and Dietetics, malnutrition is prevalent but underrecognized in the United States. That does not surprise Kohlmeier, who said, "This is what happens when you don't teach nutrition."
He oversees UNC's Nutrition in Medicine project, which offers educational modules for medical students. But Kohlmeier said these are far from enough. "You cannot learn in two hours what it takes 20 hours to learn," he said. In a 2015 survey of 121 four-year medical schools, Kohlmeier and colleagues found that 71 percent did not require at least 25 hours of nutrition education and that fewer than 20 percent required a nutrition course -- fewer even than 15 years before.
"The biggest thing that drives a lot of medical schools to put particular things in their curriculum is what gets tested on the boards. And unfortunately, as of right now, doctors are not tested on what foods a patient should eat," said Tracy Rydel, a clinical associate professor of medicine at the Stanford School of Medicine.
Stanford and UNC are among medical schools working to turn that tide by integrating nutrition into their curriculums. Others include Tulane, Vanderbilt, Tufts, Texas Tech, Oakland University in Michigan, and Boston University. Some, such as Stanford and Tulane, have established teaching kitchens. Proponents say this hands-on element may be particularly valuable because it can help physicians discuss food with patients in a more knowledgeable and engaged manner; and if it instills healthier eating habits in the students, that's a bonus for their future patients, because physicians who eat wisely tend to give better advice about eating.
"Just like it was really important that doctors stopped smoking -- that made them advocates for not smoking," Willett said. "Doctors need to set an example, both for their own good and for the good of their patient."
The Association of American Medical Colleges reports a more than 50 percent increase since 2011 in schools offering an elective course that covers nutrition, but that tally counts electives that merely include and don't necessarily focus on the subject.
AAMC medical education expert Lisa Howley is optimistic. "All of our schools are addressing this in some capacity. Some are doing it quite intensively, and others [not as well] - there's a spectrum," she said. "For those who are somewhere on the lower end of that spectrum, it would be lovely to see them learn from their colleagues and, through shared resources, be able to even further integrate this content into their curriculum."
Teaching nutrition requires expertise and resources, but some efforts are underway to streamline the process so every school doesn't need to start from scratch. Rydel and colleagues are working to centralize nutrition-related research and recommendations for medical schools, and the American Society for Nutrition announced in September that it would lead a coordinating center for nutrition education.
Gwen Tillman, the nutrition group's vice president of education and development, said the center probably will work with medical schools and residency programs to find ways to incorporate nutrition into their curriculums.
The nonprofit Gaples Institute, meanwhile, focuses on doctors fresh out of medical school and on established physicians, educating both in the basics of nutrition and strategies for incorporating nutritional counseling into a busy practice.
For many, the minor role of nutrition in medicine underscores the emphasis that the U.S. health-care system places on treatment over prevention. There's little or no incentive for a physician to sit down and talk with patients about food and healthy habits, Rydel said. "A counseling visit is not nearly as incentivized as a procedural visit," she said.
Marion Nestle, a nutrition professor at New York University, said that even though the efforts at medical schools are significant, what's really needed is for the reimbursement system to encourage preventive health care, and diet should be covered by licensing examinations and viewed as standard medical practice. "Until then, we are talking about Band-Aids," she said.
Willett said that the initiatives in schools are crucial. He recalled a major study in 2015 that encouraged more-aggressive treatment with drugs that can lower blood pressure even though obesity and excess weight are major causes of hypertension.
"There was not a single statement I saw anywhere that we should encourage weight loss and sodium reduction or increased potassium intake, which means more fruits and vegetables," he said. "That just is such a glaring example of the result of our extremely unbalanced medical education."