Food For Thought: Teaching History of Nutrition to Medical Students

Since our major diseases, such as obesity, dental caries, diabetes, cardiovascular and kidney diseases, are associated in part with faulty nutrition, more emphasis should be given to this subject in the medical curriculum; nutrition is rapidly becoming an important tool in the hands of the modern physician.[1] [emphasis added]

Neither clinical nutrition nor medical history is taught very much in U.S. and Canadian medical schools, much less the subspecialized intersection that is the history of nutritional science and practices. While there are few laments about the relative lack of medical history, it seems a commonplace assertion these days that doctors (and other health professionals) receive insufficient training in nutrition.[2] Unofficial guidelines recommending 25-44 contact hours were developed in the 1980s,[3] but researchers estimate that at most a third of medical schools have met those targets.[4] Even though many of the leading causes of morbidity and mortality today are associated with poor diet, nutrition is not one of the competencies required for graduation.[5] It has gotten to the point that medical students are calling on their instructors to fill the gap and starting “culinary medicine clubs” in order to teach each other what the official curriculum doesn’t cover.[6] Interestingly, a real or perceived mismatch between demand and educational content is not new, as the quotation above from the late 1950s demonstrates.[7] What, then, is “modern” medicine, that more than 60 years later, the topic is still cited as a “deficiency” in medical training at all levels?[8] We have never been modern.[9]

Likewise, almost one third of North American medical schools have mandatory medical history content in their curricula, although 80% of respondents to the most recent survey indicated it is present to some degree.[10] This despite the fact that medical history provides opportunities for discussing the sort of knowledge that cannot be found in a systematic review or looked up on a formulary: the intimacies of patient-provider relationships, changing social roles and definitions of disease, or how standards of evidence drive practice. Some history must creep in, as familiar categories of analysis such as sex, gender, race, class, age, and dis/ability have been folded into the “social determinants of health” now frequently used to evoke the contexts in which patients seek health and care.[11] There are no widely accepted guidelines for the amount of medical history to which future physicians should be exposed, although the consensus is surely “more than nothing.” On a small scale, I have developed a genre of lecture that combines “how we got here” with current best practices; topics have included the racist history of spirometry and the resurgence of “black lung” among Appalachian coal miners; the history of food rations in Germany during World War I and the treatment of acute gastrointestinal illness in pediatrics; and the experiences of women as breast cancer surgery patients paired with the latest screening guidelines. This essay describes how I introduced history of medicine themes on a larger scale, within an elective course on clinical nutrition for undergraduate medical students.[12]

            Neither nutrition nor history of medicine have been well represented at my institution. Through a curricular assessment in 2018, a colleague found that medical students receive a mere ~10 hours of formal nutrition instruction.[13] Most of that is delivered in the first two, preclinical years; in the clinical years, infant and child feeding received more attention than adult or “general” nutrition. This fits (inter)national patterns: nutrition is often presented as part of biochemistry and/or the gastrointestinal system organ block, but clinical instructors don’t feel confident mentoring trainees about this issue.[14] Meanwhile, the popularity of an in-person history of medicine elective with significant reading taught by a rheumatologist and a librarian waned due to increasing pressure on fourth-year medical students to travel for residency interviews from October to January and to take Step 2CK early enough to have a score by the time residency rank lists were due in February. Old age and ill health forced the class to be cancelled, also in 2018.

In 2021, I decided to remedy this paucity of content in both areas by offering a month-long remote elective that combines clinical nutrition skills with history of nutrition knowledge. The course meets for two hours a day, five days a week, for four weeks in January, the tail end of residency interview season. It is designed for senior (third- or fourth-year) medical students who have some clinical experience but does not itself include real or simulated patient interaction. Each week has a different theme: general or adult nutrition, pediatric feeding topics, obesity and weight management, and surgical or artificial nutrition. Historical background is woven into the presentation of contemporary topics such as hyperlipidemia, growth charts, and (total) parenteral nutrition ([T]PN, or providing hydration and nutrients through an intravenous catheter). For instance, each student researches a different “fad diet,” and all read a selection of scholarly articles on the history of dieting.[15] I lead not quite half of the 18-20 class sessions, have invited guests to lecture for a similar number, and organize student presentations for the rest of them. The final course grade is pass-fail.

Unsurprisingly, the advent of the COVID pandemic has changed the way (history of) nutrition can be taught. In the half-semester undergraduate course on obesity and childhood I taught in Spring 2020, we were going to taste-test diet foods on Day 2; that was the session I dropped to accommodate the switch to online learning. Some campuses have returned to in-person instruction with or without masks and might allow communal eating again, but some individuals are still wary of SARS-CoV-2 transmission. An outdoor setting might be more palatable for experimenting with historical or contemporary recipes than even a well-ventilated test kitchen; be cautious about assuming all students have access to suitable cooking facilities if you decide to have them replicate something at home. Online instruction does have its benefits: it allows exposed or sick participants who feel well enough to participate. (The CDC has since relaxed quarantine recommendations, and institutional policies may vary.) Because residency interviews have been virtual since 2020, medical students have been able to travel for vacation or to see their families and still log in for the synchronous sessions. Guest lecturers can connect from their offices or clinics without having to take time out of their day to come to the medical school. And interacting through a screen allows easy integration of primary and secondary content. For example, while the next student presenter loads their slides, I have their classmates type in the chat something they learned; this immediate recall exercise is a “make it stick” principle.[16] The chat also allows me to gloss the guest lecturer’s presentation without interrupting them, if I think they may have used an unfamiliar term or referenced a study or organization whose URL I can share.

While clinician-educators might acknowledge the wisdom of teaching basic nutrition, why would students need to know anything about its history? There are many reasons why the next generation of nurses, doctors, dentists, or pharmacists should be taught dietary science. A patient with diabetes confesses they were told to “count carbs” but doesn’t know what a “carbohydrate” is. Another wonders whether an infant can be raised healthfully on a vegetarian or vegan diet. A third asks if Noom, Whole 30, or interval fasting can help them lose weight without medication or surgery. Someone who pays even a little attention to mass media might be forgiven for thinking the only nutrition topic of interest today is obesity and weight loss. This list shows just the opposite without even mentioning food-drug interactions or the innumerable “nutritional supplements” patients try to prevent or treat everything from infections to arthritis to cognitive decline.

Are there as many reasons to teach history of nutrition? I think a history of scientific and popular discussion of obesity is actually a good place to start. Were there fat people in the past? Was thinness always seen as beautiful? Are there other ways to value bodies than for their beauty and to evaluate them than for health versus sickness? The course I designed includes both conventional teaching about medically supervised weight loss and bariatric surgery as well as two sessions historicizing fatness and complicating mainstream beliefs about dieting. During the week on pediatric nutrition, students learn about the history of the standardization of body measurements, from Adolphe Quetelet comparing national populations to Ansel Keys looking for the healthiest percentage of fat in both one’s diet and one’s body. Sociologist Amanda Czerniawski describes how life insurance companies gathered data about their largely white, male, and middle-class enrollees that eventually came to stand in for the whole diverse nation.[17] With the National Institutes of Health’s (NIH) adoption in 1998 of the World Health Organization’s (WHO) definition of a “normal” body mass index (BMI) as 18-25 kg/m2, overweight as 25-29 kg/m2, and obese as >30 kg/m2, what had been statistically normal and descriptive became instead normative and prescriptive.[18] 29 million Americans became “overweight” overnight.[19] Collectively, Americans have been growing taller and living longer in addition to weighing more, but the focus has been on applying body mass index—originally a population-level metric—to individuals for medical decision making. This is useful historical context for budding clinicians.

Junior providers also gain insight into the identity they are being asked to adopt when they learn about the development of their fields. I have the students read pediatrician-historian Jeffrey P. Brosco’s essay about the development of infant and child growth charts, which is part of the larger story of the professionalization of pediatrics as a discipline.[20] Whereas in Europe, pediatricians specialize in diseases of children, in North America they have (also) established themselves as advisors for normal health and development: hence the ubiquitous Well-Child Check (WCC) full of “anticipatory guidance.” This is the basis for the medicalization of infant and child feeding, as historian Rima Apple explains in “Constructing Mothers,” which I assign for the session on breastfeeding, formula, and weaning.[21] So as not to become color-by-number providers who obediently click through computerized best-practice advisories, medical professionals should be aware of the cultural forces that they and their patients bring to clinical encounters. These power struggles may surface as “noncompliance,” when parents follow feeding advice from someone other than a doctor (a friend, family member, “natural healer,” etc.). Clinicians trained in only medical models of health and disease may not appreciate that it is not inevitable that physicians should be (the) experts on what otherwise healthy children eat. This human side of medicine is why I include “The Bizarre and Racist History of BMI”[22] and “A Letter to the Doctor Who Told Me to ‘Watch’ My Daughter’s Weight.”[23] I want to help them have honest, thoughtful conversations with their patients, not to mention with friends, family, or themselves.[24]

Sometimes knowing the history leads to better clinical care. The second lesson I teach on obesity offers an anti-dieting approach through a history of the Health At Every Size (HAES®) movement. Weight Watchers (now WW) started modern dieting culture in 1966, and the roots of HAES® grew from fat activist Llewellyn “Lew” Louderback’s 1967 Saturday Evening Post column entitled “More People Should Be Fat!”[25] In a medical and popular culture saturated with fat shaming—sometimes couched as medical concern trolling—I want to provide another, equally scientific viewpoint. Students read journal articles reviewing the poor success of conventional diet and exercise advice and learn about the nineteenth-century body-as-combustion-engine model behind “calories in/calories out.”[26] We discuss the obesity (really, overweight) paradox that shows people with slightly higher BMIs, in aggregate, live longer with fewer comorbidities than those with BMIs in the “normal,” extremely low, or extremely high range.[27] Finally, we address the growing evidence about the dangers of weight cycling (better known as “yo-yo dieting”).[28] When they inevitably counsel patients about losing weight, they should provide realistic goals and consider advising patients that it may be better for them to adopt healthy habits and stabilize at a higher weight than to lose and regain drastic poundage.

Obesity is not the only nutritional topic the class historicizes. For example, diabetes mellitus has been the subject of multiple good and usable histories about the discovery of insulin, the relationship of clinical practice to research in “Big Pharma,” and the experiences of patients living with a (sub)acute disease turned chronic condition.[29] Sometimes I just want to share a good story with them, such as how surgeon Stanley J. Dudrick was trying to feed beagle puppies by vein instead of by mouth, and his team finally found the polyvinyl tubing that enabled the development of (T)PN at a Pep Boys car-parts store near the University of Pennsylvania campus.[30] Other times the history fills in details they could not have lived through personally. Today we teach students that when it comes to infant feeding, “fed is best.” For them to understand the middle ground this pithy saying seeks, they need to know that “breast is best” was a feminist rallying cry after a generation of women dutifully bottle fed their infants “scientifically” designed formula.[31]

Then there are the tendrils of history that continue to reach into the present. For instance, why does this patient-facing brochure single out “African-Americans/blacks” [sic] for a particularly low-sodium diet?[32] The answer is an unproven but popular theory called the “slavery hypertension hypothesis” that developed between the 1960s and 1980s.[33] It attempts to explain why Black Americans have disproportionately high rates of hypertension. Some authors speculated that Africans living inland would have had low-salt diets, so when they were captured and transported as slaves to the Americas, where salt was prevalent, their bodies tended to retain salt, leading to high blood pressure. Another version rationalizes that individuals with salt-avid physiology were more likely to survive the Middle Passage to pass on those genes to their progeny. Not only have television personalities Dr. Oz and Oprah spread this idea, but it has been taught in medical schools. However, no responsible gene or genes have ever been found. There has been only a single peer-reviewed publication about the hypothesis (in 1991); other abstracts or posters have only drawn conclusions without any objective data. While on the one hand the “hypothesis” makes sense on its surface, on the other hand we know that the population of Black Americans is incredibly diverse. There are plenty of reasons for Black patients to have high blood pressure—beginning with systemic racism—so they should not be singled out for dietary advice. I pair physiologists Heidi Lujan and Stephen DiCarlo’s short article with one of the more accessible pieces written about the heart failure drug isosorbide dinitrate-hydralazine hydrochloride (BiDil).[34] We watch the relevant scenes from the television show House, M.D. and discuss how race and racism shape clinical encounters today.[35]

Teaching nutrition to medical students provides an excellent opportunity to include historical pearls that range widely from issues of body studies, professionalization, race and gender, to intellectual history. These are intended to complement what they learn from the main curriculum and make them more aware and well-rounded clinicians. The participants in the pilot class (AY 2021-22) seemed to appreciate the historical content. On an anonymous post-course survey, 100% of the 17 students agreed (24%) or strongly agreed (74%) that it had increased their historical knowledge. 65% (n=11) thought the amount of time spent was just right, 29% (n=5) too much, and 6% (n=1) not enough.[36] Formal and informal feedback from students and colleagues has been so positive that I am now conducting a multi-institutional medical education project to teach the syllabus at other medical schools and study its adoption.

In conclusion, if the definition of modernity is supposed to be the separation of Nature and Culture, “modern medicine” likes to think of itself as a purely scientific endeavor. Anecdotally, it certainly feels more technological than it does either natural or humanistic, especially in the hospital, where doctors spend more time in front of a computer than in front of a patient (typically 2/3 of a 10-11-hour shift).[37] There is so much laboratory, radiological, and consultant data to collect, assimilate, and document, that medical providers spend less than 10 minutes per day with each inpatient.[38] In the clinic it is a little better, where the average visit is twice as long (15-20 minutes), but physicians spend as much as half of a typical 11-hour day on “desk work,” with 1-2 more hours waiting for them after dinner.[39] “Nobody” admits to knowing anything about nutrition, but they order 2-gram sodium diets for patients with heart failure; they dutifully track infants’ growth curves; they advise patients with diarrhea to follow a “BRAT” diet of bananas, rice, applesauce, and toast; and they “advance diet as tolerated” (ADAT) for patients recovering from surgery or pancreatitis. Because knowledge regarding food has been relegated to “culture,” “modern” medical practitioners both know and don’t know clinically useful information about food, drink, and body size or composition. They don’t know that they know, and so they are not modern. If their consciousness is hybrid, their lectures and courses might as well be hybrids too, combinations of past, present, stories, science, and good questions.

This essay is dedicated to Bruno Latour (1947-2022), who inspired my interests in science studies as an early graduate student, and to Johnathon Erlen (1946-2022), whose shoes I will never entirely fill at the University of Pittsburgh or the C.F. Reynolds Medical History Society.