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The Rise of Nutrition

Thanks to advances in genetics, biochemistry, and behavioral studies, a field long considered a secondary science is getting its due. And Penn Nursing faculty and students are taking the lead.

Nutrition lies at the intersection of nursing science and clinical work, behavior, and medicine, and nurses are literally close to the subject. As Penn Nursing lecturer Kerry Shields, MSN, RN, PCCNP, says, “If they’re not eating, we’re feeding.”

Yet most Americans are understandably confused about what constitutes the ideal diet for a family.

Add health issues, time constraints, food ability and affordability, and such factors as culture and personal identity, and the complexity of nutrition can become overwhelming even for well-informed patients. Yet, health care professionals have traditionally been given relatively little education in the science.

Penn Nursing is working to close the health care gap by elevating nutrition’s profile as a leading health science. Working with colleagues throughout the University of Pennsylvania, Nursing faculty and students are pioneering in research that ranges from community health and food availability to studies of gut flora to neuroscience that allows chemo patients to maintain their appetites. “The common thread in human nutrition is food, people, health,” says Karen Glanz, PhD, MPH, George A. Weiss University PIK Professor. She notes that it covers a wide range of health, from human, therapeutic, and community nutrition to nutritional epidemiology.

Nutrition is anything but a one-size-fits-all science. As the old saying goes, one person’s food is another’s poison. Getting a particular patient to eat healthfully depends on a host of factors, starting with taste preferences developed as early as in utero.

And so, as with any good meal, we probably should begin at the beginning.


MATERNITY: Tasting Womb

A mother who wants a child to eat vegetables might start early—very early. “We have good evidence that the child will develop flavor preferences based on the maternal diet,” says Kimberly Kovach Trout, PhD, CNM, APRN, FACNM, assistant professor of women’s health and director of the nurse-midwifery graduate program. Noting that the sense of smell contributes 90 percent of flavor, she points out that odor molecules can travel through amniotic fluid. These molecules not only introduce sensations to the fetus; they can also implant a memory. “We have known for a long time that there’s a link between odor and memory,” Dr. Trout says. “Think Proust in classic literature and the memories evoked by the aroma of madeleine cookies.” Women who undergo amniocentesis after eating garlic have amniotic fluid with a detectable garlic odor. What’s more, infants in utero can detect it. They increase their swallowing when sugar is injected into the amniotic fluid; bitter substances make them swallow less. On the other hand, one study showed that mothers who drank carrot juice in pregnancy had babies accept carrots more readily when they were introduced to solid food. The randomized study videotaped the infants’ expressions; those whose mothers had drunk only water and no carrot juice throughout pregnancy made “yuck” faces more often when confronting their first carrots. “What really stunned me was how few clinicians who work with pregnant women know about this,” Dr. Trout says. She surveyed maternity care staff at a leading teaching hospital and found that 90 percent of the clinicians were unaware of the influence of a maternal diet on infants’ flavor preferences.

CONCLUSION: “Start with in utero preferences,” Dr. Trout says. “You’re more likely to eat the foods you’re exposed to. Part of my mission is to tell clinicians about prenatal and postnatal flavor learning so they can tell their clients.”


INFANCY: Humans Feed Humans

“Think of breastfeeding as a kind of programming,” says Diane Spatz, PhD, RN-BC, FAAN, professor of perinatal nursing and the Helen M. Shearer Term Professor of Nutrition. “Every day a mom is breastfeeding, her milk tastes different, exposing her baby to different tastes. This sets up healthy lifestyle habits.” Formula, on the other hand, has a monotone flavor, offering little in the way of a taste education for an infant.

But of course breast milk contributes far more than increasing the odds of an unpicky eater. A mother naturally tailors macronutrients—proteins, fats, carbohydrates—to her baby’s needs. Human growth hormones in mother’s milk enable tissues to grow appropriately, and may even help prevent lung problems. (Lungs do not fully grow until age eight.) The protein lactoferrin attacks a variety of bacteria and fungi. A breastfed baby is more likely to have a larger brain mass and a smaller BMI. “When the baby is at the breast,” Dr. Spatz says, “the baby regulates how much he needs to take in. When full, he falls off and falls asleep. With formula, the mother is going to try and keep pumping milk into the baby.” Then there are the immunobiological components, including antibodies, along with antioxidants that protect the baby’s eyes, lungs, and brain.

Dr. Spatz says that babies should get human milk exclusively for the first six months. After six months, the mother can introduce complementary foods. How long should breastfeeding continue? American position statements say sixth months to a year or more; authorities in some nations recommend two years or more. “We don’t see a lot of women breastfeeding infants beyond a year in America, because many women don’t even get to six months,” she says. “There’s no sense of urgency during the first two weeks in developing the milk supply.” Besides, women often have to get back to work or school, with little support in the transition. The Children’s Hospital of Pennsylvania is an exception. “We have a very comprehensive employee program at CHOP,” she says. Almost 80 percent of new mothers employed at the hospital breastfeed for six months, with a fifth lasting more than a year. “If we spent more time helping moms meet their goals for the first six months, everybody would be breastfeeding for two years,” she asserts. “It doesn’t get harder; it gets more enjoyable. Many mothers tell me they don’t want to stop.” She notes a paucity of literature about mothers who breastfeed beyond a year—or, for that matter, about tandem breastfeeding with an older sibling and a baby simultaneously.

“Human milk can literally make the difference between life and death,” she says. Take necrotizing enterocolitis; for a baby born critically ill, human milk reduces the likelihood of NEC by 77 percent. The odds of late onset sepsis also get reduced significantly. An ill or preterm baby fed human milk tends to get off IV nutrition more quickly, which in turn reduces the odds of complications, infection, and liver damage.

“You have to think of human milk as a medical intervention that’s as important as a ventilator—a medical necessity,” Dr. Spatz says. “But there’s a laissez-faire attitude toward milk supply” among many clinicians. She says a mother should begin expressing with a hospital grade pump within the first hour, “even after a Caesarian.” This is standard procedure at the Children’s Hospital of Pennsylvania. “At CHOP, we roll the equipment into the operating room immediately after the operation.” She adds: “I can tell you from my experience with CHOP along with research studies and work I’ve done internationally, if we spent more time helping mothers breastfeed in the first two weeks, we would solve most of the world’s breastfeeding problems.”

CONCLUSION: The most critical period of breastfeeding happens in the first two weeks after birth.

CHILDHOOD: Vegging Out

The good news: “It’s never too late” to get a toddler to eat a good diet,” says Kimberly Trout. The bad news: on any given day, according to a large survey, 25 to 30 percent of toddlers eat no fruits, and 20 to 25 percent consume no vegetables. “Repeated exposure to different healthy foods can make a difference,” Trout says.

Associate Professor Tanja Kral, PhD, agrees. “Food neophobia—fear of trying new foods—is one aspect of fussy eating behavior. But picky eating and food neophobia tend to decline with age. Exposing the child to a vegetable 12 to 15 times can increase their liking.” Dr. Kral adds that parents should be advised to offer kids multiple vegetable side dishes. “This gives them ownership in what they’re choosing, and can increase intake of a vegetable,” she says.

Still, picky eating can form a complex science all its own. Dr. Kral has studied sibling behaviors, in which family dynamics play a role in who eats what. Parents modeling healthy eating can help nurture healthy eaters. In addition, the home environment—what parents bring from the grocery store or fast-food restaurants—makes a difference. “How a parent presents a meal, the sizes of plates, cups, and utensils, all can determine how much a child eats,” she says.

For children, “you have to pull in where they are developmentally,” says Sharon Irving, PhD, CRNP, FCCM, FAAN, assistant professor of pediatric nursing. Toddlers, for instance, have finished the greatest growth period of their lives. Babies double or triple their weight in the first 12 to 14 months; that acceleration slows about the same time children start consuming solid food for most of their diet. “People with toddlers say, ‘He won’t eat.’ I say that’s their job,” Dr. Irving says. “They eat on the run, not on a schedule.” 

The child’s weight status becomes a big factor for health care professionals, especially when she has overweight or obesity. “The food environment in the home is especially important” in this case, says Dr. Kral. Have a bowl of fruit available, while leaving chips or cookies as an occasional treat. During meals, try decreasing the size of the entrée while offering two vegetables and one fruit as side dishes. Dr. Kral conducted one study in which children offered a larger portion of unsweetened apple sauce as part of a pasta meal ate 40 percent more of the apple sauce and less of the pasta. On the other hand, increasing the portion size of vegetables did not increase their intake. Still, the pasta itself can be made healthier, by mixing in vegetables, changing the sauce, and lowering the caloric content. Given the right food environment, Dr. Kral says, most children should do fine: “Studies have found that when children are born, they have an innate ability to regulate their intake.” Not all, though. Genetics can come in to play, with obesity requiring a clinical care team. Then there is the obesogenic environment, which can disrupt satiety control.

An old New England tale illustrates the phenomenon: when a poor woman was asked how she managed to feed her eight children, she replied, “I cook what they don’t like and give them as much as they want.” Actually, sensory specific satiety works with likeable food as well. When a child—or an adult for that matter—consumes a meal, the pleasantness of taste declines to the point where he stops eating, even before feeling full. He’s sated, in other words, because his senses are no longer fully stimulated. This is why we tend to eat more at a buffet; the variety of foods keeps us from sensory-specific satiety. The secret is to increase variety through fruits and vegetables, not cookies and ice cream.

CONCLUSION: Advise parents to think of food not just as a meal but as an environment, offering a choice of fruits and vegetables and saving salty, fatty, and sugary foods as treats.


The two most rapid periods of human growth are infancy and puberty. When it comes to an adolescent with obesity, the challenge is to control calorie consumption while ensuring that the patient is getting adequate nutrition. On top of that, teens “are in this space of semi-autonomy, where the family should be involved in weight management,” says Assistant Professor Ariana Chao, PhD, CRNP. “Navigating that dynamic can be challenging.” The stakes are high; four out of five obese teens continue to be obese into adulthood. Only one medication has been approved by the FDA for weight management in youth. Orlistat, a reversible gastrointestinal lipase inhibitor, limits absorption of dietary fat. A more common treatment is behavioral counseling. The U.S. Preventive Services Task Force recommends at least 26 hours of counseling per patient.

“When I help patients, I try to counsel them that weight doesn’t define their self-worth,” Dr. Chao says. “A lot of factors influence their weight, such as genetics and environment. Some of the conversation is helping people not to feel a failure if they gain weight and encourage them to continue to make healthy lifestyle changes.” On the other hand, she adds, “there isn’t a magic pill when it comes to nutrition. It takes time and effort to make healthy lifestyle changes.”

What about diet? Would the diabetic diet help obese patients—adults as well as adolescents? “In 2018, there is no such thing as one diet for people with diabetes,” says Kimberly Trout. “We have largely gone away from rigid prescriptions,” she explains. Some recent research suggests that certain individuals may be able to eat slightly more carbohydrates than in the traditional diabetic diets, so long as those carbs are complex. Certain foods will cause some women to experience a spike in blood sugar while other women show no change—despite taking into account factors such as the glycemic index.

All of which does not mean a clinical nurse can have nothing to say to a patient about diet. “The studies clearly head toward calorie, carbohydrate and portion control for type 2’s,” says Dr. Trout. She points out that the American Diabetes Association’s 2018 clinical guidelines recommend both the Mediterranean and the DASH diets. DASH (Dietary Approaches to Stop Hypertension), promoted by the NIH’s Heart, Lung & Blood Institute, is rich in fruits and vegetables, supports low-fat dairy intake, and limits sodium. Besides lowering hypertension even in patients who failed to lose weight, the DASH diet reduces hypertension disorders among pregnant women, according to Professor of Nutrition Sciences Charlene Compher, PhD, RD, CNSC, LDN, FADA, FASPEN.

When it comes to dietary behavior, though, the key is mindfulness, notes Dr. Chao. Perhaps one of the greatest diets of all is the legendary Poet’s Diet. As the story goes, an obese poet visits his doctor, who tells the man he will die unless he can control his caloric intake. “I’ve tried every diet,” the poet replies. “Nothing works for me.” The doctor tells him to forget the diets he has heard of, and tells him instead simply to write down every single thing he eats that month. The poet goes home, instinctively grabs a bag of potato chips…and pauses. Does this poet really want the first line to be potato chips? He’s a poet. First lines count. He agonizes for hours on the perfect first line of food, and chooses a carrot and a perfectly ripe, glistening peach. Then he ponders for the next few hours on the second line—the food that will continue his manuscript for the next month. By the time he comes back to the doctor, he has lost impressive weight.

CONCLUSION: What’s good for many obese and diabetic patients—namely, a diet with plenty of fruits and vegetables and low in saturated fats–is generally good for healthy adults.


THE SCIENCE: Food at the Molecular Level

“When i started clinical practice many years ago,” Dr. Compher says, “I used to have to try to sell people on the importance of nutrition. I don’t have to do that anymore. Biology keeps drilling down and finding relationships between nutrients and health in every direction.” Then there is the burgeoning field of  epigenetics, showing how genes can be modified with vitamin intake. “It’s a field that has taken off in the past ten years,” Dr. Compher says. “I will be watching that area avidly for just how it is that nutrient intake can affect gene transcription throughout the whole body.” Add to epigenetics the research being done at Penn
and elsewhere on precision nutrition, which promises to enable practitioners to personalize a diet according to the patient’s genetic makeup. Algorithms are being devised to predict an individual’s blood sugar level after a meal. Other researchers are studying metabolic pathways and the gut microbiome.

Even neuroscience is entering the picture. Associate Professor Bart De Jonghe, PhD, associate director of nutrition science programs, is studying the signals in the brain associated with appetite, nausea, and vomiting. “These are complex neurobiological systems,” he says. “If you’re eating a Thanksgiving dinner and you’re full, feeling bloated, that’s a different sensation from feeling nausea from food poisoning at three a.m.”

Dr. De Jonghe and his colleagues have been working to disentangle that neurobiology, identifying various areas of the brain that are anatomically and chemically connected to control these behaviors. The research shows promise for cancer patients suffering from nausea and from the metallic taste many get from chemo. “You can selectively deliver drugs to the brain post-chemotherapy,” he says. “And you can isolate the brain area that’s dramatically activated by a drug that causes nausea or vomiting, and block chemical transmission between those sites.” He is currently experimenting with a diabetes drug developed by a collaborator, which attaches B-12 to the formula. The vitamin prevents entry of the drug into the brain, reducing nausea almost 80 percent while maintaining the hypoglycemic profile. “I believe that, ideally, no drug should have any side effects,” he says. “Every drug should do what it’s supposed to do, and exactly nothing else. I’m optimistic about designing next-generation drugs that come close to this standard—that are better tolerated by patients.”

Biochemical and genetic research in nutrition has obvious utility in intravenous feeding, a specialization of Dr. Compher’s. “We know that what we give patients has to be the same type of nutrients that they need in their bloodstream,” she says. “If you ate a hamburger today, you would digest it and break it down into amino and fatty acids; you’d break the bun down for the glucose; and there would be micronutrients. All that would enter into your system.” If a chunk of hamburger got introduced directly into your bloodstream, on the other hand, “you’d have an allergic reaction,” she says. To complicate matters, Dr. Compher and her colleagues—including a nurse clinical specialist, an NP, and a physician—work with patients with severe Crohn’s disease, which is on the increase both in the U.S. and globally. “It’s a disorder associated with genetic risk,” she says. “But there’s also an environmental feature, dysbiosis, an abnormal response to bacteria in the G.I. tract,” she says. “It’s possible that our modern diet is partially to blame. We’re trying to find whether some foods are triggers.” The team must design and order intravenous feedings for Crohn’s patients whose absorption is too limited for them to survive on their own. In addition, the team works with patients with short bowel syndrome following surgery for intestinal vascular disease. The team provides clinical management of nutrition for CHOP children who have needed intravenous feeding since infancy and have been transferred when they became adults. And they work with patients with mitochondrial syndromes that result in bowel malfunctions, as well as some cancer patients undergoing chemotherapy. “Each patient presents a unique problem requiring a unique feeding,” she says. “My role as a clinical dietitian is to make sure we’re meeting the nutrient requirements while not giving toxic levels of anything.” For example, she says, “we have to make sure we don’t give them so much of a metal that they store it in a part of the body where it shouldn’t be.”

CONCLUSION: Eventually, clinical nurses will work with teams to individualize nutrition based on personalized genetics, microbiotic traits, and behavioral characteristics.

COMMUNITY HEALTH: The Social Determinants

Terri Lipman, PhD, CRNP, FAAN, Miriam Stirl Endowed Term Professor of nutrition, spent years as a nurse practitioner trying to educate families to change their food behavior. “I did this without an appreciation for the root causes of poor nutrition in under-resourced families”: food insecurity and insufficient access to good food. “Both obesity and food insecurity disparately affect families living in poverty,” she says. “There are areas of Philadelphia that are second only to the Bronx in rates of child hunger.” While health care focuses on addressing genetics, biology, and behavior, she says, “these factors together account for only about 25 percent of health outcomes. Social determinants of health represent the remaining 75 percent.”

Eating unhealthful food is not just a matter of cost per calorie—the common belief that the high obesity rate among residents of low-income neighborhoods is necessarily caused by lower expense of calorie-dense foods. “Some fruits and vegetables are not that expensive,” Dr. Lipman says. “But if you have to travel on several buses to a supermarket that sells fresh produce, while around the corner from your home is a store with easily accessible high calorie packaged food, you’re going to go where the food is the most easily accessed.”

Behavioral approaches can be perceived as placing blame on families. “The notion that under-resourced families have the time, money, and necessary transportation to buy fresh fruits and vegetables—that’s unrealistic. And it makes us complicit in ignoring factors that lead to lack of access to healthy food.”

And food itself is not the only key determinant of a family’s nutrition. “A family’s total income doesn’t define whether they can comfortably afford foods that are healthful for their family,” she says. “Other costs of living, such as housing, clothing, and transportation are all competing for the same money—sometimes leading to an inadequate food budget.”

Terri Lipman agrees. “For a family with housing insecurity, buying fruits and vegetables may not be high on their priority list.” She directs much of her research and clinical attention to West and Southwest Philadelphia, areas with high levels of poverty. The key to having families eat healthier food? “Community engagement,” she says. Noting that community gardens in particular have been successful in promoting a sense of ownership, she points out the success of Bartram Gardens in Southwest Philly, where high school students and residents till a working farm. “The community has easy access to those fruits and vegetables,” she says. “They feel a sense of ownership. They feel welcome. It’s very different from taking a few buses to a grocery store that may be crowded, unfriendly, and has no connection to the community.”

A second answer: financial support. Penn Nursing faculty are working on a grant proposal that links anchor institutions with the community, providing backing for full grocery stores in food deserts.

A third answer: nutrition education that recognizes the importance of introducing healthful foods in innovative ways. Penn nurse practitioner students work with high school students in the Netter Center’s Agatston Urban Nutrition Program to bring healthful eating to the community. When the subject of cauliflower came up among elementary school children, the response was a definite no. Next meeting, the Agatston Program high school students brought the children a dish of mashed cauliflower. “The kids said, ‘These are the best mashed potatoes we’ve ever had.’” Dr. Lipman’s nursing students hand out recipes that connect with foods of various cultures, substituting healthful ingredients that blend in with the accustomed taste. Similarly, the high school students in the Agatston Program came to a physical activity program with large coolers filled with fruit-flavored water—strawberry, watermelon, and lemon. “Community members said they never knew water could be so delicious,” she says. “The idea came from youth in the community demonstrating that water can compete with the sugary beverages that strongly contribute to obesity.”

CONCLUSION: Behavioral and biophysical approaches alone won’t solve America’s nutrition problems. Food is a social phenomenon.

NURSING EDUCATION: On Par with Physics?

You need look no further than Penn to see nutrition’s elevation as a major science. Penn Nursing started its nutrition minor, jointly shared with Arts & Sciences, in 1995, and more than 315 students have graduated with it, taking three electives ranging from growth and development to genetics to diabetes. The second major in nutrition science began in the 2017 academic year; ten have graduated. An additional 70 are currently enrolled in either the second major or the minor. “In the nutrition classrooms, our nursing students enjoy integrating with every other major on campus that you can imagine,” says Dr. Compher, who directs nutrition programs. “It’s a rich learning environment.” She tries to incorporate students into clinical applications and includes some in her own research.

Bart De Jonghe, who works with Dr. Compher as assistant director of nutrition programs, tells students that “nutrition courses will put you ahead of everyone else.” He notes that the average person eats 30,000 meals in a lifetime. “Being armed with nursing science and nutrition science, that really gives you a handle for working with patients in ways that encompass the spiritual, the mental, and the physical. That’s a person’s overall health. If you understand what food means to someone, what it means to prevent nutritionally related disease—that has a lot of legs when you’re in a treatment setting.” He adds: “I’d love to see nutrition science held in the same regard as physics or biology.”

To see how well nutrition education works for students, we called two 2018 BSN double majors, Charis Anderson, RN, and Rachael Peters, RN, and asked each for her take on the popular Keto diet (short for “ketogenic”). The diet has its users reduce carbs to 5-10 percent of calories and protein to 15-30 percent while increasing fat consumption to 60-75 percent, with the promise that the body would go into ketosis and convert fat into energy. Each student spoke like a good scientist, explaining the theory behind the diet and its risks without actually coming out and saying the diet is a terrible idea. “I prefer reading research articles over trusting nutrition information shared in the news,” Peters said. “Penn taught me not to trust everything—to make sure that everything is evidence based.” She noted that one class on nutritional neuroscience consisted of analyzing research articles. “It was really eye-opening,” she said. “Our professor wanted us to see that the author may say one thing and the data may say another.”

Charis Anderson used the diet as a way to show the problems with fad diets in general. “It’s like you’re picking what you want while sacrificing other aspects of your health,” she said. “In this case you may be choosing weight loss at the expense of your cardiovascular health.” On the other hand, she noted that refractory epilepsy can be treated with a Keto diet. “That blew my mind. It can be helpful. But I was a Penn student so the moment I heard that I jumped on the research, and I was seeing so much connection to cardiovascular compromise. Plus, your brain wants glucose for fuel, not ketone bodies. Any understanding of physiology should indicate that maybe it’s not a longterm solution. It’s not balanced.”


“We talk about balance all the time,” Anderson said.

And what will they do with their nutrition knowledge? Anderson spent the summer after graduation at a tech startup in San Francisco, working on an online platform for travel nurses. In September she began a new job as an RN in oncology and hematology at Lucille Packard Children’s Hospital, with Stanford Healthcare. Peters is beginning a two year stint as an RN in the intensive care unit at Penn Princeton Medical Center, a work commitment that came with her Sands Scholarship at Penn. While neither seems directly aimed toward a nutrition career, Peters emphasizes the deeper benefits of the double major. “We really learned down to the foundation of why disease occurs. Take cardiovascular disease; learning about oxidative stress helped me understand how plaque builds up in the body. Studying metabolism gave me new insights into how we create and utilize biology. Other classes gave me a perspective into nutrition in the clinical setting and helped me explore the impact of food insecurity.”

Anderson summed it up: “Nutrition and health care aren’t separate topics,” she said. “I couldn’t stop studying nutrition, because nutrition is health care.”

CONCLUSION: Nutrition is integral to health care, and Penn Nursing is responding.