Taste Really Matters
Do you like the same foods as your mother — a shared yearning for salty pretzels, tart root vegetables, or sweet pastries? If so, you probably picked up your food preferences not as much from what Mom put on the dinner table over the years, but from what she ate during the nine months she was pregnant with you. In the nurture/nature, debate, this is a case where in utero nurturing trumps nature by imprinting food preferences on a fetus that can last a lifetime.
So Kimberly Trout, Ph.D., C.N.M., tells her students at Georgetown University School of Nursing & Health Studies — imparting information she believes isn’t well known among the general population or among healthcare workers who take care of women who are pregnant.
Trout, who came to Georgetown University Medical Center (GUMC) in August as director of the Nurse Midwifery/Women’s Health Nurse Practitioner program, believes that the emerging science of “flavor learning” has widespread public health implications for future control of obesity and diabetes.
“Mothers need to know that what they eat during pregnancy can influence what their children will eat for the rest of their lives,” says Trout. “This represents a real opportunity for women to reduce risk of nutritional disorders in their family.
“When I tell women this, they feel empowered because they want to do whatever they can to improve their baby’s health,” says Trout, who still practices as a midwife, and sees patients every Friday at Pennsylvania Hospital in Philadelphia.
Trout says she is relying on solid evidence on prenatal flavor learning to advise her patients and teach her students. For example, a journal published by the U.S. Centers for Disease Control and Prevention (CDC) issued a peer-reviewed paper in 2009 that detailed taste acquisition and preference that starts in utero. It says researchers have found that amniotic fluid can take on the odors and flavors of whatever mom last ate. Fetuses begin swallowing about a teaspoon of amniotic fluid a day as soon as at 10 weeks of gestation, and fetal taste buds are mature in utero by 13 to 15 weeks. Intake of amniotic fluid increases to an average of nearly two cups a day by the end of term. Evidence also shows that a fetus begins to respond to odors, which are an important component of flavor, at about 28 weeks.
“We know that about 90 percent of flavor is odor, and the link between odor and memory is well established,” Trout says.
The report offered an evolutionary rationale to flavor learning, saying, “The foods that women eat when they are pregnant and nursing are precisely the ones that their infants should prefer because the mothers’ eating them teaches the child that these foods are available, safe, and nutritious.”
“Dr. Julie Mennella, who pioneered the research on flavor learning, suggests that flavor learning prepares babies for the foods of their culture,” Trout adds. (Mennella is affiliated with the Monell Chemical Senses Center in Philadelphia.) The downside is that if that “culture” features fast food and loads of sweets, children will be at higher risk of developing obesity and diabetes, she says, citing one study that found that even before their second birthday, many American toddlers develop the unhealthy eating habits of adults.
Flavor learning is just the latest thread of research that links the fetal environment to development of adult diseases, Trout says. “More and more, researchers are understanding that what happens in the uterus has a huge impact on the rest of a person’s life,” she says.
Trout pulled together a lot of the scientific evidence into a review published online October 22 in the journal, Current Diabetes Report. She hopes the science of flavor learning spreads to obstetricians, midwives, nurses and other care givers and their patients, because there is little evidence that healthcare providers, even those at teaching hospitals, are aware of it.
And, in addition to citing science when she teaches future midwives, Trout can offer some apropos anecdotal evidence. While Trout was pregnant with her daughter, she rigorously followed a strict nutritional plan that she had taped to her refrigerator. The result? “My daughter eats the best diet in the world, and is a wonderful cook.”
Her son? He prefers fast food like chicken wings, the kind of foods Trout ate while working as an intern, working long hours. “I often ate at the Taco Bell right next to the hospital — well before I knew anything about flavor learning.
“When mothers ask me what they should be eating, I have a nice little story to tell them,” Trout says with a laugh.
By Renee Twombly, GUMC Communications