Pregnant and nursing mothers have new reason to eat well, suggests a new study.
Flavors in a mom's diet shape her baby's brain, the study found, and that may alter her child's lifelong likes and dislikes for certain foods. The findings could help mothers start as early as possible to turn their children into healthy eaters.
"It's clear in humans that the more varied nutrition of the mom, the more open the baby is going to be to different things," said Diego Restrepo, a neuroscientist at the University of Colorado, Denver. "What's new here is that what a mother eats changes the brain of her baby."
Scientists have long known that, for humans and other mammals, what a mother eats influences the flavor of her amniotic fluid and later her breast milk, said Julie Mennella, a biopsychologist at Monell Chemical Senses Center in Philadelphia. Research has also shown that the flavors babies are exposed to -- both in the womb and in the months after birth -- influence what they later choose to eat.
In one of Mennella's studies, for example, mothers who drank carrot juice during pregnancy or while nursing had babies who, by about six months of age, chose to eat larger amounts of carrot-flavored cereal compared to babies whose mothers had drunk only water during pregnancy. The carrot-exposed babies also made fewer negative faces while eating the flavored cereal.
In the new study, Restrepo and colleagues fed a variety of diets to pregnant mice. Some mouse moms got a standard, mostly flavorless chow. Others ate food that was spiked with a strong flavor, such as cherry or mint. Three weeks after birth, when weaning was complete, the researchers allowed the babies to sniff at scented or unscented food pellets during a series of three-minute trials.
Babies born to mothers that had eaten mint-flavored food spent about 70 percent of the time in their trials sniffing at mint-scented pellets, the researchers reported in the journal Proceedings of the Royal Society B. Prenatal cherry exposure had the same effect on a baby's desire to smell cherry-scented foods. Those numbers were about the same whether moms had eaten the flavors while pregnant, nursing or both.
Babies of the less daring eaters, on the other hand, only spent 30 percent of their time sniffing at the strong scents. Those results confirmed what earlier studies have found. To take the research one step further, the scientists also looked into the brains of the baby mice.
In particular, they focused on structures called glomeruli, which are receptors that respond to individual odors and from there, send messages to the brain about what you just smelled. One glomerulus, for example, reacts to the odor of mint. Another reacts to cherry. And odors, scientists now know, are the root of flavor and taste.
In the mice that had been exposed to a strong flavor through their mothers, results showed that the glomeruli for that odor were 50 percent bigger compared to mice that hadn't been exposed.
Those brain differences could offer a biological explanation for why children might be more receptive later in life to the flavors they experience in their earliest months.
The study also gives insight into one of the very first ways we learn about what to eat. In our ancestors and in other mammals, the system probably evolved to make sure babies only ate what was safe and healthy for them.
For humans today, the new insights could help guide women as they make some of their very first parenting decisions.
"It's a beautiful, beautiful system that confers an advantage to a baby learning about foods," Mennella said. "The earliest and best way for women to start is to enjoy these healthy, nutritious diets rich in fruits and vegetables while pregnant and lactating. The consequences are going to be far-reaching."