The research could lead to ways to prevent disease where diet is a factor, says a Yale University psychologist familiar with the study.
"One of the most consistent aspects of culture are food habits, and we suspect that those habits begin very early in life. And a lot of animal studies suggest that pre-natal and early post-natal exposures to flavor influences later responses," says Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia.
To test the theory, Beauchamp and lead study author Julie Menella used three groups of pregnant mothers planning to breast-feed.
One group drank carrot juice four days a week for three weeks during the last three months of pregnancy, and then water while breast-feeding. A second group drank water while pregnant and carrot juice during lactation. And a control group of women drank water while pregnant and breast-feeding.
When the mothers introduced solid food to their infants, the researchers videotaped the babies while feeding them cereal made with water or cereal made with carrot juice.
"Carrot was chosen because it has a fairly innocuous flavor, and we knew from prior experience that the flavor gets into human milk, and we assumed that it gets into amniotic fluid," Beauchamp says.
The infants exposed to carrot flavor "exhibited less negative and more positive expressions, and the recording of the facial expressions was done by independent observers who did not know which group the baby was in," Beauchamp says.
The findings appear in the June issue of Pediatrics.
Beauchamp says mothers who "eat a variety of different flavored food during pregnancy and during breast-feeding" may have children "more willing to accept a wider variety of tastes later on."
Linda Bartoshuk, a professor of surgery and psychology at Yale University, says, "Understanding how food preferences are acquired would be an enormous boon for public health and could lead to a way to prevent disease."
"If you can affect the food preferences of a child in the uterus and during breast-feeding, and you can affect those food preferences for the adult that child turns into, you might be able to influence the kinds of disorders where diet is a factor," she says.
Bartoshuk calls the new research "top of the line."
"The scientists who did this research are very smart -- real pioneers in this area. Understanding the big picture of how humans acquire taste may also help us understand what factors are involved in human food behavior, which is a very complex subject with tremendous health implications."