Genetic variations in the sensitivity of taste buds to bitter flavors may help explain why some kids are vehemently opposed to vegetables, a study out Monday suggests.
The study, of 143 children and their mothers, focused on natural variations in a recently discovered gene known as TAS2R38, which governs a taste receptor for bitterness.
For most genes, people carry two active copies - which can vary slightly from one another - on each of two paired chromosomes. Researchers found that moms and kids who carried at least one copy of a “sensitive” form of the gene were typically able to pick up even a hint of bitter flavor in a test drink - with the children being particularly adept at it.
These children were also stronger devotees of sugar and sweetened drinks and cereals compared with their peers who carried two copies of a “bitter-insensitive” form of TAS2R38.
The findings may help explain why some children are particularly tough negotiators when it comes to eating their veggies, the study authors report in the journal Pediatrics.
The study results could also eventually serve up some new answers to the age-old vegetable dilemma, according to lead author Dr. Julie A. Mennella.
“Everyone wants to increase fruit and vegetable intake in children,” Mennella, a researcher at the Monell Chemical Senses Center in Philadelphia, told Reuters Health.
A naturally strong aversion to bitter flavor, she noted, may make children particularly likely to turn up their noses at vegetables. Understanding the complexities of children’s food preferences may aid in figuring out ways to deal with them, according to Mennella.
For example, she said, it’s possible that some added salt could make vegetables more palatable to a naturally bitter-sensitive child.
Parents should remember, however, that children are not miniature adults. “Children are really living in a different sensory world,” Mennella said, noting that babies, for example, are well-known “connoisseurs of sweets.”
This sweet tooth, she said, would seem to be a matter of basic biology in a fast-developing child, since carbohydrates are the body’s prime energy source.
In their study, Mennella and her colleagues found a clear genetic influence over children’s preferences for sugar, but not that of mothers. While children with at least one copy of the bitter-sensitive gene had a bigger sweet tooth than bitter-insensitive children, gene variations were not important in women’s preferences for sweets.
Instead, race and ethnicity were the strongest factors - suggesting, the researchers say, that as people age, cultural and other environmental influences “override” genetic effects on the choice to eat sugary foods.
The study included 143 children ages 5 to 10 and their mothers. The researchers swabbed cell samples from inside the check to analyze variations in the TAS2R38 gene, and tested the mothers’ and children’s sensitivity to solutions containing various concentrations of a bitter-tasting compound. They also questioned the adults and children on their food preferences.
Mennella and her colleagues found that children who had two copies of the bitter-sensitive form of TAS2R38 were best able to detect a “yucky” flavor in the test drinks, even at the most diluted concentration. Next came the kids with one copy of the bitter-sensitive gene.
Similar effects were seen in the mothers - though, when it came to carriers of only one copy of the bitter-sensitive gene, the children were more sensitive than the adults to the least bitter drink.
Overall, 79 percent of the children had one or two copies of the bitter-sensitive form of the gene.
Despite such numbers, though, frustrated parents should not just attribute their children’s resistance to vegetables to the immutable forces of genetics and surrender the dinner-table battle, according to Mennella.
“No,” she said, “I wouldn’t give up.”
SOURCE: Pediatrics, February 2005.
Revision date: July 7, 2011
Last revised: by Janet A. Staessen, MD, PhD