By Stephen Daniells
A mother’s likes and dislikes, particularly for fruit and vegetables, is passed on to her infant during breastfeeding, suggests new research from the US.
A study of 45 infants, just under half of which were breastfed, showed that a baby’s preference for a certain food is dependent on its mother’s tastes, but only if the baby is breastfed, report researchers in this month’s issue of Pediatrics.
The study deepens our understanding of the evolution of taste preferences, and could aid the development of modern tools for both nutritional counselling and food development.
Such research may also help explain why children and adults like and dislike foods and could be important for the understanding of eating problems, such as obesity with over 22 million children under five are severely overweight.
“Vegetable and fruit consumption is linked to lower risks of obesity and certain cancers,” said senior author Julie Mennella from the Monell Chemical Senses Center. “The best predictor of how much fruits and vegetables children eat is whether they like the tastes of these foods. If we can get babies to learn to like these tastes, we can get them off to an early start of healthy eating.”
Mennella and Catherine Forestell recruited four- to eight-month-old infants and randomly assigned them to one of two intervention groups – the first was fed green beans, and the second fed green beans plus peaches for eight days.
During the first exposure, the researchers report that infant intake of peaches was greater if the child were breastfed and the mothers liked peaches. This suggested that the enhanced peach acceptance of their infants might be attributed to increased exposure to fruit flavours through breast milk.
“It’s a beautiful system,” said Mennella. “Flavours from the mother’s diet are transmitted through amniotic fluid and mother’s milk. So, a baby learns to like a food’s taste when the mother eats that food on a regular basis.”
For green beans, there was no difference in intake on the initial exposure between breast- or formula-fed infants, but both groups of mothers reported eating green beans and green vegetables infrequently, at levels below current recommendations
Eight days of repeated green bean exposure led to an enhanced acceptance of the vegetable, increasing intake by almost three-fold, with or without peaches.
“Breastfeeding confers an advantage in initial acceptance of a food, but only if mothers eat the food regularly,” wrote Forestell and Mennella. “Once weaned, infants who receive repeated dietary exposure to a food eat more of it and may learn to like its flavour. However, because infants innately display facial expressions of distaste in response to certain flavours, caregivers may hesitate to continue offering these foods.”
“Babies are born with a dislike for bitter tastes,” explained Mennella. “If mothers want their babies to learn to like to eat vegetables, especially green vegetables, they need to provide them with opportunities to taste these foods.”
Researchers from the same institute previously reported that genetic variants of a bitter taste receptor called TAS2R38 can detect glucosinolates, a class of compounds with potentially harmful physiological actions, in natural foods. This leads to avoidance of these foods (Current Biology, Vol. 16, R792-R794).
Glucosinolate-containing vegetables include watercress, broccoli, bok choy, kale, kohlrabi, and turnip. Many of these vegetables contain compounds that have been linked to lower incidences of certain diseases, most notably cancers, and form an integral part of the ‘five-a-day’ regime. However, studies have shown that many people are falling short of their fruit and vegetable quota, perhaps due to dislike of certain vegetables.
December 2007, Volume 120, Number 6, Pages 1247-1254 (doi:10.1542/peds.2007-0858)
“Early Determinants of Fruit and Vegetable Acceptance”
Authors: Catherine A. Forestell, and Julie A. Mennella