Our goal was to evaluate the effects of breastfeeding and dietary experiences on acceptance of a fruit and a green vegetable by 4- to 8-month-old infants.
METHODS. Forty-five infants, 44% of whom were breastfed, were assigned randomly to 1 of 2 treatment groups. One group was fed green beans, and the other was fed green beans and then peaches at the same time of day for 8 consecutive days. Acceptance of both foods, as determined by a variety of measures, was assessed before and after the home-exposure period.
RESULTS. During the initial exposure, infants ate more calories from peaches than from green beans. Breastfed infants showed greater liking of peaches, as did their mothers, who ate more fruits in general than did mothers who formula fed. Although formula-feeding mothers ate more green beans, there was no difference in their infants’ acceptance of this vegetable. For breastfed and formula-fed infants, repeated dietary exposure to green beans, with or without peaches, resulted in greater consumption of green beans (56.8 vs 93.6 g). Only infants who experienced green beans with peaches displayed fewer facial expressions of distaste during feeding. Mothers were apparently unaware of these changes in acceptance.
CONCLUSIONS. Breastfeeding confers an advantage in initial acceptance of a food, but only if mothers eat the food regularly. Once weaned, infants who receive repeated dietary exposure to a food eat more of it and may learn to like its flavor. However, because infants innately display facial expressions of distaste in response to certain flavors, caregivers may hesitate to continue offering these foods. Mothers should be encouraged to provide their infants with repeated opportunities to taste fruits and vegetables and should focus not only on their infants’ facial expressions but also on their willingness to continue feeding.
Because consumption of vegetables and fruits is linked to lower risks of obesity and certain cancers, health organizations throughout the world recommend 5 to 13 servings of fruits and vegetables per day, depending on caloric intake. Despite such recommendations, adults are not eating enough fruits and vegetables, and neither are children. The 2004 Feeding Infants and Toddlers study, which was designed to update knowledge on the feeding patterns of US children, alarmingly revealed that toddlers ate more fruits than vegetables and 1 in 4 did not consume even 1 vegetable on a given day. They were more likely to be eating fatty foods and sweet-tasting snacks and beverages and less likely to be eating bitter-tasting vegetables. None of the top 5 vegetables consumed by toddlers was a dark-green vegetable.
From the perspective of the ontogeny of taste,6,7 these data are not surprising because of the functional importance of taste in nutrient selection, especially in children. It has been hypothesized that preferences for sweet tastes evolved to solve a basic nutritional problem of attracting children to sources of high calories during periods of maximal growth, whereas bitter rejection evolved to protect against poisoning, because many toxic substances are bitter and distasteful by nature. Consequently, preferences for foods (eg, dark-green vegetables) and beverages (eg, coffee) that taste bitter are largely learned.
When asked whether there is an optimal way to introduce fruits and vegetables into infants’ diets, health professionals are faced with a difficult challenge because of the paucity of evidence-based research. Many research studies that revealed relationships between food habits in childhood and those later in life were correlational in nature and consequently inconclusive. Because of the lack of research, many feeding practices are based on idiosyncratic parental behavior, family traditions, or medical lore. Such lore relates that infants should not have any experience with fruits before they are introduced to green vegetables, because their inherent sweet preferences might interfere with acceptance of foods that taste bitter. Although no data support the contention that experience with fruits hinders vegetable acceptance, there is evidence suggesting that other early experiences promote healthy eating patterns.
The first type of experience results from the mother’s eating habits during pregnancy. Specifically, prenatal experiences with food flavors, which are transmitted from the mother’s diet to the amniotic fluid, lead to greater acceptance and enjoyment of those foods during weaning. In an experimental study, infants whose mothers were assigned randomly to drink carrot juice during the last trimester of pregnancy enjoyed carrot-flavored cereals more than did infants whose mothers did not drink carrot juice or eat carrots.
Similar findings were observed for infants whose mothers were assigned randomly to drink carrot juice during lactation, which leads us to the second type of experience, namely, breastfeeding. If their mothers eat fruits and vegetables, then breastfed infants learn about these dietary choices, because a variety of food flavors are transmitted to human milk. These varied sensory experiences with food flavors may help explain why breastfed infants are less picky and more willing to try new foods which contributes to greater fruit and vegetable consumption in childhood.
The third type of experience, which occurs once children begin eating solid foods, involves repeated dietary exposure. Children became more accepting of a food after repeated exposure. Merely looking at the food was not sufficient. Children had to taste the food to learn to like it.
The present study followed from this body of research and was designed to elucidate some of the factors that contribute to acceptance of a green vegetable and a fruit initially and after different types of dietary exposure. Three hypotheses were tested. First, we hypothesized that, relative to formula-fed infants, breastfed infants would be more accepting of a novel food, but only if their mothers consumed such foods regularly. Second, we hypothesized that repeated exposure to green beans would lead to greater acceptance of that food. Third, we hypothesized that infants would be more accepting of green beans if their previous dietary experience with this food was associated with a fruit, because research reveals that liking for a bitter-tasting vegetable or beverage is enhanced if it is associated with sweet tastes.
Catherine A. Forestell, PhD and Julie A. Mennella, PhD
Monell Chemical Senses Center, Philadelphia, Pennsylvania
Published online November 30, 2007
PEDIATRICS Vol. 120 No. 6 December 2007, pp. 1247-1254 (doi:10.1542/peds.2007-0858)