Prenatal and Postnatal Influences on Fruit and Vegetable Acceptance throughout Childhood
The establishment of a balanced diet early in life that includes adequate intake of fruits and vegetables lays an important foundation for long-term physical, cognitive and emotional health. Because fruit and vegetable intake is associated with prevention of several noncommunicable diseases such as obesity1 and cancer,2 various health authorities recommend consumption of five to ten servings daily.3, 4 However, adults’ intake of fruits and vegetables remains substantially below recommended levels.5,6 Moreover, recent evidence indicates that these poor eating habits begin early in life.
By two years of age, many children are eating too many sweet and salty snacks, which are displacing healthy alternatives like fruits and vegetables.7, 8 As most parents and caregivers will testify, increasing young children’s fruit and vegetable consumption can pose a considerable challenge, since their food intake is controlled by a myriad of innate predispositions and individual preferences. For example, because children are innately predisposed to dislike bitter tastes,9,10 they typically avoid cruciferous and leafy vegetables.
Children also have an innate preference for sweet tastes that persists throughout infancy and childhood.11, 12
Although fruits are predominantly sweet, they are also avoided likely because of the widespread availability of a variety of highly palatable, energy-dense alternatives such as sweetened beverages and desserts.
Another significant predictor of low fruit and vegetable intake is neophobia,13, 14 or the innate tendency to reject new foods,15 which is especially prevalent between two and three years of age.16 While these innate predispositions likely evolved, in part, to attract children to familiar sources of calories and avoid bitter-tasting toxins, in our current environment they can lead to maladaptive feeding patterns that result in reduced dietary variety and inadequate nutrition. However, as will be discussed in this article, early flavor experiences which occur during gestation and lactation may interact with these innate predispositions to enhance children’s flavor preferences and improve long-term eating habits.
Early Flavor Learning
Psychophysical studies have shown that children’s first exposure to flavors occurs before birth in the intrauterine environment. Flavors of foods within mothers’ diets, such as garlic,17 alter the odor of amniotic fluid, which is swallowed and inhaled by the fetus by the last trimester of pregnancy. After birth, exposure to these flavors continues, since the flavor of breast milk also reflects the mothers’ dietary choices.18
These flavor changes in amniotic fluid and breast milk are not only perceived by the fetus and infant respectively, but they bias preferences after birth as well.19, 20
This has been demonstrated experimentally in a study in which infants, whose mothers consumed carrot juice either during pregnancy or the first two months of lactation, displayed fewer negative responses while eating carrotflavored cereal when compared to plain cereal at six months of age.21
These early exposures to flavors within the mothers’ diet may serve to heighten children’s hedonic responses to these flavors when they are later experienced in foods at weaning. Exposure to dietary flavors in amniotic fluid and breast milk may be one way that infants learn which foods are "safe", thereby reducing food neophobia and increasing infants’ readiness to accept new flavors. In one study, when infants were fed a green vegetable daily over a 10-day exposure period, breastfed infants increased their acceptance of the green vegetable more dramatically than formula-fed infants.22
Further research has shown that these early feeding experiences may have long-term consequences. For example, girls who were breastfed for at least six months were less likely to be picky eaters at 7 years of age.23
One explanation for these findings is that unlike formula feeding, which exposes infants to a monotony of flavors, breastfeeding provides varied sensory experiences, which may facilitate diet diversity throughout development.
Although more research is needed to understand how early experiences affect later consumption of foods such as fruits and vegetables, it appears that repeated exposure to a variety of flavors within amniotic fluid and breast milk enhances children’s acceptance and preference for novel foods at weaning. Because the development of preferences for healthy food choices begins during gestation and breastfeeding, it is the first, but not the only way in which children learn about the foods that are accepted and preferred by their mothers. As children grow and mature, the effects of these early experiences interact with a host of other factors, many of which are determined by children’s parents. Factors, such as genetic make-up (i.e., sensitivity to bitter tastes),24 childfeeding strategies,16, 25 food availability26 and social modeling of healthy eating habits27 are just a few of the variables that interact and contribute to the development of life-long preferences for fruits and vegetables and healthy eating patterns in general.
- McCrory MA et al. Am J Clin Nut 1999;69:440-7.
- Willett WC & Trichopoulos D. Cancer Causes & Control 1996;7:178-80.
- WHO. Technical Report Series No. 916. Geneva, 2003.
- US DHHS/USDA. Dietary Guidelines for Americans 2005. 6th ed. Washington, DC: US Government Printing Office; January 2005.
- Patterson BH et al. Am J Pub Health 1990;80:1443-9.
- Thompson B et al. J Am Diet Assoc 1999;99:1241-8.
- Fox MK et al. J Am Diet Assoc 2004;104:s22-30.
- Birch LL. J Nut Educ 1979;11:189-192.
- Steiner JE. Facial expressions of the neonate infant indicating the hedonics of food-related chemical stimuli. In: Weiffenbach JM, ed. Taste and Development: The Genesis of Sweet Preference. Washington, DC: U.S. Government Printing Office, 1977.
- Kajiura H et al. Dev Psych 1992;25:375-86.
- Desor JA et al. Preference for sweet in humans: infants, children and adults. In: Weiffenbach JM, ed. Taste and Development: The Genesis of Sweet Preference. Washington, DC: US Government Printing Office; 1977:161-72
- Pepino MY & Mennella JA. Chem Senses 2005;30:319-20.
- Cooke L et al. Appetite 2003;41:95-6
- Wardle J et al. J Am Diet Assoc 2005;105:227-32.
- Rozin P. The selection of food by rats, humans and other animals. In: Rosenblatt R et al (eds). Advances in the study of behavior. New York: Academic Press, 1976; 21-76.
- Birch LL et al. Appetite 1987;9:171-8.
- Mennella JA et al. Chem Senses 1995;20:207-9.
- Mennella JA. J Hum Lact 1995;11:39-45.
- Hepper P. Int J Prenat and Perinat Psych Med 1995;7:147-51.
- Schaal B et al. Chem Senses 2000;25:729-37.
- Mennella, JA et al. Pediatrics 2001, 107: e88.
- Sullivan SA & Birch LL. Pediatrics 1994;93:271-7.
- Galloway AT et al. J Am Diet Assoc 2003;103:692-8.
- Mennella JA et al. Pediatrics 2005;115:e216-22.
- Sturm R & Datar A. Metropolitan Area Food Prices and Children’s Weight Gain U.S. Department of Agriculture, Economic Research Service, Contractor and Cooperator Report #14, December 2005. (Accessed March 21, 2006 at http://www.ers.usda.gov/Publications/CCR14/ )
- Fisher JO et al. J Am Diet Assoc 2002; 102:58-64.
- Brown R & Ogden J. Health Educ Res 2004;19:261-71.