Factors contributing to individual differences in sucrose preference.

Abstract

Although heightened throughout childhood and adolescence, sweet taste preference declines during late adolescence (Desor et al., 1977; Desor and Beauchamp, 1987). Despite such age-related changes in sweet preferences, individual variation, due to both genetics (Bartoshuk, 2000) and experience (Beauchamp and Moran, 1982, 1984), exists at both ends of the age spectrum (Desor et al., 1977; Beauchamp and Moran, 1982). For example, infants and teenagers of African descent preferred significantly higher levels of sucrose when compared to similarly aged Caucasians (Desor et al., 1977; Bacon et al., 1994). Moreover, experience with sugar water during infancy results in greater preference for sweet tastes during the second year of life (Beauchamp and Moran, 1984). The goal of the present study was twofold. First, we determined whether racial and ethnic differences in sweet preference are present during childhood and adulthood. Secondly, we explored whether early exposure to sweetened water modifies sweet preferences during childhood. We tested 62 children and 55 mothers of African-American, non-Hispanic descent and 66 children and 56 mothers of non-Hispanic, European descent, hereafter referred to as Black and White, respectively. Included in this sample were 17 sibling pairs. The children ranged in age from 6 to 10 years (mean = 7.8 ± 0.1 years) and the mothers were, on average, 36.0 ± 0.6 years. Each child’s race/ethnicity was defined by mother’s report of the racial background of both herself and the biological father, according to standard US Census categories. All children and parents were racially concordant. We use the term race/ethnicity herein when describing our groups because it best represents both the genetic and cultural components of the sample (Sankar and Cho, 2002). All testing procedures were approved by the Office of Regulatory Affairs at the University of Pennsylvania and informed consent was obtained from each mother and assent from each child 7 years of age or older. Children and their mothers were individually tested with identical procedures to allow for comparisons. A forced-choice, paired comparison, tracking technique which avoids response bias was used to assess sucrose preferences (Cowart and Beauchamp, 1990). In brief, subjects were presented with pairs of solutions differing in sucrose concentration (0.09, 0.18, 0.35, 0.70 and 1.05M). They were asked to taste the solutions without swallowing and point to which of the pair they liked better. Each subsequent pair was then determined by the subject’s preceding preference choice. The entire task was then repeated with stimulus pairs presented in reverse order. The most preferred solution for each subject was the geometric mean of the sucrose concentrations chosen during the two trials. Mothers were queried about several socio-demographic variables and all but 20 answered questions regarding the practice of feeding sweetened water to their children when they were infants. From these latter data, two groups were formed: those who were frequently fed sweetened water and those who were never or rarely (<10 times) fed sweetened water. Children were weighed and measured for height (Detecto Model 439, Physician Scale; Webb City, MO) and body mass index (BMI, kg/m2) was computed. Black mothers were significantly younger (33.6 ± 0.8 versus 38.4 ± 0.7 years) and more likely to be single (71% versus 2%), with lower household incomes and fewer years of education (13.4 ± 0.2 versus 14.8 ± 0.3 years) when compared to White mothers (all Ps < 0.001). There were significant effects of race/ethnicity on children’s age (P < 0.025); Black children were older (8.1 ± 0.2 years) than White children (7.4 ± 0.1 years). No statistical differences were observed between the two groups in the children’s BMI categories, however. Despite the various demographic and age differences between the two racial/ethnic groups, further analyses revealed that none of these measured demographic factors were significantly related to the level of sucrose preferred by either children or adults. As a group, children preferred significantly higher concentrations of sucrose than mothers [t(237 df) = 4.07, P < 0.0001]. Black children (P < 0.001) and mothers (P < 0.001) preferred significantly higher concentrations of sucrose than White children and mothers, respectively (see Figure 1). Although 38% of the Black children were routinely fed sugar water as babies, this custom was experienced by only 6% of the White children [ χ2(df = 1) = 16.50, P < 0.0001]. However, regardless of race/ethinicity, early exposure to sugar water was related to the level of sucrose preferred during childhood [ t(106 df) = 2.20; P = 0.03]. Children who were routinely fed sugar water during infancy preferred significantly higher levels of sucrose (0.66 ± 0.07 M) when compared to those who were rarely or minimally exposed (0.48 ± 0.04 M). Consistent with previous findings in infants (Beauchamp and Moran, 1982) and