Early Determinants of Fruit and Vegetable Acceptance

Abstract

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.
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.
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.
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.

Full text

Early Determinants of Fruit and Vegetable Acceptance
Catherine A. Forestell, PhD and Julie A. Mennella, PhD
Monell Chemical Senses Center, Philadelphia, Pennsylvania
Abstract
OBJECTIVE—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.
Keywords
breastfeeding; flavor; fruits and vegetables; nutrition; infants
Because consumption of vegetables and fruits is linked to lower risks of obesity and certain
cancers,
1
health organizations throughout the world recommend 5 to 13 servings of fruits and
vegetables per day, depending on caloric intake.
2,3
Despite such recommendations, adults are
not eating enough fruits and vegetables,
3
and neither are children.
4,5
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.
4,5
None of the top 5 vegetables consumed by toddlers was a dark-green vegetable.
5
Address correspondence to Julie A. Mennella, PhD, Monell Chemical Senses Center, 3500 Market St, Philadelphia, PA 19104-3308. E-
mail: mennella@monell.org.
Dr Forestell’s current affiliation is Department of Psychology, College of William and Mary, Williamsburg, VA.
The authors have indicated they have no financial relationships relevant to this article to disclose
NIH Public Access
Author Manuscript
Pediatrics. Author manuscript; available in PMC 2008 March 18.
Published in final edited form as:
Pediatrics. 2007 December ; 120(6): 1247–1254.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

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,
8
whereas
bitter rejection evolved to protect against poisoning, because many toxic substances are bitter
and distasteful by nature.
9
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.
10,11
Many research studies that revealed relationships between food
habits in childhood and those later in life were correlational in nature
12,13
and consequently
inconclusive.
11
Because of the lack of research, many feeding practices are based on
idiosyncratic parental behavior, family traditions, or medical lore.
14,15
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,
16
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.
17
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.
17
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.
18,19
These varied sensory experiences with food flavors may help explain why breastfed infants
are less picky
20
and more willing to try new foods,
21,22
which contributes to greater fruit and
vegetable consumption in childhood.
13,23,24
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.
16,22
Merely looking at the food was not sufficient. Children had to taste the food to learn to
like it.
25
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.
26,27
Forestell and Mennella Page 2
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

METHODS
Subjects
Forty-five mothers whose infants had been born at term and healthy and were between the ages
of 4 and 8 months were recruited through advertisements in local newspapers, breastfeeding
support groups, and the Supplemental Nutrition Program for Women, Infants, and Children in
Philadelphia, Pennsylvania. Twenty of the mothers in this study were Supplemental Nutrition
Program for Women, Infants, and Children participants, 12 of whom had some college
education and 10 of whom breastfed their infants. The ethnicity of the subjects was 36.4%
black, 45.5% white, 6.8% Hispanic, and 11.4% other/mixed ethnicity.
Only infants who had been weaned to cereal but had very little experience with fruits and
vegetables qualified for the study. At the start of the study, infants had been eating cereal for
6.7 ± 1.6 weeks. Ten of the infants had been fed bananas, applesauce, or an orange vegetable
1 or 2 times, and 1 ate bananas daily. None had exposure to green beans, and only 1 had tasted
peaches. Twenty of the infants were currently breastfeeding and had been breastfed exclusively
for at least the first 2 months of life, whereas 21 were formula fed and had no or very little (ie,
<7 days) experience with breastfeeding. The remaining 4 infants were both breastfed and
formula fed. The Office of Regulatory Affairs at the University of Pennsylvania approved all
procedures, and informed consent was obtained from each mother.
Procedures
To accustom infants to some aspects of the testing procedures, mothers were sent some items
(eg, bib) to use during the 3 days preceding and throughout the experimental period.
16
No
additional foods or beverages were introduced into the infants’ diet during the study. To
increase compliance, telephone contact was made with the mothers, who recorded the time of
day and types and quantities of foods and liquids they fed their infants throughout the study.
All of the mothers complied with these instructions.
Foods
The target foods, namely, puréed green beans (Stage 2; 1.30 J/g [0.31 cal/g]) and peaches (Stage
2; 2.97 J/g [0.71 cal/g]), were commercially available infant foods from Gerber Products
(Fremont, MI). The maximal amounts extracted from the containers were ~ 113 g of green
beans and ~ 99 g of peaches.
Experimental Design
Mother/infant dyads participated in a 12-day experimental study. Each mother brought her
infant to the Monell Chemical Senses Center 2 days before (days 1 and 2) and after (days 11
and 12) an 8-day home-exposure period. On days 1 and 11, we evaluated infants’ acceptance
of green beans; on days 2 and 12, we evaluated their acceptance of peaches. Infants were
assigned randomly to 1 of 2 treatment groups. One group (group GB) was fed green beans,
whereas the other (group GB-P) was fed green beans and then (within 1 hour) peaches
throughout the 8-day home-exposure period (days 3–10). To minimize possible effects
attributable to different levels of satiation, the test sessions at the Monell Chemical Senses
Center and on each exposure day occurred at the same time of day, with infants having last
been fed 2.6 ± 0.1 hours before feeding.
Monell Chemical Senses Center Test Sessions
Using methods established in our laboratory,
16,28
testing occurred under naturalistic
conditions, in which infants determined the pacing and duration of the feeding. Mothers fed at
their customary pace until the child rejected the food ≥3 consecutive times or finished 2 jars
Forestell and Mennella Page 3
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

of food. Immediately after each feeding session, the mothers rated, on a 9-point scale, how
much they thought their infant liked the food; greater numbers reflected greater liking.
Home-Exposure Period
At the end of the second test day, mothers were given jars of puréed infant food for the home-
exposure period. Each jar was labeled with the date on which the contents of that particular jar
should be fed. On each exposure day, mothers, who were trained at the Monell Chemical Senses
Center, offered their infants the contents of 1 jar of puréed green beans until the infant either
refused the food on ≥3 consecutive occasions or finished the contents of the jar. Only 1 child
finished the jar on each day of the exposure period. Within the next hour, mothers in group
GB-P offered their infants the contents of 1 jar of puréed peaches. Mothers refrained from
feeding the infants any milk or other solid food during the 1-hour periods that preceded and
followed these feedings, to ensure that the infants were hungry during the feeding and to avoid
any interference during the postingestive period, respectively.
29
Mothers then resealed each
jar and stored it in a freezer until they returned the jars to the Monell Chemical Senses Center
on day 11.
Videotape Analyses
In addition to determining intake, which primarily reflects how much a food is wanted,
30
we
measured the infants’ facial expressions during feeding, which are measures of hedonic
responses or liking in nonverbal animals,
30
including human infants.
17,31–33
Each videotape
was subjected to frame-by-frame analysis by means of a Windows-based, event recorder
program, the Observer (Noldus Information Technology, Heerlen, Netherlands). A trained
rater who was certified in the Facial Action Coding System
34
and who was unaware of the
infants’ group designation scored the first 2 minutes of each test session for all except 3 infants.
We focused on brow movements (ie, brow lowering and inner brow raises), nose wrinkling,
upper-lip raising, squinting, and gaping, as illustrated in Fig 1, because these facial expressions
have been identified as prototypical of distaste
31,34
and are more discriminating in gauging
infants’ like and dislike of tastes and flavors.
17,31,32
Gaping and 2 other facial responses
(dimpling and lip tightening) were not included in the final analyses, because at least two thirds
of the infants did not display these faces while being fed green beans. Because of marked
individual differences in the types of facial responses made during feeding, we also report on
the total number of distaste facial expressions for each spoonful offered.
Questionnaires
Mothers were queried about their infants’ feeding history and various aspects of their own
eating habits, such as the frequency with which they ate various vegetables and fruits. All
except 1 completed a 10-item scale that measured their food neophobia (the propensity to
approach or to avoid novel foods) and an 8-item scale that measured general neophobia.
35
All
except 1 mother completed a 95-item questionnaire that measured infant temperament.
36
Statistical Analyses
For each infant, we determined total food intake (grams and calories), duration of feeding
(minutes), rate of feeding (grams per minute), frequency of distaste facial expressions made
per spoonful offered during the first 2 minutes of the feeding, and mothers’ ratings of their
infants’ enjoyment of the food for each test session at the Monell Chemical Senses Center. To
determine whether there were differences between infants’ initial responses to green beans and
peaches, repeated-measures analyses of variance were conducted with food (green beans or
peaches) as the within-subjects variable. To determine whether breastfeeding affected initial
acceptance, separate 1-way analyses of variance were conducted with feeding history
(breastfed or formula fed) as the between-subjects variable for each measure. The 4 infants
Forestell and Mennella Page 4
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

who were both breastfed and formula fed were excluded from this analysis because of the small
sample size. Similar analyses were conducted on lactating and formula-feeding mothers’
dietary habits.
To determine the effects of dietary treatment on green bean and peach acceptance, 2-way
repeated-measures analyses of variance were conducted with treatment group (group GB or
group GB-P) as the between-subjects factor and time (before or after home exposure) as the
within-subjects factor. Four infants were excluded from the analyses of green bean acceptance
and 3 from those of peach acceptance because mothers were non-compliant with test
procedures (n = 2), infants were sick during testing or exposure (n = 2), or infants ate the
maximum amount of food offered during their initial exposure (n = 3). All summary statistics
are expressed as mean ± SEM.
RESULTS
Subject Characteristics
There were no significant differences between the 2 treatment groups in any of the
characteristics measured (Table 1). Infants who were exclusively breastfed for the first few
months of life were not significantly different from formula-fed infants in their age, weight-
for-age percentile, and temperament or their mothers’ age and income (data not shown).
Lactating mothers had more years of education (P < .02) and weaned their infants to cereal
later (P < .001) than did those who fed exclusively formula. However, there was no relationship
between initial acceptance of green beans or peaches and the amount of time the infants had
been fed cereal.
Initial Acceptance and Liking
Initially, infants ate more calories from peaches (201.7 ± 24.3 J [48.2 ± 5.8 cal]) than from
green beans (73.6 ± 9.6 J [17.6 ± 2.3 cal]; P < .001). As they ate, the majority of infants displayed
squints (95%), brow movements (82%), and upper-lip raises (76%), whereas less than one half
(42%) wrinkled their noses. Although there were marked differences in the prevalence of these
facial expressions among individuals and in response to the food being eaten, the facial displays
were related to food acceptance. For example, infants who squinted more or displayed more
distaste expressions overall ate peaches (P < .03) and green beans (P < .05) at slower rates.
Infants who were breastfed for the first few months of life consumed significantly more peaches
(P < .001) (Fig 2A) for longer periods of time (P < .01) at a faster rate (P < .03) and displayed
fewer upper-lip raises (P < .05) and negative facial responses overall during feeding (P < .05)
(Fig 2B), compared with formula-fed infants. As shown in Fig 2C, the mothers of the breastfed
infants ate significantly more fruits during the previous week, compared with formula-feeding
mothers (P < .04).
Although formula-feeding and breastfeeding mothers reported that they ate green beans and
green vegetables at levels below current recommendations (green beans were eaten 1.7 ± 0.20
times and green vegetables 4.3 ± 0.50 times during the week preceding testing), formula-
feeding mothers ate more green beans after the birth of their child than lactating mothers (2.4
± 0.4 times per week, compared with 1.1 ± 0.3 times per week; P < .02). Despite the formula-
feeding mothers’ more frequent consumption, there were no significant differences between
formula-fed and breastfed infants’ initial intake of green beans or the type of facial responses
made during feeding.
Forestell and Mennella Page 5
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

Effects of Repeated Exposure on Acceptance and Liking
During the exposure period, the 2 treatment groups ate similar amounts of green beans (average
daily intake: 68.6 ± 7.6 g for group GB and 61.9 ± 5.8 g for group GB-P); group GB-P ate, on
average, 47.4 ± 15.8 g of peaches each day of the home-exposure period. As shown in Table
2, such repeated exposure with (group GB-P) or without (group GB) peaches led to significant
increases in infants’ consumption of green beans (P < .001) and the rate at which they ate this
food (P < .001). By dividing the amount of green beans consumed after exposure by the amount
consumed before exposure for each infant (after/before), we found that the infants increased
their intake of green beans almost threefold (2.7 ± 0.5-fold), on average. There was no
significant interaction between infants’ feeding history and treatment group; both breastfed
and formula-fed infants increased acceptance of green beans after the home-exposure period.
As shown in Fig 3, there was a significant interaction between the treatment group and the time
for the types of facial expressions made during feeding of green beans (P < .04). Although
there were no differences in the numbers of facial displays group GB infants made while eating
green beans on the 2 test days at the Monell Chemical Senses Center, group GB-P infants, who
were fed green beans and peaches, made fewer brow movements (P < .01), squints (P < .003),
and upper-lip raises (P < .02) while eating green beans after, compared with before, the home-
exposure period. Mothers were apparently unaware of this difference, because their ratings of
enjoyment did not increase after the home-exposure period for either treatment group (Table
2).
Neither treatment group increased intake or displayed fewer distaste facial responses while
eating peaches and the mothers’ rating of the infants’ enjoyment of peaches did not change
after the home-exposure period. As shown in Table 2, both groups of infants ate the peaches
at a faster rate (P < .005), which might indicate that they were becoming more efficient feeders.
DISCUSSION
Breastfeeding confers an advantage when infants first taste a food, but only if their mothers
regularly eat similar-tasting foods. Breastfed infants were more accepting of peaches, when
first introduced, than were formula-fed infants, as determined by intake, rate of consumption,
and facial expressions. This enhanced acceptance of fruit could be attributable to more exposure
to fruit flavors, because their mothers ate more fruits during lactation.
The frequency with which mothers need to eat a food to enhance their children’s liking remains
unknown. The 1 randomized, experimental study revealed that breastfed infants whose mothers
drank carrot juice 4 days/week during the first 2 months of lactation or the last trimester of
pregnancy were more accepting of carrot-flavored foods, compared with breastfed infants
whose mothers avoided carrots during this time period. Because carrot flavor and several other
flavors are transmitted to amniotic fluid
37
and mother’s milk,
18,19
experiences with flavors
before and after birth at the very least predispose young infants to respond favorably to those
familiar flavors, which facilitates the transition from fetal life through the breastfeeding period
to the initiation of a varied, solid-food diet.
Unlike a previous report,
22
breastfeeding did not confer an advantage for green bean
acceptance, either before or after exposure to this vegetable. The absence of an effect could be
attributable to the low levels of exposure resulting from the low frequency of consumption by
lactating mothers, effects of in utero exposure to green bean flavor for both breastfeeding and
formula-feeding infants, or an interaction of the 2 factors. Because lactating mothers ate green
beans and vegetables infrequently and at levels well below current recommendations,
3
we
hypothesize that experience with breastfeeding alone is not sufficient to enhance initial
acceptance. Moreover, merely being exposed to the sight or smell of the food seemed to be
Forestell and Mennella Page 6
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

insufficient to enhance acceptance, because, although formula-feeding mothers were more
likely to eat green beans, their infants ate similar amounts of this food. As has been observed
with older children,
25
infants must taste the food to learn to like it.
Repeated opportunities to taste green beans enhanced acceptance to a similar extent for
breastfed and formula-fed infants, a finding that is consistent with previous studies with
infants
16
and children.
38,39
In the present study, we used commercial infant foods because
of the consistency of flavor and quality control. What is not known is whether experience with
such infant foods hinders the transition to eating fresh fruits or raw or cooked vegetables, which
differ in flavor and texture. Findings from the present study suggest that, the more familiar the
flavor experience, the better the likelihood of acceptance.
Although 8 exposures might be sufficient to increase willingness to consume green beans, it
remains unknown how many exposures to green beans alone are needed to increase liking of
this food. What did seem to affect the liking of green beans was whether the infants were fed
peaches shortly after they ate green beans during the 8 days of exposure. These findings are
consistent with previous work that revealed that the liking for a less-palatable food or beverage
is enhanced when the food or beverage is associated with sweet tastes.
26,27
How the timing
of fruit introduction to infants’ diets, as well as that during the course of a meal, affects overall
vegetable acceptance remains unknown. Specifically, we do not know whether feeding peaches
before green beans would modify infants’ acceptance of the latter. Nevertheless, the present
data do suggest that the hunger state of the child at the time of exposure may be important.
Infants who were exposed repeatedly to green beans and peaches (group GB-P) did not eat
more peaches after the home-exposure period. We hypothesize that, because the infants always
ate peaches after the green beans and possibly when sated, they did not have the opportunity
to learn that peaches alleviate hunger. This is consistent with a previous report in which adults
who were exposed repeatedly to a novel fruit snack while satiated failed to increase
consumption and had less desire to eat the snack.
40
More study of how hunger state facilitates
the development of liking for foods is warranted.
Eating peaches and green beans activated distinct, stereotyped, motor behaviors involving the
orofacial region. There were individual differences in the display of these facial expressions
while eating, which in some cases predicted the rate at which infants ate a particular food.
Whether these individual differences reflect genetic variations in taste sensitivity remains
unknown.
41
Experience modified intake, but only those who experienced peaches after green
beans seemed to like the taste of the green beans more after exposure. Although measures of
liking are related to intake,
42
they are governed by separate neural substrates
30
and do not
always change in tandem.
30,43
Facial expressions, which indicate the intensity and hedonics of perceived sensations, might
have evolved to signal that infants are eating something harmful and consequently might have
been used by mothers to protect the infants. Given the evolutionary significance of the innate
facial responses to certain tastes,
33
it is not surprising that mothers are often hesitant to continue
feeding a food they believe their infants dislike. We suggest that mothers should be encouraged
to focus on their infants’ willingness to eat the food and not just on the distaste facial
expressions made during feeding. Mothers should also be aware that, with repeated dietary
exposure, it may take longer to observe changes in facial expressions than in intake.
CONCLUSIONS
The best predictor of how many fruits and vegetables children eat is whether they like the taste
of these foods.
44
Additional experimental studies, as well as randomized nutritional
interventions that focus on maternal dietary habits during pregnancy and lactation and infant
Forestell and Mennella Page 7
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

dietary experiences, are needed for better understanding of how liking for the flavor of foods
develops.
11
Acknowledgements
This work was supported by National Institutes of Health grant HD37119. Dr Forestell was the recipient of a Canadian
Institutes of Health research postdoctoral fellowship.
We acknowledge Jennifer Kwak, Amanda Jagolino, and Lindsay Morgan for expert technical assistance; Linda Kilby
and the Supplemental Nutrition Program for Women, Infants, and Children Center of Philadelphia, Pennsylvania, for
help in recruiting mothers; Gerber Products for supplying the infant foods; and Dr Gary Beauchamp for comments on
an earlier version of the manuscript.
References
1. Bazzano L, He J, Ogden LG, et al. Fruit and vegetable intake and risk of cardiovascular disease in US
adults: the First National Health and Nutrition Examination Survey epidemiologic follow-up study.
Am J Clin Nutr 2002;76:93–99. [PubMed: 12081821]
2. World Health Organization. Diet, Nutrition and the Prevention of Chronic Disease: Report of a Joint
WHO/FAO Expert Consultation. Geneva, Switzerland: World Health Organization; 2003. WHO
Technical Report Series, No. 916
3. US Department of Agriculture. Dietary Guidelines for Americans 2005. 6. Washington, DC: US
Government Printing Office; 2005.
4. Fox MK, Pac S, Devaney B, Jankowski L. Feeding Infants and Toddlers Study: what foods are infants
and toddlers eating? J Am Diet Assoc 2004;104(suppl):s22–s30. [PubMed: 14702014]
5. Mennella JA, Ziegler P, Briefel R, Novak T. Feeding Infants and Toddlers Study: the types of foods
fed to Hispanic infants and toddlers. J Am Diet Assoc 2006;106(suppl):s96–s106. [PubMed:
16376634]
6. Desor, J.; Maller, O.; Greene, LS. Preference for sweet in humans: infants, children, and adults. In:
Weiffenback, JM., editor. Taste and Development: The Genesis of Sweet Preference. Washington,
DC: US Government Printing Office; 1977. p. 161-173.
7. Kajiura H, Cowart BJ, Beauchamp GK. Early developmental change in bitter taste responses in human
infants. Dev Psychobiol 1992;25:375–386. [PubMed: 1526325]
8. Drewnowski A. Sensory control of energy density at different life stages. Proc Nutr Soc 2000;59:239–
244. [PubMed: 10946792]
9. Glendinning JI. Is the bitter rejection response always adaptive? Physiol Behav 1994;56:1217–1227.
[PubMed: 7878094]
10. Butte N, Cobb K, Dwyer J, Graney L, Heird W, Rickard K. The Start Healthy feeding guidelines for
infants and toddlers. J Am Diet Assoc 2004;104:442–454. [PubMed: 14993870]
11. Lucas A. Programming by early nutrition: an experimental approach. J Nutr 1998;128(suppl):401S–
406S. [PubMed: 9478036]
12. Skinner JD, Carruth BR, Wendy B, Ziegler PJ. Children’s food preferences: a longitudinal analysis.
J Am Diet Assoc 2002;102:1638–1647. [PubMed: 12449287]
13. Nicklaus S, Boggio V, Chabanet C, Issanchou S. A prospective study of food variety seeking in
childhood, adolescence and early adult life. Appetite 2005;44:289–297. [PubMed: 15927730]
14. Gidding SS, Dennison BA, Birch LL, et al. Dietary recommendations for children and adolescents:
a guide for practitioners [published correction appears in Pediatrics. 2006;118:1323]. Pediatrics
2006;117:544–559. [PubMed: 16452380]
15. Mennella JA, Turnbull B, Ziegler PJ, Martinez H. Infant feeding practices and early flavor experiences
in Mexican infants: an intra-cultural study. J Am Diet Assoc 2005;105:908–915. [PubMed:
15942540]
16. Gerrish CJ, Mennella JA. Flavor variety enhances food acceptance in formula-fed infants. Am J Clin
Nutr 2001;73:1080–1085. [PubMed: 11382663]
17. Mennella, JA.; Jagnow, CP.; Beauchamp, GK. Prenatal and post-natal flavor learning by human
infants. Pediatrics. 2001. Available at: www.pediatrics.org/cgi/content/full/107/6/e88
Forestell and Mennella Page 8
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

18. Mennella JA, Beauchamp GK. Maternal diet alters the sensory qualities of human milk and the
nursling’s behavior. Pediatrics 1991;88:737–744. [PubMed: 1896276]
19. Mennella, JA. The chemical senses and the development of flavor preferences in humans. In:
Hartmann, PE.; Hale, T., editors. Textbook of Human Lactation. Amarillo, TX: Hale Publishing;
2007. p. 403-413.
20. Galloway AT, Lee Y, Birch LL. Predictors and consequences of food neophobia and pickiness in
young girls. J Am Diet Assoc 2003;103:692–698. [PubMed: 12778039]
21. Mennella JA, Beauchamp GK. Developmental changes in the acceptance of protein hydrolysate
formula. J Dev Behav Pediatr 1996;17:386–391. [PubMed: 8960567]
22. Sullivan SA, Birch LL. Infant dietary experience and acceptance of solid foods. Pediatrics
1994;93:271–277. [PubMed: 8121740]
23. Cooke LJ, Wardle J, Gibson EL, Sapochnik M, Sheiham A, Lawson M. Demographic, familial and
trait predictors of fruit and vegetable consumption by pre-school children. Public Health Nutr
2004;7:295–302. [PubMed: 15003137]
24. Skinner JD, Carruth BR, Bounds W, Ziegler P, Reidy K. Do food-related experiences in the first 2
years of life predict dietary variety in school-aged children? J Nutr Educ Behav 2002;34:310–315.
[PubMed: 12556269]
25. Birch LL, McPhee L, Shoba BC, Pirok E, Steinberg L. What kind of exposure reduces children’s
food neophobia? Looking vs. tasting. Appetite 1987;9:171–178. [PubMed: 3435134]
26. Stein LJ, Nagai H, Nakagawa M, Beauchamp GK. Effects of repeated exposure and health-related
information on hedonic evaluation and acceptance of a bitter beverage. Appetite 2003;40:119–129.
[PubMed: 12781161]
27. Havermans RC, Jansen A. Increasing children’s liking of vegetables through flavour-flavour learning.
Appetite 2007;48:259–262. [PubMed: 17113192]
28. Mennella JA, Beauchamp GK. Mothers’ milk enhances the acceptance of cereal during weaning.
Pediatr Res 1997;41:188–192. [PubMed: 9029637]
29. Cannon DS, Best MR, Batson JD, Brown ER, Rubenstein JA, Carrell LE. Interfering with taste
aversion learning in rats: the role of associative interference. Appetite 1985;6:1–19. [PubMed:
2986548]
30. Berridge KC. Food reward: brain substrates of wanting and liking. Neurosci Biobehav Rev 1996;20:1–
25. [PubMed: 8622814]
31. Rosenstein D, Oster H. Differential facial responses to four basic tastes in newborns. Child Dev
1988;59:1555–1568. [PubMed: 3208567]
32. Soussignan R, Schaal B, Marlier L, Jiang T. Facial and autonomic responses to biological and artificial
olfactory stimuli in human neonates: re-examining early hedonic discrimination of odors. Physiol
Behav 1997;62:745–758. [PubMed: 9284493]
33. Steiner JE, Glaser D, Hawilo ME, Berridge KC. Comparative expression of hedonic impact: affective
reactions to taste by human infants and other primates. Neurosci Biobehav Rev 2001;25:53–74.
[PubMed: 11166078]
34. Ekman, P.; Friesen, WV.; Hagar, JC. Facial Action Coding System on CD-ROM. Salt Lake City, UT:
Network Information Research; 2002.
35. Pliner P, Hobden K. Development of a scale to measure the trait of food neophobia in humans. Appetite
1992;19:105–120. [PubMed: 1489209]
36. Carey WB, McDevitt SC. Revision of the Infant Temperament Questionnaire. Pediatrics
1978;61:735–739. [PubMed: 662513]
37. Mennella JA, Johnson A, Beauchamp GK. Garlic ingestion by pregnant women alters the odor of
amniotic fluid. Chem Senses 1995;20:207–209. [PubMed: 7583013]
38. Wardle J, Herrera ML, Cooke L, Gibson EL. Modifying children’s food preferences: the effects of
exposure and reward on acceptance of an unfamiliar vegetable. Eur J Clin Nutr 2003;57:341–348.
[PubMed: 12571670]
39. Wardle J, Cooke LJ, Gibson EL, Sapochnik M, Sheiham A, Lawson M. Increasing children’s
acceptance of vegetables; a randomized trial of parent-led exposure. Appetite 2003;40:155–162.
[PubMed: 12781165]
Forestell and Mennella Page 9
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

40. Gibson EL, Wardle J. Effect of contingent hunger state on development of appetite for a novel fruit
snack. Appetite 2001;37:91–101. [PubMed: 11606035]
41. Mennella JA, Pepino MY, Reed DR. Genetic and environmental determinants of bitter perception
and sweet preferences. Pediatrics 2005;115:216–222.
42. Sclafani A, Ackroff K. Nutrient-conditioned flavor preference and incentive value measured by
progressive ratio licking in rats. Physiol Behav 2006;88:88–94. [PubMed: 16626765]
43. Forestell CA, LoLordo VM. Palatability shifts in taste and flavour preference conditioning. Q J Exp
Psychol B 2003;56:140–160. [PubMed: 12623544]
44. Resnicow K, Davis-Hearn M, Smith M, et al. Social-cognitive predictors of fruit and vegetable intake
in children. Health Psychol 1997;16:272–276. [PubMed: 9152706]
Forestell and Mennella Page 10
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

FIGURE 1.
Examples of types of facial expressions displayed during the first 2 minutes of feeding: brow
lowerer (A), inner brow raise (B), squint (C), nose wrinkle (D), upper-lip raise (E), and gape
(F).
Forestell and Mennella Page 11
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

FIGURE 2.
Amounts of peaches consumed (A) and number of distaste expressions displayed per spoonful
of peaches (B) by breastfeeding and formula-feeding infants during their first feeding of
peaches at the Monell Chemical Senses Center and number of times lactating and formula-
feeding mothers reported eating fruits during the previous week (C).
a
P < .05, compared with
breastfed infants (A and B) or lactating mothers (C).
Forestell and Mennella Page 12
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

FIGURE 3.
The cumulative number of brow movements (brow lowerers and inner brow raises combined),
squints, upper-lip raises, and nose wrinkles made during green bean feeding, before and after
the home-exposure period. Panel A shows data from group GB infants who were fed only green
beans and panel B shows data from group GB-P infants who were fed both green beans and
peaches during the 8-day home-exposure period. Infants in group GB-P displayed fewer brow
movements (P < .02), squints (P < .01), and distaste expressions overall (P < .001) per spoonful
of green beans after the 8-day home-exposure period, compared with before the exposure
period.
Forestell and Mennella Page 13
Pediatrics. Author manuscript; available in PMC 2008 March 18.
NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript

NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript
Forestell and Mennella Page 14
TABLE 1
Subject Characteristics
Characteristic Group GB Group GB-P
Infants
Age, mean ± SEM, mo 5.6 ± 0.2 5.9 ± 0.2
Gender, female/male 6/10 15/14
Infants’ feeding history
Breastfed, never formula fed, n 7 13
Formula fed, never breastfed, n 9 12
Both breastfed and formula fed, n 0 4
Age at cereal introduction, mean ± SEM, mo 3.9 ± 0.3 4.2 ± 0.2
Mothers
Age, mean ± SEM, y 32.2 ± 1.4 31.6 ± 0.9
BMI, mean ± SEM, kg/m
2
30.2 ± 2.4 27.1 ± 1.0
Multiparous, n 12 23
Years of schooling, mean ± SEM 14.7 ± 0.5 14.8 ± 0.4
Food neophobia score (range: 10–70), mean ± SEM 30.6 ± 3.6 36.3 ± 2.6
General neophobia score (range: 8–56), mean ± SEM 24.4 ± 2.1 24.2 ± 1.8
Mother/infant pairs, n 16 29
Pediatrics. Author manuscript; available in PMC 2008 March 18.

NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript
Forestell and Mennella Page 15
TABLE 2
Infants’ Acceptance of Green Beans and Peaches Before and After 8-Day Exposure Period
Group GB Group GB-P Both Groups
Green beans
Intake, mean ± SEM, g
Before exposure 65.3 ± 12.5 52.3 ± 9.0 56.8 ± 7.3
After exposure
97.5 ± 17.3
a
91.6 ± 12.4
a
93.6 ± 10.0
a
Rate of consumption, mean ± SEM, g/min
Before exposure 4.8 ± 0.8 3.9 ± 0.5 4.2 ± 0.4
After exposure
6.6 ± 1.0
a
6.3 ± 0.7
a
6.4 ± 0.6
a
Mothers’ rating of infants’ liking, mean ± SEM
Before exposure 6.4 ± 0.5 7.1 ± 0.4 6.9 ± 0.3
After exposure 6.9 ± 0.6 6.9 ± 0.4 6.9 ± 0.3
Peaches
Intake, mean ± SEM, g
Before exposure 70.9 ± 14.0 67.7 ± 10.4 68.8 ± 8.3
After exposure 74.7 ± 15.1 79.2 ± 11.2 77.6 ± 8.9
Rate of consumption, mean ± SEM, g/min
Before exposure 4.8 ± 0.7 4.4 ± 0.5 4.5 ± 0.4
After exposure
5.8 ± 0.8
a
5.9 ± 0.6
a
5.8 ± 0.4
a
Mothers’ rating of infants’ liking, mean ± SEM
Before exposure 6.8 ± 0.5 7.1 ± 0.4 7.0 ± 0.3
After exposure 6.5 ± 0.6 6.4 ± 0.5 6.4 ± 0.4
Group GB was fed green beans, and group GB-P was fed green beans and then peaches during the exposure period.
a
Significant at P < .05, compared with before exposure.
Pediatrics. Author manuscript; available in PMC 2008 March 18.