Study foods

The majority of studies tested the effects of repeated exposure to fruits or vegetables. Two tested the effect of repeated exposure of a fruit or multiple fruits (Brown, 1980, Lundy, 1998), 10 tested repeated exposure of a vegetable or multiple vegetables (Ahern, 2014, Caton, 2013, Coulthard, 2014, Fildes, 2015, Gerrish, 2001, Hetherington, 2015, Maier, 2007, Paul, 2011, Remy, 2013, Sullivan, 1994), and four studies tested repeated exposure of both fruits and vegetables (Barends, 2013, Birch, 1998, Forestell, 2007, Mennella, 2008). Five studies tested other types of foods including vegetables and meat (Maier, 2008), gruel (Traore, 2005), dietary sodium (Harris, 1987, Stein, 2012), and maternal dietary exposure to caraway flavor (Hausner, 2010). The majority of study foods were manufactured baby foods.

Repeated exposure: type, number, frequency, and duration

The type of exposure (single food or multiple foods), number, frequency (number of exposures per day or week), and duration of exposure period differed among studies. Thirteen studies examined repeated exposure to a single food (Ahern, 2014, Birch, 1998, Caton, 2013, Coulthard, 2014, Forestell, 2007, Gerrish, 2001, Hausner, 2010, Mennella, 2008, Paul, 2011, Remy, 2013, Sullivan, 1994, Traore, 2005, Lundy, 1998) and twelve studies examined repeated exposure to a multiple foods (either fruits or vegetables) (Barends, 2013, Brown, 1980, Coulthard, 2014, Fildes, 2015, Forestell, 2007, Gerrish, 2001, Harris, 1987, Hetherington, 2015, Maier, 2007, Maier, 2008, Mennella, 2008, Stein, 2012). The number of repeated exposures to foods ranged from 6 times (Ahern, 2014, Paul, 2011) to 47 total times (Hetherington, 2015), with duration of exposure periods ranging from 6 days (Paul, 2011) to 3 months (Brown, 1980). Frequency of exposures varied from 2 times/day (Hetherington, 2015, Traore, 2005) to 2-3 times/week (Ahern, 2014, Remy, 2013), but the majority of studies tested 1 exposure/day.

Outcomes

For the purposes of this review, a change in acceptability was defined as a change in at least one of the following five behavioral measures: food intake (weighed amount of food consumed), caregiver or researcher perception of infants’ liking of a food, duration of feeding session, rate of feeding, and facial and/or body responses during feeding. Facial/body responses included: frequency of facial expressions of distaste (Forestell, 2007); number of spoons accepted and refused (Hausner, 2010); and, body and facial reactions, eagerness verse refusal, and number of chewing cycles (Lundy, 1998). Studies had to include at least one of these measures to be included in the body of evidence and the combination of outcomes examined within studies varied.

Table 1

Outcomes measured by study.

Limitations

The NEL bias assessment summary table indicated certain areas that may be of concern for internal validity purposes; however it was determined that these were not considered to be significant limitations for the body of evidence. These included: lack of blinding of researchers, outcome assessors, or participants, limited reporting of randomization methods, validity/reliability of outcome measures, and not accounting for key confounders.

• Blinding is a common difficulty with feeding studies, given the nature of the exposure. Few studies indicated whether researchers or outcome assessors were blinded to the conditions. In this body of evidence, caregivers feeding infants may have been aware of the foods but were not likely aware of the research question or hypothesis. Caregiver blinding is less of a concern due to the infant-led feeding paradigm used to conclude feeding sessions.
• Few studies reported the method for randomization of participants to exposure/intervention. This was considered to be more of a reporting issue than a flaw of the design.
• Validity and reliability of outcome measures was identified as a risk of bias because over half of the studies measured perceived liking which was not consider to be a valid/reliable measure. However, perceived liking was only one of several outcome measures and therefore does not limit the validity of the overall findings.
• All key confounders identified a priori by the collaborative were not accounted for consistently across studies.

There were other limitations and/or methodological differences that are important to consider when synthesizing the evidence. These include:

• Variations in target and test foods across studies;
• Variations in number, frequency, and duration of exposures;
• Study design: strongest design is within-subject design, with pre- and post-exposure measures, however this design was not used consistently across all studies;
• Age range: although age is limited to the birth to 24 month population, there can be significant variation in eating behaviors within this age range.

Assessment of individual studies prior to synthesis

Individual studies were reviewed and assessed based on internal validity, sufficiency of sample sizes, directness, and generalizability. While all studies in the body of evidence are considered in addressing this systematic review question, it was determined that five studies (3 controlled trials: Hausner, 2010, Maier, 2008, Traore, 2005; 2 cohort studies: Harris, 1987, Stein, 2012) should be weighed less heavily, mostly due to issues of directness of addressing the systematic review question, and lack of data. Thus, the evidence synthesis will focus on the remaining 16 studies. (Tables 2 and 3)

Does repeated exposure increase acceptability of an exposed food?

Fourteen studies examined the relationship between repeated exposure to a single vegetable or fruit or multiple vegetables or fruits on acceptability of an exposed food (single vegetable or fruit: Ahern, 2014, Birch, 1998, Caton, 2013, Forestell, 2007, Gerrish, 2001, Lundy, 1998, Mennella, 2008, Paul, 2011, Remy, 2013, Sullivan, 1994; multiple vegetables or fruits: Barends, 2013, Brown, 1980, Forestell, 2007, Hetherington, 2015, Maier, 2007, Mennella, 2008). Each study showed an increase in at least one measure of food acceptability from before to after the exposure period.

Of the 10 studies that examined the relationship of repeated exposure to a single food on acceptability of that food, nine tested repeated exposure to a vegetable (Ahern, 2014, Birch, 1998, Caton, 2013, Forestell, 2007, Gerrish, 2001, Mennella, 2008, Paul, 2011, Remy, 2013, Sullivan, 1994) and three to a fruit (Birch, 1998, Mennella, 2008, Lundy, 1998). Again, all studies showed an increase in acceptability, and more specifically, eight of the 10 studies showed an increase in intake of the exposed food from before to after the exposure period. Two studies found an increase in other measures of acceptability, feeding rate (Mennella, 2008) and facial and body response (Lundy, 1998).

Five studies found that repeatedly exposing children to multiple vegetables or multiple fruits led to increased acceptability of an exposed food after compared to before the exposure period (Barends, 2013; Forestell, 2007; Hetherington, 2015; Maier, 2007; Mennella, 2008). Four studies provided multiple vegetables (Barends, 2013; Hetherington, 2015; Maier, 2007; Mennella, 2008), 1 provided multiple fruits (Barends, 2013), and 1 provided a vegetable and fruit (Forestell, 2007). In these studies with the exception of Forestell (2007) and Mennella (2008), a single vegetable or fruit was served alone at an eating occasion and the type of vegetable or fruit varied across eating occasions, with one eating occasion per day at the same time each day (Table 1). In the study by Forestell (2007), green beans were served first, followed by peaches within 1 hour, and in Mennella (2008) one group of infants received two vegetables per eating occasion. All studies showed an increase in either intake or feeding rate of an exposed food after compared to before the repeated exposure period (Table 1). One study, however, had mixed findings (Barends, 2013). In Barends et al. (2013), four study groups were tested: two groups were exposed to different combinations of fruits (1 group was exposed to apples, bananas, pears; another group was exposed to plums, bananas, pears) and two were exposed to different combinations of vegetables (1 group was exposed to green beans, broccoli, cauliflower; another group was exposed to artichoke, broccoli, cauliflower). One group exposed to fruits (plums, bananas, pears) and 1 group exposed to vegetables (green beans, broccoli, cauliflower) had greater intake and perceived liking of an exposed food (plums and green beans, respectively) after the exposure period. Meanwhile, there was no change in intake or perceived liking within the group exposed to apples, bananas, and pears when tested for acceptability of apples or the group exposed to artichoke, broccoli, and cauliflower when tested for acceptability of artichokes.

Adding sugar, salt, fat, or changing the texture of the exposed food

Seven studies tested the effect of repeated exposure to a food with altered properties, specifically added sweetness (Ahern, 2014, Brown, 1980, Caton, 2013, Remy, 2013), salt (Sullivan, 1994), oil (Caton, 2013, Remy, 2013) or altered texture (Birch, 1998, Lundy, 1998), on acceptability of the plain version of that food. Results varied based on the sensory characteristics that were altered.

• Adding sweetness or salt to a vegetable enhanced acceptability of the plain version of that vegetable. Three studies showed that from before to after 6-10 exposures to a vegetable with added sweetness (Ahern, 2014, Caton, 2013, Remy, 2013) and in one study a vegetable with added salt (Sullivan, 1994), intake of the plain vegetable increased. However, in a study comparing a 3-month exposure of normally-sweetened fruits to unsweetened fruits, the group of infants exposed to sweetened fruits consumed less sweetened and unsweetened fruit during post-exposure testing than the group exposed to unsweetened fruit (Brown, 1980). There was no difference in intake between sweetened or unsweetened fruits within either group.
• When the exposure food was a vegetable with added oil, results were mixed. One study showed that intake of plain artichoke increased after 10 exposures to artichoke with added sunflower oil (Caton, 2013), while another study (Remy, 2013) did not find a change in intake of plain artichoke after 10 exposures to artichoke with oil.
• Two studies tested the effect of repeated exposure on acceptability of foods with differing textures; it is important to note that altering the texture likely changes other sensory properties such as appearance and taste. In Birch, 1998, after 10 exposures to manufactured baby food (either banana or peas) there was no change in intake of a homemade version of that food compared to initial intake of the manufactured version. Lundy, 1998 found that children responded differently to pureed, lumpy, or diced apples depending on the versions to which they had been exposed. Compared to infants who were only exposed to pureed apples, those exposed to pureed and lumpy apples or just lumpy apples showed more positive responses (head movements) for pureed apples. Similarly, infants exposed to pureed, lumpy, and diced apples and those exposed to lumpy and diced apples showed more positive vocalizations to diced apples than infants exposed to only pureed and diced apples.

Does repeated exposure increase acceptability of a novel food?

Within the body of evidence, several studies examined if repeated exposure to a single or multiple foods impacted acceptance of a new food. Some studies looked at the impact on acceptance of a new food within the same category, i.e. exposure to fruit on acceptance of a new fruit, and some looked at the impact of exposure to a food on acceptance to a food from a different category, i.e. exposure to a fruit on acceptance of a novel vegetable and vice versa.

There were seven studies that examined the impact of repeated exposure of a single or multiple vegetables or fruits on acceptability of a new food from that category. All seven tested the impact of repeated exposure to one or more vegetables on a new vegetable (Barends, 2013, Birch, 1998, Caton, 2013, Coulthard, 2014, Fildes, 2015, Gerrish, 2001, Mennella, 2008), while three also tested the impact of repeated exposure to one or more fruits on a new fruit (Barends, 2013, Birch, 1998, Mennella, 2008). Most studies found that repeated exposure to one or more vegetables or fruits can increase acceptance to a new vegetable or fruit, respectively.

• Repeated exposure of vegetables on acceptability of a new vegetable

Of the five studies (Birch, 1998, Caton, 2013, Coulthard, 2014, Gerrish, 2001, Mennella, 2008) that tested the impact of repeated exposure to a single vegetable on acceptability of a new vegetable, results varied. Birch, 1998 found that 10 exposures to peas led to increased intake of carrots or corn. Caton, 2013 found that 10 exposures to either plain artichoke, sweetened artichoke, or artichoke with added oil increased intake of carrots. However, Gerrish, 2001 showed no change in acceptability of carrots after 9 exposures to potatoes, and Mennella, 2008 found no change in acceptability of carrots or spinach after 8 exposures to green beans. Coulthard, 2014 compared repeated exposure to carrots or a variety of vegetables (parsnips, zucchini, and sweet potatoes) and the age of complementary food introduction on acceptability of peas. There was a significant interaction such that infants who were introduced to foods after 5.5 months and were exposed to a variety of vegetables consumed more peas than those introduced to foods before 5.5 months and were exposed to a single vegetable.

Five studies (Barends, 2013, Coulthard, 2014, Fildes, 2015, Gerrish, 2001, Mennella, 2008) that looked at the impact of repeated exposure to multiple vegetables on acceptability of a new vegetable all showed increased acceptability of a new vegetable in at least one study group. There was one group in Mennella, 2008 that did not increase acceptability of a novel vegetable. In this study, two groups were exposed to a variety of vegetables: one group received four vegetables (squash, spinach, peas, and carrots), 1/day over eight days; the other group was given the same four vegetables but 2 different vegetables at the test meal each day over eight days for a total of 16 exposures. The group that received one vegetable per day (8 exposures) did not increase acceptability of a new vegetable (green beans) but the group given two vegetables per day (16 exposures) increased intake and feeding rate of green beans. Also, in Fildes, 2015, one group of parents was instructed to introduce 5 vegetables to their infants (1/day for 5 days then repeat for a total of 15 days) while another group was not given specific instructions about introducing vegetables. After 15 days, there was no difference in intake or maternal perceived liking of a novel vegetable, artichoke, between groups. However, researchers that were not blinded to the intervention status rated liking of the new vegetable greater for the infants introduced to a variety of vegetables.

• Repeated exposure of fruits on acceptability of a new fruit

Fewer studies tested the impact of repeated exposure of a single or multiple fruits on acceptability of a new fruit. Only one study (Birch, 1998) tested the effect of repeated exposure to a single fruit on new fruits. This study found that 10 exposures to bananas increased intake of a new fruit, pears or peaches. Two studies (Barends, 2013, Mennella, 2008) tested the effect of repeated exposure to multiple fruits on a new fruit. Mennella, 2008 found that 8 total exposures to peaches, prunes, and apples (1/d for 8 days) increased intake of a new fruit, pears. Barends, 2013 had 2 groups of infants that were exposed to a different variety of fruits. After 14 total exposures to apples, bananas, and pears, there was no change in acceptability of a new fruit, plums. However, in another group, infants that received 14 total exposures to plums, bananas, and pears did increase their intake of a new fruit, apples, after the exposure period.

Seven studies tested the relationship between repeated exposure to one or more vegetables or fruits on a new food from a different food category. Four studies examined the impact of exposure to one or more vegetables on acceptance of a new fruit (Barends, 2013, Birch, 1998, Fildes, 2015, Forestell, 2007) and three studies examined the impact of exposure to one or more fruits on acceptance of a new vegetable (Barends, 2013, Birch, 1998, Mennella, 2008). Additionally, two studies looked at the impact of repeated exposure to one or more vegetables on acceptance of chicken (Gerrish, 2001, Sullivan, 1994). Of the seven studies, three used a weaker analysis (between-group rather than within-subject) to address this relationship (Barends, 2013, Fildes, 2015, Gerrish, 2001). One study (Mennella, 2008), which used a within-subject analysis, found that repeated exposure to either a single fruit or multiple fruits led to a faster feeding rate of a new vegetable; the other studies did not support this finding. This body of evidence indicates that repeated exposure to a food(s) does not interfere with initial acceptance of a new food from a different food category. In other words, early eating experience with fruits is not likely to affect acceptability of a new vegetable, and vice versa.

• Repeated exposure of vegetables on acceptability of a new fruit

Four studies examined the impact of exposure to one or more vegetables on acceptance of a new fruit (Barends, 2013; Birch, 1998; Fildes, 2015; Forestell, 2007). Birch et al. (1998) and Forestell (2007) tested the effect of repeated exposure to a single vegetable (peas and green beans, respectively) on intake of a new fruit (bananas and peaches, respectively). Birch (1998) found no difference in banana intake after 10 exposures to peas, while Forestell (2007) found that babies ate peaches faster after having 8 exposures to green beans. Barends et al. (2013) investigated repeated exposure to multiple vegetables (artichokes, broccoli, cauliflower or green beans, broccoli, cauliflower) on acceptance of a new fruit (apples). Fildes et al. (2015) investigated repeated exposure to five vegetables (vegetables differed among participants) on acceptance of a new fruit (peaches). Neither of these studies showed that repeated exposure to a variety of vegetables affected acceptability of a new fruit (Barends, 2013; Fildes, 2015).

• Repeated exposure of fruit on acceptability of a new vegetable

Three studies examined the impact of exposure to one or more fruits on acceptance of a new vegetable (Barends, 2013, Birch, 1998, Mennella, 2008). Mennella, 2008 found that 8 exposures to either pears alone or 8 total exposures to peaches, prunes, and apples increased infants feeding rate of green beans. However, 10 exposures to peas did not change intake of a new fruit (Birch, 1998) and 14 total exposures to a variety of fruits (apples, bananas, and pears; or, plums, bananas, and pears) did not impact initial acceptability of a new vegetable (Barends, 2013).

How many exposures are needed to see an effect?

For the generally healthy, 4 to 24 month, US population, the evidence suggests that eight or more exposures will lead to an increase in at least one measure of food acceptability. The studies in this body of evidence were not necessarily designed to determine the minimum number of exposures required to see an effect on acceptability.

While the range of exposures was six to 30 across the studies, most designs provided infants and toddlers with 8 to 10 exposures and found a change in acceptability at the end of this period. Some studies found changes in food intake after as little as one (Birch, 1998), three (Ahern, 2014), five (Caton, 2013), or six (Paul, 2011) exposures.

When interpreting this data, it is important to consider individual differences in response to repeated exposure. Some children may require fewer or more exposures before changes in acceptability begin to emerge. Additionally, some children may never like a particular food regardless of the number of exposures. The type/quality of food provided may also impact whether or not a child’s acceptability increases with repeated exposure.

Did caregivers perceive increases in child’s acceptability after repeated exposures?

Acceptability was defined a priori as a change in one of the following outcome measures: food intake, length and rate of feeding, facial or body responses, and perceived liking as rated by caregiver or researcher. There were two measures, however, that were the predominant means of capturing a change in acceptability: weighed food intake and, to a smaller extent, feeding rate. Perceived liking was included to as an outcome to assess whether caregivers actually notice a change in their child’s acceptance of a food. Interestingly, mothers/caregivers were unlikely to rate their child’s liking of a food higher after repeated exposure despite a significant increase in intake or feeding rate.

Assessment of the body of evidence

The body of evidence was deemed to be moderate in strength mostly due to inconsistencies in study methods, specifically differences in study foods and number of exposures. However, the evidence was considered to be high quality due to the within-subject design used in many of the studies and the consistency of findings. Findings were mostly based on the effect of repeated exposure to vegetables (primarily) and fruits (secondarily); few studies tested repeated exposure to other types of foods. The body of evidence is both practically and clinically important because it addresses the critical issue of introduction of foods and the development of healthy eating habits.

• Internal Validity (Quality): the majority of the evidence is from controlled trials using within-subject pre-/post-exposure measures of weighed food intake as the indicator of acceptability. Five of the 21 studies were considered less strongly due to concerns of quality.
• Adequacy (Quantity): There were 21 studies in the body of evidence by multiple different research groups in the US and Europe. Some studies had small samples sizes (adequate for within-subject design) and only a few indicated power; over 1,100 infant/child participants were in the total analytic sample across the body of evidence.
• Consistency/Impact: Findings are consistent in direction such that there is a positive effect of repeated exposure or no effect of repeated exposure, but there was no decline in acceptability of fruits or vegetables after repeated exposure. Given the public health importance of increasing fruit and vegetable consumption in young children, even small increases are of practical significance.
• Generalizability: the majority of evidence included infants and children within the US and other developed (European) countries aged 4 to 24 months. There was a mix of race/ethnicities and an even split of boys and girls.
• Limitations: Findings are limited to the effects of repeated exposure to fruits and vegetables. Variation in study foods and repeated exposure methodology (number of exposures, frequency, and duration). Some study designs lacked pre-/post-exposure measurements; between-subject measurements are not as strong.

Table 2

Summary table of the 16 studies most strongly considered in the evidence synthesis.

Table 3

Studies considered less heavily during synthesis. The following 5 studies met the inclusion criteria for this question; however, upon closer assessment certain factors from each study deemed it to be weighed less heavily by the expert group when synthesizing (more...)

Pubmed

• Date(s) Searched: 10/30/15; 3/10/2016; 6/29/2017
• Date range: 1980-6/29/2017
• Search Terms:
  food accepta* OR food preference* OR food enjoy* OR food perception*[tiab] OR dietary preference*[tiab] OR dietary habit* OR food habits[mh] OR food choice*[tiab] OR eating preference*[tiab] OR eating habit* OR eating choice* OR dietary choice* OR food discriminat* OR beverage accepta* OR beverage preference* OR beverage choice* OR taste discrimination* OR taste preference* OR gustatory discrimination* OR gustatory preference* OR taste accepta* OR gustatory habit* OR taste habit* OR gustatory choice* OR gustatory accepta* OR food aversion* OR eating aversion* OR taste aversion* OR gustatory aversion* OR beverage aversion* OR flavor learning* OR flavor preference* OR flavour learning* OR flavour preference*
  OR “Taste”[Mesh] OR gustation*[tiab] OR taste sense*[tiab] OR “Taste Threshold”[Mesh] OR “Taste Perception”[Mesh] OR distaste OR hedoni* OR palatable OR unpalatable
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  AND
  (food*[tiab] OR “Food and Beverages”[Mesh] OR beverage*[tiab] OR Cereal*[tiab] OR bread*[tiab] OR whole grain*[tiab] OR juice*[tiab] OR milk[tiab] OR “Milk”[Mesh] OR dairy[tiab] OR “Dairy Products”[Mesh] OR meat[tiab] OR cheese[tiab] OR yogurt[tiab] OR yoghurt*[tiab] OR fruit*[tiab] OR “Fruit”[Mesh] OR vegetable*[tiab] OR “Vegetables”[Mesh] OR egg*[tiab] OR “Eggs”[Mesh] OR nut[tiab] OR nuts[tiab] OR peas[tiab] OR beans[tiab] OR legume*[tiab] OR snack*[tiab] OR meals OR meal)
  OR
  (“Facial Expression”[Mesh] OR ((facial[tiab] OR face[tiab]) AND (expression* OR response* OR react*)) OR reject* OR dislike* OR disliking OR neophobi*) AND (food OR dietary OR diet OR eating OR beverage* OR taste OR gustatory OR flavor* OR flavor*)
  OR
  (accepta* OR preference* OR enjoy* OR choice* OR habit* OR discrimination* OR aversion* OR avert* OR neophobi*)
  AND
  (food*[tiab] OR “Food and Beverages”[Mesh] OR beverage*[tiab] OR Cereal*[tiab] OR bread*[tiab] OR whole grain*[tiab] OR juice*[tiab] OR milk[tiab] OR “Milk”[Mesh] OR dairy[tiab] OR “Dairy Products”[Mesh] OR meat[tiab] OR cheese[tiab] OR yogurt[tiab] OR yoghurt*[tiab] OR fruit*[tiab] OR “Fruit”[Mesh] OR vegetable*[tiab] OR “Vegetables”[Mesh] OR egg*[tiab] OR “Eggs”[Mesh] OR nut[tiab] OR nuts[tiab] OR peas[tiab] OR beans[tiab] OR legume*[tiab] OR rice OR soup OR snack*[tiab] OR meals OR meal)
  AND
  infant* OR baby OR babies OR toddler* OR newborn*[tiab] OR “Child, Preschool”[Mesh] OR preschool*[tiab] OR pre-school*[tiab] OR “early childhood”[tiab] OR early year*[tiab] OR pre-k[tiab] OR pre-primary[tiab] OR under five*[ti] OR young child*[ti] OR “head start”[tiab] OR prekindergarten[tiab] OR pre-kindergarten[tiab] OR weanling*
  (“Study Characteristics” [Publication Type] OR “clinical trial”[ptyp] OR “Epidemiologic Studies”[Mesh] OR “Support of Research”[ptyp] OR cohort[tiab] OR observational[tiab] OR retrospective[tiab] OR longitudinal[tiab]) NOT (editorial[ptyp] OR comment[ptyp] OR news[ptyp] OR letter[ptyp] OR review[ptyp] OR systematic[sb])
  Update 3: 3/7/2016
  NOT (editorial[ptyp] OR comment[ptyp] OR news[ptyp] OR letter[ptyp] OR review[ptyp] OR systematic[sb])

Embase

• Date(s) Searched: 11/2/2015; 6/29/2017
• Date range: 1980-6/29/2017
• Search Terms:
  ((food* OR diet* OR eating OR taste* OR gustatory OR flavo*r*) NEAR/7 (accepta* OR prefer* OR choice* OR habit* OR discrimination* OR select* OR liking OR like* OR enjoy* OR aver* OR reject* OR dislik* OR neophobi* OR react*)):ti,ab OR (‘taste discrimination’/exp OR ‘food preference’/exp OR ‘taste aversion’/exp OR ‘taste preference’/exp OR ‘taste acuity’/exp OR palatab* OR unpalatab* OR ‘palatability’/exp OR tasty OR tastiness)
  OR
  ((food/exp OR ‘baby food’/exp OR ‘cereal’/exp OR ‘dairy product’/exp OR ‘egg’/exp OR ‘fruit’/exp OR ‘meat’/exp OR ‘sea food’/exp OR ‘milk’/exp OR fish/exp OR ‘poultry’/exp OR ‘beverage’/exp OR ‘vegetable’/exp OR nut/exp OR pea/exp OR meal/exp) AND (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion OR reject* OR dislik* OR neophobic* OR react* OR distaste* OR hedoni* OR taste* OR tasty OR tastiness))
  OR
  ((‘whole grain’ OR ‘whole grains’ OR dairy OR egg OR eggs OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR poultry OR beverage* OR vegetable OR vegetable* OR pea OR peas OR nut OR nuts OR cereal OR bread* OR yog*urt* OR cheese* OR juice* OR rice OR soup OR snack* OR meal* OR beans OR legume*) NEAR/7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR avers* OR reject* OR dislik* OR neophobic* OR react* OR distaste* OR hedoni* OR taste* OR tasty OR tastiness)):ti,ab
  OR
  ((facial OR face) NEAR/7 (expression* OR respons* OR react*)) AND (‘whole grain’ OR ‘whole grains’ OR dairy OR egg OR eggs OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR poultry OR beverage* OR vegetables* OR pea OR peas OR nut OR nuts OR cereal OR bread* OR yog*urt* OR cheese* OR juice* OR rice OR soup OR snack* OR meal OR meals OR beans OR legume*OR food/exp OR ‘baby food’/exp OR ‘cereal’/exp OR ‘dairy product’/exp OR ‘egg’/exp OR ‘fruit’/exp OR ‘meat’/exp OR ‘sea food’/exp OR ‘milk’/exp OR fish/exp OR ‘poultry’/exp OR ‘beverage’/exp OR ‘vegetable’/exp OR nut/exp OR pea/exp OR meal/exp)
  Embase only
  OR ((nutrient* NEAR/3 dense*) OR (nutrient* NEAR/3 rich*)) AND (food* OR beverage*):ti,ab ?
  AND
  (infant*:ti,ab OR infant/exp) OR (baby OR babies OR toddler* OR newborn* OR nurser*):ti,ab OR ‘newborn’/exp OR ‘newborn care’/exp OR preschool*:ti,ab OR “early years”:ti,ab OR pre-school:ti,ab OR ‘preschool child’/exp OR ‘infancy’/exp OR “early childhood”:ti,ab OR pre-k:ti,ab OR ‘nursery’/exp OR ‘nursery school’/exp OR prekindergarten:ti,ab OR pre-kindergarten:ti,ab OR weanling:ti,ab (postnatal, perinatal?)
  OR ([newborn]/lim OR [infant]/lim OR [child]/lim OR [preschool]/lim)
  AND ([in process]/lim OR [article]/lim OR [article in press]/lim)
  NOT [medline]/lim
  ‘clinical article’/exp OR ‘clinical trial’:ti,ab OR ‘controlled study’:ti,ab OR ‘clinical study’:ti,ab OR ‘randomized controlled’:ti,ab OR ‘clinical study’:ti,ab OR ‘cohort analysis’/exp OR cohort:ti,ab OR ‘types of study’/exp

Cochrane

• Date(s) Searched: 11/4/15; updated 7/3/17
• Date range: 1980-7/3/2017
• Search Terms:
  (food* OR beverage* OR diet* OR eating OR taste* OR tasty OR tastiness OR gustatory OR flavo*r* OR distaste*) NEAR/3 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR avers* OR facial OR face OR reject* OR dislik* OR neophobi* OR hedoni*)
  ((Face OR facial) NEAR/4 (react* OR respons* OR expressi*)) need?
  ((‘whole grain’ OR ‘whole grains’ OR dairy OR egg OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR poultry OR vegetables* OR pea OR nut OR cereal OR beverage* OR bread* OR seafood OR yog*urt* OR cheese* OR juice* OR beans OR legume* OR snack* OR meal*) NEAR/7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion* OR facial OR face OR reject* OR dislik* OR neophobic* OR hedoni* OR distaste* OR taste* OR tasty OR tastiness)):ti,ab
  (Palatab* OR unpalatab*):ti,ab
  AND
  infant* OR baby OR babies OR toddler* OR newborn* OR nurser* OR preschool* OR pre-school OR “early childhood” OR “early years” OR pre-k OR prekindergarten OR pre-kindergarten OR weanling*
  NOT pubmed OR Embase

PsychNET

• Date(s) searched: 2/4/2016; updated 7/3/17
• Date range: 1980-7/3/2017
• Search Terms:
  (food* OR beverage* OR diet* OR eating OR taste* OR tasty OR tastiness OR gustatory OR flavo*) NEAR/3 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR avers* OR facial OR face OR reject* OR dislik* OR neophobi* OR hedoni*) 520
  ((Face OR facial) NEAR/4 (react* OR respons* OR expressi*)):ti,ab need?
  ((‘whole grain’ OR ‘whole grains’ OR dairy OR egg* OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR vegetables* OR pea OR nut OR cereal OR beverage* OR bread* OR seafood OR yogurt* OR yoghurt* OR cheese* OR juice* OR beans OR legume* OR snack* OR meal*) NEAR/3 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion* OR facial OR face OR reject* OR dislik* OR neophobic* OR hedoni* OR distaste* OR taste* OR tasty OR tastiness)) 9 none selected
  (Palatab* OR unpalatab*):ti,ab
  AND
  infant* OR baby OR babies OR toddler* OR newborn* OR nurser* OR preschool* OR pre-school OR “early childhood” OR “early years” OR pre-k OR prekindergarten OR pre-kindergarten OR weanling*
  limits: peer review; 0-23 months
  Index Terms: {Food Preferences} OR {Food Refusal} OR {Taste Buds} OR {Taste Perception} AND Year: 1980 To 9999 AND Peer-Reviewed Journals only

ERIC (Proquest)

• Date searched: 2/9/16
• Search terms:
  SU.EXACT(“Food”) AND (SU.EXACT(“Toddlers”) OR SU.EXACT(“Infants”)) AND (SU.EXACT(“Preferences”) OR SU.EXACT(“Motor Reactions”) OR SU.EXACT(“Emotional Response”) OR SU.EXACT(“Patterned Responses”) OR SU.EXACT(“Behavior”) OR SU.EXACT(“Responses”)) 5 results 2/9/16; imported 1
  (food* OR beverage* OR diet* OR eating OR taste* OR tasty OR tastiness OR gustatory OR flavo*) NEAR/3 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR avers* OR facial OR face OR reject* OR dislik* OR neophobi* OR hedoni*)
  ((whole PRE/1 grain*) OR dairy OR egg* OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR vegetables* OR pea* OR nut OR cereal OR beverage* OR bread* OR seafood OR yogurt* OR cheese* OR juice* OR bean* OR legume* OR snack* OR meal*) NEAR/3 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion* OR facial OR face OR reject* OR dislik* OR neophobic* OR hedoni* OR distaste* OR taste* OR tasty OR tastiness))
  (Palatab* OR unpalatab*);
  (Face OR facial) NEAR/4 (react* OR respons* OR expressi*));
  infant* OR baby OR babies OR toddler* OR newborn* OR nurser* OR preschool* OR pre-school OR “early childhood” OR “early years” OR pre-k OR prekindergarten OR pre-kindergarten OR weanling*
  limit to year/peer review;

CINAHL/PsychInfo/ERIC/SocINDEX with Full Text/PsycARTICLES/ Social Sciences Full Text

• Date(s) Searched: 11/4/15 (CINAHL) ; 1/16 (ERIC, PsychInfo, Social Sciences Full Text (H.W. Wilson), SocINDEX with Full Text)
• Search Terms:
  ((MH “Food and Beverages+”) OR (MH “Food”) OR (MH “Diet”) OR (MH “Eating”) OR (MH “Eating Behavior”) OR (MH “Meals+”) OR (MH “Taste”) OR (MH “Taste Buds”) OR (MH “Cereals”) OR (MH “Dairy Products”) OR (MH “Yogurt”) OR (MH “Cheese”) OR (MH “Milk”) OR (MH “Eggs”) OR (MH “Fruit”) OR (MH “Fruit Juices”) OR (MH “Meat”) OR (MH “Seafood”) OR (MH “Fish”) OR (MH “Poultry”) OR (MH “Vegetables”) OR (MH “Nuts”) OR (MH “Legumes”) OR (MH “Bread”) OR (MH “Facial Expression”)) AND (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion* OR dislike* OR disliking OR hedoni* OR distaste* OR tasty OR tastiness)
  OR (MH “Food Preferences”) OR (MH “Food Habits”) OR unpalatab* OR palatab* Limiters - English Language; Peer Reviewed; Exclude MEDLINE records; Age Groups: All Infant 14
  Limit to “all infant” OR
  (MH “Infant”) OR (MH “Infant, Newborn”) OR (MH “Infant Behavior”) OR (MH “Infant Feeding”) OR (MH “Infant Feeding Schedules”) OR (MH “Child, Preschool”)

PsycARTICLES, Social Sciences Full Text (H.W. Wilson), SocINDEX with Full Text

• Search date: 1/28/16
• Search terms:
  ((food* OR beverage* OR diet* OR eating OR taste* OR gustatory OR flavo#r*) N7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR aversion* OR avert* OR face OR facial OR reject* OR dislik* OR neophobi* OR react* OR respons* OR expressi* OR hedoni* OR distaste* OR tasty OR tastiness)) 51 using N3 (240 (NOT whole grain..search string) and selected…; 114 with journal limits) Next time ck with PubMed journals! 24 in PsychArt, Soc Sci Full, SocIndex; 3 selected.
  (‘whole grain’ OR ‘whole grains’ OR dairy OR egg OR eggs OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR poultry OR vegetables* OR pea OR peas OR nut OR nuts OR cereal OR beverage* OR bread* OR seafood OR yog#urt* OR cheese* OR juice* OR snack* OR meal OR meals) N7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR aversion* OR avert* OR face OR facial OR reject* OR dislik* OR neophobi* OR react* OR respons* OR expressi* OR distaste* OR taste* OR tasty OR tastiness) 15 using N3 (109 and selected 34); 6 for psych/soc databases;0 selected
  Limit to selected PsychArt, Soc Sci Full, SocIndex journals
  Narrow by Journal: - adolescence
  Narrow by Journal: - child development
  Narrow by Journal: - developmental psychology
  Narrow by Journal: - family relations
  Narrow by Journal: - food, culture & society
  Narrow by Journal: - food, culture & society
  Narrow by Journal: - health psychology
  Narrow by Journal: - journal of applied psychology
  Narrow by Journal: - journal of applied social psychology
  Narrow by Journal: - journal of child & family studies
  Narrow by Journal: - journal of comparative family studies
  Narrow by Journal: - journal of family psychology
  Narrow by Journal: - journal of health & social behavior
  Narrow by Journal: - journal of marriage & family
  Narrow by Journal: - journal of popular culture
  Narrow by Journal: - social science journal
  Limit to CINAHL only journals:
  (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR avert* OR aversion* OR dislike* OR disliking OR hedoni* OR distaste* OR tasty OR tastiness OR (DE “Likes & dislikes”))
  AND
  DE “Food” OR DE “Beverages (Nonalcoholic)” OR (DE “Diets”) OR (DE “Eating Behavior”) OR (DE “Mealtimes”) OR DE “Food Intake” OR DE “Food Preparation” (psychInfo) 66 found.

Navigator: FSTA/BIOSIS/CAB

• Date(s) Searched: 11/4/15
• Search Terms:
  ((food* OR beverage* OR diet* OR eating OR taste* OR gustatory OR flavor* OR flavor*) NEAR/7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR aversion* OR avert* OR face OR facial OR reject* OR dislik* OR neophobi* OR react* OR respons* OR expressi* OR hedoni* OR distaste* OR tasty OR tastiness))
  (“whole grain” OR “whole grains” OR dairy OR egg OR eggs OR meat OR poultry OR seafood OR fruit* OR milk OR fish* OR poultry OR vegetables* OR pea OR peas OR nut OR nuts OR cereal OR beverage* OR bread* OR seafood OR yogurt* OR yoghurt* OR cheese* OR juice* OR snack* OR meal OR meals) NEAR/7 (accepta* OR prefer* OR choice* OR habit* OR discriminat* OR select* OR liking OR like* OR enjoy* OR aversion* OR avert* OR face OR facial OR reject* OR dislik* OR neophobi* OR react* OR respons* OR expressi* OR distaste* OR taste* OR tasty OR tastiness)
  infant* OR baby OR babies OR toddler* OR newborn* OR nurser* OR preschool* OR pre-school OR “early childhood” OR “early years” OR pre-k OR prekindergarten OR pre-kindergarten OR weanling*

ScienceDirect or Web of science

• Date(s) Searched: 11/9/2015
• Search Terms:
  ((food OR beverage OR diet OR eating OR taste OR gustatory OR flavor) w/3 (accepta* OR prefer* OR choice OR habit* OR discriminat* OR select* OR like* OR enjoy* OR avert* OR aversion OR face OR facial OR dislike OR reject OR neophobi* OR respons* OR react*))
  OR
  (‘whole grain’ OR ‘whole grains’ OR dairy OR eggs OR meat OR poultry OR seafood OR fruit OR milk OR fish OR poultry OR vegetables OR peas OR nuts OR cereal OR beverage OR bread OR seafood OR yogurt OR cheese OR juice) w/3 (accepta* OR prefer* OR choice OR habit* OR discriminat* OR select* OR like OR enjoy* OR avert* OR aversion OR face OR facial OR dislike OR distaste OR reject OR neophobi* OR respons* OR react*)
  AND
  (infant* OR (baby OR babies OR toddler OR newborn OR nurser*) OR preschool* OR pre-school OR “early childhood” OR pre-k OR prekindergarten OR pre-kindergarten OR “early years” OR weanling)

Figure 2

Flow chart of literature search and screening results.

This flow chart illustrates the literature search and screening results for articles examining the relationship between repeated exposure (timing, quantity, and frequency) to foods and early food acceptance. The results of the electronic database searches were screened independently by two NESR analysts in a step-wise manner by reviewing titles, abstracts, and full text articles to determine which articles met the criteria for inclusion. A manual search was done to ascertain articles not identified through the electronic database search. This systematic review included 21 articles.