According to Fox (2003) What Characteristic of Foods Is Used to Help Promote Fashionable Trends?

Every bit most parents and caregivers are enlightened, feeding children a nutritionally balanced nutrition can be challenging. Children are born with a biological predisposition to prefer sweet and to avoid biting foods such as green leafy vegetables. It has been hypothesized that this predisposition evolved to attract children to free energy-dense foods while discouraging the consumption of toxins. Although this may have enhanced survival in environments historically characterized by food scarcity, it is conspicuously maladaptive in many of today's nutrient environments where children are surrounded by an abundance of sugariness-tasting, unhealthful foods and beverages that place them at risk for excessive weight gain. Because overweight or obese children tend to go overweight or obese adults who are at gamble for a range of cardiovascular diseases, information technology is of main importance to develop effective evidence-based strategies to promote the development of healthy eating styles. Fortunately, accumulating testify suggests that, starting before birth and standing throughout development, there are repeated and varied opportunities for children to acquire to enjoy the flavors of healthful foods. Because flavors are transmitted from the maternal nutrition to amniotic fluid and breast milk, mothers who eat a diversity of healthful foods throughout pregnancy and lactation provide their infants with an opportunity to learn to similar these flavors. This in plow eases the transition to healthful foods at weaning. In contrast, infants fed formula learn to adopt its invariant season profile, which differs from breast milk, and may initially exist less accepting of flavors not found in formula. This process can continue throughout weaning and into childhood if infants are repeatedly exposed to a variety of healthful foods, even if they initially dislike them. These early-life sensory experiences establish nutrient preferences and dietary patterns that prepare the phase for lifelong dietary habits.

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Cardinal Messages

• Children's dietary habits reflect their basic biology, which predisposes them to prefer sweet tastes and to avoid bitter-tasting foods such as green leafy vegetables. Although once adaptive, in modern food environments children's proclivity for unhealthful foods tin can place them at gamble for obesity and a number of diseases.

• Flavors from the female parent'south nutrition are transmitted to amniotic fluid and breast milk, and children accept repeated and varied opportunities to learn to similar the flavors of healthful foods they will likely run across during weaning.

• At weaning, 8-ten exposures to a food will increase intake fifty-fifty if the food is initially rejected; further exposures may be required to increment liking. Exposing infants to a diversity of flavors promotes infants' willingness to swallow novel foods.

Introduction

Parents and caregivers face the ubiquitous challenge of providing their children with a balanced diet that promotes salubrious growth and development. The USDA [ane] recommends that families meet this challenge past feeding children a diverse, food-dense diet that contains vegetables, fruits, whole grains, low-fatty dairy products, and quality protein sources. As many parents complaining, meeting these dietary recommendations is difficult for a number of reasons - non the to the lowest degree of which is that children tend to dislike vegetables and prefer sugar-sweetened foods and beverages. As a effect, children generally avert eating most vegetables and forgo consumption of natural sources of sugars such equally fruit in favor of foods and beverages that are high in added sugars [2,three]. This preference for uncomplicated sugars and energy-dense foods over nutrient-rich alternatives has dire wellness consequences. Children's poor dietary habits are a risk factor for several diseases, including pediatric obesity, blazon 2 diabetes, and hypertension, which take traditionally afflicted older adults [four,5].

This article provides an understanding of why children prefer or dislike certain foods and how we can shift their inborn preferences through early sensory feel. It begins with a cursory overview of the ontogeny of sweet and bitter taste perception, both of which have important functional significance in children's consumption of healthful, biting-tasting vegetables and unhealthful, sweet-tasting desserts and beverages. It then reviews how early flavor experiences interact with the plasticity of the chemosensory organization to shift children's preferences and acceptance of fruit and vegetables. In sum, this inquiry shows that, although children are born with biological predispositions to prefer highly sweetness-tasting foods and beverages over healthful, less sugariness alternatives, their preferences can be altered by early experiences from gestation through weaning and practice non necessarily determine lifelong dietary habits.

Taste and Flavor Perception

Flavor is a powerful determinant of human consummatory behavior. Although in everyday language the terms flavor and sense of taste are often used interchangeably, flavor refers to the integrated sensation that arises from the combined input of gustatory modality, chemosensation, and olfaction [six]. For example, when we consume an orange soda, sugars and citric acid come up into contact with taste receptors throughout the oral crenel and the gut, which send letters to the brain that allow us to perceive the sweet and sour taste of this beverage. We also experience the bite of carbon dioxide, which activates trigeminal nervus fibers that innervate the nasal and oral crenel, triggering chemosensation. In addition, the citrus odor travels retronasally along the dorsum of the nasopharynx toward the roof of the nasal crenel, reaching olfactory receptors located in the epithelium of the nasal cavity. Unlike the limited number of chief tastes, which consist of sweet, sour, bitter, savory, and salty, there are thousands of distinctive odors with separable sensations that allow us to experience a rich assortment of flavors.

Relative to other sensory capacities such as vision and audition, the sense of taste begins to emerge relatively early on. Behavioral studies using a variety of techniques suggest that by the last trimester of prenatal evolution sense of taste buds are capable of detecting and communicating data to cardinal nervous system structures responsible for organizing and decision-making affective behaviors (for a more extensive review meet [7]). Similarly, the olfactory bulb and receptor cells are functional by the last trimester. Given the all-encompassing prenatal evolution of the chemosensory system, it is non surprising that the newborn is sensitive and responsive to odor, taste, and season stimuli at birth.

Age-Related Changes in Response to Sweet and Bitter Gustation

Accumulating research suggests that preferences for basic tastes are a major determinant of children'due south food choices and acceptance patterns [eight,9,10,11]. Over the by few decades, our understanding of children's perception and preference for basic tastes has grown substantially (for a review come across [seven]). We at present know that children live in their ain sensory world, with their sensitivities and preferences for tastes changing throughout childhood. Responses to bones tastes are remarkably similar beyond cultures and species, which suggests these responses are a product of children'southward basic biology.

Sweetness Gustation

In nature, most sugars (due east.yard., fructose, maltose, and sucrose) have a small molecular weight and are constitute primarily in plants. These sugars provide sources of glucose, a key source of energy. For infants, the sweet sugar lactose constitute in breast milk can besides be metabolized to provide glucose energy. Indirect evidence from early on studies of fetuses [12], together with findings from studies of premature infants, suggests that detection of sweetness taste stimuli is possible during belatedly gestation [thirteen]. This early on experience may fix newborns to detect and accept the basic sense of taste of sweet found in chest milk, which contributes to their survival.

Palatable tastes, such every bit sucrose, are thought to induce sensory pleasure, which elicits appetitive reactions. As shown in Effigy 1, tasting 0.73 M sucrose elicits facial relaxation, sucking movements, and sometimes smiling in newborns, as commencement described by Steiner [fourteen] and afterward by Rosenstein and Oster [xv]. Consistent with this, inquiry has repeatedly demonstrated that infants preferentially consume sweet-tasting solutions relative to water and tin differentiate varying degrees of sweetness (0.05-0.thirty Thou) and different kinds of sugars; sucrose, fructose, glucose, and lactose [xvi]. These findings converge with physiological findings; for example, administration of drops of aqueous sucrose (0.73 Chiliad) to the tongues of newborn infants produced greater relative left-side activation in both frontal and parietal regions of the brain, which is considered to be a reliable indicator of positive emotion [17].

Fig. 1

Newborn's orofacial responses to the sweet taste of 0.73 M sucrose (left) and the bitter taste of 0.003 One thousand quinine (right) presented approximately ii h after birth, before the start postnatal feed. Using a syringe, 0.2 mL of each gustation solution at room temperature was presented to the central portion of the dorsal surface of the babe'south natural language. Reprinted with permission from [15].

Compared to adults, who on average adopt 0.44 M sucrose, 5- to 10-yr-quondam children accept a much sweeter tooth, preferring 0.54 M sucrose [xviii], almost double the concentration of most soft drinks [19]. The college preference for sucrose observed throughout childhood may be related to rapid concrete growth during this fourth dimension [20]. This hypothesis is supported by bear witness that adolescents with higher sweet preferences also accept higher levels of a biomarker for bone growth than practice those with lower sweet preferences [21]. Because this biomarker increases during growth spurts, age-related declines in preference for sugariness taste may correspond with cessation of physical growth [22,23].

Bitter Taste

In contrast to sweet taste, biting gustation appears to exist disliked by infants at birth; as shown in Figure 1, they gape when a bitter quinine solution (0.003 One thousand) or urea solution (0.15-0.25 M) is placed on the natural language [14,xv]. All the same, intake studies reveal that newborns consume similar amounts of 0.18-0.48 M urea in water or in a weak sucrose solution compared to the diluent alone [24,25]. Differential consumption of bitter urea solutions does not occur until infants are approximately 2 weeks of age [26] and is evidenced throughout childhood by a full general avoidance of biting-tasting foods. Together, the orofacial and consumption studies suggest that intake regulation of bitter solutions may mature postnatally.

Recent research in adults and children has focused on understanding the office genes play in individual differences in sensitivity to biting tastes. Of the 25 human biting gustatory modality receptor genes currently identified, TAS2R38 is the almost ordinarily studied (for a review see [27]). Polymorphisms in the genes that encode this receptor decide much of the variation in sense of taste sensitivity for a class of biting-tasting chemicals that includes synthetic thiourea compounds (e.g., propylthiouracil [PROP]) and natural plant toxins (east.yard., goitrin) establish in cruciferous vegetables such as broccoli [28]. Due in part to polymorphisms on the TAS2R38 cistron, some individuals accept a high sensitivity threshold for this form of bitter tastes, while others have lower thresholds and as a result are more sensitive to the bitterness in cruciferous vegetables [29]. In add-on to these individual differences, psychophysical studies have shown that PROP sensitivity appears to decrease with age. Children heterozygous for a TAS2R38 variant perceived lower concentrations of this bitter chemical than did heterozygous adolescents, who in plow detected lower concentrations than heterozygous adults [xxx,31]. Such sensitivity to this class of biting tastes may contribute to reduced acceptance of cruciferous vegetables during childhood.

Development, Today's Obesogenic Surroundings, and Sensory Learning: A Biting-Sweet Story

How practise nosotros explain children'south biological predispositions to prefer sugariness-tasting and dislike bitter-tasting foods, even though they atomic number 82 to maladaptive outcomes that threaten health? Looking back in our evolutionary history reveals that human'southward electric current gustation perceptions and preferences have been largely shaped by the ecological niches of our evolutionary ancestors. In order to adapt to specific environments that comprise some types of nutrient but not others, our taste has changed and, past extension, and so has our genome. Early hominoids used their sense of gustatory modality to place nutritious nutrient items amid an expansive dietary repertoire. Preference for sweet tastes is thought to have evolved to attract us to energy-producing sugars that are important for growth and evolution.

Withal, eating tin be dangerous - many risks are associated with making poor food selections, including the potentially lethal ingestion of harmful parasites, bacteria, and chemicals. As a result, rejection of bitter likely evolved to prevent ingestion of potentially dangerous substances, such as poisons, many of which we perceive as bitter. Although these biological predispositions were at one fourth dimension adaptive, helping us select nutrients and avoid toxins, today preferences for sugary foods and avoidance of bitter vegetables do not provide an adaptive advantage in environments with like shooting fish in a barrel admission to a multifariousness of palatable, energy-dumbo foods and rubber fruits and vegetables.

Over the past century, pregnant changes in our food surround have occurred, including an increase in the number of fast food restaurants and availability of low-cost, energy-dense food options. These changes have been fueled past marketing strategies that target children'south inborn preferences for sugariness taste [32]. Children tin can increase their preference for a food production subsequently only a single exposure to a commercial, and this is strengthened with repeated exposures. In turn, these preferences affect their product purchase requests, which ultimately influence their parents' purchasing decisions [33].

The marketing influence on children's food preferences is of particular business concern for a number of reasons. First, as discussed above, nosotros do not demand to encourage consumption of unhealthful foods, given that children are already predisposed to preferentially consume them. Not but are children attracted to the sweetness taste of sugar in these foods, but the presence of sugar can also effectively suppress or mask the bitterness [34,35] that is inherent in some foods and beverages (east.g., caffeinated energy drinks) that children would otherwise avoid.

2d, through familiarization with sweetened versions of foods and beverages that are not inherently sweet-tasting, such equally yogurt, milk, or cereal, children develop an expectation that foods should taste sweet [36]. Equally a result of the intrinsic plasticity of the sense of taste system, preferences for sweeter-tasting foods and beverages are readily caused through early exposure to sweet gustatory modality. For case, longitudinal studies have shown that newborn infants who were regularly fed sugar water preferred significantly higher concentrations of sucrose solutions ii years later compared to those who had no such experience [37]. Although correlational, these studies suggest that early dietary exposure to sweet foods is associated with later enhanced acceptance of sweet tastes. However, the opposite is besides true: just as children's preferences for sweet-tasting foods can be strengthened, preferences for healthful foods can increase as a event of early exposure to the flavors of these foods.

Accumulating evidence suggests that, starting before birth and continuing throughout evolution, repeated and varied opportunities to learn virtually the flavors of healthful foods increase later acceptance and consumption of these foods [38]. During fetal development, the intrauterine environment is rich in olfactory property volatiles (i.e., flavors) that change as a function of the mothers' diet. As discussed above, it is likely that the fetus is sensitive to and learning nearly this ever-changing flavor profile; past the last trimester the taste and olfactory receptors are functional, and the fetus is actively swallowing between 500 and 1,000 mL of amniotic fluid each mean solar day [39]. Subsequently birth, infants are exposed to a diet that is typically solely milk-based, consisting of breast milk, artificial milk (formula), or both. While the flavor of chest milk, like amniotic fluid, reflects the mother's diet, the invariant flavor profile of formula does not (Fig. 2).

Fig. two

Flavor experiences during pre- and postnatal development. Mutual flavors are initially experienced during the fetal period in utero, during postnatal feeding, and during weaning. After birth, the American University of Pediatrics recommends feeding only breast milk for the beginning 6 months of life, followed past a combination of solid foods and breast milk until the infant is at least 1 year erstwhile. This gradual transition to a diet consisting primarily of solid foods is represented past the gradated borders in the figure. Breastmilk serves to bridge the flavor experiences during the fetal period to those at weaning (represented past solid black arrows). Many mothers choose to feed their infants formula exclusively, or to feed a combination of breastmilk and formula (as represented past the dotted double arrow). In contrast to the varied sensory experiences of breastmilk, the flavor of formula is monotone and lacks the volatiles of the foods of the female parent's diet. These experiences nevertheless impact infants' credence of similar flavors at weaning (every bit represented past the solid grey arrow).

Amniotic Fluid and Breast Milk

A wide variety of flavors ingested by the mother are transmitted to amniotic fluid during pregnancy and to breast milk during lactation, including garlic [xl], vanilla [41], anise [42], and carrot [43]. This ongoing exposure to the flavors inside amniotic fluid and breast milk biases the infant's flavor preferences for these foods. In 1 report, mothers consumed carrot juice either for 3 consecutive weeks during the terminal trimester of pregnancy, or during lactation, while those in a command grouping drank water during pregnancy and lactation and avoided carrots [43]. Infants exposed to the target flavor, either prenatally or postnatally, preferred carrot-flavored relative to patently cereal, whereas the control group showed no such preference. Further work in not-homo animals has replicated these effects and has additionally shown that dogs exposed to aniseed throughout the perinatal menstruation (i.e., pre- and postnatal exposure) displayed greater flavor preferences for aniseed at weaning than those exposed to aniseed either pre- or postnatally [44].

These results support the contention that the continuity of flavor experiences provided by breastfeeding helps with the transition to solid foods at weaning. This is further supported past findings that breastfed infants are more than accepting of fruit than are formula-fed infants, merely only if their mothers regularly ate this food during lactation [45]. Breastfed children may also be more willing to take novel foods [46] and less picky as they abound older [47,48], particularly if their mothers consume a varied diet, which provides a more varied flavor profile in breast milk.

Formula

Infants who are exclusively formula-fed often receive just i type of formula, which limits their exposure to varied season experiences [49]. Despite the lack of season diversity, dissimilar types and brands of formulas vary in their feature flavor profile, due to differences in their composition and processing [fifty]. For example, cow-milk-based formulas (CMFs) are described as having low levels of sweetness, with sour and cereal-similar characteristics, whereas soy-protein-based formulas take sweet, sour, and bitter tastes. Extensively hydrolyzed protein formulas (ePHFs), the feeding regimen of choice for formula-fed infants who cannot tolerate intact proteins, have high levels of free amino acids, because its proteins are broken down by enzymes. These gratis amino acids impart a savory, bitter, and sour gustation contour, every bit well every bit unpleasant smell volatiles (eastward.g., sulfur volatiles that are establish in cruciferous vegetables, such every bit broccoli [51,52]). Yet, infants fed ePHF early on in life readily learn to accept its "off" flavors [53].

By taking advantage of the inherent differences in the season profiles among these formulas, researchers accept shown that infants develop flavor preferences that reflect the blazon of formula they are fed. Compared to infants fed CMF, those fed ePHF ate more than savory-, sour-, and bitter-tasting infant cereals at a faster charge per unit and showed fewer facial expressions of distaste during feeding [54]. Moreover, ePHF-fed besides as breastfed infants were more likely to brandish positive facial reactions to savory-tasting cereal, possibly because breast milk [55] and ePHF [56] are both loftier in the savory amino acid glutamate. Other research has shown that the length of time infants are fed ePHF influences their responses to savory nutrient; those fed ePHF for at to the lowest degree 3 months showed greater credence of a savory broth relative to a evidently broth [57]. Bear witness shows that these early preferences tin can exist long-lasting. Several years after the last formula exposure, children fed ePHF during infancy were more than probable to prefer a sour-tasting apple juice than were children fed CMF [58]. They were also more probable to preferentially eat broccoli, which has flavor notes similar to ePHF [58]. In combination, these studies reveal that the tastes to which infants are exposed during formula feedings affect their acceptance of foods at weaning. However, if these flavors are not part of the family'due south diet, infants may not reap the benefits of this early sensory learning. Rather, preferences for the foods that the family eats volition be acquired at weaning through repeated exposure.

Complementary Feeding: Increasing Preferences for Fruit and Vegetables

At weaning, children transition from a milk-based to a mixed diet that consists of breast milk or formula and a variety of complementary foods. With the milk-based diet, infants larn to prefer foods through repeated exposure (with formula) or through exposure to a variety of flavors (with chest milk). The same is true for children at weaning: converging show from several experimental studies indicates that children require 8-10 exposures to the taste of a food in club to increase acceptance of it. It is of import to note, however, that increased intake does not always coincide with increased liking[45]. Even when infants begin to consume more of a food after repeated exposure, they may continue to display negative facial responses (such as squinting) while eating information technology. Because these negative orofacial responses persist later increased acceptance, parents are less probable to offering the nutrient again [59]. To produce shifts in liking that mirror the changes in intake, exposure needs to continue beyond credence until liking occurs (i.e., when the infant begins to show fewer facial expressions of distaste) [45,lx].

Relative to merely repeating exposure to the aforementioned food, exposing infants to a variety of flavors has the added advantage of promoting infants' willingness to consume novel foods. Every bit shown in Figure 3, 8 days of exposure to a variety of vegetables increases credence of a novel-tasting vegetable [61,62] but not of a novel fruit [61]. Similarly, 8 days of exposure to a variety of fruits increases credence of a novel fruit simply non of a novel green vegetable [61]. It appears that the variety of foods presented must share some flavor characteristics of the novel nutrient in order to increase its acceptance. More recent research has shown that exposure to flavor diversity continues to be constructive in increasing acceptance of fruit betwixt 4 and 8 years of historic period [63]. However, this report did not detect a like increase in children's preferences for vegetables, which suggests that shifting older children's preference for vegetables may require other strategies such as associative conditioning [64].

Fig. 3

Infants' intake of light-green beans (a) and pears (b) before (white bars) and after (black bars) an 8-day dwelling house exposure menses in which they were fed green beans, a variety of orange and green vegetables, a variety of fruit, or pears. Infants increased their intake of dark-green beans if they were fed green beans or a variety of vegetables, but not fruit, at abode. They also increased their intake of pears if they had been fed pears or a diversity of fruit at habitation. This suggests that, for flavor variety to increase consumption of a novel vegetable, there must be some overlap betwixt the flavor profiles of the diversity of foods fed and the novel nutrient [61]. * Significant difference at p < 0.05. ⁺ Significant difference at p < 0.08.

It appears that additional factors may moderate the ease with which infants learn flavor preferences for healthful foods, such as personal characteristics of the kid. For example, children who were high in arroyo temperament were less likely to express facial expressions of distaste (i.due east., gape) and consumed more than of a bitter greenish vegetable [65]. Infants with approach temperaments may be more likely to endeavour a greater variety of fruits and vegetables before the onset of neophobia at effectually 2 years of historic period. Every bit discussed above, we are too gaining a improve understanding of the molecular mechanisms underlying individual differences in taste sensitivity. For instance, considering of genotype differences, some individuals are more than sensitive to the bitter sense of taste of some vegetables and as a upshot may be probable to swallow these foods (e.g., [29,66]). Withal another factor shown to be important is the parents' feeding style. Osborne and Forestell [63] found that when children were exposed to a multifariousness of fruits and vegetables, they were less likely to develop a preference for a novel fruit when their mothers reported pressuring them to consume. Thus, it appears that early on and repeated sensory experiences, kid temperament, taste receptor genotype, as well as the quality of mother-child interactions during feeding are merely a few of the factors that interact to make up one's mind food preferences during babyhood.

Final Remarks

While no single factor is responsible for the dramatic increases in overweight and obesity in the Us over the past century, it is generally accepted that the consumption of saccharide-sweetened products, particularly beverages, is causally linked to increases in chance of chronic diseases, including blazon ii diabetes, cardiovascular affliction, hypertension, and stroke [67]. This is concerning because children are built-in with biological predispositions to preferentially eat sweetness-tasting foods and beverages instead of other more healthful foods, such as green vegetables.

Whether this early proclivity for sweet tastes leads to later on unhealthy dietary habits depends in part on the child's early sensory experiences. Health care providers should encourage pregnant and nursing women to swallow healthful diets with a variety of flavors. Infants who are formula-fed should be exposed to a variety of flavors, specially those associated with fruits and vegetables, while the female parent is meaning and again at weaning. Although we cannot completely change children's innate liking of sweets and disliking of bitterness, we accept learned that early sensory experiences, which begin with the flavors of foods the mother eats during pregnancy and lactation, can shape and modify early season and nutrient preferences, thereby increasing infants' credence of the foods available in their environment. Thus, a mother's healthy diet increases the likelihood that her child volition adopt these same healthy foods. Repeated exposure to salubrious foods at weaning volition maintain and expand these preferences. Infants' healthy dietary repertoire volition go along to abound if they are exposed to a variety of healthy foods at weaning and throughout babyhood.

To be certain, whether children take the opportunity to learn about healthful flavors early on in life depends on many factors. A family unit's decisions about food purchases and consumption are influenced by a range of socioenvironmental factors, such as culture, fiscal status, and education (due east.m., [68]). An appreciation and a greater agreement of the complication underlying food choices in families and how these affect the evolution of children'south food preferences will assistance in the evolution of show-based strategies and programs to facilitate children's early on acceptance of fruit and vegetables.

Disclosure Argument

The author declares that no financial or other conflict of interest exists in relation to the contents of the paper. The writing of this commodity was supported past Nestlé Diet Constitute.

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