Flavor perception in human infants: development and functional significance.

Monell Chemical Senses Center, Philadelphia, PA 19104, USA.
Digestion (Impact Factor: 1.94). 01/2011; 83 Suppl 1:1-6. DOI:10.1159/000323397
Source: PubMed

ABSTRACT Foods people consume impact on their health in many ways. In particular, excess intake of salty, sweet and fatty foods and inadequate intake of fruits and vegetables have been related to many diseases including diabetes, hypertension, cardiovascular disease and some cancers. The flavor of a food determines its acceptability and modulates intake. It is thus critical to understand the factors that influence flavor preferences in humans.
To outline several of the important factors that shape flavor preferences in humans.
We review a series of studies, mainly from our laboratories, on the important role of early experiences with flavors on subsequent flavor preference and food intake.
Some taste preferences and aversions (e.g. liking for sweet, salty and umami; disliking for bitter) are innately organized, although early experiences can modify their expression. In utero events may impact on later taste and flavor preferences and modulate intake of nutrients. Both before and after birth, humans are exposed to a bewildering variety of flavors that influence subsequent liking and choice. Fetuses are exposed to flavors in amniotic fluid modulating preferences later in life and flavor learning continues after birth. Experience with flavors that are bitter, sour or have umami characteristics, as well as volatile flavors such as carrot and garlic, occurs through flavorings in breast milk, infant formula and early foods. These early experiences mold long-term food and flavor preferences which can impact upon later health.

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    ABSTRACT: The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development of acceptable LNS products for infants 6-24 months and for pregnant and lactating women, for use in studies in three countries (Burkina Faso, Ghana and Malawi). This paper shares the rationale for a series of decisions in supplement formulation and design, including those related to ration size, ingredients, nutrient content, safety and quality, and packaging. Most iLiNS supplements have a daily ration size of 20 g and are intended for home fortification of local diets. For infants, this ration size is designed to avoid displacement of breast milk and to allow for dietary diversity including any locally available and accessible nutrient-dense foods. Selection of ingredients depends on acceptability of flavour, micronutrient, anti-nutrient and essential fatty acid contents. The nutrient content of LNS designed to prevent undernutrition reflects the likelihood that in many resource-poor settings, diets of the most nutritionally vulnerable individuals (infants, young children, and pregnant and lactating women) are likely to be deficient in multiple micronutrients and, possibly, in essential fatty acids. During ingredient procurement and LNS production, safety and quality control procedures are required to prevent contamination with toxins or pathogens and to ensure that the product remains stable and palatable over time. Packaging design decisions must include consideration of product protection, stability, convenience and portion control.
    Maternal and Child Nutrition 05/2013; · 2.11 Impact Factor
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    ABSTRACT: The sense of taste is stimulated when nutrients or other chemical compounds activate specialized receptor cells within the oral cavity. Taste helps us decide what to eat and influences how efficiently we digest these foods. Human taste abilities have been shaped, in large part, by the ecological niches our evolutionary ancestors occupied and by the nutrients they sought. Early hominoids sought nutrition within a closed tropical forest environment, probably eating mostly fruit and leaves, and early hominids left this environment for the savannah and greatly expanded their dietary repertoire. They would have used their sense of taste to identify nutritious food items. The risks of making poor food selections when foraging not only entail wasted energy and metabolic harm from eating foods of low nutrient and energy content, but also the harmful and potentially lethal ingestion of toxins. The learned consequences of ingested foods may subse-quently guide our future food choices. The evolved taste abilities of humans are still useful for the one billion humans living with very low food security by helping them identify nutrients. But for those who have easy access to tasty, energy-dense foods our sensitivities for sugary, salty and fatty foods have also helped cause over nutrition-related diseases, such as obesity and diabetes. Introduction Taste is a sensory modality involving the oral perception of food-derived chemicals that stimulate receptor cells within taste buds. Taste principally serves two functions: it enables the evaluation of foods for toxicity and nutrients while helping us decide what to ingest and it prepares the body to metabolize foods once they have been ingested. Taste percepts are elicited by molecules that stimulate the taste buds in epithelia of the oral cavity and pharynx (back of the throat) [1] (Box 1). Moreover, taste drives a primal sense of 'acceptable' or 'unacceptable' for what is sampled. Taste combines with smell and tactile sensations to form flavors, which allows us to identify and recognize food items as familiar or novel. If familiar, we can anticipate the metabolic consequences of ingesting the food. If novel, we can use these sensory cues to learn about the physiological outcomes of ingestion. If the outcome is positive, taste will signal pleasure and reward — both directly from the plea-surable quality of the taste itself, as well as from associated metabolic consequences. Some animals also use taste to understand social chemical cues, but there is no evidence presently that it plays this role for humans (Box 2). Taste-stimuli are typically released when food is chewed, dissolved into saliva and pre-digested by oral enzymes, such as amylase, lipase, and proteases [2]. Humans, and possibly many other omnivores, perceive nutrients and toxins qualitatively as sweet, salty, sour, savory, and bitter tasting [1]. Simple carbohydrates are experienced as sweet, the amino acids glutamate, aspartate and selected ribonu-cleic acids are experienced as savory (or umami), sodium salts, and salts of a few other cations, are experienced as salty, acids are experienced as sour, and many toxic com-pounds are experienced as bitter. The set of compounds that elicits bitter taste is by far the largest and most structur-ally diverse, and, consequently, humans possess about 25 functional bitter taste receptor genes (T2Rs). In addition, a variety of other nutrient taste qualities have been suggested, including specific taste percepts from water, starch, malto-dextrins, calcium, and fatty acids [3]. There is, however, presently little agreement on how humans perceive these chemicals and, consequently, on whether we would describe our oral experiences with them as unique tastes. Humans taste with the edges and dorsal surface of the tongue, soft palate (the roof of the mouth toward the back of the oral cavity), and pharynx (Figure 1) [4]. These tissues comprise the gustatory epithelia. We do not taste with our lips, the underside of our tongue, our hard palate (behind our upper incisors), or the inside of our cheeks, although young children may have taste buds in more areas of the oral cavity than do adults [5]. The sensory organ within these epithelia is the taste bud — a microscopic rosette shaped cluster of approximately 80–100 receptor cells, in which chemicals are detected by transmembrane receptors (Figure 1) [4]. The human taste receptors have not all been confirmed in vivo except for selected toxin/bitter and a glutamate/umami receptor. Nevertheless, for many stimuli there are strong hypotheses of the identity of human taste receptors based on mouse and fly research. The principal receptor hypothesized to transduce human sweet stimuli is T1R2/T1R3, for umami stimuli it is T1R1/T1R3 (although mGluR1, mGluR4 and NMDA have been implicated), and for bitter taste stimuli it is the family of T2Rs. For salty stimuli there is growing evidence that the epithelial sodium channel (ENaC), in part, transduces salty taste, and for sour taste stimuli acid sensing ion channels (ASICs) and possibly other proton detectors are involved. Whereas it was once hypoth-esized that these receptors should be expressed in partic-ular zones according to presumed taste quality regions of the mouth, we now believe that the receptor expression zones are heavily overlapping in most regions of the mouth. The taste bud serves as the first stage of gustatory signal processing and there are many ways in which cells within a bud communicate with one another, including electric coupling via gap junctions and cell to cell chemical commu-nication via glutamate, serotonin, and ATP among other possible transmitters [6]. Taste buds reside within small bumps or folds on the tongue, called 'papillae', in addition to the smooth epithelia of the soft palate and pharynx [1] (Figure 1). Taste receptor cells within the buds are electrically active epithelial cells that can depolarize and release neurotransmitters. Whereas these taste receptor cells are not neurons themselves, they do communicate with nearby neurons via synaptic transmission and intercellular com-munication using ATP and other neurochemicals [6,7]. Taste receptor cells are continuously replaced in the bud every 9 to 15 days, to compensate for mechanical, thermal, or toxin-induced damage to the gustatory epithelia [8]. Moreover,
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    ABSTRACT: Food neophobia, that is the reluctance to try novel foods, is an attitude that dramatically affects human feeding behavior in many different aspects among which food preferences and food choices appear to be the most thoroughly considered. This attitude has an important evolutionary meaning since it protects the individual from ingesting potentially dangerous substances. On the other hand, it fosters an avoidance behavior that can extend even toward useful food elements. A strong link exists between food neophobia and both the variety in one person's diet and previous exposures to different foods. In this review, the more recent findings about food neophobia will be concisely described. Given the suggested connection between the exposure to different foods and food neophobia, this review will focus on the relation between this attitude and human chemosensory abilities. Olfaction, in particular, is a sensory modality that has a central role in flavor perception and in food preference acquisition. Therefore, the latest evidences about its relation with food neophobia will be discussed along with the applied and cognitive implications.
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