Early Development of Taste and Flavor Preferences and Consequences on Eating Behavior
Sophie Nicklaus, Camille Schwartz, Sandrine Monnery-Patris, and Sylvie Issanchou
Early childhood is an important period for the development of health. Recent researches using different approaches (experimental and epidemiological) have shown the importance of this early period for metabolic programming. This general concept of “Developmental Origin of Health and Disease” (DOHAD) has been refined in humans to highlight the importance of the first 1,000 days for the development of the health status. Eating behavior also develops during this period, in particular because from conception until the age of 2 years, the mode of feeding drastically evolves, which involves that the child has to learn “how” to eat, but also what to eat, how much food to eat, and in which context. After birth, when foods are orally exposed, infants discover the intrinsic properties of foods, with a variety of tastes, flavors, textures, as well as energy densities. Here, we focus on deciphering the involvement of taste and olfaction in the early establishment of eating behavior. In the frame of the OPALINE French birth cohort (Observatory of Food Preferences in Infants and Children), taste and flavor preferences were studied in children in relation with food acceptance over the first 2 years of life.
At birth, previous works revealed evidence of differential preferences across tastes, with a preference for the sweet taste and a rejection of the bitter taste, and very few evidence of inborn flavor preference, except when infants had been previously exposed to flavors from the maternal diet. The later evolution of taste and flavor preferences has received little attention. Within the OPALINE cohort, we studied longitudinally in a group of 285 infants the evolution of taste preferences from 3 to 20 months  and the evolution of flavor preferences from 8 to 22 months . Taste acceptance trajectories for all primary tastes and for a fat emulsion were modeled. For saltiness, acceptance increased sharply between the ages of 1 3 and 12 months. The trajectories of acceptance were parallel for sweetness, sourness, and the umami taste between 3 and 20 months, with sweetness being preferred. Between 12 and 20 months, the acceptance of all tastes, except bitterness, decreased, and at 20 months, only sweetness was not rejected. The acceptance of bitterness remained stable. For the fat emulsion, acceptance evolved from indifference to rejection. Between 8 and 22 months, unpleasant food odors (trimethylamine, dimethyl disulfide, and butyric acid) lead to avoidance behavior in infants, but pleasant food odors did not elicit specific behavior. Developmental changes were dependent on taste and flavor; thus, a general change in taste or flavor perception is unlikely.
Taste exposure (i.e., dietary exposure to a variety of foods) might partly explain the taste acceptance trajectories. We showed that a longer breastfeeding duration (likely associated to a longer exposure to the umami tasting glutamate found in breast milk) was associated to a higher preference for the umami taste at 6 months . Moreover, simultaneous to the introduction to complementary foods, taste differential reactivity (within-subject variability across tastes) clearly increased. At the beginning of the complementary feeding period, we showed that a higher preference for sweet, sour, and umami tastes was associated to a higher acceptance of sweet-, sour-, and umami-tasting foods, respectively , and, similarly, that rejection of the odor of trimethylamine and of dimethyl disulfide were related to the rejection of fish and sulfurous cheeses, respectively . Further in development, at 20 months, food neophobia was associated to flavor differential reactivity (within subject variability across flavors) but not to taste differential reactivity (within-subject variability across tastes) , underlining the importance of olfaction in the development of neophobic reactions. Further studies are necessary to establish a more complete understanding of the programming effect of early dietary taste and flavor exposure on later food choices.
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