The general principles observed are likely of broader significance, indicating a fundamental feature of mammalian development and reflecting the importance of familiarizing infants with flavors that their mothers consume and transmit to breast milk. This trial was registered at clinicaltrials.gov as NCT00994747.

Background & Aims Emerging research has revealed the existence of periods in which the developing brain has heightened sensitivity to environmental influences. We discovered a sensitive period, <4 months of age, when exposure to the flavor of extensively hydrolyzed protein hydrolysate formulas (ePHF) determines its hedonic tone. This formula has pronounced bitter, sour, and savory tastes compared to cow-milk-based formulas (CMF). This study aimed to determine the effects of duration of exposure during the sensitive period on a food containing an exemplar of the savory flavor. Methods Formula-fed infants were randomized into four groups at age 0.5 months: one control group fed the control cow-milk formula (CMF) for 8 months, and three groups fed ePHF for 1, 3, or 8 months and CMF otherwise. When infants were 8.5 months, their acceptance of a savory and plain broth was measured. Results Infants fed hydrolysate formula for 3 or 8 months, but not 1 month, showed greater acceptance of the savory broth relative to the plain broth (p<0.01) and consumed it at a faster rate (p=0.01). Conclusions The duration of flavor exposure affects infants’ earliest responses to foods: a 3-month exposure to this formula shifted the hedonic tone for savory flavor.

Objectives/Hypothesis This study evaluated two versions of a test for olfactory function to determine suitability for use in a pediatric population. Study Design Cross-sectional cohort study. Method In phase 1, 369 children (ages 3–17 years) and 277 adults (parents) were tested. Children began with identification and familiarity judgments to pictures representing target odors and distractors. Odors were administered via a six-item scratch and sniff test. Each answer sheet contained the correct odor source and three distractors. In phase 2, 50 children (ages 3–4 years) and 43 adults were given a revised version with eight odors judged more representative of the source and familiar to children. Results Both completion time and identification accuracy in phase 1 improved with age. Accuracy of children 5 years old and above equaled adults for two of the three best odors. In phase 2, adults' accuracy significantly improved relative to phase 1 (92% vs. 68%), and exceeded that of 4 year olds for four of eight odors and 3 year olds for seven of eight odors. Conclusions Children as young as 3 years of age can perform olfactory testing, but take longer than do older children and adults (7.44 vs. 5.66 vs. 3.71 minutes). Identification accuracy also increases as a function of age. The current six-item National Institutes of Health Toolbox Odor Identification Test is a brief, easily conducted test for evaluating olfactory ability. Collection of normative data for children of all ages and adults is needed to determine the clinical utility of the test and its interpretations for pathological conditions.

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