repeated dietary exposure
process / process-repeated-exposure
反復曝露
Repeated dietary exposure is a regimen used in simple-exposure interventions in which a food is tasted repeatedly without an accompanying reward.
On this page (6 sections)
Reading the bitterness
Repeated exposure is an intervention that has people taste the same food repeatedly without a reward, aiming to change liking or intake of that food. Bitterness is cited as one major reason children reject vegetables, and becoming accustomed to vegetables, including bitter ones, underlies this analysis. A meta-analysis mainly of infants and young children, covering 43 papers and 117 comparisons, found higher vegetable liking (standardized mean difference 0.35) and intake (0.23) with repeated exposure than with no exposure. This corresponded to about 0.6 points on a 9-point liking scale. However, the authors themselves say 「効果量は小さい」 (in translation: "the effect sizes are small"); many included studies had high risk of bias, and comparisons were not stratified by bitterness intensity.
In the same analysis, the effect on liking for a novel vegetable did not persist to the longest follow-up (standardized mean difference 0.15, not statistically significant). In contrast, a study of 95 infants who had just begun complementary feeding reported that improved liking after 10 repeated exposures to artichoke purée remained stable for three months after exposure. Because the age groups differ, this may indicate age-related differences in how long an effect persists rather than a contradiction.
In one adult study, after a commercially available bitter-sweet drink was consumed at home once daily for 7 days, liking for that drink rose 68%, while a control drink tasted only in the laboratory did not change. In another experiment, repeated consumption for two weeks of EGCG, a tea catechin dissolved in water, reduced ratings of bitterness for that same EGCG solution compared with repeated consumption of water alone. These results concern a particular compound and a particular drink; they cannot be generalized to dishes or foods as a whole.
Sources for this overview
Checked for this overview: Checked effect sizes for liking and intake after repeated exposure. / Checked the authors' summary that effect sizes were small. / Checked that the effect did not persist to the longest follow-up.
Checked for this overview: Checked that the infant effect remained stable through 3 months.
Checked for this overview: Checked a 68% increase in liking after 7 days of exposure to the bitter-sweet drink.
Checked for this overview: Checked lower bitterness ratings after 2 weeks of repeated EGCG consumption.
Follow the connections
repeated dietary exposure →can decrease→ bitterness →can be measured separately …→ astringency
Structured claims — open a section to read each claim's confidence, evidence and limits
Sensory (5)
Scope: A meta-analysis of between-subjects comparisons (the review as a whole covered 43 papers and 117 comparisons; this result rests on 17 comparisons and 820 participants for liking, and 21 comparisons and 1130 participants for intake). Mainly infants and children
Note: The effect size is small, and many of the original studies are at high risk of bias. Bitterness is mentioned as a major factor in vegetable rejection, but there is no analysis stratified by bitterness intensity.
Show data
process-repeated-exposure —increases→ (the claim sentence above)Scope: A follow-up analysis within the same meta-analysis (between-subjects comparisons). Follow-up periods were often short and inconsistent
Note: The authors' overview: 『Effect sizes, however, are small, and limited evidence suggests long-term benefits』. A counter/limiting claim showing the limits of the durability of acquired liking. Durability may be age-window dependent: in infants (95 in all, 32 in the basic-purée group), learning to accept the same vegetable was stable up to 3 months later (Remy 2013). That result concerns the same repeated vegetable, a different question from durability of liking for a different new vegetable, so on 2026-10-21 the evidence relation was changed from contradicts to contextualizes (in checking the question on whether people stop disliking bitter vegetables with repetition).
Show data
process-repeated-exposure —has_limited_long_term_persistence_of→ (the claim sentence above)Scope: Participants (number and age not given in the abstract), 1 commercially available bittersweet beverage (Stein 2003)
Note: A single study. The beverage's composition (presence or absence of caffeine) and n are not reported in the abstract, and the mechanistic attribution (post-ingestive association) remains the authors' speculation.
Show data
process-repeated-exposure —increases→ (the claim sentence above)Scope: An evaluation after repeatedly taking EGCG, a type of tea catechin, dissolved in water for 2 weeks
Note: This is a comparison with repeating water alone, and does not show a mechanism of becoming accustomed to all foods.
Show data
process-repeated-exposure —can_decrease→ sensation-bitterScope: A small pilot study of 10 healthy women using an oral gel containing capsaicin
Note: This is a result in which no difference was found in a trial with few participants, and is not proof that there is no effect at all.
Show data
process-repeated-exposure —does_not_significantly_influence→ (the claim sentence above)