A prospective study on symptom generation according to spicy food intake and <scp>TRPV</scp> 1 genotypes in functional dyspepsia patients

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p> Capsaicin is an ingredient of red peppers that binds to transient receptor potential vanilloid subtype 1 ( <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1), and Koreans eat more capsaicin‐rich food than do Japanese. This study aimed to compare symptom generation according to <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 genotypes and the intake of spicy foods. </jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p> Consecutive functional dyspepsia ( <jats:styled-content style="fixed-case">FD</jats:styled-content> ) patients who were evaluated at Konkuk University Medical Centre (Korea) and Keio University Hospital (Japan) were included. Questionnaires on spicy food intake, patient assessment of gastrointestinal symptoms ( <jats:styled-content style="fixed-case">PAGI</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SYM</jats:styled-content> ), patient assessment of quality of life, and hospital anxiety and depression scale were provided. Blood was sampled for the detection of <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 polymorphisms, and upper gastrointestinal endoscopy was performed with biopsies. </jats:p> </jats:sec> <jats:sec> <jats:title>Key Results</jats:title> <jats:p> Of 121 included subjects, 35 and 28 carried the <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 <jats:styled-content style="fixed-case">CC</jats:styled-content> and <jats:styled-content style="fixed-case">GG</jats:styled-content> genotypes, respectively, with the prevalence rates not differing between Japan and Korea. The prevalence of <jats:styled-content style="fixed-case">FD</jats:styled-content> subtypes did not differ with the spicy food intake, <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 genotypes, or <jats:italic>Helicobacter pylori</jats:italic> infection. Neither <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 polymorphisms nor <jats:italic>H. pylori</jats:italic> infections were related to scores on the <jats:styled-content style="fixed-case">PAGI</jats:styled-content> ‐ <jats:styled-content style="fixed-case">SYM</jats:styled-content> questionnaires, but spicy food intake was positively correlated with the scores for stomach fullness ( <jats:italic>p</jats:italic> = 0.001) and retching ( <jats:italic>p</jats:italic> = 0.001). Using the linear regression analysis, stomach fullness was associated with spicy food intake ( <jats:italic>p</jats:italic> = 0.007), whereas retching was related to younger age ( <jats:italic>p</jats:italic> < 0.001) and female gender ( <jats:italic>p</jats:italic> = 0.014). </jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions & Inferences</jats:title> <jats:p> Upper gastrointestinal symptoms are more common in subjects with a higher consumption of spicy foods, younger age and female gender, regardless of <jats:styled-content style="fixed-case">TRPV</jats:styled-content> 1 genotypes and the <jats:italic>H. pylori</jats:italic> infection status. Capsaicin‐rich foods may induce stomach fullness. </jats:p> </jats:sec>