Dietary Characteristics Associated With High Defecation Frequency and Constipation in Japanese Adults: A Cross-Sectional Study.

Aims: The aim of this study was to evaluate the association between defecation frequency and dietary characteristics in adult men and women to identify factors associated with appropriate defecation frequency. Methods: We performed a cross-sectional study of 11,595 participants (n = 6142 men and 5453 women) aged 30-79 years using annual health check data collected between 2018 and 2023. Data on dietary characteristics and defecation frequency were collected using a self-reported questionnaire. Participants were divided according to defecation frequency into high- (≥ 3 times/day) and middle-frequency defecation groups, and a constipation group (≤ every 3 days). Results: The proportion of high-frequency defecation was higher in men, whereas constipation was higher in women. For both sexes, high-frequency defecation was associated with higher BMI, triglyceride, and hepatic enzyme levels, whereas constipation was associated with lower BMI, triglyceride, and hepatic enzyme levels. Multivariable-adjusted logistic regression analysis indicated that, in men, high-frequency defecation was associated with eating a snack after dinner. The risk of constipation was negatively associated with frequent consumption of vegetables in both sexes, and fruits in women only. The prevalence of constipation was positively and strongly associated with skipping breakfast every day in both men and women. Conclusion: This study found a correlation between increased defecation frequency and obesity-related characteristics, such as elevated BMI, triglycerides, and hepatic enzyme levels, in both men and women. Fiber-rich food intake may have a preventive effect against constipation, whereas skipping breakfast every day was associated with constipation prevalence in both sexes.