Prevalence and biopsychosocial associations of functional constipation: a cross-sectional study among adults in Türkiye

Background Functional constipation is a prevalent functional gastrointestinal disorder with substantial public health implications. Evidence on its biopsychosocial determinants in middle-income settings is limited. This study aimed to determine the prevalence of functional constipation and its associations with sociodemographic characteristics, dietary habits, eating behaviors, physical activity, and anthropometric factors among adults in Türkiye. Methods This study was conducted with 429 individuals aged 19–64 years who presented for examination and follow-up at the Department of Internal Medicine outpatient clinic of a public hospital in Türkiye. Functional constipation was defined by Rome IV criteria. Constipation severity was assessed with the Constipation Severity Instrument. Eating disorder risk was screened using the five-item The Sick, Control, One Stone, Fat, Food (SCOFF) Questionnaire; picky eating was measured with the Adult Picky Eating Questionnaire. Anthropometrics were measured to compute body mass index (BMI). Physical activity and selected dietary frequencies were self-reported. Predictors of functional constipation were examined via binary logistic regression with covariates informed by prior literature. Statistical significance was set at α = 0.05. Results Participants’ mean age was 38.2 ± 15.0 years; 53.1% were female; 50.6% had BMI ≥ 25 kg/m². The prevalence of functional constipation was 21.0% (90/429). In multivariable analyses, higher age (OR = 1.029, 95% CI: 1.005–1.055) and female sex (OR = 1.899, 95% CI: 1.007–3.578) were associated with greater odds of functional constipation. Eating disorder risk was also associated with greater odds of functional constipation (per point on SCOFF: OR = 1.280, 95% CI: 1.024–1.600). In contrast, higher BMI was associated with lower odds (OR = 0.932, 95% CI: 0.879–0.989), and engaging in physical activity was associated with substantially lower odds of functional constipation (OR = 0.168, 95% CI: 0.095–0.300). Family history, smoking, alcohol use, water intake, and frequencies of meat, vegetable, and fruit consumption were not significant in the adjusted model; meal skipping showed borderline significance (OR = 2.001, 95% CI: 0.996–4.020; p = 0.051). Conclusions The findings of the study indicate that functional constipation has a considerable prevalence in this clinical adult sample. Functional constipation was associated with older age, female sex, and eating disorder risk, and was inversely associated with higher BMI and physical activity. The results support the routine assessment of eating disorder risk and the promotion of physical activity as part of comprehensive management strategies. Prospective studies are needed to clarify the causal pathways underlying these observed associations.