Association of Mediterranean Diet Adherence With Chronic Constipation and Chronic Diarrhea: Findings From NHANES

This study investigated the association of Mediterranean diet (MED) adherence with chronic constipation and chronic diarrhea, using a nationally representative sample of U.S. adults. This cross-sectional study analyzed 11,612 participants from the 2005 to 2010 National Health and Nutrition Examination Survey (NHANES). Adherence to MED was assessed through the alternative Mediterranean diet (aMED) index. Bowel habits were categorized using the Bristol Stool Form Scale (BSFS), with chronic constipation defined as BSFS types 1-2, and chronic diarrhea as types 6-7, based on the usual or most common stool type reported by participants. Multivariate logistic regression models and subgroup analyses were employed to assess associations of MED adherence with chronic constipation and chronic diarrhea. Restricted cubic spline analyses were conducted to explore potential nonlinear relationships. Higher aMED scores were associated with a lower likelihood of chronic constipation (OR: 0.82, 95% CI: 0.75, 0.89). Participants in the highest aMED category had 43% lower odds of chronic constipation compared to those in the lowest category (OR: 0.57, 95% CI: 0.43, 0.75). Subgroup analysis indicated that this association was strongest among obese individuals (BMI ≥ 30 kg/m²) (OR: 0.69, 95% CI: 0.58, 0.82). No significant associations were observed between aMED scores and chronic diarrhea in the fully adjusted model. Adherence to the Mediterranean diet was significantly associated with lower prevalence of chronic constipation but showed no significant relationship with chronic diarrhea in the U.S. population. Further longitudinal research is needed to clarify causality and explore population-specific effects.