Association between dietary phosphorus intake and chronic constipation in adults: evidence from the National Health and Nutrition Examination Survey

BACKGROUND: Several studies suggest a link between micronutrients and constipation. However, the relationship between constipation and phosphorus has rarely been examined. The main aim of this study was to investigate the association between changes in the prevalence of chronic constipation and dietary phosphorus intake among adult respondents of the National Health and Nutritional Examination Survey (NHANES). METHODS: Data were extracted from the NHANES database for the years 2005–2010. A total of 13,948 people were included in the analysis. Dietary information was collected using the respondents’ 24-h dietary records. We conducted multiple logistic regression analyses to examine the correlation between phosphorus intake and poor bowel movement. The primary and secondary outcomes was constipation defined by stool consistency and stool frequency, respectively. RESULTS: Following multi-variate adjustment in model III, a significant association between chronic constipation and each additional 0.1-g intake of dietary phosphorus (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.95, 1.00; P = 0.034 for stool consistency vs. OR, 0.94; 95% CI, 0.90, 0.99; P = 0.027 for stool frequency) was observed. Following multi-variate adjustment in model III, OR values and 95% CI from the second to fourth quartiles compared to the first quartile (reference group) were 0.92 (0.66, 1.27), 0.73 (0.47, 1.13), and 0.39 (0.20, 0.76), respectively, using the stool frequency definition. CONCLUSIONS: This study revealed a negative correlation between phosphorus intake and chronic constipation. This may be due to the fact that dietary phosphorus intake is associated with softer stools and increased stool frequency. Further studies in different settings should be considered to verify these findings. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12876-022-02629-8.