The incidence of chronic diarrhea decreases with increasing serum calcium levels: a cross-sectional study based on NHANES 2005–2010

BACKGROUND: Chronic diarrhea is difficult to prevent and treat due to its complex etiology and pathogenesis. It places a huge burden on patients and public healthcare. It is known that the regulation of body homeostasis relies heavily on calcium. However, in the general population, the relationship between calcium and chronic diarrhea remains uncertain. METHODS: We assessed the association between serum calcium and diarrhea using data from the 2005–2010 National Health and Nutrition Examination Survey (NHANES). Serum calcium level was measured from collected blood samples. Diarrhea was assessed using the Bristol Stool Scale (BSFS) (types 1–7). The stability of the results was assessed using logistic regression and sensitivity analysis. The dose–response association between serum calcium and the risk of diarrhea was analyzed using a restricted cubic spline plot. RESULTS: This study included 12,342 participants. In each of the five models, an increased calcium level was negatively associated with the incidence of diarrhea (OR[95%CI]:0.26 [0.13–0.53], 0.28 [0.14–0.58], 0.4 [0.19–0.82], 0.27 [0.11–0.64] and 0.24 [0.10–0.59], respectively). When serum calcium was analyzed as a categorical variable, a significant association between serum calcium and diarrhea prevalence was found. The restricted cubic spline plot showed a linear relationship between serum calcium and diarrhea. Sensitivity analysis confirmed that the results were stable. CONCLUSION: The results of our cross-sectional study suggest that a higher level of serum calcium may reduce the incidence of diarrhea. In the future, this finding should be further validated in a randomized controlled trial. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12876-023-03029-2.