The Effect of Self-Reported Lactose Intolerance and Dairy Consumption on Bone Mineral Density among American Hip Arthroplasty Patients: A Cross-Sectional Study

The relationship between osteoporosis and lactose intolerance is unclear. This study aims to evaluate the association between self-reported lactose intolerance and symptom severity caused by lactose malabsorption and bone mineral density (BMD). A total of 496 American hip arthroplasty patients took part in this study. Information on BMD and socio-demographic factors were retrospectively extracted from medical records. BMD of the lumbar spine (LS), femoral neck of the operative hip (FNOH), and femoral neck of the non-operative hip (FNH) were measured via dual-energy x-ray absorptiometry scans (DXA). Patients also completed a survey regarding dietary and lifestyle habits from the time of surgery. We found that 9.3% of participants reported lactose intolerance and 33.3%% suffered from either osteopenia or osteoporosis in at least one (location). The population that did not self-identify as lactose intolerant consumed significantly more dairy (p < 0.0001) and animal protein (p = 0.004) than those with intolerance. There was no significant difference in BMD between self-identified lactose intolerant individuals and non-lactose intolerant individuals. In a stepwise multiple regression analysis, body mass index (BMI) and age were the only common predictors of BMD for all locations (p < 0.05). However, yogurt intake was a significant predictor of BMD of FNOH in the multivariate analysis. This study suggests that lactose intolerance is not associated with bone mineral density. We also found that being vegan or vegetarian may increase the risk of low BMD.