1Department of Endocrinology and Metabolism, The First Affiliated Hospital of Soochow University, Suzhou, China
2Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, No. 199 Ren’ai Road, Suzhou, China
Summary: In the present meta-analysis, reductions in the risk of hip fracture with milk consumption were only observed among American adults, but not among Scandinavian adults, possibly because milk products are more commonly fortified with vitamin D in the former population than in Scandinavian countries. The reduction in the risk of hip fracture was also observed with yogurt consumption, which is often associated with healthy lifestyles and dietary patterns that contribute to improved bone health.
Introduction: Although dairy products contain bone-beneficial nutrients, the association between dairy consumption and the risk of hip fracture remains equivocal. Fueling this uncertainty, the elevated risk of hip fracture in association with milk consumption was observed in a cohort of Swedish women. A systematic review and meta-analysis of prospective cohort studies was performed to critically evaluate the association, or lack thereof, between dairy consumption (milk, yogurt, and cheese) and the risk of hip fracture.
Methods: A random effects model was used to generate the summary relative risks (RRs) with their 95% confidence intervals (CIs) for the associations of interest.
Results: In the meta-analysis of the highest versus lowest category of consumption, higher consumption of yogurt (RR 0.78, 95% CI 0.68, 0.90), but not milk (RR 0.86, 95% CI 0.73, 1.02) or cheese (RR 0.85, 95% CI 0.66, 1.08), was associated with a lower risk of hip fracture. For milk, the reduced risk of fracture with higher milk consumption was observed in the USA (RR 0.75, 95% CI 0.65, 0.87), but not in Scandinavian countries (RR 1.00, 95% CI 0.85, 1.17). These findings were further supported by the fact that American studies (RR 0.93, 95% CI 0.88, 0.98; per 1 glass/day), but not Scandinavian studies (RR 1.01, 95% CI 0.95, 1.07; per 1 glass/day), demonstrated a linear association between milk consumption and the risk of hip fracture.
Conclusions: The cumulative evidence from prospective cohort studies reassuringly suggests that the risk of hip fracture may not be elevated among people who consume milk, yogurt, and cheese, and that a greater consumption of milk or yogurt may even be associated with a lower risk of hip fracture depending on the factors that may differ across the population of interest.