A meta-analysis of milk intake and fracture risk: low utility for case finding

A low intake of calcium is widely considered to be a risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the effect of age, gender and bone mineral density (BMD) on this risk. We studied 39,563 men and women (69% female) from six prospectively studied cohorts comprising EVOS/EPOS, CaMos, DOES, the Rotterdam study, the Sheffield study and a cohort from Gothenburg. Cohorts were followed for 152,000 person-years. The effect of calcium intake as judged by the intake of milk on the risk of any fracture, any osteoporotic fracture and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age and BMD. The results of the different studies were merged by using the weighted beta-coefficients. A low intake of calcium (less than 1 glass of milk daily) was not associated with a significantly increased risk of any fracture, osteoporotic fracture or hip fracture. There was no difference in risk ratio between men and women. When both sexes were combined there was a small but non-significant increase in the risk of osteoporotic and of hip fracture. There was also a small increase in the risk of an osteoporotic fracture with age which was significant at the age of 80 years (RR=1.15; 95% CI=1.02-1.30) and above. The association was no longer significant after adjustment for BMD. No significant relationship was observed by age for low milk intake and hip fracture risk. We conclude that a self-reported low intake of milk is not associated with any marked increase in fracture risk and that the use of this risk indicator is of little or no value in case-finding strategies.