Submitted to: Journal of Bone and Mineral Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2010
Publication Date: 4/1/2011
Citation: Bischoff-Ferrari, H., Dawson-Hughes, B., Baron, J.A., Kanis, J., Orav, E.J., Staehelin, H.B., Kiel, D.P., Henschkowski, J., Spiegelman, D., Li, R., Wong, J.B., Willett, W.C., Burckhardt, P. 2011. Milk intake and risk of hip fracture in men and women: a meta-analysis of prospective cohort studies. Journal of Bone and Mineral Research. 26(4):833-839. Interpretive Summary: Milk may plausibly reduce fracture risk through its content of calcium, phosphorus, protein, and/or vitamin D. The effect of milk intake on hip fracture risk has not been examined in a randomized clinical trial and is not well established from observational studies. We therefore conducted this systematic review and meta-analysis of prospective cohort studies addressing the relationship between milk intake and hip fracture risk. Our results do not support an overall benefit of a higher milk intake in reducing the risk of hip fractures in adult women. However, we found a significant inverse association of milk intake and hip fracture risk among women exposed to vitamin D by fortification of milk products or living at lower latitudes. Among men, our results could not exclude a possible overall benefit of a higher milk intake in reducing the risk of hip fractures, but more data are needed.
Technical Abstract: Milk contains calcium, phosphorus, and protein, and is fortified with vitamin D in the US. All of these ingredients may improve bone health. However, the potential benefit of milk on hip fracture prevention is not well established. The objective of this cohort study is to assess the association of milk intake with risk of hip fracture based on a meta-analysis of cohort studies in middle aged or older men and womenEnglish and non-English publications from Medline (Ovid, Pubmed) and EMBASE up to May 2009, as well as experts in the field and reference lists were used as data sources. To compare studies on the same scale, we calculated the relative risk (RR) of hip fracture per glass of milk intake (approximately 300 mg calcium per glass of milk). Pooled analyses are based on random effects models. Data extraction occurred by two independent observers. In women (6 studies, 192,544 women, 2,977 hip fractures), there was no overall association between total milk intake and hip fracture risk (pooled RR per glass of milk per day = 0.97; 95% CI 0.92 - 1.02; Q-test p-value = 0.20). Only in the studies with higher vitamin D exposure through sunlight or fortification of milk (3 studies, 85,027 women, 958 hip fractures), was higher total milk intake associated with lower hip fracture risk (pooled RR per glass of milk per day = 0.93; 95% CI 0.86 – 1.00, meta-regression p-value for vitamin D exposed versus non-exposed cohorts =0.04). In men, (3 studies, 75149 men, 195 hip fractures), the pooled RR per daily glass of milk was 0.91 (95% CI 0.81 - 1.01). In the meta-analysis of cohort studies, there was no overall association between milk intake and hip fracture in women but more data are needed in men.