Dairy intake and risk of hip fracture in prospective cohort studies: non-linear algorithmic dose-response analysis in 486 950 adults

Previous studies on the relationship between dairy consumption and hip fracture risk have reported inconsistent findings. Therefore, we aimed to conduct an algorithmically driven non-linear dose- response meta-analysis of studies assessing dairy intake and risk of developing incident hip fracture. Meta-analysis from PubMed and Google Scholar searches for articles of prospective studies of dairy intake and risk of hip fracture, supplemented by additional detailed data provided by authors. Meta- regression derived dose-response relative risks, with comprehensive algorithmdriven dose assessment across the entire dairy consumption spectrum for non-linear associations. Review of studies published in English from 1946 through December 2021. A search yielded 13 studies, with 486 950 adults and 15 320 fractures. Non-linear dose models were found to be empirically superior to a linear explanation for the effects of milk. Milk consumption was associated with incrementally higher risk of hip fractures up to an intake of 400 g/d, with a 7 % higher risk of hip fracture per 200 g/d of milk ( RR 1 center dot 07, 95 % CI 1 center dot 05, 1 center dot 10; P < 0 center dot 0001), peaking with 15 % higher risk (RR 1 center dot 15, 95 % CI 1 center dot 09, 1 center dot 21, P < 0 center dot 0001) at 400 g/d versus 0 g/d. Although there is a dose-risk attenuation above 400 g/d, milk consumption nevertheless continued to exhibit elevated risk of hip fracture, compared to zero intake, up to 750 g/d. Meanwhile, the analysis of five cohort studies of yoghurt intake per 250 g/d found a linear inverse association with fracture risk (RR 0 center dot 85, 95 % CI 0 center dot 82, 0 center dot 89), as did the five studies of cheese intake per 43 g/d (similar to 1 serving/day) (RR 0 center dot 81, 95 % CI 0 center dot 72, 0 center dot 92); these studies did not control for socioeconomic status. However, no apparent association between total dairy intake and hip fracture ( RR per 250 g/d of total dairy = 0 center dot 97, 95 % CI 0 center dot 93, 1 center dot 004; P = 0 center dot 079). There were both non-linear effects and overall elevated risk of hip fracture associated with greater milk intake, while lower risks of hip fracture were reported for higher yoghurt and cheese intakes.

Automated summary

This study conducted an algorithmically driven non-linear dose-response meta-analysis and found different associations between dairy consumption and hip fracture risk. Milk intake was associated with an incremental increase in hip fracture risk, while yogurt and cheese intake were associated with lower hip fracture risk.