Potentially negative effects on bone mineral density were recorded mainly in populations with insufficient calcium intake or a very high coffee consumption (>9 cups per day). The author concluded that there is no evidence that caffeine has any harmful effects on bone or calcium status in subjects who ingest the RDA of calcium1.
Further meta-analyses2-7 have been undertaken which show a variability in their results. The heterogeneity in results may be caused by factors associated with different genetic groups, lifestyles and differing geographic locations of participants.
- A 2012 meta-analysis of 10 studies suggested an overall association between coffee intake in increasing the risk of fractures, especially for women2
- A 2013 meta-analysis of 6 prospective and 6 case control studies provided insufficient evidence that coffee consumption significantly increases hip fracture risk. The authors did find a significant association between coffee consumption and hip fracture risk amongst subgroups of females, elderly participants and North Americans. The authors concluded that the many confounding factors limited the ability to draw conclusions3
- A further 2013 meta-analysis of 14 studies suggested no significant association between coffee consumption and the risk of hip fracture. However, individuals who drank 1-4 cups of tea per day appeared to have lower risk of hip fractures4
- A 2014 meta-analysis of 15 studies evaluating the role of coffee consumption in fracture risk suggested that daily consumption of coffee is associated with an increased risk of fractures in women in a dose dependent fashion and a contrasting decreased risk in men5
- A 2017 review of multiple health outcomes in relation to coffee consumption considered bone health and suggested there was an association between coffee drinking and risk of fracture in women, but not in men7
- A further 2017 meta-analysis of prospective cohort studies suggested that there was no association between coffee consumption and risk of hip fracture in developed countries6
- A systematic review of the effects of caffeine consumption across different population groups concluded that consumption of up to 400 mg caffeine/day in healthy adults is not associated with a negative impact on bone health13
It has been suggested that ethnicity may impact results, particularly in Asian populations14
- Research from Korea in 2016 concluded that the study does not support the idea that coffee is a risk factor for impaired bone health in Korean premenopausal women14. In fact later work by the same group suggested that a moderate intake of coffee may have protective benefits in postmenopausal Korean women15
- Further work by the same group in a cohort of Korean young men also suggested that coffee consumption is not significantly associated with their bone status and metabolism according to the calcium intake level16
- A further 2018 meta-analysis in an Asian cohort suggested that drinking more than 4 cups of coffee a day is associated with a higher hip fracture risk, while a lower intake of coffee may alleviate risk in postmenopausal women17
- A 2018 study in smokers concluded that coffee consumption did not substantially alter bone health status in this group18
Additional work assessing the association between coffee consumption and bone mineral density and fracture risk have also provided inconclusive results.
- A 2013 Swedish longitudinal population-based cohort suggested that there was no evidence of a higher rate of any fracture or hip fracture with increasing coffee consumption. High coffee consumption was associated with a small reduction in bone mineral density but this did not translate into an increased risk of fracture8
- A 2016 Brazilian study suggested that intakes of ‘sweet foods, coffee and tea’ appeared to exert a negative effect on bone mineral density, even when demineralisation of bone was already present19 Confounding factors may introduce variability into studies including genetics, recall of levels of coffee consumption and additions to coffee such as milk