Diet and risk of hip fracture in adults using data linkage

Background: Hip fractures commonly initiate hospitalisation and health decline in older adults, and are becoming increasingly prevalent in the global ageing population. Long-term dietary habits impact musculoskeletal health, but associations between diet and hip fracture risk are unclear due to limited and inconsistent evidence. Specifically, vegetarian diets are becoming increasingly popular in developed countries, but often lack nutrients related to musculoskeletal health. Therefore, this thesis aimed to better understand associations between dietary habits and hip fracture risk in adults. Methods: Associations between food and nutrient intakes, as well as meat-free diets (regular meat-eater, occasional meat-eater, pescatarian, or vegetarian) with hip fracture risk were investigated using data from two large prospective cohort studies in the UK: the UK Women’s Cohort Study (UKWCS, n=26,000 women) and the UK Biobank (n=410,000 men and women). In both datasets, dietary data were collected using a food frequency questionnaire at recruitment, and incident hip fractures were identified by linkage to national hospital records. Results: In the UKWCS, a linear dose-response relationship was observed between dietary protein, as well as combined tea and coffee intake, with hip fracture risk. In both the UKWCS and UK Biobank, vegetarians but not occasional meat-eaters or pescatarians were at a greater risk of hip fracture than regular meat-eaters, regardless of sex. All associations remained after adjustment for confounders. Conclusion: This thesis strengthens the evidence that British vegetarians are at a greater risk of hip fracture than meat-eaters, and shows for the first time in a British population that dietary protein and combined tea and coffee consumption are each associated with a lower risk of hip fracture. Further prospective cohort studies and randomised controlled trials are needed to confirm if these findings are causal before dietary recommendations for preventing hip fractures can be formed.