Fluid Intake and Dietary Factors and the Risk of Incident Kidney Stones in UK Biobank: A Population-based Prospective Cohort Study

Fluid intake and diet are thought to influence kidney stone risk. However, prospective studies have been limited to small samples sizes and/or restricted measures.To investigate whether fluid intake and dietary factors are associated with the risk of developing a first kidney stone.Participants were selected from UK Biobank, a population-based prospective cohort study.Cox proportional hazards models were used to investigate the association between fluid intake and dietary factors and the risk of a first incident kidney stone, ascertained from hospital inpatient records.After exclusion, 439 072 participants were available for the analysis, of whom 2057 had hospital admission with an incident kidney stone over a mean of 6.1 yr of follow-up. For every additional drink (200 ml) consumed per day of total fluid, the risk of kidney stones declined by 13% (hazard ratio [HR] = 0.87, 95% confidence interval [CI] 0.85-0.89). Similar patterns of associations were observed for tea, coffee, and alcohol, although no association was observed for water intake. Fruit and fibre intake was also associated with a lower risk (HR per 100 g increase of fruits per day = 0.88, 95% CI 0.83-0.93, and HR per 10 g fibre per day = 0.82, 95% CI 0.77-0.87), whereas meat and salt intake was associated with a higher risk (HR per 50 g increase in meat per week = 1.17, 95% CI 1.05-1.29, and HR for always vs never/rarely added salt to food = 1.33, 95% CI 1.12-1.58). Vegetable, fish, and cheese intake was not associated with kidney stone risk.The finding that high intake of total fluid, fruit, and fibre was associated with a lower risk of hospitalisation for a first kidney stone suggests that modifiable dietary factors could be targeted to prevent kidney stone development.We found that higher intake of total fluid, specifically tea, coffee, and alcohol (but not water), and consumption of fruit and foods high in fibre are linked with a reduced likelihood of developing kidney stones.