Fluid Intake and Dietary Factors and the Risk of Incident Kidney Stones
abstract
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Access this abstract now Full Text Available for ClinicalKey SubscribersBACKGROUND
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.
OBJECTIVE
To investigate whether fluid intake and dietary factors are associated with the risk of developing a first kidney stone.
DESIGN, SETTING, AND PARTICIPANTS
Participants were selected from UK Biobank, a population-based prospective cohort study.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS
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.
RESULTS AND LIMITATIONS
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.
CONCLUSIONS
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.
PATIENT SUMMARY
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.
Additional Info
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Fluid Intake and Dietary Factors and the Risk of Incident Kidney Stones in UK Biobank: A Population-Based Prospective Cohort Study
Eur Urol Focus 2019 May 10;[EPub Ahead of Print], TJ Littlejohns, NL Neal, KE Bradbury, H Heers, NE Allen, BW TurneyFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
This interesting paper considers the influence of fluid intake and diet on the incidence of kidney stones based on a large population database of residents in the UK. After excluding those with prior stones and individuals who had made major diet changes within 5 years of the study, data from a cohort of 439,072 participants who had completed a socioeconomic, lifestyle, and health-related questionnaire were crosslinked to inpatient hospital records for association with a kidney stone diagnosis. A total of 2057 participants developed a kidney stone, and Cox proportional models were used to investigate the association between fluid intake and diet in this group of first time stone formers.
Preventative strategies for kidney stone formation have always seemed to be as much about the art of medicine as the available science. A lack of well-designed trials, both for pharmacologic interventions and dietary modification, has undermined evidence-based approaches to management of this common condition. The authors find that increased fluid intake and consumption of fruit and diets high in fiber reduced the likelihood of developing a kidney stone. Interestingly, tea, coffee, and alcohol demonstrated a protective effect but water did not, which is contrary to prior available information. Diets that were higher in meat and salt intake increased the risk of developing a kidney stone. The authors speculate that the diuretic effect of tea, coffee, and alcohol may explain the enhanced beneficial effect of these beverages and that the benefit of fruit may reside in the citrate available in this food group.
Although the paper is, for the most part, supportive of current guidelines and practices in kidney stone prophylaxis, its real strength is the very large sample size and range of measures available on dietary factors. It offers great practical advice for urologists and patients in efforts to prevent this common, morbid, and expensive medical condition.