High fluid intake reduces kidney stone risk

The aim of this study was to establish the role of fluid intake in the prevention of kidney stones. Authors reported a significantly reduced risk of kidney stones, including recurrent kidney stones, among individuals with a high fluid intake.

Kidney stones are small mineral deposits that can form in or near the kidneys. It has been estimated that about 10 to 15% of people will experience kidney stones at some point in their lives. The likelihood of experiencing a second episode is about 50% within 5 years. Identifying risk factors is important to help prevent recurrent kidney stones.

High fluid intake is a simple and inexpensive strategy for kidney stone prevention. Drinking enough fluids means that the urine will have lower concentrations of waste produces, including calcium-rich substances that can form stones. Exactly how important fluid intake is in the prevention of recurrent kidney stones has not been fully established.

Results from 9 separate studies involving a total of 273,685 adults were pooled into a single analysis to examine the risk of kidney stones in individuals with high fluid intake. Of the 9 studies, 2 were randomized-controlled trials (studies where participants are randomly assigned to groups) and 7 were observational studies.

From the 2 randomized-controlled trials, the overall risk of kidney stones was 60% lower if fluid intake was high. The risk of recurrent kidney stones was also reduced by 60% if fluid intake was high. Similar results were obtained in an analysis of the 7 observational studies. In these studies, the risk of kidney stones was reduced by 51% if fluid intake was high. The risk of recurrent kidney stones was reduced by 80%.

The benefit of high fluid intake was observed among both men and women. When accounting for factors such as age, weight, alcohol consumption, and use of supplements, the risk of kidney stones was still reduced by 32% with high fluid intake.

Authors concluded that the risk of kidney stones, including recurrent kidney stones, is significantly lower among individuals with a high fluid intake. Authors advised that this provides strong evidence in support of the common recommendation to increase water intake in order to reduce stone risk.