Drinking plenty of water poses no harm on kidney function

While water intake is cross-sectionally associated with urine flow and concentration, as well as kidney function, its impact over time does not seem to be significant, a recent study has found.

The study included 4,554 participants (aged 18–95 years, 54.4 percent women) from whom relevant information were collected at baseline, including their intake habits of water and other beverages. Other relevant factors included estimated glomerular filtration rate (eGFR), overnight urine parameters, and urinary markers of diet. Participants were followed for 15 years.

Multivariable regression analysis showed a significant cross-sectional correlation of higher water intake with higher overnight urine flow (β, 0.163; p<0.001) and lower overnight urine osmolality (β, –0.184; p<0.001). Greater water intake was also associated with lower urine/serum creatinine ratio (β, –0.151; p<0.001).

Moreover, high water intake correlated significantly with minor reductions in baseline eGFR at baseline as well as with a heightened prevalence of decreased eGFR.

However, no time-dependent effect was reported: high water intake did not significantly affect longitudinal trends in kidney function, eGFR, and death. Intake of other nonwater beverages exerted no cross-sectional or longitudinal effects on any outcome of interest.

“This study indicated that minor reductions in urine concentration and eGFR could be at times the consequence of an excessive water intake rather than a certain sign of kidney dysfunction,” the researchers said.

“This study did not support a clinically significant role of the intake of water and other beverages in the decline of kidney function over time, at least for the pattern of drinking explorable in the study cohort,” they added.