The Effects of 6 Months of Increased Water Intake on Blood Sodium, Glomerular Filtration Rate, Blood Pressure, and Quality of Life in Elderly (Aged 55–75) Men

To study whether there are any negative or positive effects of 6 months of increased fluid intake in reasonably healthy elderly men.Randomized trial.Community-based.One hundred forty-one healthy participants aged 55 to 75.One group was given the advice to increase their daily fluid intake by 1.5 L of water; the other group was given placebo medication (8 mL inactive syrup per day).At 6 months blood sodium, glomerular filtration rate (GFR), blood pressure, and quality of life (QOL) were measured. The changes in water turnover were measured using deuterium.Most subjects did not manage to increase their fluid intake by 1.5 L. The average increase in the intervention group was approximately 1 L. Twenty-four-hour water turnover in the water group was 359 mL (95% confidence interval=171-548) higher than that of the control group at 6-month follow-up. Blood pressure, sodium level, GFR, and QOL did not change significantly in either group during the intervention period. In addition, the cases reporting a worsening on the effect measures were equally distributed over the two study groups.The advice to increase fluid intake by 1.5 L had no negative effects in reasonably healthy men aged 55 to 75.