Increasing the fluid intake by a litre every day does not have any negative effects in healthy older men. Dutch researchers from the Maastricht University found that older people are often dehydrated, partly because their sensation of thirst is blunted. On the other hand, the elderly can easily become over-hydrated, because their kidneys tend to work less efficiently. Retaining excess water can dilute the level of sodium in the body, which can have serious consequences. The researchers investigated whether there is any harm in hydrating elderly people. Despite the lack of evidence on this topic many people assume all kinds of effects; some claim positive effects, others warn against overhydration. To investigate the general effects of increased fluid intake, the researchers examined data from a study involving 141 healthy men aged 55 to 75 years. In random order they were either advised to increase their water intake by a litre and a half per day, or were given a spoonful of placebo syrup per day. After 6 months, the men who were urged to drink more water had managed to boost their daily fluid intake by an average of about a litre every day. There were no significant differences between the two group in blood pressure, sodium level or the filtration rate of the their kidneys. The findings suggest that increase in fluid intake did not have any negative effects. Therefore, it seems unreasonable to worry about the harmful effects of drinking extra water. However, this does not mean that one cannot drink too much. Excessive intakes of water - more than 10 litres - can be harmful.
Journal of the American Geriatric Society,
April 2006