健康的老年人多喝水对身体没有负面影响

Increasing fluid intake by about a liter per day appears to have no negative effects in healthy older men, Dutch researchers report. 

Dr. Mark G. Spigt of Maastricht University and colleagues note in the Journal of the American Geriatric Society that older people are often dehydrated（脱水的）, partly because their sensation of thirst may be blunted. On the other hand, the elderly can easily become overly hydrated, because their kidneys tend to work less efficiently. Retaining excess water can dilute（稀释） the level of sodium in the body, which can have serious consequences. 

"We did this analysis," Spigt told Reuters Health, "because it was unknown whether it could do harm to hydrate 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 liter and a half per day, or were given a spoonful of a placebo syrup（糖浆，果汁） per day. 

After 6 months, the men urged to drink more water had managed to boost their daily fluid intake by an average of about a liter per day. There were no significant differences between the two group in blood pressure, sodium level or the filtration（过滤） rate of the their kidneys. 

The researchers thus conclude that the advice to increase fluid intake had no negative effects. 

Summing up, Spigt added, "It seems unreasonable to worry about the harmful effects of drinking extra water." However, he warned, "This does not mean that one cannot drink too much. Excessive intakes of water -- more than 10 liters -- can be harmful."