Graedon: Eight glasses of water is just an urban myth

When we ask how much water is healthy for us, the standard response is eight glasses of water per day. If someone had high blood pressure, could eight glasses of water per day be too much? I was thinking that since the first thing most doctors turn to for treating high blood pressure is a diuretic, maybe the problem is consuming too much water in the first place, as well as too much salt. Has there been any research on this?

There is surprisingly little research on the optimum amount of water most people should drink. Although it is a common belief that people need eight glasses daily, there is no scientific support for this idea (Journal of the American Society of Nephrology, June 2008). The National Academy of Sciences recommends drinking when thirsty rather than consuming a specific number of glasses daily.

It is unlikely that drinking water raises blood pressure. A healthy body regulates fluids and electrolytes quickly. Although diuretics lower blood pressure, the exact mechanism remains mysterious (Journal of the Renin-Angiotensin-Aldosterone System, December 2004).

My 86-year-old sister takes amitriptyline. I worry that this drug could be affecting her balance.

She uses a cane and always seems unsteady on her feet. She has fallen many times.

Is it safe for someone her age to take amitriptyline?

This antidepressant generally is considered inappropriate for older people. Although it is sometimes prescribed to ease nerve pain or help people sleep, amitriptyline can cause mental confusion, lack of coordination, dizziness, dry mouth, blurred vision and constipation.

There is a list of drugs that should normally not be prescribed to older people, and amitriptyline is a prime example. We are sending you our Guide to Drugs and Older People with this li