The benefits of drinking water have become so exaggerated that people who follow official advice may even do themselves harm, a doctor warns.
Bottles of mineral water are now so ubiquitous that health-conscious people cannot make even a short journey without one. Yet the warnings about maintaining fluid levels are "not only nonsense, but thoroughly debunked nonsense", Margaret McCartney, a general practitioner in Glasgow, said.
Official advice issued by the NHS says that people should "try to drink about six to eight glasses of water (or other fluids) a day to prevent dehydration". Many schools also require pupils to bring a water bottle to school. But Dr McCartney said there is no high-quality evidence to support these claims, which are repeated by bottled-water companies to boost their sales.
The idea that we are all short of water is thought to derive from a 1945 recommendation that adults should consume 2.5l of water daily, 1ml for every calorie consumed, though this advice has only caught on in the last decade. But the crucial part of the recommendation is usually ignored – that "most of this quantity is contained in prepared foods".