“Even a baked potato is 75 per cent water, said nutrition Prof. Susan Barr of the University of British Columbia, who sat on a Canadian-U.S. committee that looked at fluid intake.

“‘There’s nothing magical about water from a glass of water as opposed to water from a food or any other beverage,’ Barr said.

Drinking caffeinated beverages such as tea and coffee do not lead to dehydration, said Dr. Stanley Goldfarb, a nephrologist at the University of Pennsylvania who reviewed research claims on drinking eight glasses of water and studied how the kidneys handle it.