Deborah Cohen, Investigations Editor (2012) BMJ 2012;345:e4737
Prehydrate; drink ahead of thirst; train your gut to tolerate more fluid; your brain doesn’t know you’re thirsty—the public and athletes alike are bombarded with messages about what they should drink, and when, during exercise. But these drinking dogmas are relatively new. In the 1970s, marathon runners were discouraged from drinking fluids for fear that it would slow them down, says Professor Tim Noakes, Discovery health chair of exercise and sports science at Cape Town University. At the first New York marathon in 1970, there was little discussion about the role of hydration—it was thought to have little scientific value.
So how did the importance of hydration gain traction? An investigation by the BMJ has found that companies have sponsored scientists, who have gone on to develop a whole area of science dedicated to hydration. These same scientists advise influential sports medicine organisations, which have developed guidelines that have filtered down to everyday health advice. These guidelines have influenced the European Food Safety Authority, the EU agency that provides independent advice on the evidence underpinning health claims relating to food and drink. And they have spread fear about the dangers of dehydration.