Diluting the rehydration recipe made it work better
In hospitalised children with diarrhoea, a weaker solution left the odds of needing an unplanned drip at 0.59 times the older recipe's, with less stool and less vomiting.
What the study found
The weaker rehydration recipe beat the stronger one
This is the evidence that changed the World Health Organization's own recipe. In hospitalised children with diarrhoea, a reduced-osmolarity solution left the odds of needing an unplanned drip at 0.59 times the older formula's, with less stool, less vomiting and no extra low-sodium risk.
The caveat · Against the old recipe, not water
Hospitalised children with acute diarrhoea, compared against another rehydration solution rather than against water, so nothing here reaches a well person drinking one. This is the 2002 version of a review since updated, cited for the finding that changed the formulation. The trials were mostly unblinded and largely in low- and middle-income hospital settings. Low blood sodium was looked for in only six trials with events in three, so that reassurance rests on thin data.