Rules on sugar in hydration drinks are outdated and it is "astonishing" New Zealand has failed to follow latest practice, the founder of a sports drinks company says.
The Ministry for Primary Industries has told SOS Hydration its product must have five times more sugar added if it is to meet the definition of an electrolyte drink.
The company says its drink has been proven to rehydrate three times faster than water.
Indy car racer Scott Dixon, America's Cup skipper Peter Burling and Olympians Hamish Carter and Nick Willis are among those who have endorsed the drink.
SOS Hydration co-founder Thomas Mayo told Morning Report the regulations were outdated, and research showed high levels of sugar were no longer needed for hydration.
"What we're seeing on a global research scale is that level [of sugar] is constantly decreasing."
Sugar and salt molecules helped the absorption of water, but the Australia New Zealand Food Standards Code had energy confused with hydration.
"They've added in carbohydrates into this equation and it's not required.
"Why in a hospital are you given - to treat dehydration - a product that doesn't contain that but on the sports field you are?"
He said the company met criteria set out by the World Health Organization Oral Rehydration Solution Guidelines.
"It is astonishing that in 2017 MPI is not following best practice and taking into account the guidelines set by the World Health Organisation and the lead set by the US and the EU," Mr Mayo said.
"Given this overwhelming global consensus, it is unacceptable that MPI's reliance on out of date science is forcing Kiwis young and old into consuming higher levels of sugar than needed for rehydration purposes."
In a statement, a ministry spokesperson said MPI was implementing the code set by Food Standards Australia and New Zealand (FSANZ).
To qualify as an electrolyte drink under the code it had to contain 50-100 g/l of sugars.
"This carbohydrate requirement purely comes down to physiology - an electrolyte drink needs to have the right amount and types of sugar present to hasten rehydration.
"This is necessary to meet the hydration claim that can only be made on compliant electrolyte drinks - that it prevents or treats mild dehydration due to sustained strenuous exercise."
Mr Mayo said the Food Standard code of compliance for sports drinks is under review but it could be a long time before this is completed.
"The government needs to take action now and prioritise action on this issue."
Health and Sports Minister Jonathan Coleman said it was up to MPI and Food Safety Minister David Bennett to look at the guidelines.
"It's a technical issue around food and drink formulation," he said.