'Sixth sense' can detect energy content in drinks - scientists

Researchers from the University of Auckland found that that muscles respond to carbohydrate sugars even before they are swallowed. Photo / Wikimedia Commons image from user Ewkaa

Merely putting sugar into your mouth boosts muscle strength for three minutes, New Zealand research has shown.

The same research revealed the tongue can detect energy content in drinks using a "sixth sense" even when it cannot be tasted.

Researchers from the University of Auckland published the study in the journal Brain Research, showing for the first time that muscles respond to carbohydrate sugars even before they are swallowed.

One second after study participants received a carbohydrate drink, neural activity controlling muscles increased by 30 percent and muscle strength two per cent. The effect lasted for three minutes.

A placebo drink that tasted the same but lacked carbohydrates failed to stimulate the same result.

"It might not sound like much, but a two per cent increase in muscle strength is enormous, especially at the elite level. It's the difference between winning an Olympic medal or not," said study co-author Dr Cathy Stinear.

"There appears to be a pathway in the brain that tells our muscles when energy is on the way," said lead researcher Dr Nicholas Gant, from the Department of Sport and Exercise Science.

That participants reacted differently to identically-tasting liquids showed "detecting energy may be a sixth taste sense in humans", Dr Gant said.

"The carbohydrate and placebo solutions used in the experiment were of identical flavour and sweetness, confirming that receptors in the mouth can process other sensory information aside from the basic taste qualities of food," he said.

It was the first time a reflex linking taste and muscle activity had been described, Dr Stinear said.