"People don't consume as much calcium as nutritionists would like, and one reason for this is that foods high in calcium don't taste good to many people," said Dr Michael G. Tordoff in a presentation to the 236th National Meeting of the American Chemical Society.

"Tweaking its taste could encourage a calcium-deficient population to consume more of this key nutrient."

"By understanding how calcium is detected in the mouth, we can either make it easier to consume by reducing its bad taste or even make pharmacological agents that make it taste better."

Researchers at Monell Chemical Senses Center in Philadelphia discovered that the taste of calcium is detected by two distinct receptors on the mouse's tongue.

One is a calcium-sensing receptor called CaSR, also found in the parathyroid glands, kidney, brain and gastrointestinal tract.

"We didn't know it was on the tongue before," Dr Tordoff said.

The other is a receptor known as T1R3, a component of the 'sweet-taste' receptor -- a finding that researchers described as 'very unexpected.'

Dr Tordoff and his colleagues looked at the calcium preferences of 40 different strains of mice.

"Most mice dislike calcium, but we found a very unusual strain that drinks it avidly," he said.

"By comparing the genes of this strain with other strains, we were able to identify the two calcium taste genes."

Now they must see if humans have a similar capacity.

"It remains to be seen if what we have discovered in mice -- the existence of two calcium taste genes -- holds true for humans," said Dr Tordoff.

"We know people have the sweet-taste gene, Tas1r3, and the gene involved with the calcium-sensing receptor, CaSR."

"We don't know if we have the same forms of genes as the mice have, but it seems pretty likely they have the same function."

But what does calcium actually taste of?

"Calcium tastes calciumy," Dr Tordoff said.

"There isn't a better word for it."

"It is bitter, perhaps even a little sour."

"But it's much more because there are actual receptors for calcium, not just bitter or sour compounds."