This essential element is like a double edged sword, as too little is can be just dangerous as too much, with either side having the possibility of adverse effects to the health of humans, animals, and even to fruit flies. Biologists have been working to enhance the scientific understandings of calcium taste.
Calcium doesn’t fit into one of the 5 established tastes that the tongue’s receptors are able to identify which are salty, sour, sweet, savory, and bitter. Calcium has been described as slightly bitter and sour. Scientists as UC Santa Barbara working with colleagues in Korea have been able to establish that calcium taste also exists in fruit flies. The team discovered a unique class of gustatory receptor neurons that are required for the taste of calcium in these model organisms, the flies appeared to be indifferent to both high and low levels of calcium.
The findings of this study have been published in the journal Neuron. This study was conducted to understand the underlying mechanisms that are used to respond to the presence of calcium in food. Petris dishes having one side containing solely sugar and the other containing a mix of sugar and a high level of calcium were used by the researcher to conduct this experiment with fruit flies. Normal flies that had rejected the side of the dish with high calcium levels survived. Mutated flies that had one of the 3 GRNs removed were unable to distinguish between the 2 different sides to the dish, which resulted in the consumption of too much calcium causing viability issues leading to death over time.
It was found that calcium avoidance had occurred through 2 mechanisms, the activation of a unique class of GRNs that is distinct from those that sense compounds that are bitter, which also cause a stop feeding signal when they are activated. Additionally calcium also inhibits the sugar activated GRNs.
High levels of calcium in humans is associated with several diseases and may even be life threatening. The researchers suggest that the taste of calcium may serve to function primarily as a deterrent.