Too Much Salt

The landscape of taste receptors consists of cells responsive to sweet, sour, bitter, sodium salt, and umami tastes. Sweet and umami tastes attract animals, while sour and bitter tastes generally repulse them. Sodium salt tastes straddle the fence, in that low salt doses are attractive and high doses are aversive. Before work published online this week in Nature, how salty tastes elicit different responses was still a mystery. Charles S. Zuker and colleagues at Columbia University and the NIH showed in mice that bitter and sour taste receptors respond to highly salty tastes and then communicate to the brain that the salty taste is repulsive. Mice without functioning bitter and sour taste receptors still find salty tastes attractive, but do not find highly salty tastes repulsive.