Consuming too much sodium increases the risk of heart disease and stroke, two of the leading causes of death in the U.S. Some lower sodium products are on the market, but many consumers avoid these foods because they think the foods won't be tasty enough or flavorful enough. To develop more palatable products, researchers are trying to gain a better understanding of how the body processes and perceives saltiness. Although saliva is thought to play a role, it's unclear exactly what components of the liquid could explain the differences in salt perception among people. In a small study, Thomas Hofmann and colleagues sought to fill that knowledge gap.
The researchers classified volunteers into sensitive and non-sensitive groups according to how salty the participants thought various sodium chloride solutions were. Using liquid chromatography and mass spectrometry, the team identified several salivary proteins that differed between those who could readily detect salt and those who couldn't. Surprisingly, they found the largest differences in the resting saliva of the subjects compared to saliva produced after swishing around a salty solution. In their resting saliva, sensitive subjects had higher amounts of endopeptidases, enzymes that cut up proteins, than non-sensitive subjects.
The researchers suggest that the enzymes could be modifying sodium channels, which would increase the amount of sodium that gets into cells. Alternatively, the enzymes could be cutting proteins in the saliva to produce salt-enhancing peptides in people who are sensitive.