Is there really such a thing as having one, tiny salty snack and feeling satisfied?

True, diets with too much salt can lead to dehydration, high blood pressure, kidney damage, and weight gain. But while the United States Department of Agriculture suggests that adults limit their salt intake to 2,300 milligrams per day, do we really need such rules if our bodies can figure it out for themselves?

New research suggests that we have our own internal means of measuring how much salt is too much salt. In a study on fruit flies, scientists added increasing concentrations of salt to the tongue of a fruit fly and monitored its reactions.

At low levels, the fly was pleased, and attracted to the substance. At increasing levels, the fly became averted to the substance. The relation between salt concentration and repellent reactions is an important one.

These differing reactions occur at the molecular level. When salt is placed on the tongue, signals are sent to the brain to relay that message. When there is little salt, there seems to be a threshold for which we remain attracted to the food, as salt tastes better at lower levels. However, when there is a lot of salt, excess messages are sent to the brain to warn it of the salt levels and the fly becomes averted to that food.

But there's n doubt that salt is necessary for bodily functions. Yali Zhang, Ph.D. and principal investigator of the study, explains, "The body needs sodium for crucial tasks like putting our muscles into action and letting brain cells communicate with each other, but too much sodium will cause heart problems and other health concerns." To maintain health, Zhang says, humans and other animals perceive foods with relatively low-salt concentrations as palatable, and find foods with very high salt content unappetizing.

On the cellular level, salt must enter cells before they can perform vital functions. The element sodium, which makes up salt compounds, is crucial for the processes by which messages are relayed in the body.

In an experiment where researchers removed the receptors that can sense and send signals to the brain about salt levels, they found that all salt levels became repellent, even low levels that were once attractive. The switch to repellent is an important one; it indicates that the receptors serve to regulate, instead of simply identify, salt levels. If there is a regulatory system already in place for salt, should we follow our instincts?

It is likely that similar mechanisms operate in humans, by measuring salt levels in the blood instead of just on the tongue.

This finding indicates that without subscribing to diets that restrict sodium, we are still able to monitor our salt intake, simply be being attracted to proper amounts and averted from excess, thanks to our bodily reactions.

Source: Zhang YV, Ni J, Montell C. The Molecular Basis for Attractive Salt-Taste Coding in Drosophila. Science. 2013.

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