Worth one's salt? Too much sparks an addiction, say scientists

Published on 11/03/2009 20:50

SALT is a "drug" that puts people in a better mood, which is why we eat more than is good for us, according to new research.

Britons consume about 10g a day – at least 8g more than the body needs.

A study showed that rats deficient in common table salt shied away from activities they normally enjoyed, such as drinking a sugary substance or pressing a bar that stimulated a pleasant sensation in their brains.

Psychologist Dr Kim Johnson said: "Things that normally would be pleasurable for rats didn't elicit the same degree of relish, which leads us to believe that a salt deficit and the craving associated with it can induce one of the key symptoms associated with depression."

His researchers said a loss of pleasure in normally pleasing activities is one of the most important features of psychological depression.

Dr Johnson, of Iowa University, said the idea that salt was a mood-boosting substance could explain why people were so tempted to over-ingest it.

Dr Johnson said: "Most of our biological systems require sodium to function properly, but as a species that didn't have ready access to it, our kidneys evolved to become salt misers."

Now scientists are finding evidence that it is an abused, addictive substance – almost like a drug.

One sign of addiction is using a substance even when it is known to be harmful. Many people are told to reduce sodium due to health concerns, but have trouble doing so because they like the taste and find low-sodium foods bland.

Another strong aspect of addiction is the development of intense cravings when drugs are withheld. Experiments by Dr Johnson and colleagues indicate similar changes in brain activity whether rats are exposed to drugs or salt deficiency.