Eating too much salt can cause significant changes to your behavior - study

For years, many articles and public service ads have encouraged the public to reduce the amount of salt in food. At the same time, some manufacturers have reduced the amount of sodium in their products. 

The reason is clear. Salt is involved in raising blood pressure, and a study conducted this year even found that adding salt to food reduces more than two years of life expectancy for men and one and a half years for women. 

But, according to a new study by the University of Edinburgh, salt can cause significant behavioral changes, too.

The recommended salt intake for adults is less than six grams per day, but intake for most people is usually nine grams. This, as mentioned, can increase blood pressure, which in turn increases the risk of heart attacks, strokes and vascular dementia. Although effects on the heart and circulatory system have been well established, little was known about the effect of a high-salt diet on human behavior, which is what intrigued scientists at the University of Edinburgh.

The study found that a high-salt diet increased stress hormone levels by 75% in mice. Mice naturally eat a low-salt diet, yet here salt consumption mimicked typical human intake. The researchers found that the resting stress hormone levels increase and that the hormonal response in mice to environmental stress was double that of those on a normal diet.

Specifically, salt increased the activity of the genes responsible for the brain proteins that control the body's response to stress.

You are what you eat

Professor Matthew Bailey from the University of Edinburgh's Center for Cardiovascular Sciences stated that people are what they eat, and understanding how high-salt foods affect mental health is an important step toward improving well-being. He said this research shows that high amounts of salt also change the way our brain deals with stress.

Although both of these studies improve our understanding of the effects of a high-salt diet on the brain, researchers caution that we should be careful in translating the results to humans. 

There are vast differences in how animals and humans absorb, use and metabolize salt, according to the researchers, so comparisons between rodents and humans should be interpreted with caution, given the uncertainty in estimating the minimum salt requirements in mice, the relatively short exposure in animal models compared to lifetime exposure in humans, and the little known estimate of human salt consumption.