A diet containing lots of salt can contribute to increased levels of stress, a new study shows.
Scientists found in studies of mice that a high-salt diet increased the levels of a stress hormone by 75 per cent.
Experts hope the findings will encourage a review of public health policy around salt consumption, with a view to manufacturers reducing the amount of salt in processed food.
The recommended salt intake for adults is less than six grams a day but most people regularly eat about nine grams.
This can contribute to higher blood pressure, which increases the risks of heart attacks, strokes and vascular dementia.
While effects on the heart and circulatory system have been well established, little was known about the impact of a high-salt diet on a person’s behaviour.
To study this, experts from the University of Edinburgh used mice, who ordinarily have a low-salt diet, and gave them high-salt food to reflect the typical intake of humans.
They found that not only did resting stress hormone levels increase, but the mice’s hormone response to environmental stress was double that of mice that had a normal diet.
Salt intake increased the activity of genes that produce the proteins in the brain which control how the body responds to stress.
Experts say further studies are already underway to understand if a high-salt intake leads to other behavioural changes such as anxiety and aggression.
The study is published in Cardiovascular Research. It was funded by the British Heart Foundation and Kidney Research UK.
Matthew Bailey, Professor of Renal Physiology at the University of Edinburgh’s Centre for Cardiovascular Science, said: “We are what we eat and understanding how high-salt food changes our mental health is an important step to improving wellbeing. We know that eating too much salt damages our heart, blood vessels and kidneys. This study now tells us that high salt in our food also changes the way our brain handles stress.”