Researchers in the US have found that feeding mice a high-salt diet led to memory problems that may be triggered by changes to the immune system in the gut. The findings were published today in the scientific journal, Nature Neuroscience.
Despite only accounting for around 2% of body weight, the human brain requires approximately 15% of the body’s blood supply. Changes to the blood supply can have wide-reaching effects, and have been linked to changes in the brains of people with dementia.
Scientists at Cornell University investigated the effect of feeding a high salt diet to mice, finding that those that consistently ate high levels of salt performed worse in memory tests. They found that excess salt was linked to a reduction in blood flow in the regions of the brain important for memory.
The changes to the blood supply in the brain were also linked to changes in the gut. Researchers found that cells in the small intestine expanded in mice on a high salt diet, which caused an increase in an inflammatory protein called IL-17. Circulating in the mice’s blood supply, IL-17 caused a number of changes to the cells lining blood vessels in the brain, reducing blood flow and causing memory problems.
Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK, said:
“We know that too much salt can be bad for the heart and this study suggests it can also have negative consequences for the brain. Interestingly, this research not only highlights the importance of the immune system for brain health but also suggests that changes in the gut can play a role. While this research was in mice, the findings highlight the importance of cutting out excess salt in our diets, as well as identifying possible new avenues in the search for treatments to help those with memory problems or dementia.
“Alzheimer’s Research UK is currently funding research exploring ways to support people in mid-life to adopt a healthier diet, as well as exploring the role of the gut in contributing to our brain health. Eating a balanced diet, not smoking, only drinking in moderation, staying mentally and physically active, and controlling blood pressure and cholesterol can all help to maintain brain health as we age.”