Usually, the reason for monitoring your salt intake depends on the health of your cardiovascular system. However, our brain can also suffer from excessive salt.
While high blood pressure is an obvious place to search for a cause, the details have turned out to be a little more complicated – and point to another bridge linking the gut to the brain.
Back in January, researchers at the Feil Family Brain and Mind Research Institute in New York used mice to identify the biochemical pathway responsible for the risk of stroke and dementia in people taking too much sodium ,
It has become clear for some years now that we have an increased risk of cerebrovascular disease (CSV) due to high-salt diets.
This generic term covers all types of abnormalities and involves a general limitation of the capillaries of the brain, in turn, can lead to an increased risk of diseases such as stroke and dementia.
Of course, it's not surprising to associate salty diets with problems in the blood vessels of the brain. At the very least, this should not be the case, since the sodium ion has the ability to draw water into the vascular system and build up the pressure of so-called hypertension.
But in science even the most basic assumptions deserve a kick. That's a good thing, because it turns out that this link between stroke risk and dementia and salt intake is not just due to increased blood pressure.
The research team sought an alternative explanation following research that good old table salt can promote autoimmune disease by making a certain type of white blood cell a nuisance.
These T helper lymphocytes are a chemical that promotes inflammation, called interleukin-1
Put mice on a high salt diet, the researchers found indeed impaired the perception and signs of circulatory disorders.
Considering that "mice are not human," they have become a suitable model for investigation, especially when we are tinkering with their genes.
In particular, the team used both normal mice and some genes whose genes were altered to overproduce interleukin-17 even with a relatively low-salt diet.
All this points to a high-salt diet. The gut's immune system is made to produce a signal that affects the blood vessels in key areas of the brain – the hippocampus and the wrinkled outer layer, the cortex.
It was crucial that this impairment was present even with high blood pressure. That is, even if we were to treat the hypertension that results from a sodium-rich diet, there could be an increased risk of stroke and dementia.
Disruption of this immunological pathway helped to reduce signs of cognitive impairment. Better yet, reducing the amount of salt also helped.
For the health conscious among us, these results are one more reason to pay attention to what's in our mouths, and try to reduce the sodium to about 5 grams a day, where possible.
But there is one more message that should be removed from this study.
Our abdomen and central nervous system look like spirited BFFs who exchange love and hate messages through a network of neurological and biochemical connections.
It was not until this year that studies were discovered that revealed new neuronal circuits in the gut and brain, molecular pathways connecting the intestinal flora and brain cells, and links between nutritional and mood disorders.
All this combines a growing research group associates the composition of microbial citizens of our digestive system with the development of Parkinson's disease.
You can bet that by 2019 we will see more studies restricting the complex interaction of microbes, the immune system and neurology, connecting the gut and brain into a complex system.
There are likely to be more connections between these two vital body systems. Finding them could make all the difference to our mental health.
This research was published in Nature Neuroscience .