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It’s a general rule of thumb that excess of anything can be harmful. There are several already known effects of having too much salt. Adverse effects of excess salt include increased blood pressure, damage to the heart, kidneys, and even the bones. However, a study published in the journal Nature Neuroscience notes that having too much salt can cause cognitive deficits.

The authors of the study explained that endothelial cells inside the cerebral blood vessels play a role in increasing the risk of negative effects on the brain. What does it have to do with salt? A lot actually. Endothelial cells play a vital role in lining our blood vessels and regulating vascular tone. If an excess amount of dietary salt is taken, then it can lead to the dysfunction of these cells.

The brain relies heavily on a steady flow of oxygen. Take that away, and it becomes really hard for the brain to function, which results in a lot of problems because the brain is the central unit. Excess salt can not only lead to cardiovascular disease, but it leads to problems in the gut, our immune system and eventually the brain.

Image: Stanford

The Study

The research, led by Ladecola and his team experimented with mice to see the effects of a diet high in salt. A lot of people frown upon experimental studies on mice because they feel that the discoveries aren’t exactly applicable to humans. That may be a valid point but it’s not entirely true.

The internal system for mice is similar to that of humans. Therefore, it’s no coincidence that mice were chosen as the test subjects. A lot of times, the discoveries made on mice hold true for humans as well. Moreover, it’s not possible to test on humans due to ethical problems.

As far as this study goes, the researchers fed a group of mice a diet high in salt for 12 weeks. The diet given was appropriate and comparable to a “human” diet high in salt. Tests were then conducted and they made some interesting findings.

The Results

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After the first few weeks of giving the excessive salt, researchers found endothelial dysfunction in the mice. They also saw reduced blood flow to the brain as well. Both are huge red flags, especially the latter. If the brain does not receive an adequate amount of blood, then it cannot function properly. The cognitive effects theory was reinforced by the fact that the behavioral tests showed a cognitive decline in the rodents.

One interesting thing to note, however, is that there wasn’t much of a change in the blood pressure. Perhaps blood pressure changes may occur after a much longer time than 12 weeks as compared to cognitive decline. Another important thing researchers noticed was the increase in the gut’s TH17 white blood cells.

These TH17 white blood cells, if high in number can increase the levels of a pro-inflammatory molecule called plasma interleukin-17 (IL-17). One may eat a lot of foods that counter inflammation. However, if their diet consists of too much salt then all the positive anti-inflammatory effects of other foods are just negated.

It’s not just TH17 though. Researchers found a molecular pathway through which they saw that higher levels of IL-17 in the blood led to possibilities of negative cognitive and cerebrovascular effects.

The researchers then applied their findings elsewhere…

Unlike many studies, the researchers here took their testing to the next level. They tried the experiments on human cells too to see if IL-17 would produce the same results. The results were pretty interesting.

The researchers treated human endothelial cells with IL-17 and obtained similar results to the ones they saw with mice. Ladecola and his colleagues explained:

The findings unveil a gut-brain axis by which environmental factors linked to the diet lead to an adaptive immune response in the gut, promoting […] neurovascular dysregulation and cognitive impairment.”

The human testing legitimizes the findings of this experiment even further. There’s always a possibility of uncertainty even with mice because humans, in the end, are different. However, now there can be no doubt about the findings of this study. However, there’s also a silver lining to it.

You can reverse the negative effects

Thankfully, the damage done to the brain through excess salt can be reversed. It’s actually a simple fix (in theory) and something that seems to keep popping up over and over again. After the 12 week period, the mice were given a normal diet again and their situation improved quite a bit. The authors of the study write:

“The harmful effects of [a high-salt diet] were abrogated by returning the mice to a normal diet, pointing to [the] reversibility of the vascular dysfunction and cognitive impairment,”.

The researchers also experimented with a drug that was able to reverse the effects of excessive salt on the brain. In particular, the amino acid L-arginine had a huge impact in reverting the mice back to their normal states.

What are the takeaways from this study?

We already knew that too much salt is bad for you. The results of this study give another reason to avoid having too much salt in your diet. Another huge takeaway is the root of the problem itself and how easy the fix is. A lot of people’s diets nowadays include a lot of junk food or other unhealthy foods.

These foods have highly processed sugars and salts which are the root of so many diseases and problems. As the study points out, the damage is reversible. How? By fixing your diet. It sounds simple but it might not be that easy in implementation. It takes real sacrifice to change your lifestyle. It definitely doesn’t happen overnight. However, given the adverse health effects of the unhealthy foods one eats, it’s a highly necessary change.

By shifting to a much healthier diet, people can improve their cognitive ability instead of lessening it. As far as the study goes, there’s another key takeaway here. Dietary changes may not help some people reverse the damage as it might be too little too late. However, as the study found, the L-arginine amino acid was highly effective. Perhaps the findings of the study will lead to a new class of drugs that can combat the negative effects of excess salt.


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