Does a high salt diet cause cognitive impairment?

Ever since the early seventies, salt has been demonized by the health community. And with direct links to high blood pressure and heart disease, there is a reason why it has long been considered a highly unhealthy food.

However, over the last decade, we have started to see that salt may impact the human body in a number of ways that we didn’t initially suspect – in fact, some people even seem to believe that it is linked to an early onset of cognitive decline.

But is that really the case?

Does salt cause cognitive impairment?

Effects of high salt diet on the brain

To first understand whether salt plays a role in the onset of cognitive impairment or not, we need to know what salt does in the brain (Faraco, 2019).

So, how does salt affect the brain?

First and foremost, research has shown that a diet high in salt can trigger the overproduction of a key compound called interleukin-17 (or IL-17 for short). This unique molecule increases inflammation in the brain, while simultaneously stopping your brain cells from producing nitric oxide. 

Nitric oxide is a compound that causes your blood vessels to widen in diameter, increasing blood flow. 

Consequently, by both increasing inflammation and limiting nitric oxide production, salt can actually reduce blood flow to the brain.

However, it doesn’t stop there.

New research has shown that it isn’t necessarily the reduced blood flow to the brain that causes dementia, but something known as tau protein.

Tau protein

Under normal circumstances, tau proteins are found in your brain, where they support nerve cell function by providing them with structural stability. By providing this stability, they ultimately allowing nutrients to flow freely into those nerve cells of the brain, increasing their ability to function.

Interestingly, it appears that nitric oxide helps ensure that tau proteins remain in the cell, and not floating around your brain – which is exactly what happens when the brain has insufficient nitric oxide.

To make matters worse, when tau proteins detach from the cells of your brain, they have the potential to build up and accumulate in your brain tissue, thus leading to cognitive decline.

The degenerative disorders caused by tau accumulation are known as Tauopathies – and this new research suggests they may be linked directly to salt intake.

What cognitive impairments are linked to high salt diet?

So, let’s get back to salt and cognitive function.

We know that salt consumption has the potential to increase the accumulation of tau protein in the brain – and we now know that this has the potential to cause cognitive issues (which are commonly known as tauopathies).

Specific cognitive diseases linked to excess tau protein include (Orr, 2017):

• Alzheimer’s disease 
• Progressive supranuclear palsy
• Corticobasal syndrome
• Dementia
• Chronic traumatic encephalopathy

However, outside of these specific diseases, it is also important to highlight that tau accumulation has been linked to a multitude of other nasty signs and symptoms. 

These include (Josephs, 2017):

• Unexplained falls and a loss of balance
• Speech impediment
• Resting tremor
• Memory loss, and loss of knowledge
• Issues with calculations
• Behavioral change
• Feelings of depression and anxiety

So, I guess looking at this, there is evidence to suggest that the accumulation of tau protein in the brain may also cause various symptoms of brain fog – suggesting a potential link between salt and brain fog.

Where is the research heading?

Taking this super interesting information into account, I wanted to discuss where the research is heading.

I should first note that while a clear link between tau accumulation and cognitive decline has been demonstrated in humans, most of the early research discussed today regarding salt intake and tau accumulation has only been proven in animals.

This ultimately means that future research should aim to explore whether this link does also exist in humans.

Assuming research does indeed prove this to be true, then we can feel confident in recommending people limit their salt intake to maintain cognitive function across the entirety of their lifespan. 

How much salt is recommended?

Although all this information certainly paints salt in a negative light, we need to remember that we also need it to maintain health and function on a daily basis (Campbell, 2004).

Most of the salt in your body sits within your blood and in the fluid surrounding your cells, in which it helps keep these fluids in a balanced state. Additionally, salt also plays a key role in ensuring normal nerve and muscle function.

In short, it is important.

However, having too much of it poses some issues – like those outlined in this article, for instance.

You might be wondering what the recommended daily salt intake is for adults – and fortunately, there are some very clear guidelines around this.

The dietary guidelines for Americans recommend an intake of less than 2300mg of salt per day. While this may sound like a lot, I should note only that it amounts to one full teaspoon.

Exceeding 2300mg is when we start to see certain health issues arise.

But the scary thing is, most American adults tend to eat more than 3400mgs of salt per day – which is obviously well above the upper limit.

Restaurant vs home cooking salt consumption

A large part of this overconsumption comes as a result of eating out often (Park, 2009).

Most processed meat and salads found in takeaway food places have been preserved in salt. As a result, their salt content is through the roof. 

Similarly, although eating out at a restaurant might seem like a good way to keep your salt intake down, often it isn’t. As bad as it is for health, salt is one of the most heavily used compounds in restaurant cooking. From steak to salad, it is used with almost any dish you can think of. 

In short, it makes everything more palatable.

This is why eating out is not always the best option if you want to keep your salt intake down…

Tips to decrease salt 

The last thing I wanted to do in this article offers some practical tips you can use to turn your high salt diet into a low salt diet – so, without further due, here are my favorites:

• Start reading the food label on packaged foods to observe how much salt is in a serving
• Purchase all your meats and vegetables fresh (pre-packaged options often have salt included as a preservative)
• Prepare your own foods
• Rinse any canned foods that contain salt (such as beans and tuna)
• Before dining out, do your research and look for low salt options

And lastly, you can also substitute salt with some delicious spices.

You may also like:The Importance of Nutrition on Brain Health

Spices to replace salt with

My favorite spices to replace salt with include:

• Cinnamon 
• Turmeric
• Rosemary
• Nutmeg 
• Cayenne
• Oregano
• Paprika
• Lemon juice

While these great salt alternatives won’t work with every dish, they can be mixed and matched to suit your individual taste preferences. With this, they can also be tailored to what food you are cooking at the time.

Hell, if you get it right, this single tip may even become a life (or brain?) saver.

Take-Home Message

It is well known that high salt intake can contribute to the development of cardiovascular issues. However, with recent research demonstrating a clear link between salt intake and cognitive decline, now is the time to lower your salt intake for good.

So, make sure you start implementing the tips outlined in this article ASAP, and let us know how you go – we always love to hear from you!

References

Faraco, Giuseppe, et al. “Dietary salt promotes cognitive impairment through tau phosphorylation.” Nature 574.7780 (2019): 686-690.

Orr, Miranda E., A. Campbell Sullivan, and Bess Frost. “A brief overview of tauopathy: causes, consequences, and therapeutic strategies.” Trends in pharmacological sciences 38.7 (2017): 637-648.

Josephs, Keith A. “Current understanding of neurodegenerative diseases associated with the protein tau.” Mayo Clinic Proceedings. Vol. 92. No. 8. Elsevier, 2017.

Campbell, Sheila. “Dietary Reference Intakes: Water, potassium, sodium, chloride, and sulfate.” Clinical Nutrition Insight 30.6 (2004): 1-4.

Park, Hae-Ryun, et al. “Workers intake too much salt from dishes of eating out and food service cafeterias; direct chemical analysis of sodium content.” Nutrition research and practice 3.4 (2009): 328-333.

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