Fact Checked by Dr. Anthony Gustin, DC, MS | Published September 25, 2019 by Corey Nelson

What Does Ketosis Do to the Brain?

Ketosis refers to the natural production of ketone bodies by your liver. Ketone bodies, or ketones for short, are energy-rich molecules that your body produces in the absence of carbohydrates.

When you’re producing ketones, it means your body is running on fat for fuel instead of relying on carbs and sugar.

To achieve and maintain ketosis, you must eat no more than 30-50 grams of carbs per day.

When it comes to the brain, there are two key aspects to understand about ketosis and the keto diet:

  • Ketones have measurable effects on your brain.
  • The absence of carbohydrates also has effects on brain tissue and brain function.

In other words, certain brain effects of ketosis are due to the presence of ketones, while others are due to the absence of carbohydrates from your diet.

You can also achieve some of the effects of ketosis by using supplements like medium-chain triglyceride oil (MCT oil) and ketone esters, without eliminating carbs .

Here’s what you need to know about ketones and the brain:

  • Ketones are the most efficient brain fuel, and absorb more readily than glucose (simple sugar).
  • Ketones have anti-inflammatory and antioxidant effects in the brain, meaning they can prevent or limit damage to cells.
  • Ketones in your brain result in epigenetic changes, including DNA methylation and gene expression.

And here’s what happens to your brain when you dramatically reduce carb intake:

  • There’s less free radical production from glucose, meaning less cellular damage.
  • Your body, including your brain, become more sensitive to the effects of the hormone insulin.
  • Similar to a fasting state, autophagy and mitophagy take place–meaning your brain can eliminate or “recycle” damaged tissue, cells, and mitochondria.

Remember, the above facts are what we know from current peer-reviewed research. These findings are general, and are not specific to people with Alzheimer’s disease.

Can a Keto Diet Prevent Alzheimer’s?

Let’s establish an essential fact up front: there’s no research yet definitely proving keto can prevent Alzheimer’s.

However, there are plenty of promising findings. In this section, you’ll learn how keto might reduce your risk of Alzheimer’s by improving modifiable risk factors.

Keto and Modifiable Risk Factors

As discussed in a previous section, up to a third of all Alzheimer’s cases may be preventable by targeting the risk factors that can be changed (as opposed to aging, genes, or familial history, which are not modifiable).

First of all, let’s review the known modifiable risk factors:

  • Traumatic brain injury (TBI)
  • Insulin resistance 
  • High blood pressure 
  • Chronic inflammation 
  • Overweight or obesity 
  • Smoking

Now it’s time to take a look at how keto interacts with each of these risk factors.

Traumatic Brain Injury

While no one chooses to get TBIs or concussions, there’s substantial evidence that keto reduces the adverse effects of TBIs in animals, and may do the same in humans. 

These effects certainly apply after TBIs, but if you are already in ketosis before you receive a head injury, the benefits of keto for TBIs are even more pronounced.

Translation: TBIs increase your risk of Alzheimer’s, but keto appears to reduce damage from TBIs.

Insulin Resistance

Next up, insulin resistance. 

Some researchers have begun calling Alzheimer’s “type 3 diabetes” because severe insulin resistance increases risk of the disease by up to four-fold. 

The pathogenesis of Alzheimer’s dementia has a lot in common with diabetes, too. Diabetes and Alzheimer’s both involve glucose hypometabolism, mitochondrial dysfunction, and free radical damage.

Insulin resistance occurs primarily because of excessive carbohydrate intake. So it’s hardly surprising that a low carbohydrate keto diet is a fantastic way to improve insulin sensitivity, including in your brain.

Numerous studies demonstrate that going keto can help you achieve better scores on blood tests like fasting insulin, fasting blood glucose, and glycated hemoglobin. 

In other words, insulin resistance increases Alzheimer’s risk, but keto can increase insulin sensitivity. 

For even better results, pair keto with regular exercise.

High Blood Pressure

So far, so good! How about blood pressure?

According to a systematic review from The British Journal of Nutrition, keto can result in significant drops in blood pressure. 

Not only that, the effect goes above and beyond what can be explained by sodium restriction and weight loss. 

In other words, keto may have a unique ability to lower blood pressure not found with other diets. That’s excellent news when it comes to lowering your risk of Alzheimer’s.

Chronic Inflammation

Chronic inflammation in your body can increase your risk of Alzheimer’s disease. 

High blood sugar, for example, is a known cause of chronic inflammation, and also correlates to Alzheimer’s risk.

Keto enhances your mitochondrial health and reduces oxidative stress. It also boosts your body’s natural ability to suppress inflammation.

Overweight or Obesity

The fact that keto is fantastic for losing weight is hardly a secret.

But unlike other diets, the ketogenic diet allows you to lose weight with minimal hunger and plenty of energy. 

Not only that, most people don’t even need to count calories to lose weight on keto.

All you need to do is study up on keto macros, make a keto grocery list, and follow through consistently. (It’s also a good idea to measure your ketone levels when you start, to make sure you’re actually in ketosis.)

Smoking

If you smoke, quitting may lower your risk of Alzheimer’s disease by up to 58%.

But how does that relate to the ketogenic diet?

Believe it or not, a 2010 study published in the journal Trials concluded going keto may even make it easier to quit smoking for overweight adults. Win-win!

Can Keto Reverse Alzheimer’s?

The short answer: no one knows yet if keto can reverse Alzheimer’s.

There are no randomized controlled trials of the diet in Alzheimer’s patients, meaning there simply isn’t enough data to say one way or the other.

However, some doctors do currently use the ketogenic diet to treat Alzheimer’s.

There’s also promising evidence demonstrating improved cognition from studies of mild cognitive impairment (MCI) patients given ketogenic supplements like MCT oil and exogenous ketone bodies.

And according to the authors of a 2019 study from the high-impact journal Nutrition:

“the ketogenic diet could be an effective treatment and prevention for Alzheimer’s disease, but both ketone production and carbohydrate restriction may be needed to achieve this.”

Next, we’ll take an in-depth look at how ketosis interacts with known mechanisms that contribute to the progression of Alzheimer’s.

Ketosis and Alzheimer’s Pathogenesis

As covered previously, here are the four key pathways that appear to contribute to Alzheimer’s progression:

  • Vascular dysfunction and blood-brain-barrier issues 
  • Glucose hypometabolism (insufficient glucose) 
  • Mitochondrial dysfunction, resulting in reduced energy production in the brain 
  • Free radical damage, which creates a vicious cycle in combination with the other three mechanisms

Can keto help address these disease progression mechanisms?

Here’s what current evidence suggests.

According to recent research, going keto may increase cerebral blood flow and help repair the vascular damage that occurs in Alzheimer’s patients.

Evidence also demonstrates that the keto diet compensates for glucose hypometabolism by supplying ketones as an alternative fuel source. 

And a study of 23 adults with mild cognitive impairment, which can be a precursor to Alzheimer’s disease, found that ketones improved memory and cognitive function in the participants.

Finally, ketones and ketosis work to improve mitochondrial function, delivering more energy to the brain. As a result, they also decrease inflammation and damage from free radicals.

In summation, the keto diet does appear to address the four known pathways that contribute to the progression of Alzheimer’s. 

However, the degree to which it can halt or even reverse the disease remains to be discovered.