Do You Know What The Blood Brain Barrier Is?



Written by: Kusha Karvandi

Do You Know What The Blood Brain Barrier Is?

In 1885, German scientist Paul Ehrlich injected a blue dye into the bloodstream of mice. Ehrlich’s goal was to find new compounds that could attack disease-causing microbes. But in the course of this work (which later earned him a Nobel Prize for creating a cure for syphilis), he stumbled into a very strange discovery.

After injecting the mice with his blue dye, he found that the dye stained all of the mices’ organs blue — everything except their brains. In 1913, this experiment was repeated instead injecting the blue dye directly into the mices’ brains. And this time their brains were stained blue, but the other organs were not.

After major technological advancements in the 1960s, scientists were finally able to gain a better understanding of this blood-brain barrier. What they learned is that the brain had similar blood vessels to the rest of the body, except that the endothelial cells in the brain were tightly held together, creating a nearly impermeable barrier between the brain and bloodstream.


The primary purpose of the blood-brain barrier is to block harmful toxins and bacteria from entering the brain. But the brain also requires hormones, glucose and amino acid from other organs of the body.

How does the blood-brain barrier decide what gets through?

What scientists found was that very small molecules and fat-soluble molecules such as antidepressant medications, alcohol, cocaine and certain hormones were able to more easily pass through the barrier. Whereas, larger molecules such as glucose and insulin, required transport proteins to be carried across. These transport proteins live in the brain’s blood vessel walls and selectively pull in the appropriate molecules into the brain.

How exactly does the blood-brain barrier become leaky?

One way is via the blood-brain barrier’s biological twin, the gut-blood barrier, which is highly interlinked. When an individual with gluten sensitivity, for example, consumes gluten, they break down the tight junctions of the intestinal wall, which creates an inflammatory cascade that makes its way to the brain.

Cytokines are cell signaling proteins that play a role in cellular communication in immune responses and stimulate the movement of cells toward sites of inflammation. An inflammatory cascade triggered by gluten sensitivity primarily damages the blood brain barrier through cytokine trafficking – creating openings in the barrier for both intended and unintended molecules to pass through.

How do you reverse this?

One way may be to check with your doctor about getting gluten sensitivity panels (such as Cyrex Labs Arrays 3 & 4) to check for both gluten sensitivity as well as gluten cross reactivity. Approximately 50% of those with gluten sensitivity also have dairy sensitivity due to cross reactivity.

With this information, you can begin to make the necessary dietary and lifestyle changes to repair your gut, brain and integrated function.


Kusha Karvandi
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Kusha Karvandi

Entrepreneur and Fitness Enthusiast at The Exerscribe
Kusha Karvandi is an entrepreneur and fitness enthusiast with a passion for "biohacking" to help others live their best life. Kusha has 9 years experience as a personal trainer and health club manager, with over 10,000 session hours serviced and 15 certifications. He is the author of Nutriscribe, known for its no-nonsense, no calorie counting approach to weight loss and healthy eating. To round out his passion for helping others get in shape, Kusha has made it his mission to ensure that everyone has a unique personal training experience through his app, Exerscribe, which provides custom and adaptable workout plans to anyone with a gym membership.
Kusha Karvandi
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