Many of us know about ‘leaky gut’, but did you know that the same mechanisms that can increase your gut lining permeability exist with your brain lining? We all have a membraneous filter that separates our circulating blood from the precious extracellular fluid that circulates around the brain. This finely woven mesh of astroglia cells and blood vessels surrounds and protects the brain, allowing only allow nano-sized particles in or out as needed and keeping harmful larger substances such as bacteria and neurotoxins out.
Just like the gut lining, this blood brain barrier is composed of ‘tight junctions’ between cells that can open to selectively permit molecules necessary for neural function into the brain. The blood brain barrier is extremely vulnerable to many aspects of modern life, such as systemic inflammation and high cortisol from chronic stress. These and other factors can degrade the integrity of the tight junctions, creating an effect very similar to leaky gut. When this happens, toxins, microbes and other substances that normally would bounce off a healthy blood brain barrier are able to pass through, activating an inflammatory response inside the brain. Evidence is also emerging that indicates the amyloid plaques in the brain characteristic of Alzheimer’s disease may be forming at least in part to stave off infection from bacteria, viruses and yeast.
Immune reactions to gluten can also lead to a ‘leaky brain’. Zonulin is a protein that opens up the tight junctions in the blood brain barrier (and in the intestinal lining), thus regulating how permeable the barrier is. For people with celiac disease and gluten sensitivity, gluten triggers zonulin to open these junctions. Importantly, many researchers believe zonulin release isn’t specific to the gluten intolerant population - some research suggests that gluten opens these junctions in all people.
In addition to stress, gluten and systemic inflammation, other factors that degrade the blood brain barrier are elevated homocysteine (homocysteine, measured by a simple blood test, is an inflammatory compound that elevates with B vitamin deficiency), alcohol, poor diet and antioxidant status, advanced glycosylated end products (these are free radicals created with elevated blood glucose where the glucose cannot enter the cells), and harmful free radical compounds such as pollutants, all of which trigger inflammation. The most common symptoms of a leaky blood brain barrier are brain fog or reduced brain function after exposure to environmental insults such as inflammatory foods, gasoline fumes or chemical cleaning products.
Testing for a Leaky Blood Brain Barrier
The tight junctions of a healthy blood brain barrier only allow nanoparticles, which are very tiny, to pass through while preventing the passage of antigens and harmful environmental compounds. GABA, a supplement popular for producing a calming, relaxing effect, exceeds the nanoparticle size and does not have a blood brain barrier transport protein. Therefore, it should not be able to cross a healthy blood brain barrier. If you take GABA and notice it has an effect, you probably have a leaky blood brain barrier.
To test this, take 800-1,000 milligrams of GABA and give yourself a two to three hour window to see whether it affects you. Feeling no change after taking GABA is a good sign your blood brain barrier is intact, while feeling either more relaxed and sedated or anxious and irritable indicates a permeable blood brain barrier. It can be useful to do the GABA challenge periodically to see how various things might affect you. For instance, if you’re gluten intolerant a GABA challenge can show you that eating gluten will cause leaky brain for a week or two. However, try not to take GABA regularly or you risk shutting your GABA receptor sites.
Healing Your Blood Brain Barrier
The good news is that even though the blood brain barrier degrades quickly, it has to potential to regenerate quickly. For instance, high stress degrades the blood brain barrier, but reducing stress can allow it to repair. It’s important to note that ‘stress’ in this sense is not just mental-emotional stress, but also physiological stress which can be induced by infections, lack of sleep, food sensitivities, gut bacterial imbalance and leaky gut, constantly fluctuating blood sugar, and smoking and other lifestyle factors – it’s all the same to your body, which creates an immune response in an attempt to get back to homeostasis. Simply stabilizing your blood glucose and cortisol levels, reducing inflammatory triggers such as gluten, clearing up a gut infection or chronic virus, boosting dietary antioxidants and supplementing with flavonoids proven to dampen inflammation can help restore the blood brain barrier and protect your brain.