What You Need To Know About The Blood Brain Barrier

What is the Blood Brain Barrier?!

So you quite possibly have heard of leaky gut, but have you heard of leaky brain?!

Just like the gut has a semi-permeable membrane that regulates what gets absorbed from the gut and into the blood stream (the gut barrier), the brain also has a semi permeable barrier called the blood bran barrier (BBB).  Because our brain is such a complicated and sensitive bio-electrical system, the BBB – made primarily from endothelial cells – regulates what is and isn’t allowed into the blood flow of the brain.

Its role is to create a safe haven for the brain, protecting it from things like bacterial components and damaging chemicals.  It also has a role in regulating communication between the gut and the central nervous system (which comprises the brain and spinal chord).  So intricate is this filtering system that no brain cell is more than 40-50 microns distance from a brain endothelial cell.

The significance of increased permeability is that molecules that normally wouldn’t be able to enter the brain manage to gain access, and an inflammatory response is triggered as a result.  A leaky brain is more susceptible to substances like heavy metals, pathogen likes bacteria and viruses, environmental toxins other damaging chemicals.

The fascinating thing is that many of the mechanisms that regulate permeability (or leakiness) of the gut barrier also directly affect the blood brain barrier permeability.

Zonulin, the enzyme released when gluten is consumed, and toxins  produced from intestinal bacterial overgrowth (called lipopolysacchires or LPS for short) are two significant factors that that increase gut barrier and blood brain barrier leakiness.

LPS is a very interesting area of research because we now understand that LPS increases the transport of insulin into the brain, which can result in insulin resistance systemically.  This then affects our metabolism, blood sugar regulation and systemic inflammation.  LPS also results in the release of inflammatory molecules called pro-inflammatory cytokines (there are anti-inflammatory cytokines too, but LPS does not result in the release of these).  Pro-inflammatory cytokines are linked to many neurological and mental health conditions, so much so that depression and anxiety are often being treated with anti-inflammatory medications or interventions rather than the old school anti-depressants and anxiolytics.  We must think beyond just reducing the inflammation though, and also look at healing the gut and restoring healthy gut flora so that we’re not continuously adding to the inflammation

Symptoms of a leaky, inflamed brain are quite broad and can range from mildly annoying to severe.  Brain fog for example, is commonly an early sign of increased BBB permeability.  Other symptoms and conditions related to increased blood brain barrier permeability and resulting inflammation include depression, anxiety, fatigue, ADHD, bi-polar disorder, autoimmune conditions affecting the central nervous system such as multiple sclerosis and Parkinson’s disease and dementia conditions such as Alzheimer’s disease.

BBB hyper-permeability can become a vicious cycle, as resultant inflammation in the brain means messages from the brain to the gastrointestinal tract are not so effective, which can then result in suboptimal digestion, dysbiosis (bacterial imbalance in the intestines) and leaky gut, which then can exacerbate the leaky brain!

So to heal a leaky brain, one must first take measures to reduce inflammation and to heal the gut.

The word inflammation means on fire and there’s a common saying in functional medicine that states “fire in the gut equals fire in the brain”.  This statement could rightfully be reversed as well to fire in the brain equals fire in the gut.  As you’ve just read, it’s a two way street.  This is why food choices are so important.  To heal an inflamed leaky brain and gut, it is important to eliminate the most common food stuffs that trigger and inflammatory response, with a focus on including lots of anti-oxidant and anti-inflammatory plants foods and gut healing broth’s and fermented foods.


To understand what else we can do to support the healing of a leaky blood brain barrier, let’s look at some of the contributing factors of a leaky brain:


Factors that increase BBB

  • High blood sugar (blood test glucose, HbA1c)
  • High blood homocysteine
  • Gluten (zonulin)
  • Heavy metals such as lead, cadmium, arsenic, mercury
  • LPS – toxins produced by bacteria in the gut
  • LPS increases the transport of insulin through the BBB and can result in peripheral insulin resistance
  • LPS releases pro-inflammatory cytokines
  • Some infections including HIV
  • Oxidative stress
  • Alcohol
  • Environmental and metabolic toxins
  • Food additives such as MSG and aspartame
  • Leaky gut syndrome (intestinal hypermermeability)
  • Psychological stress
  • Systemic inflammation / autoimmune disease.
  • Elevations in nitric oxide



How to reduce neural inflammation and support healthy BBB:


  • Follow an ancestral model of eating – mostly plants, small to moderate protein, good quality fats.
  • Heal your gut
  • Restore healthy gut flora
  • Antioxidants – vitamin C, astaxanthin, NAC, bioflavonoids, blueberries, cinnamon, resveratrol
  • Anti-inflammatories such as: bioflavonoids (e.g. rutin and quercetin), curcumin, turmeric (there are other compounds within turmeric other than curcumin which have anti-inflammatory activity), good quality fish oils.
  • Luteolin – a flavonoid found in many plant foods is bt=oth antioxidant and anti-inflammatory and helps to reduce LPS induced inflammation.
  • Baical Skullcap, a medicinal herb, contains a flavonoid called baicalein reduces cytotoxic nitric oxide production
  • Avoid sugars and high carbohydrate foods
  • Optimise your blood sugar regulation and insulin and leptin sensitivity (another reason to eat more cinnamon too!).
  • Manage stress (see my blog post on Stress, sleep and cortisol for tips on how to manage your stress better).
  • Get your blood tested for homocysteine, hs-CRP, ESR, triglycerides, HbA1c, blood glucose, insulin, leptin and vitamin D (25OHD) and ensure these are in optimal ranges (not just within the reference range).
  • Get regular exercise.
  • Eliminate artificial sweeteners and MSG
  • Ditch the grains (easy to do on paleo!).
  • Clean up your household cleaning products and beauty and body care products – switch to safe options.  See my the post on cleaning with chemicals.


So whether it’s simply to improve your concentration, or whether you experience depression or anxiety, or whether you are trying to address or prevent Alzheimer’s disease or multiple sclerosis you now know the link between the gut and the brain and the importance to address both for any of these conditions.  Likewise, for any gut problems, it’s also essential to address the brain to make sure the two way street of communication between the two systems is in tip top condition.  Of course as with any conditions, it’s recommended you work with a health care practitioner who is knowledgeable about the topics discussed here.  Together you’ll go on a journey to discover new levels of wellbeing and vitality.





http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3877994/ – metals.

http://www.ncbi.nlm.nih.gov/pubmed/16904139 – LPS, leptin, insulin, BBB













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