I often tell my patients that such-and-such does or does not “cross into the blood-brain barrier.” A few days ago, one patient asked, “What is
the blood-brain barrier?” Okay, let's talk about this!
What is the Blood-Brain Barrier?
The blood-brain barrier is a protective barrier that actually decides
which substances can cross from the bloodstream into the brain. The blood-brain barrier is semi-permeable (meaning: it lets some things through, and not others). The brain actually has its own “security system,”1
if you will. Therefore, all substances traveling through the blood vessels will not necessarily diffuse (get) into the brain. The types of things that tend to be able to diffuse into the brain from the blood are substances that can dissolve in fat. The cell membrane (covering of the cell), called the “lipid bi-layer,” is, itself, made of fat.
The Difference Between the Body's Environment and the Brain's Environment
The Body's Environment
In the the body, the smallest blood vessels which come right up to the cells and exchange substances with them (bringing nutrients and removing wastes) are called called capillaries
. The capillaries go out to ordinary places – to the stomach, heart, muscles, etc., and are able to exchange substances fairly freely between cell and capillary. The body's levels of hormones, amino acids, etc., fluctuate during the day after meals, exercise, or during stressful periods.2
The Brain's Environment
In the brain, however, the situation is quite different. The cells in the brain are clustered together more tightly. They're joined by complex tight junctions3
which do not allow substances to come and go as they please; this is the blood-brain barrier
–a composition of specialized brain microvascular endothelial cells (BMECs).4
It is a very selective permeability barrier which allows water, lipid soluble molecules, some gasses, brain-essential amino acids, and glucose, but keeps other things out. That is one of the things that makes it somewhat difficult to get therapeutic substances across the blood-brain barrier.5
The blood-brain barrier strives to keep a constant controlled environment in the brain.
Three Functions of the Blood-Brain Barrier
- Protects the brain from "foreign substances" in the bloodstream that may be harmful to the brain.
- Protects the brain from hormones, etc., that fluctuate throughout the day in the rest of the body.
- Maintains a constant controlled environment for the brain.
Things That Can Break down the Blood-Brain Barrier
- Hypertension (high blood pressure)
- A very high concentration of a substance in the blood (hyperosmolitity)
- Exposure to microwaves
- Exposure to radiation
- Exposure to infections
- Injury to the brain: trauma, ischemia, inflammation, pressure6
Getting Nutrients Through the Blood-Brain Barrier
Since we now know that good fats (nuts, avocados, olive oil, coconut oil, etc.) are good
for the brain, and fat soluble substances can cross the blood-brain barrier, it is essential that the supplements taken for brain health can actually do their job. They need to be mycelized in oil (fat) in order to get to their destination. Our curcumin supplement, Curcumin Rapid Absorb
, is mycelized in its own oil in order to allow it to absorb across the blood-brain barrier
The same concept applies to magnesium
. Do you know what type of magnesium you are taking? And for what purpose? There are types of magnesium that do not cross well into the blood-brain barrier (which can have a laxative effect), and types that do cross well into the blood-brain barrier (which have a calming effect). >>>Watch for our upcoming blog post about different magnesium compounds.
It is important for you to arm yourself with knowledge and learn why
you are taking certain supplements or medications, and how they work in the body.
The Doctor Emi Team
1. Bates M. The Blood-Brain Barrier. 2 July 2014 | Review Date: 2 July 2014. BrainFacts.org - Neuroanatomy. Accessed September 13, 2016. (BrainFacts)
2. Dash P. Blood-brain Barrier Maintains the Constancy of the Brain's Internal Environment. Chapter 11: Blood Brain Barrier and Cerebral Metabolism. Neuroscience. The University of Texas. Accessed September 13, 2016. (UTH)
3. Butt AM, Jones HC, Abbott NJ. Electrical resistance across the blood-brain barrier in anaesthetized rats: a developmental study. J Physiol. 1990 Oct;429:47-62. PMID: 2277354 PMCID: PMC1181686. Accessed September 13, 2016. (PubMed)
4. Lippmann E, Azarin S, Kay J, et al. Human Blood-Brain Barrier Endothelial Cells Derived from Pluripotent Stem Cells. Nat Biotechnol. Author manuscript; available in PMC 2013 Feb 1. Published in final edited form as:Nat Biotechnol. 2012 Aug; 30(8): 783–791. doi: 10.1038/nbt.2247 Accessed September 13, 2016.(PMC)
5. de Vries H, Kuiper J, de Boer A, Van Berkel T, Breimer D. The blood-brain barrier in neuroinflammatory diseases. Pharmacol Rev. 1997 Jun;49(2):143-55. PMID: 9228664. Accessed September 13, 2016. (PubMed)
6. Chudler Eric. The Blood Brain Barrier ("Keep Out"). Neuroscience For Kids. 2015. Last updated September 8, 2016. Accessed September 13, 2016. (WashingtonEdu)