The following Mark's Daily Apple article was written by Mark Sisson,

and is narrated by Tina Lehman.

Why the blood-brain barrier is so critical and how to maintain it.

You all know about intestinal permeability, or leaky gut.

The job of the gut lining is to be selectively permeable,

allowing helpful things passage into the body and preventing harmful things from getting in.

Leaky gut describes the failure of this vetting process. But what about

leaky brain? The similarly dynamic barrier lies between the brain and the rest of the body,

the blood-brain barrier. Since the brain is the seat of all conscious machinations and

subconscious processes that comprise human existence, anything attempting

entry receives severe scrutiny.

We want to admit glucose, amino acids, fat-soluble nutrients, and ketones.

We want to reject toxins, pathogens, and errant immune cells.

Think of the blood-brain barrier like the cordon of guards,

keeping the drunken rabble from spilling over into the VIP room in a nightclub. The blood-brain barrier,

or BBB, can get leaky, just like the gut lining. This is bad. A compromised BBB has been

implicated in many neurodegenerative diseases,

like Alzheimer's, Parkinson's, and vascular dementia.

More generally, the BBB regulates passage of inflammatory cytokines into the brain,

prevents fluctuations in serum composition from affecting brain levels,

and protects against environmental

toxins and infectious pathogens from reaching the brain.

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