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. Nutrients get through, toxins and pathogens do not. Leaky gut describes the failure of this vetting process. But what about “leaky brain”?
A 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 the 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.
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. A leaky BBB means the floodgates are open for all manner of unpleasantries to enter the brain.
Some pathogens even wield chemical weaponry that blasts open the blood-brain barrier, giving them—and anything else in the vicinity—access to the brain. To prepare for that, you must support the integrity of your blood-brain barrier.
Review this post and make sure you’re getting the B vitamins you need. Primal folks tend to overlook them.
Nourish your gut
A leaky gut accompanies, and maybe causes, a leaky brain. Funny how that works, eh?
It’s a rodent study, but it’s quite illustrative: a fecal transplant from healthy mice with pristine BBB integrity to unhealthy mice with leaky BBB and pathogen-filled guts restored the integrity of the blood-brain barrier.
This is yet another reason to eat enough magnesium-rich foods (like spinach, almonds, blackstrap molasses, winter squash), drink magnesium-rich mineral water (I love Gerolsteiner, but you can also just go down to the local Euro food market and check the labels for high-Mg waters), or take a good magnesium supplement (anything ending in “-ate” like magnesium glycinate or citrate).
Except wait: The remaining 60% of calories was split up between white sugar, wheat starch, casein, and dextrin (PDF). So this isn’t the type of 40% SFA diet you folks are eating.
Except wait again: Adding in either aged garlic extract, alpha lipoic acid (ALA), niacin, or nicotinamide completely abolished the increase in permeability.
It looks like a refined diet high in saturated fat and sugar/starch and absent any phytonutrient-rich plant foods like garlic or antioxidant supplements like ALA will cause elevated BBB permeability (in rodents). I’m not sure I’d recommend a 40% SFA diet either way, however. Balance is probably better.
Use phytonutrient-rich plants and spices
Recall the study from the last section where some garlic extract was enough to eliminate the bad BBB effects of a refined lab diet. That’s because aged garlic extract is particularly rich in phytonutrients with strong antioxidant effects. What about other fruits, vegetables, and spices with different phytonutrients—do those also help BBB function?
Alcohol is a tough one. While I just wrote a big post explaining the merits of wine consumption, ethanol is undoubtedly a poison in high doses, and I derived real benefits when I gave it up for a few months. One way alcohol exerts its negative effects is by inducing BBB dysfunction. This allows both the pleasant effects of alcohol (low-dose ethanol migrating across the BBB and directly interacting with neurons, triggering endorphins and interacting with GABA receptors) and the negative effects (high-dose ethanol migrating across the BBB to damage the neurons, leaving the door open long enough for immune cells to sneak in and cause all sorts of trouble).
Stimulate your vagal nerve
After a traumatic brain injury or stroke, the resultant increase in BBB permeability floods the brain with inflammatory cytokines, causes swelling and neuronal death, and worsens the prognosis. Stimulating the vagal nerve after such an injury decreases the BBB permeability and improves the prognosis.
One treatment for epilepsy is to wear vagal nerve stimulators which send light electronic pulses to the nerve, akin to a pacemaker for the brain. Easier options include humming, cold water exposure (even just splashing the face can help), singing, chanting, meditating, deep breathing, coughing, moving your bowels (or summoning the same abdominal pressure required for said movement; girding your core for a heavy squat or deadlift should also work along the same lines), and many more.
Perhaps an entire post on the vagal nerve is in order. It’s an interesting area that impacts more than just the BBB.
So, never eat? No. But make sure to feel actual hunger. It’s the best spice, and it confers a whole host of other benefits, including better blood-brain barrier function. Heck, try intermittent fasting for the ultimate boost to ghrelin.
You might notice that a lot of the studies I cite involve traumatic brain injuries to rodents. Dropping a weight on a rat’s head or triggering a stroke in a mouse are two of the most reliable ways to induce BBB permeability. Brain injuries are also quite common in humans, and the BBB permeability that results is a major therapeutic target, but we can’t study it so easily in people. While acute and chronic BBB permeability are different beasts, and mice are not men, they operate along the same rough pathway.
That’s about it for today, folks. I hope you feel encouraged and able to fortify your blood-brain barrier. Don’t wait for cognitive decline to set in. Get started now.
How do you improve the integrity of your blood-brain barrier? Have you even considered it prior to today?
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.