The fight for your brain begins in your gut

It was a whole different world back when I wrote my book, Boost Your Health with Bacteria.

Back then, the idea that your gut was your body’s second brain was still considered fringe—despite being one of the most basic tenets of holistic medicine. And it would be years before the Human Microbiome Project—a five-year initiative launched by the National Institutes of Health in 2008—would begin.

Today, thanks in large part to that project’s findings, even mainstream doctors are starting to recognize the expansive role that your gut bacteria play in just about every facet of your health.

And believe it or not, that includes a potentially powerful role in protecting your actual brain.

In fact, the latest research on this subject reveals even more promise against the increasing threat of Alzheimer’s disease than the drug industry has even come close to achieving.

Your microbiome matters to your memory

Given the role that gut bacteria play in strengthening your intestinal barrier and modulating your immunity, this news isn’t all that surprising. But recent studies really drive the point home—and swing the doors to potential new treatments wide open.

For example, in 2017, Swedish researchers published a study showing that intestinal bacteria can fast-forward the development of Alzheimer’s disease in mice. They found that mice with Alzheimer’s have a completely different composition of gut bacteria compared to healthy mice.

But that’s not all…

When the researchers transferred intestinal bacteria from mice with Alzheimer’s to healthy mice, they observed that the healthy mice developed significantly more beta-amyloid plaques (a peptide with strong links to dementia) in their brains… suggesting a direct causal link between gut bacteria and dementia.1

Now granted, these findings were in mice. But observational research has discovered similar connections in human subjects, too.

Another study published in 2017 found notably decreased microbial diversity in fecal samples from Alzheimer’s patients, compared to healthy, age-matched peers.2 And subsequent research has confirmed those findings.

In fact, similar findings were presented at the 2019 International Stroke Conference. Japanese researchers analyzed 128 fecal samples and discovered a number of key differences between the microbiota of patients with dementia versus those without cognitive decline. Specifically, they found higher concentrations of metabolites including ammonia, indole, skatole, and phenol—and lower levels of beneficial Bacteroides—in dementia patients.3

So, what does this mean? Well, it doesn’t necessarily prove that gut dysbiosis causes cognitive decline. But it pretty clearly establishes your microbiome as a key contributing factor.

That’s because your body relies on your gut’s bacteria to break down important brain-building substances, like omega-3 fatty acids. But your body also needs to be able to use these healthy fats to fortify your brain—and it can’t do that without a healthy, balanced microbiome.

Unfortunately, bacterial dysbiosis also weakens the gut’s lining—leading to what we call “leaky gut.” And when your guts springs a leak, your brain is all but doomed to follow…

How a leaky gut leads to a leaky brain

The technical name for leaky gut is “intestinal permeability,” and it occurs when the junctions that control what can pass through the small intestine’s lining don’t work properly. This leads to substances that are meant to be excreted (like waste, toxins, and food particles) passing into the bloodstream.

Then, the substances that escape through a leaky gut are targeted as foreign invaders by your immune system. So it attacks them just as it would any other threat—by triggering inflammation throughout your entire body.

This systemic inflammation can, of course, have particularly dire consequences for your brain.

But to really understand the link between leaky gut and Alzheimer’s, we have to consider microcirculation. (The network of tiny blood vessels and capillaries that deliver oxygen and nutrients to the smallest areas of your body, including your brain.)

In your brain, these tiny capillaries are lined with specialized endothelial cells that make up the blood-brain barrier. This barrier acts as a sort of filter—allowing essential nutrients, glucose, and oxygen into the brain while keeping harmful chemicals out.

Your brain uses as much as 80 percent of the oxygen and glucose in your body to operate. But it’s also extremely vulnerable to any potential threats, which is why the barrier needs to be nearly impermeable.

The trouble is, research shows that systemic inflammation—like the kind that results from “leaky gut”—can compromise the blood-brain barrier, too.4-5

A “leaky” blood-brain barrier is what allows damaging compounds to enter the brain and trigger inflammation. And brain inflammation is a driving force behind Alzheimer’s-related cognitive decline—leading to greater neuron death and more rapid development of symptoms.

Often, this damage starts in the hippocampus—the area of the brain critical to memory and learning, and one of the parts of the brain most affected by dementia.

Protection starts with probiotics

So now that we’ve established the vital link between your microbiome and your memory, let’s start talking about what you can do—starting today—to protect both. And as you may have already guessed, that starts with a top-shelf probiotic supplement.

Sure, this is an obvious choice for gut health. But you simply cannot afford to skip it for your brain’s sake, either.

In fact, a recent randomized, double-blind, placebo-controlled clinical trial showed that probiotics can actually boost cognitive function in human subjects.

Researchers recruited 52 older men and women with Alzheimer’s, all between the ages of 60 and 95 years. Half of the patients received a daily serving of milk enriched with four different probiotic bacterial strains—Lactobacillus acidophilus, L. casei, L. fermentum, and Bifidobacterium bifidum—for 12 weeks. The other half received untreated milk.

Results over the course of the study showed that, among the group taking probiotics, Mini-Mental State Examination (MMSE) scores—a standard measure of cognitive function—jumped significantly. Meanwhile, among the control group, these scores actually dropped, slightly.6

Of course, as a lifelong advocate for probiotics, two things about this clinical study stood out to me.

The first is that it featured a supplement containing multiple, live strains of good bacteria. This is important because, when it comes to probiotics, more isn’t necessarily better. The key is diversity of strains over quantity.

Beyond that, a good probiotic should also have its own food supply (known as prebiotics) and postbiotics (such as bacteriocins) to help to kill off the bad bugs in your gut.

That’s why I have always recommended finding a product that checks all of these boxes. In other words, one that features different strains of friendly flora—along with prebiotics, probiotics, and postbiotics.

But the second thing that caught my eye is that this study included one specific strain of good bacteria, in particular…

Double down your defenses

I’ve mentioned the unique benefits of the probiotic strain Lactobacillus fermentum ME-3 before, but it’s worth highlighting them again, since the study I mentioned above included it.

First, it’s an excellent antimicrobial that can effectively kill off pathogens and other harmful bacteria that enter the gut. Second, it helps boost your body’s production of glutathione—a critical antioxidant that declines dramatically with age.

And glutathione happens to be of particular importance for anyone seeking to ward off Alzheimer’s…

That’s because glutathione provides your brain with powerful natural protection against oxidative stress and free radical damage. And it just so happens that patients with Alzheimer’s suffer from significantly lower levels of this crucial antioxidant.

At least, that was the finding of one recent groundbreaking human study. Researchers used imaging to reveal that low levels of glutathione in the hippocampus can lead to mild cognitive impairment—which represents the earliest stage of Alzheimer’s disease.7

This finding suggests that routine screening for low glutathione levels in the hippocampus could give doctors insight into which patients’ brains are at risk—and allow them to supplement with glutathione in an effort to stall disease progression.

Researchers have also discovered that Lacotbacillus fermentum generates glutathione naturally in your gut. Which means there’s finally an easy way to boost your glutathione levels—simply by taking this probiotic strain in supplement form. Unfortunately, it’s difficult to find it as part of a multi-strain formula, so I recommend taking it on its own, alongside your daily probiotic.

Your diet makes all the difference

Of course, while I am an advocate for smart supplementation, diet is still always a critical component—especially when it comes to your microbiome, as I also discuss on page 3.

Now, I’ve written before about the brain benefits of the Mediterranean diet. This type of diet is rich in fish, fresh produce, and healthy fats (like nuts and olive oil)—and it’s one of the simplest ways to ward off dementia.

But I’ve also shared research showing that ketogenic diets are uniquely powerful against Alzheimer’s disease. In fact, one recent pilot study found that patients with mild Alzheimer’s saw significant cognitive improvements—more than any drug can currently offer—simply by sticking closely to a ketogenic diet.8

Better yet, I recently came across a rare bit of research that combined both of these subjects—diet and microbiome—into one single report. And it vindicated my entire career’s work in one fell swoop…

This was a small but well-designed pilot study—randomized, double-blind, and featuring only 17 older adults. Eleven participants were diagnosed with cognitive impairment, and six held normal cognitive function.

Researchers assigned subjects to follow a low-carb, Mediterranean-style, ketogenic diet, or a low-fat, higher-carb diet for six weeks. After that, subjects would switch to the opposite diet.

And here’s where things got interesting: Before and after each six-week diet, researchers analyzed subjects’ gut microbiome, and measured both fecal short-chain fatty acids and Alzheimer’s markers (like amyloid and tau proteins) in cerebrospinal fluid.

Unsurprisingly, they found that patients with cognitive impairment had a number of distinct chemical features in their microbiome—or “bacterial signatures,” as they’re called—compared to their healthy counterparts. And those features were also associated with higher levels of Alzheimer’s markers.

But get this: Results over the course of the study showed that, when subjects followed a low-carb, Mediterranean-style, ketogenic diet, it altered the microbiome—including these distinct bacterial signatures—in a way that correlated with lower levels of Alzheimer’s markers in both groups.

And this, folks, is exactly why good nutrition is—and always will be—the cornerstone of my Alzheimer’s prevention protocol.

For additional ways to naturally protect and restore memory, strengthen focus, and fight dementia, I encourage you to check out my Alzheimer’s Prevention and Treatment Plan. To learn more about this comprehensive online learning tool, or to enroll today, click here or call 1-866-747-9421 and ask for order code EOV3WA00.


  1. Harach T et al. “Reduction of Abeta amyloid pathology in APPPS1 transgenic mice in the absence of gut microbiota.” Scientific Reports, 2017; 7: 41802.
  2. Vogt NM, et al. “Gut microbiome alterations in Alzheimer’s disease.” Sci Rep. 2017; 7: 13537.
  3. American Heart Association. “‘Bugs’ in the gut might predict dementia in the brain.” Science Daily, 01/30/2019. (
  4. Kowalski K, et al. “Brain-Gut-Microbiota Axis in Alzheimer’s Disease.” J Neurogastroenterol Motil. 2019 Jan 31;25(1):48-60.
  5. Jiang C, et al. “The Gut Microbiota and Alzheimer’s Disease.” J Alzheimers Dis. 2017;58(1):1-15.
  6. Akbari E, et al. “Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer’s Disease: A Randomized, Double-Blind and Controlled Trial.” Frontiers in Aging Neuroscience, 2016; 8 DOI: 10.3389/fnagi.2016.00256
  7. Shukla D, et al. “A Multi-Center Study on Human Brain Glutathione Conformation using Magnetic Resonance Spectroscopy.” Journal of Alzheimer’s Disease, 2018; 1 DOI: 10.3233/JAD-180648
  8. Alzheimer’s Association International Conference (AAIC) 2017. Abstract F3-04-02.
  9. Nagpal R, et al. “Modified Mediterranean-ketogenic diet modulates gut microbiome and short-chain fatty acids in association with Alzheimer’s disease markers in subjects with mild cognitive impairment.” EBioMedicine, 2019; DOI: 10.1016/j.ebiom.2019.08.032