How Gut Bacteria Control Your Mind


You have trillions of bacteria living in your GI tract, and the little buggers are constantly at war. Competing species battle for space. Colonies stake out territory, fighting off invaders. Some strains grow out of control; others go extinct.

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This bacterial balancing act determines a great deal about your biology. We’ve known for a while that your gut biome affects your metabolism, skin, digestion, and weight. In the past few years, researchers have discovered your gut bacteria dabble in mind control, too. Your gut and brain are in constant contact thanks to a pathway called the gut-brain axis. Some bacteria make neurotransmitters, directly influencing your brain activity – for better or worse, depending on the bacteria.

Here’s how you can control your gut flora to improve everything from mood to motivation.


Get dirty to boost your mood and hack inflammation

No, not that kind of dirty (although hacking your sex life can be a great mood-booster, too).

Researchers have developed a theory called the Hygiene Hypothesis. Basically, it says our lives have become too sanitary. Washing your hands after everything you do may actually weaken your immune system, and showering daily rinses beneficial bacteria off your skin.

It’s better to be a bit dirty, which isn’t surprising when you consider that we haven’t evolved with antibacterial soap. Simply coming into contact with dirt can do a great deal for you. People with lung cancer exposed to Mycobacterium vaccae, a common soil bacterium, reported significant increases in quality of life [1]. Healthy mice fed the same strain ran a maze twice as quickly and showed less anxious behavior [2].

It’ll also diversify your gut. A more diverse gut biome links to higher blood tryptophan levels in humans [3]. Tryptophan turns into serotonin, the same mood-controlling neurotransmitter antidepressants target. No surprise that mice raised in a germ-free environment are more likely to be depressed, and mice given gut bacteria from depressed humans get blue as well [3].

So tend a garden, walk through a forest barefoot, rock climb, or roll around in a field. Getting your hands dirty once in a while could make you happier. Oh, and bring your kid with you, too. Children exposed to more dirt, dust, animals, and bacteria are less likely to develop asthma and inflammatory issues later in life [4,5].

Skip the antibiotics

Antibiotics demolish your gut biome. They kill off infections, but they wipe out all the good stuff while they do it, ruining the delicate balance in your gut. A single course of antibiotics substantially increases your risk of depression and anxiety, and taking more antibiotics after that makes the risk higher [3,6]. Worse yet, the symptoms can last for months while your biome rebalances. Antibiotics can trigger systemic inflammation [7], and in mice they decrease brain cell growth in the hippocampus, the part of your brain that controls memory [8]. Antibiotics also open your gut up to yeast and fungi, which can lead to issues like candida [9]. Not good, unless you’re in a serious emergency.

Here are 5 strong antimicrobials you can use instead of antibiotics:

  • Coconut oil
  • Oregano oil (or pure carvacrol, the active ingredient in oregano oil)
  • Tea tree oil
  • Grapefruit seed extract
  • Neem

And if you do decide to take antibiotics, add a probiotic alongside them and for a month afterward to repopulate your gut faster. It’s difficult to recommend a brand because everyone’s gut is so different; experiment and find a probiotic that works for you.


Feed your gut the right fuel to grow new brain cells

Cutting out sugar is probably the fastest, most powerful way to improve your gut biome. A number of bad bacteria and yeasts ferment sugar and use it for fuel. Eating sugar regularly can lead to serious imbalances like small intestinal bacterial overgrowth (SIBO) and Candida (a type of yeast infection), both of which trigger brain-damaging inflammation, and in rats, a high-sugar diet slowed growth of new brain cells [3].

Instead, get plenty of foods that support a strong, balanced gut. Here are a few options:

  • Prebiotic fiber feeds your good gut bacteria and causes longer-lasting change than you’ll get taking probiotics [3,11]. Raw jicama, raw asparagus, jerusalem artichoke syrup, and underripe bananas all contain lots of prebiotic fiber.
  • Green veggies are high in fiber and polyphenols that feed good bacteria and decrease inflammation [11]. Broccoli and cauliflower contain sulforaphanes that make you grow new brain cells [12].
  • Resistant starch can also provide the good guys with fuel, although not everyone tolerates it well. You may get indigestion. Raw potato starch and plantain starch are good sources of resistant starch.
  • Butyrate turns into short-chain fatty acids good bacteria can use for energy. Grass-fed butter is full of it. Grass-fed ghee has even more.
  • Brain Octane Oil and coconut oil are strong antibacterials, antivirals, and antifungals.
  • Coffee is full of polyphenols that fuel good bacteria and suppress bad ones [11]. Bulletproof Coffee has butyrate, antimicrobial compounds, and polyphenols all in one place.

What you eat significantly changes your gut bacteria within days [13], making diet the most powerful way to create a resilient gut biome.The Bulletproof Diet Roadmap (download it for free!) is a great way to balance your gut and enhance your cognitive performance. You might lose a few pounds, too.

If you want to learn more about your gut, check out hacking your microbiome to burn more fat and increase your energy. You can also subscribe below for more ways to improve your biology. Thanks for reading and have a great week!


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