I remember truly experiencing the power of the gut-brain connection when I got salmonella for the first time.
After eight days of sleeping in the bathroom and a lengthy hospital visit, it was time to start catching up on work. As I responded to emails and crossed tasks off my to-do list, I noticed I was making several unusual random errors.
I created an ad to rent out my apartment, but listed my phone number with the wrong area code. Sentences were taking me longer to read, and I was making odd grammatical errors. I’d stare at a blank screen for hours when I tried to write, and ideas seemed to be coming at a snail’s pace. It felt as though a cloud had engulfed my focus, creativity, and memory— in fact, I can’t tell you how many times I misplaced my cell phone that month.
I couldn’t understand why my brain suddenly seemed to stop working, until finally, I had an ‘Aha!’ moment: these things only began happening right after I had salmonella— a bacterial infection that’d undoubtedly wiped out a good chunk of my healthy gut bacteria— which caused a disruption in the communication between my gut and my brain.
Bacterial conditions like salmonella, and other digestive conditions such as leaky gut and candida, all weaken digestive health and contribute to intestinal inflammation— and therefore, brain fog. But these conditions don’t just manifest out of the blue— so, what causes them in the first place? The answer begins with your diet.
Brain Fog and Gut Health
If you have a hard time focusing, forget simple details, mix up your words and feel scattered or confused, don’t blame it on your brain— blame it on your gut.
Although it’s not an official medical term, brain fog is defined as a loss of mental clarity, difficulty concentrating, and forgetfulness. While these symptoms may describe how you feel before you’ve had your first morning cuppa, brain fog is actually a symptom of a deeper issue: inflammation in your body— in particular, your digestive tract.
That’s right: brain fog isn’t caused by your brain. “Fogginess” and slowed cognitive function is more closely related to digestive conditions such as leaky gut, candida, and bacterial dysbiosis. This is explained by the connection that exists between your gut and nervous system, called the gut-brain axis.
What is the Gut-Brain Axis?
The gut-brain axis (GBA), or gut-brain connection, explains the link that exists between the emotional and cognitive centers of the brain and intestinal function and gut microbiota (your healthy gut bacteria). Picture an old-school tin can telephone: one can represents your gut, the other your brain, and the string that holds them together is the “axis” that provides direct communication between the two.
While the gut-brain axis is obviously far more complex than a tin can telephone, it gives you an idea of just how closely they work together (hence why the gut is referred to as your “second brain”). In fact, studies show weakened gut health and inflammation doesn’t just contribute to brain fog, but is also a primary underlying cause of several mental health conditions, such as depression, anxiety, ADHD, and inflammatory brain conditions such as Alzheimer’s disease and dementia.
The good news is that the gut-brain connection offers the solution for regaining mental clarity: improving your gut health. Sure, a lack of sleep, stress, overeating, and even a caffeine detox can all contribute to temporary brain fog— but at the end of the day, how well your brain functions is primarily influenced by your gut.
The “Silent Killers” Destroying Your Gut and Brain
Gluten-free diets may seem like they surfaced as a health trend, but even those who don’t have Celiac disease (the inability to digest gluten) can benefit from avoiding gluten— especially if you suffer from persistent brain fog. This is because gluten is now being recognized as a major cause of leaky gut syndrome. Let me explain.
First off, your body produces a protein in your digestive tract called zonulin.
Zonulin’s primary function is to moderate the tight junctions between the cells in your digestive tract, which help prevent undigested food particles and pathogens from passing through. While this a good thing, gluten exposure can actually trigger your body to overproduce zonulin. This breaks apart the tight junctions instead.
Over time, this mechanism causes “holes” in your intestinal tract, and allows it to become permeable or “leaky”. This lets undigested food particles pass through your GI tract and into your bloodstream, which is exactly where they don’t belong. This is how we end up with leaky gut.
Now, because these substances aren’t supposed to be in your blood, your body recognizes them as foreign invaders and sounds “warning bells” by eliciting an immune response.
An immune response is meant to help you fight illness and disease (remember: your body sees these food particles as danger), so it causes inflammation— a healing response— throughout your body and digestive tract. Based on what we know about the gut-brain axis, it’s no wonder brain fog is also nicknamed “leaky brain”!
What to Eat Instead: Gluten-free grains such as brown rice, quinoa (which is actually more of a seed) and buckwheat, or grain-free flours like coconut flour, almond flour and chickpea flour.
Bone broth is also one of the best foods to add to your diet for healing leaky gut, and improving overall digestive health. This is because bone broth is rich in collagen and gelatin, two proteins that help heal and seal the gut lining, as well as glycine, an amino acid with powerful anti-inflammatory properties.
Note: Gluten isn’t only found in grains, which makes it trickier to avoid if you don’t know what else is can hide in. Gluten is found in sauces, condiments, processed deli meats, fake crab meat in sushi, and even shampoo (which can be absorbed into your body through your scalp), so reading labels is necessary when it comes to avoiding gluten.
If there’s one food that’s like a slow poison to your gut, it’s processed carbs— which includes anything made with white flour or refined sugar.
Table sugar, muffins, pastries, simple syrup, pizza dough, bread, soda, candy, alcohol, and pretty much any food found in a box, package or drive-thru will contain some form of refined carbohydrate.
Refined sugar feeds the bad bacteria in your gut, which allows them to grow and outnumber your good bacteria. If left untreated, this can lead to candida (yeast overgrowth) and bacterial dysbiosis.
Since healthy gut microbes regulate the communication between the gut and brain, when your good bacteria is depleted, you’re more likely to notice cognitive effects, including brain fog.
Since approximately 80% of your immune system cells are found in your gut, a lack of healthy bacteria can also leave you more prone to developing other inflammatory health conditions and autoimmune diseases.
Most refined carbs also contain gluten (and yes— even if processed carbs are gluten-free, they still break down into sugar and feed the bad guys).
What to Eat Instead: Replace refined flour with gluten-free grains or grain-free flours, such as the ones mentioned above. Substitute processed sugar with small amounts of natural sweeteners, such as coconut nectar, pure maple syrup, raw honey, or green leaf stevia.
You get it by now: the primary cause of brain fog is inflammation. Therefore, inflammatory foods can only make brain fog worse.
Inflammatory foods basically include all of the foods found in today’s Western diet: the processed carbs mentioned above, refined vegetable oils such as peanut, soybean, safflower, sunflower, and canola oil, dairy products, factory farmed meats, deep fried foods, and chemical laden foods such as margarine.
While processed foods are by far the most concerning for promoting inflammation, a class of vegetables called nightshades (tomatoes, eggplant, corn, potatoes, bell peppers) can also have mild inflammatory properties according to the Weston A. Price Foundation.
What to Eat Instead: Fruit, vegetables (but consider avoiding those pro-inflammatory nightshades), sea vegetables and leafy greens are nature’s most powerful anti-inflammatory foods (19). Grass-fed meats are also anti-inflammatory, as well as most nuts, seeds, and wild, fatty fish such as salmon.
Other Factors That Can Cause Brain Fog
Hidden Food Allergies / Sensitivities
Your body responds to food allergies and sensitivities with an inflammatory reaction, which has the potential to trigger inflammation in your digestive tract, as well as your brain (20).
The most common food sensitivities are wheat, gluten, dairy, corn, and soy. In fact, it’s estimated that up to 50 million Americans are lactose intolerant (more than the entire population of California) and many don’t even know it.
While it’s best to get an allergy and/or food intolerance test done by a healthcare practitioner to see which foods you may be reacting to, you can start by removing these five for a minimum of three weeks to see if you notice an improvement in your mental focus and clarity.
Food intolerances are tricky because they often have delayed reactions— sometimes up to 36 hours later. Therefore, if you’re sensitive to a certain food, brain fog can show up even if it’s been 3 days since you’ve last eaten it.
You can get tested for true allergies and food sensitivities with an IgG food intolerance blood test, which can be administered by most health care practitioners. If your test results come back with a high number of food intolerances, that’s also a telling sign that leaky gut is present.
Oxidative stress— which is caused by a buildup of toxins— is a primary cause of systemic inflammation. However, explaining how oxidative stress causes inflammation and brain fog (and ironically, how inflammation also causes oxidative stress) could be another blog post entirely. To keep things simple, Dr. Weil sums up oxidative stress nicely:
“Oxidative stress is the total burden placed on organisms by the constant production of free radicals in the normal course of metabolism plus whatever other pressures the environment brings to bear.”
So, what causes oxidative stress?
- Chronic stress
- Refined sugar
- Heavy metals (mercury, lead)
- Environmental toxins
- Chemicals in household cleaning products and body care products
- Sleep deprivation
- Vitamin and mineral deficiencies
- UV rays
- Food sensitivities
Since all of these factors contribute to oxidative stress, they can also be considered as potential underlying causes of brain fog.
As you can see, healing your brain begins by healing your gut and reducing inflammation as much as possible— primarily through your diet and lifestyle. It’s also good to consider regularly eating probiotic foods such as sauerkraut, or taking probiotic supplements to rebalance your natural stores of healthy gut bacteria.
Making changes to your diet and lifestyle is never without its challenges, but once the brain fog starts to go away, you’ll find it incredibly easy and rewarding to stick to your new “healthy gut” habits.