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The Top Causes of Brain Fog

I’ve never seen a client whose primary health concern was brain fog in and of itself, however, this is one of the most common secondary complaints I encounter. This is because there are so many connections between the gut, brain and immune system, that health challenges in one or all of these components will almost always have a deleterious impact on brain function.

So, if brain fog is right up there with other symptoms you are struggling with, you may want to consider the following underlying factors:

1. Thyroid hormone imbalances.

Having imbalanced thyroid hormones can set you up for an inflammatory-immune response which can induce inflammation in the brain, eventually leading to brain fog. Typically the thyroid gets out of whack when the hypothalamic-pituitary-adrenal (HPA) axis is imbalanced.

2. Adrenal imbalances.

Adrenal imbalances (sometimes referred to as “adrenal fatigue) can occur when your HPA axis and circadian rhythm are disrupted, causing unusually high levels of the stress hormone cortisol, or unusually low levels of this hormone. Because of the brain-hormone relationship, brain fog can be both a cause and a symptom of adrenal fatigue.

3. Hidden gut infections.

Gut microbiome imbalances, whether bacterial in nature, such as Small Intestinal Bacterial Overgrowth, or parasitic infections, will lead to malabsorption of vitamins, inflammation and immune dysregulation. Vitamin deficiencies and inflammation in the gut will always have an impact on brain function via vagus nerve function and the gut-brain axis.

4. Leaky gut syndrome.

Gut infections are often connected to and contribute to leaky gut, a condition where spaces between the tight junctions of the small intestine’s epithelial lining remain open and allow unwanted substances into the bloodstream. Having leaky gut syndrome raises your risk of developing leaky brain syndrome. With leaky gut, bacterial toxins from the gut know as lipopolysaccaharide (LPS) leak into the blood stream where they circulate around the body and induce an inflammatory response, including in the brain.

5. Candida overgrowth.

An overgrowth of yeast in the microbiome, particularly yeasts of the candida genus, raises inflammatory cells which can lead to excessive inflammation in the body and brain. Candida overgrowth can happen because of a diet high in sugar or processed and refined carbohydrates. It is also common in individuals who have had multiple rounds of antibiotics or frequent steroid use. Candida overgrowth is also very common in conjunction with mold toxicity.

6. Histamine intolerance.

Histamine intolerance occurs when the body fails to effectively break down the inflammatory chemical histamine (produced when mast cells in the gut break down) or overreacts to its presence, resulting in the production of superoxide - a dangerous free radical that causes a lot of inflammatory damage to the brain.

7. Poor sleep.

Sleep deprivation reduces the anti-inflammatory antioxidant glutathione, increasing oxidative stress in certain parts of the brain which ultimately can result in brain fog.

8. Methylation impairments.

Methylation is a biological process that’s essential for the health and purification of your organs, including your brain. Many people have genetic methylation mutations that make them poor detoxifiers, increasing the chance of systemic inflammation. Toxic exposure, infections, stress, and other adverse impacts on the body can “turn on” the sub-optimal expression of these methylation genes.

9. Mitochondria dysfunction.

Mitochondria are cell organelles that provide a majority of the chemical energy required to fuel your cell's metabolic activities. However, because the mitochondrial genome is exposed to oxidative stress through lifestyle and environmental factors, we tend to notice a steady reduction in the health of the mitochondrial genome as we age. Brain fog and excessive fatigue are common symptoms in practically every chronic disease that are associated with decreased mitochondrial function.

So now what can you do about your brain fog?

The number one step is to work with a functional medicine practitioner to assess for and overcome the above root causes. Schedule your free 15 minute discovery call to see how I can help you:

In the meantime, you can implement these 7 lifestyle changes to begin supporting your brain at home.

Reduce inflammation.

Inflammation is at the root of all disease. There are a variety of natural approaches to reduce your inflammation levels, including spices such as turmeric, and replacing inflammatory processed foods with nutrient-dense whole foods.

Heal your gut.

Your gut and brain are intrinsically linked. Introduce bone broth and probiotic-rich fermented foods into your diet - they will feed your microbiome with healthy bacteria to start your healing journey.

Try herbs.

The central nervous system (consisting of the brain and spinal cord) can be brought back into balance by adaptogenic herbs. Holy basil is especially good for brain fog since it can improve cognitive function and also helps to regulate and normalize cortisol levels.

Get enough vitamin D.

Low levels of vitamin D can raise your risk of a poor memory and brain fog. The most bioavailable source is sunlight, but if you live somewhere with harsh winters make sure you’re eating foods such as salmon, tuna, and mackerel and supplementing as needed. I always recommend taking a high quality vitamin D supplement, no matter where you live. My favorite is Bio D Mulsion Forte by Biotics Research. This form of vitamin d is administered inside the lower lip, liposomally, where it can get right into the bloodstream via the capillary beds in the mouth.

Avoid toxins as best you can.

This includes eating organic, using natural personal care products, and using plants as medicine. This tip will also aid you in healing your gut.

Get 7-8 hours of sleep per night.

Our mental clarity depends on how well we sleep. If you’re missing out on all important 💤‘s, you might find your brain feeling cloudy the next day as oxidative stress will have increased in the hypothalamus region.

Supplement with essential nutrients

B Vitamins

B vitamins are essential for methylation (an important biological process involving your genes), thus consuming activated B vitamins like B9 L-Methylfolate (L-5-MTHF) and B6 Pyridoxal-5-Phosphate (P5P) can help.

B vitamins aid in the production of neurotransmitters which function as chemical messengers and allow the brain to interact with other neurons throughout the body. B vitamins are also necessary for energy generation, so if you're feeling tired, it's possible you're deficient. Food sources of B-vitamins include:

  • Brown rice

  • Black beans

  • Eggs

  • Fish

  • And lean meats

My favorite B-complex supplement is Liposomal Methy B-Complex

Omega-3 fatty acids.

Omega-3’s are ideal for brain health since they have anti-inflammatory and neuroprotective effects. Cognitive decline can actually form as a result of elevated levels of inflammation, so eating anti-inflammatory foods is key. You can find omega-3’s in:

  • Fatty fish

  • Flaxseeds

  • Chia seeds

  • Walnuts

  • And algae oils

My favorite high quality Omega-3 supplement isis Mega Omega. You can order this here:


Magnesium is beneficial to the brain since it can promote a restful night's sleep (key for brain health). Magnesium also improves the efficiency of our brain's higher executive processes, allowing us to think more creatively and flexibly. Good sources of magnesium include:

  • Spinach

  • Almonds

  • Dark chocolate

  • Edamame

  • And banana

My favorite form of magnesium to support the brain is Acti-Mag Plus.


Probiotics (aka beneficial gut bacteria) are one of the best nutrients for brain health since everything that improves the gut can also improve the brain. Studies have proven that probiotics can also enhance your mood! Foods high in probiotics include:

  • Yogurt (if you’re not sensitive to dairy)

  • Tempeh

  • Miso

  • Kimchi

  • And sauerkraut

My favorite probiotic supplement is Megasporebiotic.

Know someone who’s been struggling with brain fog? Send this article to them!

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