Brain fog: explained

The inability to concentrate, lack of focus and poor mental clarity – what do they all have in common? These are all typical signs of brain fog, which can have a huge impact on how you think, feel and perform each day.

Cells and mitochondria

What is brain fog?

Brain fog is typically characterized by poor concentration, trouble focusing, the inability to problem solve and that ‘fuzzy head’ feeling. It dates back to the early 1800s, when physician Georg Greiner used the words “clouding of consciousness” and “fogging of the light of reason” to articulate the cognitive side-effects of different ailments. Since then, brain fog has been used to describe ‘sluggish thinking’ - which seems to have become a post-pandemic, global phenomenon. But let’s get one thing straight - brain fog isn’t a scientific term. It’s a phrase used to describe what is often related to a deeper issue – and in fact, it’s tied to many underlying health conditions.

People have been using brain fog to describe a host of cognitive symptoms that come with a wide variety of different medical issues for a very long time.
Anna Nordvig Neurologist at Weill Cornell Medicine, New York

What scientists do know is that this common sensation is just a passing feeling, but if you are experiencing brain fog on a regular basis – that's when it becomes an issue. The good news? By identifying some of the key root causes, you can take the necessary steps to help kick brain fog to the curb.

Common causes of brain fog

Overactive HPA-axis

The hypothalamic-pituitary-adrenal axis (HPA axis) is an elegant system that allows sensory information to be passed from the brain to the adrenal glands, regulating how our body responds to stress. Everyone’s stress response is different, based on previous life experiences and social, environmental, and psychological factors.

When we perceive stress, be it an unwanted phone call, a delayed flight, or an approaching work deadline, the hypothalamus in the brain activates the HPA axis, stimulating the adrenal glands to produce adrenaline and cortisol. The release of these stress hormones triggers the fight-or-flight response in the body if we encounter stressful/threatening situations. This response prepares us to either flee the situation or fight by giving the body a sense of hyper-awareness and an energy boost, often described as an “adrenaline rush”. Evolutionarily, this would have kept us safe from predators and violence, but in the modern world, this response can be triggered by situations that aren’t quite so dangerous.

If you’re experiencing constant or prolonged stress, this response will naturally be triggered more frequently. When you’re exposed to constant stress, the stress response becomes overactive and the HPA axis becomes misaligned. What this means for you is that your body is struggling to keep up with an increased stress load, and you may feel like you’re burning the candle at both ends.

Signs that your HPA axis might need some support:

  • Brain fog
  • Feeling tired but wired
  • Low energy
  • Blood sugar imbalances / cravings
  • Poor sleep
  • Dependency on stimulants to function (caffeine)

Support your stress response with MitoQ adrenal +balance

Your diet is lacking in cognitive-boosting nutrients

Common nutrient deficiencies that have been associated with brain fog include:


Almost 50% of Americans are deficient in magnesium, and as a mineral that’s depleted by stress – it's not difficult to assume why. On top of this, the combination of food processing techniques and the poor quality of our soil means that getting ahead of your daily magnesium intake can be a tricky task. Along with being a key factor that contributes to fatigue, a deficiency in magnesium has also been linked to poor cognitive performance, and poor sleep.


This vitamin is closely linked to the nervous system and supporting cognitive function. It’s also involved in the production of red blood cells, which are crucial for normal brain function and cognition.


Choline has been shown to support neurological function in many ways. It’s required to synthesize acetylcholine, a neurotransmitter that plays a role in memory, attention and learning. It also makes up a component of cell membranes, supporting the structural integrity and signaling of brain cells.


Iron deficiency is directly linked to poor cognitive function. It’s been shown that low levels of iron can compromise cognitive development, attention and memory.

Vitamin D

This vitamin (which actually works within the body more like a hormone) plays an important role in brain function and mental health. Studies have also shown that people with higher concentrations of vitamin D in their brains are associated with improved cognitive function.

Gut imbalances

The gut is commonly known as the ‘second brain’ which gives you an idea of how connected these two parts of the body really are. The gut-brain axis describes the connection between – you guessed it – the gut and the brain. This two-way communication system means that the gut and brain are constantly sending information back and forth to one another, in order to regulate the body in all sorts of ways. Because they’re so closely connected, any imbalances in the gut can directly influence the brain, and vice versa.

Neurons are cells that are responsible for carrying/communicating information between brain cells, and there are around 100 million neurons found within the gut! These neurons are thought to generate as much dopamine as the neurons in the brain – and even more serotonin. These neurotransmitters are responsible for regulating a range of brain functions, so any imbalances or deficiencies may impact brain function.

In the last few decades, researchers have also identified that brain fog may be linked to imbalances in the gut. The gut microbiome – the colony of commensal bacteria that live inside the gut – has been shown to directly contribute to brain function and cognition. The gut microbiome is so complex and diverse that any imbalances within this bustling colony can not only impact the way we digest and assimilate nutrients from the food we eat – but it can also disrupt the function of our hormones and neurotransmitters.

While it’s true that ‘you are what you eat’, when it comes to the gut microbiome - a more accurate phrase might be ‘you are what you absorb’. A balanced and healthy gut is crucial for nutrient synthesis and absorption, and if the gut microbiome is imbalanced, any efforts to increase all of those cognitive-boosting nutrients will be ineffective. If the gut isn’t able to successfully break down and utilize nutrients, our neurotransmitters, hormones and other critical chemical messengers may struggle to receive the nutrients they need to communicate with the brain and function optimally.

Oxidative stress

The creation of energy produces waste products called free radicals, which can cause damage to our cells if they are not neutralized by antioxidants. Oxidative stress is the state our body is put in when the levels of antioxidants in our body are not high enough to counteract the damaging effect of free radicals. Emerging research suggests that increased oxidative stress can cause damage to our body at a cellular level that can impact our cognitive function.

Oxidative stress can trigger an inflammatory cascade, influencing areas of the brain like the cortex, hippocampus and striatum which play a major role in learning and memory. The best way to support the reduction of free radicals and help reduce oxidative stress is to increase your dietary intake of antioxidants like glutathione and CoQ10. MitoQ is an advanced form of CoQ10 that is taken up directly by the mitochondria of the cell, replenishing antioxidant reserves right at the site of many biochemical reactions, helping to support the reduction of oxidative stress.

Learn how MitoQ supports oxidative stress

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