Could Your Gut Be Behind That Brain Fog?

Your gut health influences brain function more than you might think.

(This is the fourth article in a series by gastroenterologist Dr Ashwini Setya, in which he unpacks how lifestyle, environment, diet, and hidden exposures affect your gut health. Read the earlier pieces here, here and here.)

How often have you been at a gathering and struggled to put a name to a familiar face, or suddenly blanked on the model of your own car? When you begin forgetting everyday words, it’s easy to wonder if something is wrong with you.

Only recently—especially after the COVID-19 pandemic—has the term brain fog come into common use and entered medical literature, but this kind of syndrome has been recognised for centuries, though it has been known by different names, such as clouding of consciousness.

What exactly is brain fog, and what does your gut have to do with it? Let's break it down.

The Brain Fog 'Epidemic' and the Gut Connection

Brain fog is not a medical diagnosis but a somewhat concerning feeling that people have, that their brain is behaving like a slow device.

Brain fog may manifest as difficulty focusing or frequent forgetfulness. People may struggle to follow or keep up with conversations. Reaction times can be slow, word choice may suffer, and individuals may find themselves using more words than necessary to express a simple idea.

The concern is that it is now acquiring epidemic proportions.

Why does it happen? There are many reasons behind brain fog. One of the most studied is its possible connection with the gut.

The gut and brain communicate constantly via nerves (especially the vagus nerve), hormones, immune signals, and gut microbes. This network is known as the gut-brain axis.

Changes in gut microbes can lead to an imbalance in the microbial population (dysbiosis), which, along with “leaky gut” (a term used to describe a breach in the integrity of the inner lining of the digestive tract), can allow bacterial toxins to enter the bloodstream, triggering low-grade inflammation.

This systemic inflammation can reach the brain, promote neuroinflammation, and is linked to cognitive problems such as slower thinking and poor concentration—affecting mood, memory, and thinking speed, all key components of brain fog.

Animal and clinical research shows that changes in gut microbiota can worsen or improve cognitive function in conditions such as depression, diabetes, and postoperative cognitive problems.

Other Drivers of Brain Fog

Other factors believed to contribute to brain fog include poor sleep, high stress, nutritional deficiencies, hormonal changes, dehydration, excessive screen time, certain medications, chronic diseases, autoimmune disorders, and long COVID.

Many of these factors are also known to disrupt the gut microbiome, creating a double impact on brain health.

Cognitive decline has also been observed in women during the perimenopausal period, and in men during andropause (male menopause), along with other behavioural changes.

This is due to declining levels of estrogen and testosterone, respectively. These hormones aid glucose utilisation for energy in brain regions involved in decision-making (the prefrontal cortex) and memory (the hippocampus).

Their dwindling levels slow metabolism by affecting neurotransmitters such as dopamine and serotonin. For most people, however, brain fog improves over time as the brain adapts to lower hormone levels.

Environmental pollution also appears to be a major cause of brain fog, according to neuropsychiatrists.

Polluted air, by impairing lung function, disrupts the flow of oxygen to various organs, including the brain, interfering with the body’s ability to maintain a balanced internal environment, or milieu intérieur.

The smog outside thus leads to fogging of the brain. Reduced oxygen supply pushes the brain into survival mode—at the cost of efficiency. It is akin to running a car on adulterated or contaminated fuel.

Can Brain Fog be Fixed?

There is no magic pill. However, lifestyle modification is both essential and effective.

The importance of a balanced, low-sugar, high-fibre, nutritious diet cannot be overemphasised. It plays a crucial role in restoring microbiota balance. Diets rich in omega-3 fatty acids and phytoestrogens—found in foods such as flaxseeds and blueberries—have been shown to improve cognition by mimicking estrogen’s effects on the brain.

Ashwagandha, magnesium L-threonate, and vitamins B6, B12, and folate may help by increasing neurotransmitter levels. Hormone replacement therapy (HRT) for women can also ameliorate symptoms, though its side-effects may make it unsuitable in some cases.

Adequate hydration is critical, as hydration is fundamental to normal brain function.

Though easier said than done, limiting screen time helps in multiple ways. Reducing exposure to blue light before bedtime can improve sleep quality by increasing melatonin, the hormone that induces sleep. It also supports eye health by preventing computer vision syndrome.

Stepping out of air-conditioned offices or homes periodically—even briefly—can help, as many air-conditioned spaces have little or no air exchange, leading to prolonged exposure to stale, low-oxygen air.

Physical exercise like yoga, an outdoor game, or even a 30-minute walk increases brain oxygenation.

Give your mind breaks, whichever way you fancy, like meditation, cultivating some hobbies.

Being socially connected and laughing your guts out probably is the best medicine for this malady.

(Dr (Prof) Ashwini Kumar Setya, MD DM PGDMLE, is a Senior Consultant at Medanta Institute of Digestive & Hepatobiliary Sciences and Holy Family Hospital, New Delhi. This is an opinion piece and the views expressed above are the author’s own. The Quint neither endorses nor is responsible for the same.)