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The 12 things your brain fog can reveal about your health – and when to see a doctor

STRUGGLING to focus? Mind feeling a little hazy? If you’re dealing with brain fog it can be incredibly frustrating. 

It not only stops you from thinking clearly, but it can hinder productivity and make that to-do list just seem never-ending as you struggle to get anything done.

RK5F0J Young fatigued woman having strong headache suffering from chronic migraine
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RK5F0J Young fatigued woman having strong headache suffering from chronic migraineCredit: Alamy

Is there a medical definition of brain fog? Not exactly. 

Jodie Relf, a PCOS Dietician and spokesperson for, who says PCOS can be one potential cause of brain fog, says: “Loosely, brain fog is the feeling of not being as ‘mentally sharp’ as you usually are.

"It affects your ability to focus, memory recall and multi-tasking abilities.”

But what’s could be the driver of your brain fog? And when should you see a doctor?

Read more on brain health

These experts reveal the potential causes of your oh-so annoying brain fog…

1. PCOS 

Polycystic ovarian syndrome (PCOS) affects one in ten women in the UK, making it a common condition. It affects how the ovaries work.

“Health conditions such as PCOS cause low-grade chronic inflammation which would contribute towards this brain fog,” explains Jodie.

“It’s common in those with PCOS to struggle with fatigue, poor concentration and low mood.”

Fix it: There are other symptoms of PCOS to look out for including irregular or absent periods, hirsutism (male pattern hair growth mainly around the chin, chest and back), jawline acne, abdominal weight gain and/or difficulty losing weight. 

Concerned? Book an appointment with your GP.

2. Unhappy gut

Dr Thomas Gurry, co-founder and CEO of explains: “Your gut and brain are in constant conversation. This bi-directional communication highway is known as the gut-brain axis.”

In short, a healthy gut equals a healthy mind, and vice versa.

Dr Gurry says that one of the main determinants of gut health is the diversity and balance of the bacteria it hosts - your gut microbiome.

“A diverse microbiome, which contains a wide variety of good bacteria, is important for maximising short chain fatty acid (SCFA) production. 

“These reduce inflammation in the body and brain, and are important in reducing the risk of brain diseases including Alzeimer’s and depression.“

But, an imbalance in the gut microbiome can lead to bloating, constipation, brain fog, fatigue, and mood disturbances. 

Fix it: To boost your gut, consume a diet high in prebiotics.

“This means raising your intake of fibre from a diverse range of plant-based foods, including wholegrains (rye, oats, barley), pulses (lentils, beans, hummus), fresh veggies, nuts and seeds.

“Limiting consumption of alcohol, sweeteners and ultra-processed foods, staying active, drinking plenty of water, reducing stress and prioritising quality sleep are also important steps in nurturing a thriving gut microbiome.”

3. Trauma  

A stressful or distressing event can wreak havoc on your body and mind, and this trauma can take a while to process. 

Therapist says that we may ‘tune out’ of reality as a protective mechanism, which can lead to a loss of focus in our daily life.

Fix it: Imogen says: “Grounding exercises can help keep our mind and body regulated, such as body scan meditations, meditative breathing and soothing self-talk.”

A body scan meditation involves sitting or lying down, focusing on your breathing and then focusing on each body part, one at a time, to see how it feels. 

If you think trauma might be to blame for your foggy brain, Imogen adds that the safest way to actually process trauma is through ‘counselling with a trained professional’.

4. Over-exercising  

Excessive exercise can be a form of stress on the body, explains Jodie.

She says: “Inflammation is a perfectly normal response to exercise; when we work out our muscles work hard and experience a certain level of 'stress'.

“We then rest and recover which enables these muscles to repair; the inflammatory markers are a signal to the body to send extra nutrients to the muscles to help them recover.”

But, if we keep exercising at intense levels with little or no recovery time then this inflammation has no time to recover. 

We can then end up with chronic inflammation, which is exhausting for the body and it can manifest as brain fog.

Fix it: “If you love exercising then simply allow yourself days between intense bouts of exercise to recover, whether this is a rest day (not doing much at all) or an 'active rest day' where you do a more gentle form of exercise like walking, stretching or yoga,” advises Jodie.

5. Sugar overload  

If your diet is filled with sugar and refined carbohydrates, such as pastries, biscuits, white bread and other processed foods, then it might be time to reconsider what you’re eating.

“These foods can cause brain fog in anyone if consumed in excess,” says Jodie.

“It's very normal for our blood glucose levels to fluctuate throughout the day. 

“However, when we eat meals (or have drinks) that contain large amounts of sugar or refined carbohydrates then we can see a large rise in blood glucose levels, this will give you the feeling of having lots of energy.

“But it also results in a large drop in blood glucose levels which will likely cause feelings of brain fog - lack of energy, difficulty concentrating, irritable, low mood and craving energy dense foods to pick you up again.”

Fix it: Swap sugar-rich foods for slow-release carbohydrates such as wholegrains, fruits and vegetables. 

And instead of eating carbohydrates alone, pair them with sources of protein and healthy fats.

Jodie explains that this “slows down the release of glucose and prevents large spikes and dips, keeping our energy levels, mood and concentration more stable”.

6. Histamine intolerance

Histamine, a chemical released by our immune system, is needed for various functions in the body.

However, says that some people have histamine intolerance, which is characterised by an “inability to break down histamine efficiently”.

This can lead to various symptoms, including brain fog.

“Certain foods are naturally high in histamine or can trigger the release of histamine in the body,” says Cara.

"These foods include aged cheeses, fermented foods such as sauerkraut, processed meats, alcoholic drinks and some types of fish including tuna."

Fix it: Cut back on these foods if you think they may be causing a problem, to see if the fogginess clears.

7. Mould exposure 

Mould exposure is another surprisingly common contributor to brain fog,” says Cara.

However, this mould doesn’t need to be in your current home or workplace; it could be somewhere you lived years ago.

“Mould toxins can remain in the body for long periods of time. Mould produces mycotoxins; toxic compounds that can have a range of adverse health effects when inhaled or ingested; and can present as brain fog, difficulty concentrating, memory problems, and mood disturbances,” adds Cara.

Fix it: Cara suggests taking mould exposure seriously. “Test, don't guess and always do so with the help of a nutritional therapist who can analyse testing and provide appropriate protocols as different types of moulds may need different treatment plans," she says.

8. You’re doing too much

Over time, an overly packed calendar, a hectic work schedule and a never-ending to-do list, can become too much for us, leading to a full brain that gets little to no rest.

, a neuroscience expert and author of How to Feel Better: 4 Steps to Self-Coach Your Way to a Happier More Authentic You, says that when we relax we can access the area of our brain that does our “slower order” thinking, “which means we are more creative and can problem-solve better”.

Fix it: Ruth says that we often get our best ideas in the shower. 

"Finish off your shower with a blast of cold water,” she says.

“This improves alertness and focus throughout the day.  It seems the shock of cold water increases levels of a protective protein in the blood.”

9. Nutrient deficient 

The feel-good hormone dopamine is involved in focus and concentration.

Cara says: “Dopamine requires adequate levels of protein and nutrients such as vitamin D, Folate and iron.”

Without these, dopamine levels may be low leaving you with an inability to properly focus.

Fix it: Enjoy lean sources of protein such as chicken, eggs, fish, turkey and lean beef, as well as folate-filled foods including dark leafy greens, peanuts and whole grains. 

Find iron in meat, dried fruits and fortified foods.

The ‘sunshine vitamin’, vitamin D, is best sourced from a supplement, especially between October and March.

Cara also recommends. “Compounds in Lion’s Mane have been shown to regenerate neurons and support memory.”

10. Thyroid problems

Brain fog can be a symptom of an underactive thyroid.

However, Cara explains that other symptoms of an underactive thyroid may include weight gain, hair loss, dry skin, constipation and menstrual irregularities.

Fix it: “Always get checked by a professional who can identify if levels are suboptimal,” Cara says.

11. Menopause

Brain fog is one of the most dominant symptoms reported by women in menopause, which tends to start mid-40s (perimenopause).

Oestrogen declines over many years and is the main driver of symptoms.

It can support the production of choline, "a precursor for acetylcholine, an important neurotransmitter involved in memory", Cara says.

So women going through perimenopause may experience brain fog due to a lack of oestrogen.

Fix it: “During this stage of life, it's even more important to increase dietary choline to prevent brain fog and memory issues,” says Cara.

The richest dietary sources of choline are meat, fish, dairy, and eggs.

12. Is it your genes?

For some people, brain fog may just be something they are ‘born with’.

“As a genetic expert, I see many clients with genetic variances on key genes that affect brain function,” explains Cara.

“One of my most popular genetic tests assesses genes affecting production and transport of choline."

She adds that if these genes are downregulated, combined with insufficient dietary choline, brain fog and poor memory might be an issue.

READ MORE SUN STORIES

If you follow a plant-based diet, it can be harder to get enough choline.

But veggie friendly sources include quinoa, soybeans, kidney beans, almonds, and cruciferous vegetables like cauliflower, broccoli, and Brussels sprouts.

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