Brain fog is one of the most distressing symptoms of perimenopause. As many as 20% of women are considering leaving their jobs because of it, understandably also worried about what this means for the decades ahead.

You are told it is menopause, stress, or simply getting older. But there is a great deal more to it than that.

Brain fog can be minimised – and there is also no reason you cannot enjoy sharp cognition through this transition and well beyond it.

This article covers every layer of what may be driving your brain fog – nutrition, gut health and infections, to the light in your home and how your inner transformation is contributing. It is written for women who have tried the standard answers and are still struggling, and those who sense there is more to it.

In this article you will read about:

• Hormones as messengers
• Nutrition for the perimenopausal brain
• The importance of gut and oral health
• Toxins, mould, and environmental chemicals  and brain fog
• Infections and parasites – the most underdiagnosed drivers
• Chronic stress and information overload
• How the light in your home is affecting your brain
• The inner transformation at midlife and your brain

Your brain transforms in perimenopause

Dr Lisa Mosconi, director of the Women’s Brain Initiative at Weill Cornell Medicine and author of The Menopause Brain, has dedicated her career to the female brain. Her research confirms that the brain does go through a real transformation during perimenopause. You are not imagining it. But women whose brains were well supported – through nutrition, lifestyle, and addressing root causes – showed full recovery in cognitive function after menopause.

To add more context: brain cells continue to be made throughout our lives through neurogenesis. Even conditions like Alzheimer’s and dementia, are in many cases preventable and even reversible when root causes are addressed.

Dr Mosconi is emphatic that nutrition is the number one priority for brain health in women. I know this personally, having the experience of food affecting my brain at lightning speed. Several years ago on a ski holiday I let myself eat everything on offer for one week – non-organic breads, and fries fried in dubious oil. The cognitive consequences showed up as soon as I returned home; the brain fog was frightening. It took me two months to reverse it using all my clinical tools.

Research shows that the perimenopausal years are a critical window. What you do in it matters for the decades that follow.

Hormones are messengers

Hormones do shift in perimenopause and they affect brain function. But think of them as messengers rather than the single root cause. As they shift, they remove a buffer – the anti-inflammatory, neuroprotective work that oestrogen and progesterone have been doing since puberty. When that buffer thins, everything that was already there comes to the surface: nutrient depletion, gut dysbiosis, infections, a strained nervous system, environmental toxins, the inner life that is now pressing for attention.

Perimenopause is an unmasking. Brain fog is a signal.

Of everything that comes to the surface in perimenopause, nutritional depletion is what I see most consistently – and it is where I always start.

What brain fog may be showing:

Nutrition for the brain

Perimenopause is a time of significantly increased nutritional demand. Most women arrive at this transition already depleted, and the brain is depleted too.

For most of my adult life I was mainly vegetarian with some occasional oily fish. As I entered perimenopause, this was no longer enough. I began eating animal protein daily and felt the difference in every aspect of my health almost immediately. I am genuinely convinced I could not have gone through perimenopause naturally without this change, even with my access to nutritional science and top supplements. Meat is also grounding – psychologically as well as physically – and eating it gave me that feeling of calm.

Other than including animal protein, I also recommend:

Protein at every meal, especially at breakfast. Your brain cannot make neurotransmitters – serotonin, dopamine – without amino acids. Aim for 25–35g with meals depending on your body weight and how active you are. For context, one egg has about 7g protein. 

DHA from oily fish. The brain is 70% fat and DHA is its primary structural component – essential for neural signalling and brain repair. It is found in oily fish and organ meats but not in plant foods in usable form. Salmon, sardines, and mackerel at least three times a week.

Organ meats. Beef liver in particular is the most nutrient-dense food available – giving you B12, folate, choline, CoQ10, and haem iron in a single serving. These are the exact nutrients most depleted in perimenopausal women. If you don’t enjoy the taste, you can “hide” liver in meatballs, curries, and pates.

Fermented foods for microbiome diversity – kefir, live yogurt, sauerkraut.

Berries for anthocyanins, which cross the blood-brain barrier and directly reduce neuroinflammation.

Your gut health

When the gut is inflamed, the brain is inflamed. The gut-brain axis is a two-way neurological highway – the health of one directly influences the health of the other.

When the gut barrier is compromised – by poor diet, chronic stress, or infection – it becomes permeable (aka leaky). Inflammatory compounds that should stay in the gut enter the bloodstream and can breach the blood-brain-barrier, triggering an inflammatory cascade in the brain. Leaky gut leads to leaky brain.

Poor digestion means poor nutrient absorption, even from a good diet. Any issues like bloating, constipation or pains should ideally be resolved so that you are able to absorb nutrients from the food you eat, especially B12, magnesium, zinc and DHA that the brain depends on.

Your oral microbiome

The mouth is the beginning of the gut microbiome. It contains over 700 bacterial species. People with disrupted oral microbiomes have a 70% higher risk of developing Alzheimer’s disease (Beydoun et al, 2020). The bacterium Porphyromonas gingivalis – the primary driver of gum disease – and is found in the brain tissue of Alzheimer’s patients.

Perimenopause unmasks any oral microbiome issues. Because oestrogen receptors are in the gum tissue and oral mucosa, as hormones shift, gums become more vulnerable, saliva reduces, and pathogenic bacteria increase. Those bacteria are swallowed throughout the day feeding into the gut, and they are also in close proximity to the brain, secreting toxic compounds which can lead to brain fog.

Dental hygiene at perimenopause is really an important neurological consideration – daily water flossing, morning tongue scraping, and avoiding alcohol-based mouthwashes which may further disrupt good bacteria. I test the oral microbiome in cases of severe brain fog and persistent dental issues.

Toxins, mould and environmental chemicals

By the time we reach our forties, our toxic bucket is full. This is not about being alarmist, but unfortunately our world is full of toxins and we cannot get well without properly addressing this.

Ochratoxin A is one of the most common mould toxins I see on test results. It is found in coffee, foods like cereals, peanuts, dried fruit, and it lives in damp homes. It specifically targets the hippocampus – the brain’s memory centre – producing exactly the cognitive symptoms women in perimenopause describe plus deep fatigue.

Heavy metals accumulate in brain tissue over decades. Plastics also accumulate more in the brain than in any other organ and increase the risk of cognitive decline.

Most gluten available in UK shops today is heavily sprayed with glyphosate, a herbicide now linked to disruption of the central nervous system and the gut microbiome. When the gut barrier is compromised by glyphosate exposure, inflammatory compounds travel directly to the brain. Highest levels are found in wheat, soy, and oats.

This is not a quick fix. But once your toxic picture is understood through testing – hair tissue analysis, organic acid testing – treatment focuses on minimising exposure while supporting the body’s ability to remove them. Swapping regular coffee for a mycotoxin-free certified brand is a simple first step.

Infections and parasites

Certain infections are also significantly underdiagnosed and have established neurological connections to brain fog.

Borrelia burgdorferi – the bug associated with Lyme disease, transmitted by ticks and other insects like mosquitoes – has a specific affinity for the brain. It can trigger sustained neuroinflammation that persists long after an acute infection, producing exactly the cognitive symptoms routinely attributed to perimenopause: brain fog, word-finding difficulties, memory problems, and fatigue. 

Parasites are another driver rarely discussed in perimenopause. Both microscopic and macroscopic like threadworms release toxins that affect your health including the brain. This is best investigated and treated by a qualified practitioner.

Chronic stress and information overload

Chronic stress puts the brain in survival mode rather than memory mode. The regions responsible for memory and higher-order thinking have less energy to work with.

The strain placed on women navigating perimenopause is enormous. I myself went into perimenopause during lockdowns, while my children were stepping into their teenage years, and while I was supporting my father through the end of his life. The cognitive and life load was significant. Many of the women I work with are navigating exactly this – teenagers, ageing parents, increased career demands – all at the time the brain most needs support rather than more pressure.

Social media, constant connectivity, and the relentless stream of short-form video create a level of mental load and overwhelm that previous generations simply did not have.

Limiting social media use should actually be a top neurological decision for women.

Your light environment

If you go through your mornings under artificial light and looking at screens, this will be affecting your brain.

Screens particularly in the evening and LED and blue-spectrum light signal midday sun to the brain, not bedtime. This suppresses melatonin by more than 50% – and melatonin is not only the sleep hormone, it is a neuroprotective antioxidant and one of the brain’s primary defences against neuroinflammation.

Professor Glen Jeffery, neuroscientist at UCL’s Institute of Ophthalmology, explains why LEDs are specifically problematic. Modern LED lighting lacks the longer red and infrared wavelengths found in natural sunlight – the very wavelengths that support mitochondrial function. The brain has enormous energy demands, and mitochondrial health in brain cells directly affects mood, cognition, and resilience to damage. Spending your days under LED lighting away from natural sunlight is, in Jeffery’s words, infrared starvation.

Ayurveda, the medicine of ancient India, has known this for thousands of years – the daily practice of dinacharya begins with watching the sunrise, to sync the body with nature’s light before the day begins.

I’ve written more about how light affects your metabolism here.

Women 100 years ago didn’t have this problem to solve. They lived under different lights.

My no-negotiables for my clients and my family: blue-light blocking glasses when working on laptops after 8pm, amber lamps in the evening, and minimum 10 minutes of morning daylight without sunglasses.

When the inner transformation shows as brain fog

There is a dimension to perimenopausal brain fog beyond your physiology.

In the first half of life we acquire an identity and adapt – to family, culture, and the expectations of the world we grew up in – and we set aside parts of ourselves that didn’t fit. Our creativity, emotions like grief or anger that weren’t acceptable, parts of us we were never even aware of. According to Jungian analyst Robert A. Johnson, these accumulate in the unconscious, dragging behind us like long comet tails, and often we don’t even know they are there.

By midlife – which coincides with perimenopause – everything begins to surface. It may start as a whisper, a thought, a knowing that something needs to change.

The brain in perimenopause is already managing an enormous amount. Then adding to it all this accumulated material pressing for your attention. Perhaps the brain deprioritises what it considers most trivial like names of people you barely know – giving you the space to deal with what really matters.

In perimenopause not only is the brain recalibrating – so are you.

The invitation here is not to numb what is surfacing and carry on as before. It is to pay attention to what is being revealed on every level.

What you can do

Most of what I have described above is modifiable.

You are not a victim of your biology, and you do not need to address everything at once.

In my experience, identifying and addressing your two or three key root causes brings improvements that begin to shift everything else.

Start with nutrition as it is the foundation. Nutritional plans should ideally be personalised to your unique biology and circumstances. 

Fix your light environment – this is also your sleep solution.

Address what is underneath. Gut health and microbiome, heavy metal and mould testing, infection screening, and your psyche. 

When those are identified and addressed, improvement is often faster than expected.

Magda Jenkins is a registered Nutritional Therapist and Naturopath specialising in women’s health, based in Petersfield, Hampshire. She works with clients locally and globally via Zoom.

If this resonates, book a free discovery call at magdajenkins.com

References

Bredesen, D. (2017) The End of Alzheimer’s. Penguin.

Chang, A.M. et al. (2015) ‘Evening use of light-emitting eReaders negatively affects sleep’, PNAS, 112(4), pp. 1232–1237.

Dominy, S.S. et al. (2019) ‘Porphyromonas gingivalis in Alzheimer’s disease brains’, Science Advances, 5(1), eaau3333.

Hollis, J. (1993) The Middle Passage. Inner City Books.

Hyman, M. (2024) ‘The hidden connection between gut health and mental health’. Available at: drhyman.com

Jeffery, G. (2026) Light, Mitochondria and Health: 2 Billion Years of Evolution Under Sunlight Until Recently. BNFM conference, London, 30 April. [Personal notes.]

Johnson, R.A. and Ruhl, J. (2007) Living Your Unlived Life. Tarcher/Penguin.

Kharrazian, D. (2013) Why Isn’t My Brain Working? Elephant Press.

Mosconi, L. (2018) Brain Food. Avery/Penguin.

Mosconi, L. (2024) The Menopause Brain. Avery/Penguin.