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Oestrogen fluctuation

Oestrogen supports serotonin, dopamine, and acetylcholine activity, promotes neuronal energy metabolism, and has anti-inflammatory effects in the brain. As it fluctuates unpredictably during perimenopause, cognitive function can feel inconsistent from day to day. Neuroimaging research has documented transient changes in brain metabolism and white matter integrity during this transition (Mosconi et al., Scientific Reports, 2021).

Sleep disruption

Poor sleep impairs memory consolidation, attention, and information processing. Sleep disruption is common during perimenopause and is one of the most significant contributors to brain fog. Addressing sleep is often the most impactful first step.

Increased neuroinflammation

Oestrogen has anti-inflammatory effects in the brain. As it declines, low-grade neuroinflammation can increase, contributing to cognitive symptoms. Several of the nutrients with the best evidence for brain fog work in part through anti-inflammatory pathways.

Nutritional gaps

Deficiencies in vitamin D, B vitamins, magnesium, and omega-3 fatty acids are all associated with cognitive symptoms. In perimenopausal women, where overall nutritional demands shift, these gaps become more clinically relevant. This is where targeted supplementation is most clearly justified.

The brain uses creatine as a rapid energy buffer via the phosphocreatine system. When neurons are under metabolic stress, including from sleep deprivation or hormonal change, adequate brain creatine helps maintain cognitive performance.

The most significant development is the CONCRET-MENOPA trial (Korovljev et al., Journal of the American Nutrition Association, 2025), the first RCT examining creatine specifically in perimenopausal women with brain fog. It found significantly improved reaction time, a 16.4% increase in frontal cortex creatine levels, and a trend toward reduced mood swings.

DHA is the primary structural fatty acid in brain cell membranes, essential for neuronal integrity and synaptic function. EPA supports mood regulation through anti-inflammatory pathways. A 2022 systematic review confirmed positive effects of omega-3 supplementation on cognitive function in adults (Dighriri et al., 2022). Given that omega-3 also supports cardiovascular health and mood, it remains one of the most broadly relevant supplements for this life stage.

Magnesium L-threonate is specifically formulated to cross the blood-brain barrier more effectively than other magnesium forms. Preclinical studies showed significant increases in brain magnesium concentration and cognitive improvements. Human trials have been positive for memory and cognitive clarity, though evidence remains smaller in scale. This is the form recommended for brain fog specifically, distinct from magnesium glycinate which is better suited to sleep support.

B vitamins, particularly B12, B9, and B6, are essential for neurotransmitter synthesis and homocysteine regulation. B12 deficiency is a directly reversible cause of cognitive symptoms. The evidence is clearest where deficiency is present rather than as a general cognitive enhancer. B12 deficiency is more common in women on plant-based diets, those taking metformin, or those with gut absorption issues. A methylated B complex covers this ground efficiently.

Lion’s Mane contains compounds that stimulate nerve growth factor (NGF) synthesis, directly relevant to neuroplasticity and cognitive function. Human evidence is growing. A double-blind RCT found improvements in cognitive performance in adults with self-reported cognitive difficulty, and a 2023 RCT showed improvements in stress and cognition over 28 days (Docherty et al., Nutrients, 2023). Product quality matters significantly: choose whole fruiting body extracts, not mycelium-on-grain products.

Creapure · NSF certified

What we like

Creapure source, NSF tested, flexible dosing, clean formulation. No loading phase needed. Start at 3g daily and take consistently.

Creapure · UK brand

Hypoallergenic · Methylated forms

What we like

Methylated forms for better bioavailability, hypoallergenic, high-quality formulation, no unnecessary additives.

Brain-specific form

Fruiting body extract

What we like

One of the most transparent Lion’s Mane products available. Clearly states fruiting body, publishes beta-glucan content, and is third-party tested for purity.

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Is perimenopause brain fog permanent?

For most women, no. Research tracking cognitive function through the menopausal transition consistently shows that function tends to restabilise in post-menopause. Brain fog during perimenopause is typically transient and related to hormonal fluctuation rather than permanent cognitive decline.

Is creatine safe for women to take?

Yes. Creatine monohydrate has a strong safety record in both men and women across decades of research. It is one of the most extensively studied sports supplements. The CONCRET-MENOPA trial found all doses well tolerated with no adverse effects in perimenopausal women. There is no evidence it causes harm at standard doses of 3 to 5g daily.

What is the difference between magnesium glycinate and magnesium L-threonate?

Magnesium glycinate is best for sleep, anxiety, and general magnesium repletion. Magnesium L-threonate is specifically formulated to cross the blood-brain barrier and is better suited to cognitive support and memory. They address different goals and can be taken alongside each other.

How long before I notice a difference from these supplements?

Creatine typically takes 2 to 4 weeks of consistent daily use to saturate brain and muscle stores. B vitamins may show effects within a few weeks where deficiency is present. Magnesium L-threonate human trials have used durations of 4 to 12 weeks. Lion’s Mane studies have shown effects from 4 weeks. Consistency matters more than timing.