The female gut-brain connection
The microbiome and brain during the menstrual cycle and menopause
I don’t know about you but it makes me more than a bit mad that we don’t know more about the female body than we do. Hippocrates didn’t exactly help - he thought that women’s diseases were due to the uterus ‘wandering’ around the body that, surprise surprise, could only be cured by having more sex with her husband. He called the condition ‘hysteria’, a thankfully now defunct diagnosis yet only removed from medical lexicon in the 1980s.
Women are consistently underserved by medical science. Only 2% of research funding in the UK is spent on pregnancy, childbirth and women’s sexual health. Conditions that disproportionately affect women such as endometriosis, migraines, anxiety disorders and myalgic encephalomyelitis attract less funding and are not aligned with their sizeable burden.
In terms of gut microbiome research and women’s health, I’m a little more lenient (for now). It’s still a very young field after all with microbiome research rapidly escalating only in the last two decades or so. But we shouldn’t be complacent. There is more research to be done - and I hope more to uncover about the relationship between the gut microbiome and women’s health in particular.
Oestrogen and the brain
Female sex hormones oestrogen and progesterone ebb and flow throughout a woman’s life, rising through puberty, varying through the menstrual cycle, and in fluctuating decline through the menopause transition. During the menstrual cycle, oestrogen levels can rise eight times higher, while progesterone levels can increase by 80-fold over the course of around a month.
There’s a growing number of studies that show that female sex hormones can influence brain function and behaviour. Oestrogen interacts with your brain, with oestrogen receptors mapped out across your neural circuitry. Like individual components of a well-oiled machine, your brain contains different parts responsible for specific tasks. Your brain’s hippocampus, vital for memory, learning and regulating emotions, contains many more of these oestrogen receptors than other regions of your brain.
Female sex hormones can rapidly alter your neuroplasticity, your brain’s ability to change based on new experiences. An increase in oestrogen and decrease in progesterone during the ovulation phase of the menstrual cycle, for example, is related to an increase in hippocampus size. Although a bigger brain volume doesn’t always mean better - the hippocampus is critical for cognitive function.
A shift in sex hormones at both puberty and menopause (between 40-58 years old) is accompanied by a shift in brain function. 75% of menopausal women experience symptoms, and most are symptoms that affect the brain - fatigue, brain fog, insomnia and depression. Most hormone replacement studies suggest that replacing declining oestrogen levels has a beneficial effect on cognition, though the evidence around progesterone isn’t as clear.
Can you influence your oestrogen levels through what you eat?
Phytoestrogens
Phytoestrogens are compounds found in some plants that, when eaten, can act like oestrogen. It’s thought that they can potentially provide some relief to menopausal symptoms. Phytoestrogens are found in soy foods like tofu, soy milk and also some legumes, whole grains, fruits and veggies too. Women in Asian countries who typically eat a phytoestrogen-rich diet, tend to have fewer menopausal symptoms than Western women. However, overall the evidence has been mixed whether phytoestrogens can help with hot flushes. And there doesn’t seem to be any conclusive evidence yet on their effects on menopausal brain fog either.
Oestrogen and the microbiome
The differences in menopause symptoms between women in Asia and Western women could be down to their gut microbiome. Your gut microbiome, a collection of over 100 trillion bacteria, funghi, viruses and archaea found in your lower intestine, is one of the main controllers of your oestrogen levels. 50-60% of women in Japan have gut bacteria that are able to breakdown phytoestrogens into a form the body is able to make use of, compared to only 30% in Western women. A disrupted microbiome is also related to lower circulating levels of oestrogen in your body, and can potentially drive oestrogen-related conditions and diseases.
For now…
We don’t know enough yet whether phytoestrogens can or can’t help to manage menopause symptoms. That doesn’t mean that you can’t try eating more phytoestrogen foods if you’d like to. You could try eating 1-2 a day for three months and see if it helps you.
Tofu
Other soy foods
Flaxseeds
Sunflower seeds
Almonds
Supporting your gut microbiome too is related to multiple health benefits. You can read on a previous post ‘how to improve your gut microbiome’.
That’s it for now! If you have a thought percolating from this, I’d love to hear it - drop me a comment below.
Chat soon, Emily xx
P.S. Did you know I’m writing a book on the gut-brain connection called Genius Gut? I’m hugely excited about it and can’t wait to share it with you.
Apparently, the success of a book hugely depends on how well pre-orders do, so if you’re in the UK and feel like pre-ordering a copy it would completely make my day!
