A nutritionist explains the gut’s role in hormonal mood swings

The link between women’s gut health and hormones is transforming our understanding of our wellbeing, and nutrition, hormonal health specialist and author Marta León is dedicated to exploring this surprising connection.

“When we talk about women’s hormonal health, we can’t just focus on the ovaries,” she emphasises. “I always say that hormonal health begins in the gut.”

León examines how the microbiota directly influences women’s hormones and everything from acne and PMS to endometriosis, arguing that looking after our gut health is a key tool for both physical and emotional balance.

“While our understanding of microbiota is growing, it’s still incredible to discover just how deeply it’s connected to every part of who we are,” says the expert. “It doesn’t just affect our digestion or immune system; it plays a fundamental role in keeping our hormones in check, particularly for women.”

Léon puts a special focus on oestrobolome, a specific group of microorganisms in our gut which is actively involved in how we metabolise oestrogen. 

“If this ecosystem gets out of whack, it can lead to an excess, or a deficiency, of oestrogen circulating in the system. Essentially, by looking after our gut, we aren’t just aiding digestion – we’re tackling hormonal well-being at its root,” she explains.

Why should we be paying more attention to the oestrobolome?

“The oestrobolome is a term that many people aren’t yet familiar with, but it’s becoming increasingly important in the world of women’s health [because] when this bacterial ecosystem is in balance, it helps us clear out excess oestrogen efficiently.

“However, if it gets out of whack, whether due to a poor diet, chronic stress or the over-use of antibiotics, that oestrogen can end up recirculating and building up in the body. This can lead to a host of issues, including bloating, painful or heavy periods, migraines and even the worsening of conditions like endometriosis or fibroids.

“I really emphasise that the gut is a major regulator of our hormones, and the oestrobolome is a key piece of the puzzle. It’s so important to understand how it works because, often, the issue isn’t that we’re producing too many or too few hormones, it’s that we’re not effectively processing them.”

What would you say are the keys to finding that “perfect balance”?

“The truth is, the perfect balance isn’t some magic formula or a rigid goal to be ticked off a list. It’s a journey we take every day, simply by listening to what our bodies are telling us.

“I’d say the key is listening more closely and supporting our bodies with a bit of kindness and common sense. This is exactly where the microbiota comes into play. 

“Everything from what we eat and how we move to our sleep quality and stress levels directly impacts this ‘invisible ecosystem’ living inside us. It’s working away quietly in the background, regulating our hormones, our immune system and even our mood.”

The link between hormones and the microbiota is particularly important when it comes to women’s health, isn’t it?

“Absolutely. In fact, understanding that connection is one of the missing pieces when it comes to grasping female health in all its complexity. In the female body, sex hormones and the microbiota are in constant dialogue – and what’s really fascinating is how that conversation shifts throughout our lives, from our very first period right through to our last.

“The microbiota does so much more than just digest food or produce vitamins; it’s an active player in hormonal regulation. For women, this is incredibly important because our lives are marked by major transitions: puberty, pregnancy, breastfeeding, the menopause and the cyclical changes we experience every month. In all of these stages, the microbiota acts as a powerful ally – provided we look after it.”

Do you think women should see themselves as at the mercy of  their hormones?

“For a long time, we’ve been led to believe that our hormones are a sort of punishment – an emotional rollercoaster that we just have to put up with or keep under control. We’ve been told we’re ‘too hormonal’ as if it were some kind of character flaw. But the truth is, we aren’t hostages to our hormones; we are cyclical, changing beings, and there is something deeply powerful in that.

“It’s a bit like saying human beings are chained to their own breathing, simply because we need to breathe to survive. Hormones aren’t a life sentence; they are a fundamental part of who we are. The more we understand them, the closer we get to living in harmony with ourselves.

“When we grasp how our hormones actually work, we stop seeing them as the enemy and start seeing them as allies… The issue is that we’ve rarely been taught how to speak that language, let alone how to give our hormones the care and attention they deserve.”

The gut-brain connection & women’s health

A lot has been said lately about the gut-brain axis; how much of an impact does this relationship actually have on our health?

“The gut-brain axis is easily one of the most fascinating scientific discoveries of recent years. We now know that the gut isn’t just a digestive organ; it’s a sophisticated communication hub that is constantly ‘talking’ to our brain. This conversation happens, in large part, via the microbiota.

“That ‘dialogue’ has a direct impact on how we feel, affecting everything from our energy levels and mood to our sleep quality, stress management, and even our mental clarity.

“An inflamed gut, an unbalanced microbiota, or a diet high in ultra-processed foods doesn’t just mess with your digestion; it can manifest as irritability, low mood or anxiety. And it works both ways: if we’re living with chronic stress or anxiety, our microbiota suffers too, which in turn impacts our digestion, immunity, and, of course, our hormonal balance.

“Taking care of our mental health means paying attention to what’s going on in our heads and what’s happening in our gut. This is why more and more research is exploring the use of probiotics in the field of psychiatry. A healthy gut doesn’t just digest food well – it sustains our energy, provides emotional stability, and regulates our hormones from the inside out.”

Eating for hormonal harmony – and recognising signs of a hormonal imbalance

Which foods help maintain a healthy microbiota, and how do they actually impact our hormonal health?

“What we eat every day has a direct impact on our microbiota and, by extension, our hormonal health. Fibre, found in pulses, seeds, and seasonal fruit and veg, is the preferred fuel for our ‘good’ bacteria. Then you have prebiotics (like onions, garlic, and leeks), which help these bacteria thrive. Fermented foods such as kefir, sauerkraut, kombucha, miso, or live yoghurt also introduce beneficial bacteria.

“On the flip side, a diet heavy in refined sugars, alcohol, ultra-processed foods, and artificial sweeteners can weaken this bacterial community, leading to inflammation and hormonal imbalances. We also have to consider endocrine disruptors (environmental toxins) which, often without us even realising, can interfere with our microbiota and disrupt our hormones.”

So, how does this affect our hormones? 

“Quite directly, actually. When the microbiota is in good shape, the oestrobolome can do its job properly – breaking down and clearing out the oestrogen our body no longer needs. A diverse microbiota also lowers inflammation and improves our absorption of the building blocks of hormonal health, such as magnesium, zinc and B vitamins. It also keeps the gut-brain axis in check, which has a huge impact on our mood, how we feel throughout our cycle and how smoothly we transition into the menopause.”

What symptoms might suggest that a hormonal imbalance is linked to the microbiota?

“In women, the most common indicators are often very painful or heavy periods, abdominal bloating, trapped gas, or sluggish digestion. You might also notice sudden mood swings, premenstrual anxiety and hormonal acne, particularly around the jawline. Other signs include water retention, persistent fatigue or brain fog, and finding it unusually difficult to lose weight. 

“Recurrent vaginal infections, such as thrush, are also a major red flag, as they are often strongly linked to an imbalance in the microbiota. For those going through perimenopause or the menopause, these symptoms can feel much more intense if the gut isn’t in good shape.

“That is why I always advocate for looking at the body as a whole. We often spend our time treating the symptoms without ever addressing the underlying cause.”

What lifestyle changes would you recommend to boost hormonal health via the microbiota?

“There are small, daily habits that can truly be a game-changer for our hormonal health, starting with what we put on our plates. A diet rich in fibre provides the perfect fuel to keep our microbiota happy. Equally important is cutting back on ultra-processed foods, refined sugars and alcohol, all of which can significantly disrupt the gut.

“Another simple but powerful shift is respecting our circadian rhythms. This means getting some natural light early in the morning, sticking to regular mealtimes and prioritising a good night’s sleep. Sleeping well doesn’t just keep your stress hormone, cortisol, in check; it also improves insulin sensitivity and helps maintain a healthy oestrogen balance.

“I also recommend being more mindful of how we eat. Taking the time to chew properly, avoiding the “dash and grab” lunch, and creating a bit of headspace during meals can vastly improve digestion and the communication between your gut and brain. It’s also so vital to keep the body moving and to carve out small pockets of time each day for pleasure, calm or a bit of self-care.”

About the expert: 

Marta León is a highly respected nutritionist specialising in female hormonal health and reproductive wellness. She is the author of the Spanish language book, The Perfect Balance (El equilibrio perfecto), which explores sustainable habits for cyclical wellbeing. You can follow her work and insights on Instagram at @foodgreenmood.