We often hear about the “gut-brain axis”, but Dr. Emeran Mayer, gastroenterologist and author of “The Mind-Gut Connection,” prefers the term “brain-gut-microbiome system” because it’s not just linear one-way traffic. It’s bidirectional with multiple pathways creating feedback loops continuously throughout our lives.
“It’s the most complex system after the brain,” Mayer says, and it runs constantly in the background of our health. Here’s how this system works and what changes for women we age.
🧠 The takeaway
Your gut and brain stay in constant two-way contact for life—through nerve, hormone, and immune signals that aren’t one single path.
This system adapts fast: gut bacteria can shift their activity within 48 hours of a dietary change, making it one of the most responsive levers you have for long-term brain health.
As your body changes with age, including through the hormonal shifts of menopause, this system adjusts too. One example: a group of gut bacteria called the estrobolome can pick up some of the work of recycling estrogen once ovarian production declines.
🤔 Curious how another overlooked system shapes your hormones and brain? Read: How Oral Health Connects to Your Healthspan
Have you noticed your gut and your mood seem to affect each other?
Meet the brain-gut-microbiome system
Within this brain-gut-microbiome system, Mayer says there are multiple pathways at work—immune, hormonal, neurotransmitter, and nerve signals like the vagus nerve—most running in both directions, with feedback loops layered on top.
Mayer adds that during emotional states, your gut's contractions, secretions, and hormone release all measurably change, the same way anger or happiness shows up on your face. That back-and-forth is why your stomach can react almost instantly to a stressful moment (those pre-presentation butterflies, for example).
Your gut creates a mirror image of what emotionally goes on within the brain.
That mirroring runs in a loop, too. Sit down to a meal upset about something, and the meal itself becomes less enjoyable and harder to digest. Then, that poor digestion signals back to the brain, reinforcing the very mood that started it. This can lead to other effects that take decades to surface.
Chronic negative signaling from the brain to the gut can contribute to inflammation that isn't detected until much later in life, sometimes not for another 20 years, says Mayer. Decades of that signaling add up, contributing to things like cognitive decline.
Fortunately, the reverse holds true too. Mindfulness and meditation can change gut function. Research on gut-directed hypnosis shows measurable effects too, though Mayer notes there is less data so far on positive emotions compared to negative ones.
What changes in midlife and beyond
A concrete example of this system changing with age is hormonal transitions. Estrogen is produced by the ovaries, but it’s also made in the brain and adrenal glands, which don’t shut down on the same timeline.
Normally, once your body's done using a hormone, your liver tags it with a sugar molecule so it can be flushed out. But a group of gut microbes called the estrobolome can clip that sugar molecule right back off, making the estrogen usable again. "Microbes, just like humans, love sugar," Mayer says. Once your ovaries start producing less estrogen, as they do in perimenopause and menopause, this recycling trick starts covering a bigger share of the estrogen in your blood, up to 10%, by his estimate.
While you can't change how much estrogen your ovaries produce, you can support the estrobolome doing the recycling.
Mayer points to the same habits that build a healthy, diverse gut microbiome to aid in this recycling: largely plant-based eating, with complex carbohydrates too large for your small intestine to absorb on its own, so they reach your gut bacteria instead. He’s also watching early research into engineered probiotics designed to take over this estrogen-recycling job more precisely, potentially as an alternative to hormone therapy, though he estimates any clinical product is five to ten years out, pending safety trials.
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Why the brain-gut-microbiome system matters more for women
The cumulative load many women carry across decades, often taking on demanding careers on top of the caregiving responsibilities that already fell to women, is exactly what a resilient brain-gut-microbiome system is built to buffer against, Mayer says.
He describes that resilience as a flower with multiple petals: diet and meditation are two, but connection and sense of purpose matter just as much. Building any of them is one of the most concrete ways to support a load that's disproportionately women's to carry.
You already know the first lever: the plant-based, fiber-rich eating pattern that supports your estrobolome is also the best broad starting point here. The second is a stress-reduction practice like meditation. The encouraging part is how fast it works: gene expression in gut bacteria can shift within 48 hours of a dietary change, even if symptom relief takes longer. “It's the most plastic and adaptable part of our bodies,” Mayer says, and one of the biggest advantages we have against a rapidly changing environment.
Whatever stage of life you're in, this is one of the few systems in your body built to adapt as fast as your life demands. Your gut may be aging your brain, but the same system is just as capable of helping you carry what you're carrying.
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The information provided about wellness and health is for general informational and educational purposes only. We are not licensed medical professionals, and the content here should not be considered medical advice. Talk to a doctor before trying any of these suggestions.
