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Perimenopause changes more than hormones. According to Cynthia Thurlow it also changes the microbiome, often in ways women feel long before they understand what’s happening.
The bloating that suddenly appears after meals that never caused problems before. The brain fog. The disrupted sleep. The shifting mood, digestion, energy, and stress tolerance. In this conversation with Two Moons, Cynthia explains that many of these symptoms are not isolated issues, but part of the same biological conversation happening between the gut, the microbiome, and our hormones.
A nurse practitioner with more than 25 years of clinical experience, Cynthia has become one of the leading voices in the perimenopause space through her podcast, writing, and widely viewed TEDx talk on intermittent fasting. Her latest book, The Menopause Gut explores the connection between the microbiome and hormonal health in midlife, including how gut health may influence everything from inflammation and mood to metabolism and cognitive function.
Cynthia also reframes menopause itself not as a collapse, but as what she calls a “middle pause”, a moment that forces women to pay closer attention to the systems that have been quietly carrying them all along.
1. Your book introduces the idea that the gut microbiome and our hormones are in a bidirectional relationship where each one affects the other.
For women who are familiar with hormonal symptoms but have never thought about gut health as a root cause, how would you describe that connection in plain terms?
Think of your gut and your hormones as roommates - what one does directly affects the other's mood. Your gut microbiome contains a community of bacteria called the estrobolome, which is specifically responsible for metabolizing and recirculating estrogen throughout your body. So when your gut is out of balance, your hormones feel it, and when your hormones are shifting, your gut feels that too.
2. You write that gut microbiome diversity peaks around age 40, right at the onset of perimenopause for many women.
Is that timing a coincidence, or is there a biological reason those two transitions happen together?
This is absolutely not a coincidence - it's biology giving us a very clear signal that we need to pay attention. As estrogen begins to decline in perimenopause, it takes with it some of the microbial diversity that estrogen actually helps sustain, which is why the two transitions mirror each other so closely.
Your gut and your ovaries have been in conversation your entire reproductive life - perimenopause is just the moment that conversation gets loud enough for you to finally hear it.
3. So many perimenopausal symptoms (bloating, brain fog, mood swings, weight changes) are also symptoms of gut dysbiosis.
How do you help women figure out which is driving which, and does it matter?
Honestly, in most cases I don't think it matters which came first. What matters is that you treat both, because they are almost always feeding each other. Bloating, brain fog, mood swings, and weight changes are your body's way of telling you that something is inflamed and out of balance, and that inflammation lives in the gut regardless of what triggered it. When you restore gut health, hormonal symptoms almost always improve, so start there, and see what's left standing.
4. You emphasize fiber-rich foods as a foundation of gut health during perimenopause. Seeds - flax, sesame, pumpkin, sunflower - are particularly rich in fiber, lignans, and phytoestrogens.
How do you think about food-based phytoestrogens as a tool for hormonal support during this transition, and what does the research actually support?
Food-based phytoestrogens like those found in flaxseeds, sesame, and soy are weak estrogen mimics that can gently buffer the drop in estrogen during perimenopause, and the research, while not perfect, does support their role in reducing hot flashes and supporting bone density.
What I love about seeds specifically is that they do double duty: the fiber feeds your gut microbiome, and the lignans support your estrobolome, so you're working the gut-hormone axis from both ends at once.
This is why I always say food is your first pharmacy and you don't have to wait for a prescription to start supporting your hormones.
5. You discuss leaky gut as a driver of systemic inflammation that affects everything from metabolism to bone health.
How does estrogen decline specifically contribute to gut permeability, and is that relationship reversible?
Estrogen plays a quiet but critical role in maintaining the tight junctions of your gut lining, essentially the gates that decide what gets into your bloodstream and what doesn't. When estrogen declines, those gates loosen, and you get increased intestinal permeability, which triggers the kind of low-grade systemic inflammation that drives everything from joint pain to brain fog to accelerated bone loss.
The good news is that this is largely reversible as the gut lining is one of the fastest regenerating tissues in the body, and the right nutrition, stress reduction, and microbiome support can meaningfully restore that barrier.
6. You include stress management as a core intervention for gut health. Can you walk us through the mechanism?
How does chronic stress specifically damage the gut microbiome, and how does that then affect hormonal balance?
Chronic stress floods your system with cortisol, which directly suppresses the diversity of your gut microbiome and increases intestinal permeability, essentially it punches holes in your gut lining and starves your good bacteria at the same time.
A depleted microbiome then produces less of the short-chain fatty acids and neurotransmitters your body needs to regulate mood and inflammation, which sends your hormonal system into further dysregulation.
It becomes a loop - stress damages the gut, the damaged gut amplifies your stress response, and your hormones are caught in the crossfire.
7. You recommend realigning circadian rhythm as part of gut restoration. Seed cycling is also a circadian-adjacent practice - it works with the body's monthly rhythm rather than the daily one.
Do you see a connection between respecting natural biological rhythms at every timescale (daily, monthly, seasonal) and overall hormonal resilience?
Your body runs on rhythms at every timescale, daily, monthly, seasonal, and your microbiome is exquisitely sensitive to all of them. When we disrupt our circadian rhythm through poor sleep, irregular eating, or chronic stress, we directly alter the composition of our gut bacteria, which then disrupts hormone metabolism.
Seed cycling works in the same spirit - it asks you to tune into your body's monthly rhythm and use food intentionally within it, and I think that kind of biological attunement at every level is exactly what perimenopause is asking us to come back to.
8. You include a section on hormone replacement therapy.
For women considering HRT, does gut health affect how well HRT is absorbed or metabolized? Is there a sequencing argument for healing the gut before or alongside starting HRT?
This is one of the most underappreciated conversations in women's medicine right now. Your gut microbiome, specifically the estrobolome, determines how efficiently you metabolize and recirculate the estrogen from HRT, which means a dysbiotic gut can leave you either under-responding to your dose or accumulating estrogen metabolites that create their own problems.
I always tell women that healing the gut alongside HRT, or ideally before, is the difference between HRT working well and HRT working at its full potential.
Your gut is the translator between the medicine and your cells.
9. You use the term “middle pause” to describe the perimenopause-to-menopause transition.
What does reframing this transition as a pause rather than a decline or a loss change about how women should approach it?
Language shapes everything and when we call menopause a decline or a loss, women experience it as something being taken from them, and that grief makes it so much harder to make empowered choices.
A pause is an invitation/ it's a moment to stop, reassess, and choose how you want to move forward with the wisdom and the body you have now.
When women start seeing this transition as their biology asking them to recalibrate rather than deteriorate, the whole conversation shifts from fear to agency.
10. If a woman in early perimenopause could do only one thing for her gut health starting tomorrow, what would you tell her?
Start eating 30 different plant foods a week, not perfectly, not expensively, just diversely. Research consistently shows that plant diversity is the single strongest driver of microbiome diversity, and a diverse microbiome is the foundation everything else is built on, your hormones, your mood, your metabolism, your inflammation levels.
Count colors, not calories, and let your gut start doing the work it was designed to do.
In Conversation With
Cynthia Thurlow is a nurse practitioner, author, and host of the Everyday Wellness podcast. A globally recognized expert in perimenopause/ Menopause and intermittent fasting, her TEDx talk has 15M+ views. She has been featured on ABC, FOX5, KTLA, CW, and The Megyn Kelly Show. With 25+ years of experience, she empowers women to live their most optimal lives. Learn more at www.cynthiathurlow.com