Bloating that wasn't there before. Constipation, then loose stools, then constipation again. Heartburn from foods you used to tolerate fine. A general sense that your digestion became unreliable sometime in your late thirties or forties. If you've been attributing this to stress or diet changes, you're only partly right. Hormones are the piece most people miss.
Meet the estrobolome
The estrobolome is the collection of gut bacteria that specifically metabolize and regulate estrogen. These microbes produce an enzyme called beta-glucuronidase, which deconjugates estrogen metabolites in the gut, allowing them to be reabsorbed into circulation. In a healthy gut microbiome, this process is well-regulated. When the microbiome is disrupted, estrogen metabolism goes with it.
An overactive estrobolome can lead to estrogen recirculation. An underactive one leads to estrogen being excreted before it can be reabsorbed. Either way, the microbiome is influencing your hormonal balance directly.
How perimenopause disrupts gut function
Estrogen and progesterone both have direct effects on the gastrointestinal tract. Estrogen receptors line the gut wall; estrogen helps regulate motility, reduces intestinal permeability, and has anti-inflammatory effects on gut tissue. Progesterone relaxes smooth muscle, including the gut — which is why progesterone-dominant phases are associated with slower motility and constipation.
As these hormones fluctuate in perimenopause, the gut feels every shift. The erratic motility, increased sensitivity, and new food intolerances are tracking your hormonal cycle, often week to week.
What actually supports gut-hormone health
Fiber is foundational — soluble fiber feeds the estrobolome and supports appropriate estrogen excretion. Aim for 25–35 grams daily from whole food sources. Fermented foods provide live bacteria that support microbiome diversity. A 2021 Stanford study showed fermented food consumption increased microbiome diversity and reduced inflammatory markers more effectively than a high-fiber diet alone.
Flaxseed specifically contains lignans, a type of phytoestrogen that supports healthy estrogen metabolism in the gut — one tablespoon daily of ground flaxseed is one of the most evidence-backed nutritional interventions for perimenopausal hormonal balance.
Reducing ultra-processed foods, alcohol, and artificial sweeteners matters — all three disrupt the microbiome in documented ways. And supporting the hormonal foundation through this transition helps the gut directly: more stable estrogen means more stable gut function.
Jenna Sorrells, Ed.D., MPH
Founder of Her Rhythms. Public health expert and women's wellness advocate helping women navigate perimenopause with science-backed, phase-specific support.