Hey {{first_name}}

Last week we talked about how your liver clears oestrogen and how sluggish bile flow causes already-used oestrogen to recirculate instead of leaving your body.

I got a lot of replies on that one. The most common: "This explains so much. What do I do about it?"

So this week I went looking for the answer to that specific question.

And I found something I genuinely hadn't expected. A piece of research that's been sitting in academic journals since the 1940s and is only now starting to get talked about in health circles.

It involves a set of gut bacteria with a specific name. And what they do with your oestrogen after the liver finishes with it.

Pull up a chair. This one surprised me. ☕

Reply with your letter every answer shapes what comes next.

01 — Estrobolome 101: How Your Gut Shapes Estrogen Balance (Tiny Health, January 2026) The clearest plain-language breakdown of the estrobolome the collective set of gut bacteria and genes responsible for metabolising oestrogen. Key detail: when gut microbiome diversity drops, certain bacteria overproduce an enzyme called beta-glucuronidase, which unpacks already-processed oestrogen and allows it to be reabsorbed. An imbalanced gut can functionally drive oestrogen dominance independent of how much oestrogen your ovaries produce.

→ This is the mechanism that explains "normal hormone tests, real hormonal symptoms." Worth reading in full.

02 — Gut Microbial Beta-Glucuronidase: A Vital Regulator in Female Estrogen Metabolism (Gut Microbes, 2023) A peer-reviewed breakdown of exactly how gut bacteria produce beta-glucuronidase and what happens when its activity is too high. The paper confirms that the ratio of reabsorption to excretion controlled by this enzyme directly affects circulating oestrogen levels and downstream oestrogen-related conditions. The estrobolome is described as a functional part of the microbiome with clear clinical relevance.

→ The academic version of what I'll explain below. The mechanism is real and documented.

03 — Gut Microbiota Has the Potential to Improve Health of Menopausal Women by Regulating Estrogen (Frontiers in Endocrinology, May 2025) Published May 2025 specifically looking at how gut microbiota composition affects oestrogen levels and menopausal symptom severity. Confirms that gut bacteria with estrobolome function directly influence circulating oestrogen through enterohepatic circulation. Identifies dietary approaches including prebiotic fiber as a practical intervention for improving estrobolome balance.

→ This is where it gets actionable. The research points directly at gut bacteria diversity as the lever.

04 — The Estrobolome: Estrogen-Metabolising Pathways of the Gut Microbiome (International Journal of Cancer, April 2025) A 2025 systematic review confirming that microbial beta-glucuronidase activity is linked to circulating oestrogen levels, oestrogen dominance symptoms, and oestrogen-driven health conditions. The review notes that research in this area has accelerated significantly and that the estrobolome is now considered a clinically relevant factor in women's hormone health.

→ When multiple independent research groups are publishing on the same mechanism in 2025, something real is happening.

Last week I told you that your liver clears oestrogen via bile. That's Phase I and Phase II detox the liver packages used oestrogen for removal, bile carries it into the gut, and it exits your body.

That was the first two-thirds of the story.

Here's the part I didn't cover.

Once processed oestrogen arrives in your gut via bile, something has to finish the job.

And that something is a specific community of gut bacteria called the estrobolome.

The estrobolome is a collective term for the gut bacteria and the genes they carry that specifically metabolise oestrogen. Think of them as the gut's hormone management team. When they're working correctly, processed oestrogen moves through and exits via stool and urine. Cleared. Gone.

When they're not working correctly the situation gets complicated.

Here's the mechanism that surprised me when I read it.

Some gut bacteria produce an enzyme called beta glucuronidase. This enzyme does something specific: it unpacks already-processed oestrogen.

Remember the liver packages oestrogen in Phase II by attaching a molecule to it that makes it water-soluble and biologically inactive. Essentially tags it for removal. Beta-glucuronidase cuts that tag off. Reactivates the oestrogen.

Allows it to be reabsorbed through the intestinal wall and back into circulation.

The oestrogen your liver just cleared re-entering your bloodstream. Again.

When beta glucuronidase gets overactive, too much oestrogen stays in circulation and can overstimulate oestrogen-sensitive tissues. And the symptoms that follow cyclical bloating, breast tenderness, mood shifts, PMS that worsens year on year, skin that breaks out on schedule are not caused by your ovaries producing too much oestrogen.

If the ratio of reabsorption to excretion is disrupted, the estrogen level in the body may fluctuate significantly and further lead to estrogen-related diseases.

Your hormone test measures circulating oestrogen. It does not tell you how much of that circulating oestrogen is there because your body produced it versus how much got reabsorbed via beta-glucuronidase activity. To the test, it looks the same. To your body, it's a completely different problem.

This is where it gets practical.

Beta-glucuronidase activity is directly controlled by the diversity and balance of your gut bacteria.

When your gut microbiome is diverse and balanced, estrogen is more likely to be processed and properly cleared. But if it lacks diversity due to antibiotics, poor diet, stress, or inflammation, the estrobolome can shift in ways that increase estrogen reabsorption.

Which specific bacteria matter most? Lactobacillus and Bifidobacterium. Both are associated with healthy estrobolome balance and lower beta-glucuronidase overactivity. Both are selectively fed by prebiotic fiber specifically XOS, inulin, and FOS.

Those three XOS, inulin, FOS are not random. They're specifically documented in the research as the fiber types that increase Lactobacillus and Bifidobacterium populations in the gut. They don't just improve digestion in a general sense. They're specifically feeding the bacteria that regulate how much oestrogen your body reabsorbs every day.

Last week you learned that the liver is the upstream piece for oestrogen clearance.

Here's what's downstream: the gut bacteria that either complete that clearance or undo it.

You can have excellent liver function and well-supported bile flow but if the estrobolome is imbalanced, oestrogen that the liver successfully processed gets recirculated anyway. Both pieces of the pathway matter.

They're not competing approaches. They're sequential ones.

Constipation makes this significantly worse. An imbalanced gut may produce too much beta-glucuronidase, reactivating more oestrogen than your body needs. When transit time is slow and processed oestrogen sits in the intestine longer, there's more time for beta-glucuronidase to unpack it for reabsorption.

Bowel regularity is not a comfort issue. It's a hormone clearance issue.

Move your bowels daily. Keep transit time short. That alone reduces reabsorption opportunity.

[Affiliate disclosure: This is a paid partnership. I only feature things that make sense for this community.]

This week I want to come back to Peak BioBoost but for a completely different reason than last time.

Last time, I talked about prebiotics vs probiotics. Seeds and soil. The general case.

This week is specific.

Peak BioBoost's formula contains XOS, inulin, FOS, and acacia gum the exact prebiotic fiber types documented in the research to selectively increase Lactobacillus and Bifidobacterium populations. These are the bacteria directly responsible for balanced estrobolome function and controlled beta-glucuronidase activity.

If you read last week's newsletter and you're doing the liver-bile work upstream Peak BioBoost addresses the downstream piece. The bacteria that complete oestrogen clearance after the liver does its job.

It's tasteless. Dissolves in your morning coffee. One scoop.

→ Check out Peak BioBoost here

Shareable 1: "There are gut bacteria specifically controlling how much oestrogen your body reabsorbs every day.

They're called the estrobolome.

When they're balanced oestrogen clears properly after the liver processes it.

When they're not an enzyme called beta-glucuronidase unpacks already-processed oestrogen and puts it back into circulation.

This explains PMS that worsens every year despite 'normal' hormone tests.

Your gut bacteria are managing your hormones. 🌿"

Shareable 2: "Constipation is not just a comfort issue.

When transit time is slow, processed oestrogen sits in your intestine longer. More time for gut bacteria to reabsorb it before it exits.

Bowel regularity is a hormone clearance issue.

The estrobolome research says this clearly. Most hormone advice doesn't mention it once. 😌"

Shareable 3: "The bacteria that control oestrogen reabsorption Lactobacillus and Bifidobacterium are specifically fed by XOS, inulin, and FOS.

These are prebiotic fibers. Not probiotic supplements.

You're not adding bacteria. You're feeding the ones already there that regulate your hormones.

The upstream piece is your liver. The downstream piece is your estrobolome. Both matter. "

This one surprised me when I was researching it. The estrobolome has been in the research since the 1940s and it's only now starting to appear in mainstream health conversations.

If this connected something for you reply and tell me. Specifically: does the cyclical pattern make more sense now? I'm genuinely tracking how many people in this community have the oestrogen-clearance pattern versus the bile-flow-only pattern. They often overlap but the approach shifts slightly depending on where the breakdown is.

Talk soon,

Wilson From Nature The Cure 🌿

P.S. The 7-Day Bloat Reset addresses the upstream liver-bile piece. Peak BioBoost addresses the downstream estrobolome piece. They're not the same product targeting the same problem. They're sequential steps in the same clearance pathway. Worth knowing the difference.