What is the estrobolome? How your gut handles estrogen
The estrobolome is the group of gut bacteria that can change how much estrogen leaves your body and how much comes back in. Your liver packs used estrogen up for removal. Some gut bacteria unpack it, and it gets absorbed again. That biology is real and it applies to men as well as women. The stool tests and the supplements sold on the back of it are mostly ahead of the evidence. This note gives you the plain version and what I would do with it.
Where estrogen goes when your body is done with it
Estrogen does its work and then it has to be cleared. Most of that clearing starts in the liver.
The liver attaches a small tag to each used estrogen molecule. The tag makes the estrogen dissolve in water, which switches it off and makes it easy to remove. Some of the tagged estrogen leaves through the kidneys in urine. The rest is sent out with bile into the gut, to leave in the stool.
That second route is where the bacteria come in. Estrogen that reaches the gut still has one more checkpoint to pass.
What the gut bacteria do
Some gut bacteria make an enzyme called beta glucuronidase. The enzyme clips the tag off. Once the tag is gone, the estrogen is active again, and the gut wall can absorb it back into the blood.
So a share of the estrogen your liver sent out comes back around for another lap. Researchers named the bacteria that do this the estrobolome in 2011. The idea itself is older. The enzyme has been studied since the 1940s.
Everyone has these bacteria. The open question is how much the amount of enzyme activity in one person's gut changes that person's estrogen levels. That is where the science gets thinner.
This is true for men too
Men make estrogen. They make it from testosterone, mostly in fat tissue, and they need it for bone strength.
One of the most quoted human studies on this subject looked at men and women together. In men and in women past menopause, a more varied gut bacteria population went with higher estrogen in the urine. The same was true for higher activity of the enzyme. In women who were still cycling, the link did not show up.
That makes sense. When the ovaries are making large amounts of estrogen, they drown out the smaller effect from the gut. When the ovaries are quiet, or were never part of the picture, the gut's share becomes easier to see.
What the research can and cannot say
I want you to hold this idea at its true size.
The mechanism is solid. Bacteria do clip the tag, and estrogen does get reabsorbed. What we lack is proof that changing your gut bacteria changes your symptoms. Most human studies are small. Most show that 2 things travel together, which is different from one causing the other. Diet, age, body weight, alcohol and antibiotics all affect both the gut and estrogen, so they are hard to separate.
There is no validated test for your estrobolome. Stool tests that report beta glucuronidase cannot tell a doctor what your estrogen is doing. The enzyme works on many substances besides estrogen, including medications and compounds from plants.
In perimenopause, estrogen swings widely because of the ovaries themselves. It can run higher than it did in your thirties one month and drop the next. The gut is a small player next to that. I would never tell a woman her heavy periods or her hot flashes come from her gut bacteria.
Supplements sold for estrogen clearance, such as calcium D glucarate, rest mostly on animal studies. I have not seen good human trials. I do not recommend them.
Your liver packs estrogen up to leave. Your gut has a say in how much of it goes.
What we know moves the picture
Fiber has the most support, and it is still modest. Fiber speeds the passage of stool and feeds a wider range of bacteria. Some studies link higher fiber intake with lower estrogen in the blood, and some do not find it.
Alcohol is the firmest one. Drinking raises estrogen levels, and it is an established cause of breast cancer, with risk rising from the first drink a day.
Body fat makes estrogen in both sexes. More fat tissue means more estrogen made outside the ovaries or testes. This one is well established.
Antibiotics change the gut population. Older studies found that more estrogen left in the stool during a course of antibiotics. That is interesting biology and no reason at all to avoid an antibiotic you need.
Constipation is the one clients ask about most. Slower transit gives more time for reabsorption, which is plausible. The human evidence is limited. A daily bowel movement is worth having for plenty of other reasons.
What I would do first
I would start with fiber from food. The national guidance is about 25 grams a day for women and 38 for men, and most Americans eat around half of that. Beans, lentils, oats, berries, ground flax, vegetables. Add it slowly over 2 or 3 weeks and drink more water as you go, or you will bloat and quit.
A few cautions belong right here. If you have Crohn's, colitis, a history of bowel obstruction or IBS that flares with certain fibers, get advice from your doctor or a dietitian before you raise it. If you have a history of disordered eating, do not count grams. Add one food and leave the numbers alone. If you use a fiber supplement and take thyroid medication or other daily prescriptions, take them a few hours apart, because fiber can reduce how much of a drug you absorb.
Next I would look at how often you go. If you have a bowel movement fewer than 3 times a week, or you strain most days, tell your doctor. It is a medical symptom and it has treatments.
I would cut back on alcohol before I spent a dollar on a supplement. Of everything on this list, it has the strongest evidence.
I would ask where the liver enzymes sit on your last panel. The liver does the packing, so I like to know how it is doing. I wrote about that in Issue 014.
I would skip the stool test sold to measure your estrobolome, and the products sold to fix the result. Put that money toward groceries.
When to push harder with your doctor
Any bleeding after menopause needs to be checked. Menopause means 12 months with no period. Bleeding after that point is never something to wait on.
See a doctor soon if you soak through a pad or tampon every hour for several hours, pass large clots, bleed for more than 7 days, or bleed between periods or after sex.
If hot flashes or night sweats are wrecking your days, ask about hormone therapy. It is the most effective treatment for hot flashes, and it is a conversation for a menopause trained doctor.
Men should have new breast tissue or a lump examined. So should women, at any age.
A change in bowel habits that lasts more than a few weeks, blood in the stool or weight loss you cannot explain all need a workup. Please do not treat those with fiber and hope.
FAQ
Is the estrobolome real?
Yes. It is the name for gut bacteria that can reactivate estrogen your liver had packed up for removal. The mechanism is well described. How much it changes symptoms in any one person is still unproven.
Can I test my estrobolome?
There is no validated test. Some stool tests report an enzyme called beta glucuronidase, and that enzyme acts on many things besides estrogen. A doctor cannot use the result to tell you what your estrogen is doing.
Do probiotics balance estrogen?
I have not seen good human evidence that a probiotic changes estrogen levels in a way you would feel. Eating more fiber and a wider range of plants supports a varied gut population. That is the step with the most backing.
Does fiber lower estrogen?
Some studies link higher fiber intake with lower estrogen in the blood, and others do not find it. Fiber has clear benefits for the bowel, cholesterol and blood sugar. I recommend it for those reasons, and any effect on estrogen is a bonus.
Does the estrobolome matter for men?
Yes. Men make estrogen from testosterone and clear it the same way. In one human study the link between gut bacteria and estrogen showed up in men and in women past menopause.
In good health,
Yvette Rose
Sources
- Flores R et al. Fecal microbial determinants of fecal and systemic estrogens and estrogen metabolites: a cross sectional study. J Transl Med, 2012.
- National Cancer Institute. Alcohol and cancer risk.
This is general wellness education and not medical advice, diagnosis or treatment. Talk to a qualified professional, especially if you are pregnant, nursing, taking medication or managing a condition.