The Estrobolome is important to men and serves to regulate the oestrogen to testosterone balance, affecting all aspects of men’s health from levels of fatigue to the risk of prostate cancer; but there may well be a Testobolome too.
What is the Estrobolome?
In 2011 the term Estrobolome was coined to represent a subset of the bacteria in your microbiome and their genes that can direct and regulate how much oestrogen is reabsorbed from the gut after your liver has processed it (conjugated it by adding a molecule) for excretion. The conjugated oestrogen passes into the bile and then into the gut for excretion. And the gut is where the Estrobolome lies, waiting (1).
The bacteria in the Estrobolome possess genetic material that can produce enzymes such as beta-glucuronidase, beta-glucosidase, and sulfatase, which can direct the deconjugation and reform normal oestrogen that can then be reabsorbed into the host’s body.
The main bacteria in the Estrobolome include members of the families Lactobacillus, Bifidobacterium, Bacteriodes, Clostridiaceae, Ruminococcaceae, Clostridium, and Escherichia.
It is not just an important issue for women, where the Estrobolome regulates oestrogen deficiency or oestrogen dominance.
Men must have these families of bacteria, particularly strains of the families Lactobacillus and Bifidobacterium. Unfortunately, these two families were 96 per cent of men's microbiome at 2 months of age, but dwindle to less than 4 per cent at 50, due to factors such as a modern diet, food poisoning, environmental toxins and drugs. Without these families, levels of oestrogen are unregulated, the oestrogen - testosterone balance is weakened and the risk of prostate cancer, brittle bones and cardiovascular disease increases.
The importance of the Estrobolome to men.
In men, a healthy estrobolome function is essential for maintaining a healthy balance of oestrogen with testosterone, supporting sperm maturation, libido, erectile function, and muscle mass.
Disruptions to the gut microbiome (dysbiosis) can thus lead to estrogen increases, interfering with testosterone production and increasing the risk of metabolic disorders like obesity, insulin resistance, and cardiovascular disease not just cancer. Decreased muscle mass, poor bone health and increased risk of prostate cancer or even male breast cancer has been linked to the performance of the male estrobolome.
As men age and approach andropause, natural testosterone declines, while oestrogen may rise, further decreasing testosterone. Thus estrobolome health is vital for managing the correct testosterone levels in men, and restricting cancer but also seemingly minor symptoms like fatigue and mood changes.
What if there's a Testobolome?
Some researchers talk of an Androbolome, but in 2026, a group of researchers looked at the Testobolome (2). It turns out that conjugated testosterone (testosterone glucuronide and testosterone sulfate) can be deconjugated by β-glucuronidase and sulfatase (the same two enzymes of the Estrobolome), generating free testosterone in the bloodstream.
Men with higher serum testosterone have more diverse gut communities, with genera such as Acinetobacter (phylum Pseudomonadota), Dorea (phylum Bacillota), Ruminococcus (phylum Bacillota), and Megamonas (phylum Bacillota) significantly increased in the feces.
Of course other factors come into play.
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Dietary Inputs can support correct hormone balance or disrupt it. Useful foods would include high fiber foods such as oats, pulses, and nuts and seeds; then prebiotic foods (garlic, onions, endive, dark chocolate), and probiotics (raw cheese, raw milk, Greek yogurt, olives, kefir) to support beneficial bacteria.
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Chemicals of concern: Of course, compounds toxic to the estrobolome would include endocrine disruptors (BPA, plastics, herbicides, perfumes and chemicals in your body wash, sunscreen or toothpaste), while excessive alcohol can harm gut diversity as can antibiotics, PPIs and some common ‘safe’ drugs. In the past, we covered research that linked 13 chemicals to prostate cancer in men and perfume chemicals to men with testicular cancer.
Although there is clearly more work to be done, this emphasises the need for men and women to rebuild their microbiome as soon as something goes wrong. Women and men coming to CANCERactive with cancer, often have a history of a poor gut, early antibiotics, chronic fatigue syndrome, food poisoning, but they just keep going, often consuming pills and foods that make it worse.
If you have a poor microbiome it will affect your oestrogen and testosterone levels.
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References
1. Microbiome and malignancy; Claudia S Plottel, Martin J Blaser; Review Cell Host Microbe
. 2011 Oct 20;10(4):324-35. doi: 10.1016/j.chom.2011.10.003.
2. The testobolome in microbial testosterone metabolism and human health. Veerus, L., Subrahmanian, A. & Blaser, M.J. Nature; npj Biofilms Microbiomes 12, 9 (2026).