r/Microbiome: rules, karma requirements and posting culture

Who posts here

Two crowds share the room. One posts papers and talks in strain names, short chain fatty acids and study design. The other describes years of bloating after antibiotics in plain words and asks what to try. Basic questions stay up and get kind replies, often with a nudge to see a doctor or get blood tests, and the sidebar sends the most technical discussion to a microbiology subreddit.

• People with long running gut problems, often after antibiotics or food poisoning, looking for what worked for someone else.
• Self-experimenters comparing probiotics, fibres, fermented foods and diets, and reporting back.
• Readers who share new research, mostly as link posts, with little or no personal angle.
• A few working researchers and clinicians in the comments, who push back on unsupported claims.
• Supplement and test sellers, who are expected to disclose and are watched closely.

Karma and account requirements

What it takes to get a post through in r/Microbiome.

What you can post

What happens to a new post

Where the most recent posts ended up. Sample size: 400.

• Stayed up95%
• Removed by Reddit's filters3%
• Removed by moderators3%

Reddit counts a removal by the subreddit's own AutoModerator rules as a moderator removal, so that share is not all human. Held by AutoModerator means the post is waiting in the mod queue.

What happened when we posted here

We have posted here ourselves. This is how our own posts and comments fared.

Stayed up

91%

Removed by Reddit's filters

0%

Removed by moderators

9%

Period

January 2026 to July 2026

The rules, in the mods' words

1. 1

   No Attacking other Members

   This is a scientific sub reddit. Threads and comments are to remain civil, and discuss the microbiome. Posts or comments targeting any other member of the community individually will be removed moving forward.

2. 2

   Not science/evidence based.

   This is a science/evidence based sub. Usage of citations to support statements is highly encouraged.

3. 3

   Trolling, troublemaking, ad hominem

   Be respectful to others. Address the arguments, not the person. Trolls/troublemakers will be banned.

4. 4

   No Links without Disclosure and Discussion

   All links to websites or businesses that you own or receive monetary compensation from must be disclosed. Furthermore, any links posted must be relevant and be part of the broader discussion. Simply posting links without providing insightful commentary, will be considered spam, and will not be allowed.

5. 5

   Top level meme submission

   Memes as top level submissions are not appropriate, but can be posted in the comments.

6. 6

   No FMT sales/marketing

   No selling FMT or directing people to websites or businesses involving FMT. You will receive a warning for doing so, and if it becomes a continued issue, you will receive a ban. This is not the sub to find customers for your FMT business on.

These are the rules as archived in January 2025. Rules change. Check the sidebar before you post.

The culture

r/Microbiome has about 189,000 members and a slow pace, roughly 10 posts a day. The rules describe it as a scientific subreddit. In practice most of the feed is personal: someone lays out symptoms, tests and everything they have tried, and asks if anyone has been through the same thing. The median post gets 5 comments, and a relatable symptom thread can pull dozens.

The other half is research news. Links to new studies collect the highest scores, with few comments. The top post in our sample was a study about a fermented food, and others covered gut bacteria and hormones or engineered probiotics. Symptom threads run the other way, with modest scores and long comment sections.

The fault line is commercial products and unproven fixes. The mods have a standing AutoModerator message arguing that consumer stool tests cannot diagnose anything, and a rule against FMT sales. Members take the same line. Warnings about a supplement that made someone worse, or about a community seen as pushing one treatment, do well. Comments are longer than usual for Reddit, around 25 words, and very few contain a link.

What lands

• A recovery story with specifics: what the symptoms were, what was tried and failed, what finally changed things.
• A link to a new peer reviewed study, ideally with a short summary of the design and what it does and does not show.
• An open question that invites experience, such as how long a probiotic took to make a difference or what helped a particular kind of IBS.
• A blunt warning about a product that backfired, told as a personal account.
• Narrow practical questions, like how to tolerate lentils again.

What gets removed or ignored

• Requests to read a GI-MAP or similar stool test report. AutoModerator removes these with a long message, though some still get through.
• Posts selling FMT or pointing people to an FMT business. The rule promises a warning, then a ban.
• Links to your own site or product with no disclosure or no commentary.
• Memes as posts. They are allowed in comments only.
• Vague personal posts. Several moderator removals in our sample had titles that said nothing about the topic.

The unwritten rules

• Say what you have already ruled out. Replies start by asking about tests, diet and doctors, so put that in the post.
• Expect to be told to see a doctor. People add phrases like not asking for medical advice to their titles because threads that read as a request for a diagnosis get locked or pulled.
• Product names are met with suspicion by default. Asking if a product is a scam is a normal post. Praising one without context is not.
• Do not treat one study as settled. Commenters ask whether a mouse or hospital patient result applies to anyone else.
• Title your post with the actual topic. One word titles get less help and are more likely to be removed.

Self-promotion

The rule allows links to a business you own or are paid by only if you disclose it and the link is part of a real discussion. Posting links without commentary is defined as spam. FMT gets its own rule: no selling it and no sending people to an FMT business, with a warning first and a ban for repeats. In practice the community is hostile to anything that looks like a sales pitch, and very few comments carry links at all. A founder or formulator can post a properly argued, cited piece and have it stay up, but it has to stand as science with the product left out.

How people write here

Typical post length

95 words

Typical title length

7 words

Titles phrased as a question

39%

Typical comment length

25 words

Comments that include a link

4%

Posts that carry a flair

8%

The regulars

The accounts that showed up most in our sample. Worth reading before you post: they set the tone, and they are usually the first to reply.

Top keywords

The words and phrases that show up far more often here than in other communities, from recent posts in r/Microbiome.

• gut 142 posts
• microbiome 73 posts
• probiotics 54 posts
• probiotic 37 posts
• symptoms 73 posts
• bacteria 44 posts
• sibo 41 posts
• dysbiosis 31 posts
• bloating 44 posts
• antibiotics 36 posts
• stool 36 posts
• gut microbiome 24 posts
• stomach 45 posts
• foods 42 posts
• gas 46 posts
• diet 41 posts
• butyrate 14 posts
• severe 35 posts
• kefir 16 posts
• stools 22 posts
• food 46 posts
• eating 39 posts
• prebiotics 11 posts
• bifidobacterium 11 posts
• antibiotic 15 posts
• issues 52 posts
• strains 14 posts
• leaky gut 14 posts
• eat 40 posts
• fiber 23 posts
• digestion 17 posts
• fermented 15 posts
• akkermansia 10 posts
• histamine 13 posts
• stool test 11 posts
• bacterial 13 posts
• acid 23 posts
• gut health 15 posts
• chronic 20 posts
• gi map 9 posts

Posts that did well

• This popular fermented food may help flush nanoplastics from the body330 upvotes · 26 comments
• Fixed my gut issues after years of struggling.214 upvotes · 94 comments
• New study uncovers bacterial route to testosterone production183 upvotes · 7 comments
• Engineered Probiotic Wipes Out 43% of Colorectal Tumors in Mice: The engineered E Coli packed a triple-whammy – chemotherapy produced directly inside the tumor, an immune stimulant, and a localized form of immune checkpoint blockade.146 upvotes · 2 comments
• STAY AWAY from Good Bacteria Symbiotic108 upvotes · 61 comments
• Scientists find a natural gut compound that helps heal the intestine82 upvotes · 7 comments
• how long of consistent probiotics did it take you to rebalance your gut?54 upvotes · 69 comments
• Federal science funding cuts and grant freezes implemented in 2025 have caused severe professional and mental distress for early-career U.S. researchers, driving 60 percent of surveyed scientists to consider moving abroad and 56.7 percent to contemplate leaving academic research completely.48 upvotes · 4 comments · Scientific Article Discussion

Common questions