I believe it for anecdodal reasons. Since a few years ago I started eating vegetables and whole foods and greek yogurt, cottage cheese, my cravings for what foods I want to eat and what foods I like have changed so much. I can't stand the foods I used to love, and I love always having veggies now in my food. I'm always joking with my partner that my gut bacteria have mindcontrolled me and that I'm a zombie for my gut microbiome.
In the last three years, something related to my gut-brain connection got fucked. I'm not sure if it was some kind of post-viral inflammation causing stress, or stress of isolation causing inflammation. But it's definitely a two way street and mine got completely stuck in a feedback loop. The mainstream medical system failed to help me. Eventually some functional medicine doctors managed to help me improve via diet, supplements, herbal remedies and probiotics. Through (risky) experimentation and happenstance I found even more relief with some traditional medicines (pure Greek mastiha sap, kambo and Ayahuasca) and anti-malarial pills I had taken for unrelated reasons.

Unfortunately the mainstream medical system has been completely unable to investigate or explain what is going on with my body, but anecdotally, the theory that there is a two way street between gut bacteria and the brain completely aligns with my experience.

I'm feeling better now, though my stomach still feels sensitive and I can no longer tolerate gluten.

I get gut pain sometimes, on a semi regular basis. The day before the pain hits I have mild-euphoria, clear thinking, positive outlook, lots of energy, more social and extravert. It's not normal.

Something is going on with the brain and my gut.

It's possible that it's endorphins being released to stop any pain ... but this is about 24 hours before the crippling cramps start, and it's more a mood shift than pain killing. Before this great 24 hour, I'm normal baseline okay state.

Our gut biomes and the gut-brain axis are pretty mind-blowing in the way they facilitate our behaviors and general mental/physical health. It's amazing how much we haven't figured out yet too...especially with neural pathways.

Today's world of commercialized food (a few major foods/culprits in particular) throws inflammation at us in spades, and eating well has honestly made a huge difference in my life -- the most noticeable parts by far being cognition, energy, and mood. Every time I deviate from clean cooking and eating mainly whole foods, it's painfully obvious since my microbiome loves the new, healthier norm.

I would highly recommend this podcast (neuroscientist Andrew Huberman) if anyone wants to learn more about improving their gut health and the science and research that we know so far.

I read a book about all this recently called I Contain Multitudes. The thesis was that the gut biome controlled a lot, and given the evidence presented I thought it was compelling (as a layman) though not actionable. Based on that one piece of information I am not surprised by the OP.
So then where are we with parasites cause homosexuality?

Censor, downvote and otherwise dismiss without any intellectual pursuit. If that's what you did then it's an identity for you and evidence to the contrary won't matter.

If we are discussing gut/brain connection in one way why not in others?

This is a little scary, doesn't that mean they can hack you and cause issues from brain fog to mental illness.
Highly recommend this radiolab episode, which covers much of the content of this article including the Beaumont origin story and rat experiments in fascinating detail.
Ayurveda posited a form of gut-brain axis thousands of years ago (and is a core basis for its dietary aspects), interesting to see more scientific research delving into the details.
Tim Spector seems like a good source on this stuff, I listened to some podcasts of his and he's doing some work here in the UK with Zoe, where they test you and figure out a nuturion plan for you based on your gut bacteria and what is best for you personally.
Humans need a lot of nutrients for brain operation, so it makes sense that we would have a sophisticated system for working with the gut flora and fauna to support them so that they can help us digest food effectively. If this is the case, in a sense we then we invite the gut inhabitants, and ask them what they want so they can help us. I think it's reaching a bit to describe this as 'gut bacteria control the brain'.
Making my own kefir for 6 months did something to me I still can't quantify, like working out e.g.
Even for weight loss, some gut bacterial peptide helps. This is like semaglutide. See
Pair programming with my gut bacteria today
For the folks that take probiotics: how did you decide what to take?
There is an interesting book on the related topic - "This Is Your Brain on Food"[0]. If you like to try changes in the diet then there are a lot of suggestions in the book. But you might find the book to be quite verbose and repetitive.


There's also the Bone-Brain-Gut connection and Bone Gut connection. Bones are complex structures made of various proteins and studies have shown some microbiome as harmful to Bones or lack of diversity.

There was an experiment in mice that showed some mice devoid of any gut bacteria had better bone density than the other experiment group.

This is interesting and might suggest some bacteria can cause bone issues.

Archive link:
It is possible for a bacteria to evolve to release neurotransmitters etc.

There is a nervous system in the digestive system that is connected to the brain.

Therefore it is possible for a bacteria to evolve to influence the brain.

If it was possible for a bacteria to evolve to control their host then they would do so.

Therefore, they have done so.

sigh took them decades to realise. clap-clap

For me it's a common knowledge and I use it quite often.

BBC and NHS wildly behind the curve as usual.

This is, in fact, old hat

I have to wonder what the prevalence of psychedelics and antidepressants has done at a population level to change us.

A Multidisciplinary Hypothesis about Serotonergic Psychedelics. Is it Possible that a Portion of Brain Serotonin Comes From the Gut?

Seeking the Psilocybiome: Psychedelics meet the microbiota-gut-brain axis

Serotonin Reuptake Inhibitors and the Gut Microbiome: Significance of the Gut Microbiome in Relation to Mechanism of Action, Treatment Response, Side Effects, and Tachyphylaxis

"so we have evolved with these 'friends with benefits'."

I'll never think of my gut bacteria in the same way again.

Hate to be cynical but every time something like this comes up I can't help but thinking "You're telling me the leg bone's connected to the hip bone?"
News or articles about this keep coming out recently. but they all seem to be limited to "we think", "might" and the great potential it may have.

Since we do not know much about how the brain works to begin with I guess that is as close as we can get.

I say we dont know much about how the brain works as a I take medication for depression.

The way that works most often is that you are given a pill that may work. You take it for between 2 - 26 weeks, depending on results. (some may have a fast negative effect) and then you tell your doc if you feel better. (Sometimes complicated surveys)

if it didn't work, you get to do it over again. and again and again. until you find something that works, give up or die.

then sometimes it stops working.

One place I know does a cool, I forget the proper name. They take a "video" of how your brain is "working" (at an extremely low resolution). then they compare what they find to knowledge about what parts of the brain should be active, not active etc. From this they hope to establish a delta between "normal" and you.

Then you get to take pills and you come back (after some times) they do the whole thing over again, to see if you are now closer to "normal" or not.

The goal then being to find a chemical that brings you as close to normal as can be.

It is highly appealing in that it would offer -some- scientific basis for evaluating the drugs aside from "How do you feel".

If it -actually works- I have no idea. It was far too expensive for me, and to qualify you have to not have taken any medication already. (that would mess up the "virgin" recording).

An interesting research project would be recording tens of thousands of people who self-reported no depression in the hope that some would develop clinical depression and comparisons could be made.

If we now mix in gut bacteria into the equation, I can imagine you somehow "insert" new gut bacteria into a person and then you wait for some time and tell the doc if it worked or not. If not you can get a different psychobiotics and enter the loop. Add in regular medication for depression the number of possible permutation would become huge.

(I like to include this link to a Standford lecture on the difference between "being sad" and clinical depression

There's a hundred million neurons in our guts. It makes me think arguments about being brains in a vat, and treating the brain as a biological computer with inputs form the senses misses the fact that the brain is part of the nervous system extending throughout the body, and not some isolated system. An envatted brain isolated from the body is likely not going to function properly. The brain can only properly be understand as being part of a whole organism.
I certainly feel like my brain is in charge when I wake up, long enough to get my clothes on and out of the house on the school run and back, at which point my stomach resumes control for the rest of the day.