Is rapamycin detrimental to gut microbiome? specially L. reuteri

Recently i have been making and taking yogurt of Lactobacillus reuteri according to Dr. William Davis’ method. according to published articles, L. reuteri seems to be a wonderful bacterium capable of making vital hormone oxytocin in the gut and also acquiring ergothioneine, an important element for mitochondria function.
Does weekly dose of 6mg rapamycin kill off the bacteria in our gut and they have to be replenished?

Yeah, I use Reuteri pretty regular via Davis. I use BB12 too, and a Rhamnosus GG. I’ve always wondered if the Rapa would briefly inhibit the mtor in the bacteria and put some pressure on the microbiome. Because it is such a broad mix of microbes, some of them fungus. I would think it would have certain effects, but i have not seen where any work was done on this.

It’s not going to kill them, otherwise we would have all kinds of problems. I had my microbiome done by thorne and had all kinds of stuff in there.


Rapamycin definitely does something to the microbiome; in many of the longevity research studies they note that the size of the poops from the rapamycin-mice is much smaller than the poops from the control mice.

Many people here have also commented that as they take more rapamycin their stool / poop size decreases.

But, nobody has done a thorough analysis of rapamycin’s impact on the microbiome in any mammal to the best of my knowledge.


i recall some folks here they reported when they took high dose rapamycin and got diarrhea. I think that’s a bad sign of rapamycin killing gut bacteria.

I’ve not seen any research around this issue. What makes you think that diarrhea is a sign that gut bacteria is getting killed?

I’ll post an interview with Adam Salmon soon, the lead researcher on the Marmoset study. He talks a bit about the impact of rapamycin on stomach stem cells, and other factors. But I don’t think anyone has a good idea on why the rapamycin triggers diarrhea at higher dosing.

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i am guessing, think of taking large dose of antibiotics and getting diarrhea afterwards

Rapamycin has anti-fungal properties, and many people have reported that it clears up toe nail fungus as here: Rapamycin and toenail fungus onychomycosis

But I don’t know if anti-fungal drugs behave at all like anti-biotics. Perhaps some of the medical professionals here might be able to add their thoughts on this issue.


I was surprised to learn that L-reuteri is inhibited by stevia, which is used as a sweetener in many healthy products.

I use stevia and homemade reuteri everyday. I definitely still get benefits from the reuteri. No problems so far for me. My gut is the happiest it’s ever been.

Yes I think diarrhea would be a good time to lower your dose significantly. Leaky gut is real and can cause havoc in the body. I’ve not experienced any loose stool from rapa yet thankfully.

Edit: @pollux I’ve also been making Dr. Davis’s L. Reuteri yogurts as well as some others (mainly reuteri tho). I think it’s probably the best change I’ve made to my diet. I haven’t noticed any negative effects from the rapamycin. Make sure to stick with it because the benefits can take a while to become noticeable. He also recommends including hyaluronic acid, marine collagen, and astaxanthin. Dr. Davis’s books have really helped me, although I don’t think they’re for everyone—especially considering how unique everyone’s gut health can be. I make a huge batch every two weeks. Good luck with it.

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I had the complete opposite effect, but I also ramped up my fiber intake with psyllium husk, inulin, and homemade yogurt around the same time. Now, I get my biggest poops ever, which I actually love. Fewer wipes and fewer trips to the bathroom really suit me, especially with my sciatica acting up when sitting on the john. It’s significantly improved my quality of life.


Rapamycin definitely improved my digestion and elimination. And when I stopped for 6 weeks the benefits started to go away. I have a paper somewhere that indicates that it actually helps the microbiome. I’ve never seen anything that says it’s detrimental other than if people take too much. I think it might also be an issue if you have a seriously dysfunctional microbiome.