Three Years of Gut Microbiome Data for Flagellin Immunization and Fecal Microbiota Transplantation

I've posted in the past on a two year followup of a single-person self-experiment, a successful attempt to favorably adjust the balance of populations in the aging gut microbiome via a single treatment with flagellin immunization. This approach was intended to motivate the immune system into more aggressively destroying problematic microbes that tend to grow in number with age. As assessed using the Viome service, the intervention appeared to produce a sizable, lasting benefit to the quality of the gut microbiome in a basically healthy 50-ish individual. You can look back at those posts for the details of the protocol and further references regarding this use of flagellin.

As is the case for flagellin immunization, there is animal data to show that fecal microbiota transplantation from a young individual to an old individual rejuvenates the gut microbiome. There is a lot more of this animal data for fecal microbiota transplant, however, produced in varied species, and demonstrating that the improvement lasts for a lengthy period of time, and even results in improved health and extended life span.

Thus the same 50-ish individual mentioned above later undertook a fecal microbiota transplant, using donor material provided by a healthy, athletic 20-year-old volunteer, and further assessed the effects of this intervention on the gut microbiome. Stool samples were tested beforehand, one month afterwards, and six months afterwards. All of the measurements were again made using the Viome service. In the charts below, marks indicate that the flagellin immunization was conducted in 05/2020, and fecal microbiota transplant at the end of 08/2022. The dates marked on the horizontal axis are the dates of Viome testing.

In summary, while the flagellin intervention greatly reduced microbial diversity in the process of greatly improving other metrics, that diversity was restored by fecal microbiota transplant from a young individual. That restoration appears lasting as of the six month mark. The transplant produced small gains in some of the other metrics assessed by Viome, though not to the same degree as the flagellin immunization. That may well be because much of the potential scope for improvement was already achieved. Interestingly, neither intervention did much for Metabolic Fitness. According to Viome, half of the population falls into the 22-28 range for Metabolic Fitness (on a scale of 0 to 100!) which makes one wonder a little regarding the algorithm used in the construction of this value.

The protocol for conducting a fecal microbiota transplant at home is almost too simple to talk about, but there are a few points that are worthy of thought. The mechanics of it are straightforward. A fresh stool sample is provided by the donor, and that material is mixed with water. A few fluid ounces of the result are delivered as an enema. The recipient then lies in a suitably sloped position, abdomen higher than chest, for 30 minutes or so, in order to encourage the enema fluid to flow as deeply as possible into the intestine. Repeat this process for two to three times a few days to a week apart.

As to the points worth of thought: when fecal microbiota transplantation is conducted in the clinic as a treatment for C. difficile infection, colonic cleansing and colonoscopy equipment may be used, but more importantly, donor stool samples are screened for potentially pathogenic microbes that an older individual may respond poorly to. This screening is wise for an older recipient, as the aged immune system is far less competent than a young immune system, and that is an important factor when it comes to suppressing undesirable microbial species in the gut. What is innocuous to a young person may be much less innocuous to an old person. Rather than going through the process of finding a willing, healthy volunteer, and rolling the dice on potential issues, one can use services that will sell screened and characterized stool samples from young individuals, such as Human Microbes. This is recommended.


Great article, Reason. I was going to ask the procedure for the fecal transplant until reading down. Thanks for details on it. Be nice to know specifically what benefits the transplants reaps and how long but I assume data is still being gathered moving forward.

Posted by: Robert at April 3rd, 2023 5:25 PM

With so much research it appears that all older people ( say over 50?) Would benefit greatly from fecal transplants from a young doner.The enema icky factor may be too much for many however, along with the difficulty in choosing super healthy very young doners.
The company mentioned appears to do extensive screening and then sells the fecal matter in an easy to swallow capsule. This is only icky if you think too hard about it.
Seems like a great biohack to me!
Am I missing any downside here?
Thoughts appreciated.

Posted by: August33 at April 3rd, 2023 6:55 PM

I have personally performed myself FMT at home and can say it is by far the best intervention I have ever done trying to address aging, more than most supplements I have been taking with poor to no results, even sometimes with uncomfortable side effects. Tried Nuchido Time for a few years (cancelled my subscription), NAD injections, Vit C, magnesium, collagen supplements, vitamins, virtually half life extension store with mostly no results until I tried this stuff.

I started with a daily enema, the day after the first infusion the first thing my wife asked me was: what did you do? your face looks radiant, and it was true, I looked like 10 years younger overnight, I think it has to do with better blood supply to the skin and a huge amount of bacteria related to collagen production, present in younger adults but not any more once we age (that is my theory). Before I tried this I read a lot about FMT in other mammals and how adult mice lifespan was extended and age markers improved after being fed with stool from younger ones. This effect faded away a bit, but still persists 2 months later, my hair is now thicker too and my stool is well formed.

Donor quality (and age) seems to be crucial, after studying carefully all the options (not many really), checking donor microbiome profiles I decided to order from, the other option I had was Taymount clinic but had to travel to the UK and I couldn't find any information regarding donor's age. I started with one round of enema every 3-4 days and I keep doing a maintenance dosage (2 pills a day) until I finish my bottles, if they get a younger donor (my donor is in his 20s), I will probably order again, it seems children may be the best donors if we want to do FMT with antiaging purposes. The service and quality is amazing, they should have better marketing.

It seems fecal transplant along with blood transfusion from younger donors are right now the only real and proven methods to address aging.

Posted by: Martin at May 7th, 2023 7:23 AM
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