Hidden ability: can intestinal bacteria “reverse aging” and make us smarter and younger?

Recently, scientists discovered for the first time that transplanting the intestinal flora of young mice into aging mice can improve the cognitive function of the "mice".

Research from Ireland found that "young" intestinal bacteria can reverse the immune and metabolic differences caused by aging, which means that transplanting the microbiota of young people may become a way to "cure aging."

As early as a few years ago, studies have found that transplanting the intestinal flora of young fish to middle-aged fish can effectively improve their motility and increase their lifespan.

This study is the first time we have discovered in mammals that intestinal bacteria transplantation can have an "anti-aging" effect.

The first step of the experiment is to transplant the flora:

The fecal microbes of 3-4 month old young mice were transplanted into 19-20 month old old mice.

As a control, the other two groups were young mice transplanted with young intestinal bacteria, and old mice transplanted with old intestinal bacteria.

Step 2: Analyze the bacterial flora

Four weeks after the transplant, the intestinal flora composition of the mice was analyzed. The results showed that although there were obvious differences in the β-diversity of intestinal flora between young and old mice before the transplant, the differences gradually disappeared after the transplant.

Overall, 20 bacterial genera were significantly altered, primarily the beneficial bacteria Enterococcus, which decreased in aged mice but increased in abundance after transplantation of young mice's intestinal bacteria.

Step 3: Analyze the function

Functional analysis revealed that after transplantation of young mouse intestinal bacteria, propionic acid synthesis and acetic acid degradation by intestinal bacteria were significantly reduced. In addition, immune cells in the mesenteric lymph nodes (MLN) and circulation also changed. CD8 T immune cells increased significantly in aged mice, while these cells began to decrease after transplantation of young intestinal bacteria. At the same time, the number of CD103 dendritic cells also decreased, and the elevated level of IL-10 in the blood was also improved.

Step 4: Effects on the Brain

Due to the existence of the gut-brain axis, regulating the intestinal flora can show changes in the brain. By analyzing the brains of mice, it was found that the microglia in the brains of aging mice increased significantly. In various neurodegenerative diseases, microglia are enlarged, and intestinal bacteria transplantation can reverse this phenotype. Genes related to various neurological diseases such as Alzheimer's disease in microglia have changed.

In addition, significant changes were also seen in the hippocampus, which is associated with cognition. After intestinal bacteria transplantation, 35 metabolites that change significantly with aging returned to pre-aging levels, including aging-related retinol, γ-hydroxybutyric acid, N-ethanolylceramide, and other metabolites related to cognition and neuroinflammation.

By testing the cognitive abilities of mice, it was found that intestinal bacteria transplantation significantly improved the spatial memory ability of aging mice and had a certain effect on improving anxiety.

This is the first time this phenomenon has been discovered in mammals. Of course, we cannot simply extrapolate this to humans.

At least it can give us this revelation: the seemingly tiny intestinal flora affects our health and longevity, and by regulating the intestinal flora, there is the potential to reverse aging.

Would you consider this approach?

Boehme, M., Guzzetta, KE, Bastiaanssen, TFS et al. Microbiota from young mice counteracts selective age-associated behavioral deficits. Nat Aging 1, 666–676 (2021). https://doi.org/10.1038/s43587-021-00093-9