# NMN Supplementation Mitigates NAD+ Depletion in Radiation-Induced Colorectal Injury

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NMN & NR Supplementation · 2026-05-02


    Recent research indicates that nicotinamide mononucleotide (NMN) supplementation can mitigate NAD+ depletion associated with severe radiation-induced colorectal injury. This study highlights the intricate relationship between gut microbiota composition and NAD+ levels, particularly in the context of radiation proctitis (RP), a common complication following pelvic radiotherapy.

 What this study examined

This study investigated the role of gut microbiota and metabolomes in 55 patients undergoing pelvic radiotherapy, categorizing them based on the severity of radiation proctitis (RP). Researchers utilized multi-omics approaches to profile fecal microbiomes and metabolomes, focusing on the relationship between microbial composition and NAD+ levels. They found that patients with severe RP showed a significant reduction in NAD+ levels and an enrichment of specific Bacteroides species. The study also employed mouse models to validate the effects of fecal microbiota transplantation and NMN supplementation on radiation-induced injury.

 Why this matters for longevity research

The findings of this study have important implications for longevity research, particularly regarding the role of NAD+ in cellular health and repair mechanisms. NAD+ is a crucial coenzyme involved in various metabolic processes and is closely linked to the activity of sirtuins, proteins that play a significant role in aging and longevity. Understanding how gut microbiota influences NAD+ levels can inform strategies aimed at enhancing healthspan and potentially extending lifespan.

 Key findings

Patients with severe RP exhibited reduced fecal and tissue NAD+ levels.

Bacteroidales were enriched in patients with severe RP, while Firmicutes were more prevalent in mild cases.

Microbial genes associated with nicotinate/nicotinamide metabolism were identified as contributors to NAD+ depletion.

Fecal microbiota transplantation from severe-RP donors exacerbated colorectal injury in mouse models.

Gavage with Bacteroides worsened pathology and further decreased NAD+ levels.

NMN supplementation was found to attenuate radiation-induced injury and restore NAD+ levels.

Mechanistic studies indicated that Bacteroides reduced mitochondrial membrane potential and affected stem-cell proportions.

 The science behind it

NAD+ is essential for various biological processes, including energy metabolism, DNA repair, and cellular signaling. It acts as a substrate for sirtuins, which are implicated in the regulation of aging and longevity. The study's findings suggest that the gut microbiota, particularly certain Bacteroides species, can influence NAD+ metabolism, potentially impacting the regenerative capacity of intestinal tissues. This relationship underscores the importance of maintaining a healthy microbiome for optimal NAD+ levels, which may be crucial for enhancing healthspan.

 How it fits into the longevity field

This research contributes to a growing body of literature exploring the intersection of gut microbiota, NAD+ metabolism, and aging. Other interventions, such as caloric restriction and exercise, have also been shown to enhance NAD+ levels and promote healthspan. NMN supplementation is gaining attention as a potential strategy to counteract age-related NAD+ decline, aligning with findings from other studies that emphasize the importance of NAD+ in longevity.

 Practical takeaways

Researchers and informed readers should consider the implications of gut microbiota on NAD+ levels and overall health. The study suggests that targeting the microbiome and NAD+ metabolism may provide new avenues for mitigating radiation-induced injuries and enhancing tissue repair. Further research is needed to explore the potential of NMN and other interventions in promoting healthspan and longevity.

 FAQ

 What is the role of NAD+ in aging?

NAD+ is a vital coenzyme involved in energy metabolism and DNA repair, playing a significant role in cellular health and longevity.

 How does gut microbiota affect NAD+ levels?

Specific gut bacteria, such as Bacteroides, can influence NAD+ metabolism, potentially impacting tissue health and regenerative capacity.

 Can NMN supplementation improve healthspan?

Research suggests that NMN supplementation may help restore NAD+ levels and support cellular functions, potentially enhancing healthspan.

 Source: PubMed · Gut Microbes · published 2026-05-02.

## Sources

- PubMed · Gut Microbes: https://pubmed.ncbi.nlm.nih.gov/41807298/