NMN Consumption and the Health of Your Gut: How a Healthier Gut Microbiome Increases the Rate of Absorption and Effectiveness of NMN Intake
In this blog, a paper would be reviewed and summarized that explains the most cutting edge understanding of the effects of NMN++. It is rather apparent that the cutting edge research surrounding NMN and NAD+ has been quite robust in terms of human and animal involvement and its corresponding controls, and they highlight the strong link between gut health and NMN consumption effectiveness.
The article in discussion is a scientific paper titled "Nicotinamide riboside and nicotinamide mononucleotide facilitate NAD+ synthesis via enterohepatic circulation", published in Science Advancements (March 2025).
Here is a summary of the core findings and context of this study:
Background
NAD+ (nicotinamide adenine dinucleotide) is a critical coenzyme found in all living cells, essential for energy metabolism and cellular repair. Because NAD+ levels naturally decline as we age—contributing to various age-related metabolic and neurodegenerative disorders—taking NAD+ precursors like NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) has become popular as a potential anti-aging supplement strategy.
However, exactly how the body processes and metabolizes orally or intravenously administered NMN and NR has remained a subject of ongoing debate.
Key Discoveries of the Study
Here are the specific, key scientific findings regarding how our bodies process the popular NAD+ supplements NMN and NR:
1. Oral NMN and NR rely heavily on gut bacteria
The prevailing assumption was that when you swallow NMN or NR, your intestines absorb them mostly intact, and your cells use them directly to synthesize NAD+. This study disproves that. In reality, only a tiny fraction is directly absorbed. The vast majority travels to the lower gut, where your gut microbiota (bacteria) break them down and deamidate them into Nicotinic Acid (NA).
2. IV injections still end up in the gut
Even when NMN or NR are injected intravenously (IV)—entirely bypassing the initial digestive process—they still don’t convert directly into NAD+ in peripheral tissues. Instead, the body rapidly converts them into nicotinamide (NAM) in the bloodstream. The liver then extracts this NAM, secretes it into bile, and dumps it right back into the intestines.
3. Discovery of the "Enterohepatic Loop" for NAD+
The core discovery of the paper is a hidden biological recycling system called enterohepatic circulation. Whether you take these precursors orally or by IV, they follow this specific loop:
i. Precursors (or their metabolized fragments) accumulate in the liver and are secreted via bile into the gut.
ii. In the gut, your microbiome converts them into Nicotinic Acid (NA).
iii. The NA is reabsorbed through the intestinal wall, enters the portal vein, and travels back to the liver.
iv. The liver then uses this NA via the Preiss-Handler pathway to efficiently manufacture systemic NAD+.
4. Antibiotics completely blunt the supplement's effects
To prove the gut microbiome's role was vital, the researchers treated mice with antibiotics to clear out their gut bacteria. When these microbe-depleted mice were given NMN or NR, the systemic boost in NAD+ levels was severely reduced. Without gut bacteria to convert the compounds into Nicotinic Acid, the body could not efficiently process the supplements.
What this means for consumers
If you take NMN or NR supplements, their effectiveness isn't just about the quality of the capsule—it is deeply tied to the health and composition of your gut microbiome. If your gut bacteria are compromised (e.g., from a recent course of antibiotics), these expensive supplements may not boost your NAD+ levels effectively.
Why It Matters
Changes Our Understanding: Previously, many assumed that taking NMN or NR directly boosted NAD+ because the cells absorbed them intact and built NAD+ straight from them. This paper shows that the gut microbiome plays an absolutely essential role in transforming these precursors into a usable form (Nicotinic Acid) before the liver uses them to boost system-wide NAD+.
Supplement Design: Knowing that most NMN and NR rely heavily on the gut microbiota and an indirect metabolic loop could change how scientists design future anti-aging therapies and delivery mechanisms.
Reference
Yaku, Keisuke, et al. “Nicotinamide riboside and nicotinamide mononucleotide facilitate NAD+ synthesis via enterohepatic circulation.” Science Advances, vol. 11, no. 12, 21 Mar. 2025, https://doi.org/10.1126/sciadv.adr1538.
