Is NMN Good for Your Liver? Science-Backed Benefits And Risks

Is NMN good for your liver? Yes, potentially—early lab and animal studies suggest NMN may protect the liver from scarring (fibrosis) and reduce fat buildup.

This data is preclinical, which means that it was obtained through studies on animal models. But while we wait for clinical trials, things are looking really promising.

Let’s learn more about how NMN might be able to help your liver.

What Does Research Tell Us About NMN And Liver Fibrosis?

In mice and liver cell models, NMN inactivates the scar-forming stellate cells and reduces fibrosis.

But before we dive into it, let’s learn more about liver fibrosis.

What Is Liver Fibrosis?

Liver fibrosis is a scar-building response to repeated or chronic liver injury. It is initially reversible but can progress to cirrhosis and liver cancer if the damage continues.

The main “scar-making” cells are hepatic stellate cells (HSCs). When injury signals (like TGF-β1) activate them, they proliferate and secrete collagen and other fibrotic proteins that stiffen the liver and impair function.

How Does NMN Protect Against Fibrosis?

A 2021 study showed that NMN turned down pro-fibrotic genes and secreted proteins in activated human HSCs and reduced extracellular matrix (scar) deposition in two mouse models of liver fibrosis.

The mechanism is a little complex so let’s break it down into a series of steps:

Liver injury leads to inflammation and oxidative stress.
Oxidative stress causes the degradation of the 15-PGDH enzyme. This enzyme breaks down prostaglandin E₂ (PGE₂).
HSCs need PGE₂ to get activated and wreak fibrotic havoc.
Since there’s a lower level of 15-PGDH, your body will have more PGE₂.
As a result, more HSCs will get activated and there will be more fibrosis.

This was the complete mechanism. NMN intervenes at step 2. It prevents oxidative degradation of the 15-PGDH enzyme, which increases PGE₂ breakdown and keeps HSCs “quiet.”

Why this matters: HSCs are the main source of scar tissue in liver disease. Dampening their activation is a major therapeutic goal in conditions that can progress to cirrhosis and liver cancer.

Can NMN Help With Fatty Liver And Insulin Resistance (Diabetes)?

In high-fat-diet mice, NMN improved insulin resistance, lowered liver fat, and improved intracellular coordination to improve liver function.

A 2024 paper reported that NMN improved lipid profiles, blocked insulin resistance and boosted cholesterol metabolism in obese mice. Not only that, it also reduced the weight gained by mice on a high-fat diet.

Moreover, it also prevented an increase in liver size or “fattiness” in response to a high-fat diet, while also reducing signs of damage and fibrosis. NMN even helped in significantly lowering the AST levels. AST levels are a biomarker that tell us the degree of damage to the liver. The higher the AST level, the greater the damage.

Together, these findings suggest that NMN has a comprehensively protective role in the liver against high-fat diet. While this study was based on mice models, it still looks very promising, especially for people with obesity or other metabolic disorders.

Is NMN Safe For The Liver?

NMN’s effects on the liver have not been investigated in humans. That said, there’s some evidence that high doses of vitamin B3 may be toxic for the liver. Since vitamin B3 and NMN both promote the production of NAD+, NMN might do something similar at very high doses. However, more human studies are needed to clearly establish a safety profile of NMN in the liver.

So far, NMN has not been shown to cause liver damage primarily because human studies have not investigated its effects on the liver. However, very high doses of a vitamin B3 can worsen liver problems in certain mouse models.

On the contrary, several other studies have reported that NMN is safe for human consumption and well tolerated, even at high doses of about 2000 mg per day.

Since we don’t have long-term clinical data yet, please ensure that you consult a physician before taking high doses of NMN, especially if you already have a chronic liver condition.

Final Thoughts: Is NMN Good For Your Liver

Based on animal and cell studies, NMN looks liver-friendly—it may reduce scarring, lower fat in the liver, and restore cellular energy balance. That said, we still need well-designed human trials to confirm benefits, ideal dosing, and long-term safety.

If you’re serious about supporting your liver and overall NAD+ levels, consider trying a clean, third-party-tested NMN.

Start by discussing it with your clinician, then pair it with sleep, movement, and a fiber-rich diet. Ready to take the next step? Shop HealthspanX Ultra Pure NMN™.

References

Zong, Z., Liu, J., Wang, N., Yang, C., Wang, Q., Zhang, W., Chen, Y., Liu, X., & Deng, H. (2021). Nicotinamide mononucleotide inhibits hepatic stellate cell activation to prevent liver fibrosis via promoting PGE2 degradation. Free radical biology & medicine, 162, 571–581. https://doi.org/10.1016/j.freeradbiomed.2020.11.014
Zhu, L., Zhou, Y., Li, R., & Deng, S. (2022). Macrophages produce PGE2 to promote hepatic stellate cell autophagy and liver fibrosis. Autophagy reports, 1(1), 389–392. https://doi.org/10.1080/27694127.2022.2119513
Li, Y., Tian, X., Yu, Q., Bao, T., Dai, C., Jiang, L., Niu, K., Yang, J., Wang, S., & Wu, X. (2024). Alleviation of hepatic insulin resistance and steatosis with NMN via improving endoplasmic reticulum-Mitochondria miscommunication in the liver of HFD mice. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 175, 116682. https://doi.org/10.1016/j.biopha.2024.116682
Komatsu, M., Kanda, T., Urai, H., Kurokochi, A., Kitahama, R., Shigaki, S., Ono, T., Yukioka, H., Hasegawa, K., Tokuyama, H., Kawabe, H., Wakino, S., & Itoh, H. (2018). NNMT activation can contribute to the development of fatty liver disease by modulating the NAD + metabolism. Scientific reports, 8(1), 8637. https://doi.org/10.1038/s41598-018-26882-8
Pencina, K. M., Valderrabano, R., Wipper, B., Orkaby, A. R., Reid, K. F., Storer, T., Lin, A. P., Merugumala, S., Wilson, L., Latham, N., Ghattas-Puylara, C., Ozimek, N. E., Cheng, M., Bhargava, A., Memish-Beleva, Y., Lawney, B., Lavu, S., Swain, P. M., Apte, R. S., Sinclair, D. A., … Bhasin, S. (2023). Nicotinamide Adenine Dinucleotide Augmentation in Overweight or Obese Middle-Aged and Older Adults: A Physiologic Study. The Journal of clinical endocrinology and metabolism, 108(8), 1968–1980. https://doi.org/10.1210/clinem/dgad027