Millions of Americans take niacin supplements, also known as vitamin B3, daily to boost energy, slow aging, and support overall health.
However, B3 may be hijacked by cancer cells to make them more resistant to chemotherapy, a new study suggests.
The study, published in Cancer Letters, found that nicotinamide mononucleotide (NMN), a popular vitamin B3-related compound, made pancreatic cancer cells three to seven times more resistant to standard chemotherapy drugs in lab experiments and significantly accelerated tumor growth in mice.
The implications may be serious. Pancreatic cancer already carries a five-year survival rate of just 13 percent. In mouse models, NMN reduced chemotherapy’s typical tumor-shrinking effect from 60 percent to 70 percent down to just 20 percent to 30 percent.
“Antioxidants like NMN and associated compounds help pancreatic cancer cells grow and protect them from the therapeutic benefits of chemotherapy,” lead author Dr. Jordan Winter, a professor at Case Western Reserve University School of Medicine, told The Epoch Times.
How NMN Undermines Treatment
Supplements such as NMN, along with other variants of vitamin B3 such as nicotinamide riboside (NR) and nicotinamide (NAM), are popular for boosting nicotinamide adenine dinucleotide, or NAD—a molecule every cell needs to produce energy, repair DNA, and cope with stress.
Normally helpful for aging cells, NAD’s repair powers may backfire in cancer.
Cancer cells compete with the body for nutrients, so supplements you take to help yourself may feed the tumor instead.
NMN raises NAD levels in cancer cells, helping them repair DNA damage from chemotherapy and survive treatment, the researchers found.
In lab experiments, higher NAD made pancreatic cancer significantly harder to kill—three to seven times more resistant—with standard chemotherapy drugs such as gemcitabine, oxaliplatin, and 5-fluorouracil, commonly used for advanced pancreatic and biliary tract cancers. NMN was strongest; NR showed modest protection; NAM had little impact.
The researchers found that NMN supported cancer cell survival in several ways: by increasing energy production in cancer cells, maintaining mitochondrial function during treatment, and enhancing DNA repair caused by chemotherapy.
Chemotherapy works by damaging cancer cell DNA and creating toxic oxidative stress, both processes that require NAD.
The findings extended beyond cell studies. In mouse models of pancreatic cancer, animals given NMN or NAM developed faster-growing tumors and showed more resistance to chemotherapy—even at doses meant to reflect typical supplement use, compared with untreated mice.
Why Pancreatic Tumors Are Hard to Kill
Pancreatic cancer is notoriously difficult to treat. Tumors grow in areas with low oxygen and limited nutrients—conditions that would kill many normal cells. To survive, pancreatic cancer cells rely heavily on internal support systems—including NAD-reliant pathways.
That makes pancreatic tumors especially sensitive to NAD-boosting supplements. What helps a healthy cell cope with stress associated with aging could also give cancer cells an added advantage.
However, the effects of NAD-boosting compounds are not uniform across all cancers. In some studies of cervical, breast, liver, and lung cancers, NAM supplements appear to make chemotherapy more effective. Scientists say the difference likely comes down to the type of cancer, the dose of the supplement, and how individual tumors use energy.
A similar paradox has been observed with antioxidants such as vitamins C and E. Some studies show that they unexpectedly helped tumors even while reducing treatment side effects.
What Patients Can Do
Winter is careful to note these are preclinical findings, in cells and animal models. However, the data are striking enough that he believes that action is warranted now.
“Chemotherapy and radiation are designed to damage cancer cells through oxidative stress,” he said. “Anything that helps those cells repair that damage or reduce that stress could potentially work against treatment.”
The study doesn’t suggest that these supplements harm healthy people. However, for pancreatic cancer patients on chemotherapy, the potential risks are serious, particularly given that some patients take NAD-boosting supplements specifically to manage chemotherapy side effects, potentially creating the opposite result.
The researchers urge routine screening of supplement use in cancer patients and more clinical studies on NAD boosters and cancer therapies. For now, Winter advises patients undergoing treatment for pancreatic cancer to discuss these risks with their oncologist right away.