Popular Vitamin B3 Supplements May Help Cancer Cells Survive, Scientists Warn

A new study raises important questions about widely used NAD+ supplements, suggesting that compounds often taken to boost energy and support healthy aging may have unintended consequences in cancer treatment.

Millions of Americans take supplements like nicotinamide mononucleotide (NMN), nicotinamide riboside (NR), and nicotinamide (NAM) with the goal of boosting energy and supporting healthy aging. These compounds are marketed for their ability to raise levels of NAD+, a molecule central to metabolism and cellular repair.

Some cancer patients have also turned to these supplements, hoping they might ease the harsh side effects of chemotherapy. But emerging research suggests that this strategy could backfire.

A study from Case Western Reserve University's School of Medicine, published in Cancer Letters, found that these vitamin B3 derivatives may actually help pancreatic cancer cells survive treatment. Pancreatic cancer remains one of the most lethal cancers, with a five-year survival rate of just 13%, making any factor that affects treatment outcomes especially important.

How NAD+ Fuels Both Health and Disease

NAD+ is a molecule required for the survival and function of all cells in the body, including both healthy and cancerous ones. Supplements that raise NAD+ levels effectively supply cells with additional fuel.

In healthy individuals, this added fuel may provide benefits. However, the study found that cancer cells can exploit it to strengthen their energy production, repair DNA damage caused by chemotherapy, and avoid programmed cell death. As a result, tumors may withstand treatments that would normally destroy them.

In laboratory tests and mouse studies, the supplements, especially NMN, protected pancreatic cancer cells from three commonly used chemotherapy drugs: oxaliplatin, 5-fluorouracil, and gemcitabine.

Researchers identified three main ways the supplements interfered with treatment:

• Increasing cancer cell energy, which made tumors more robust
• Lowering oxidative stress in tumors, reducing a key mechanism chemotherapy uses to kill cancer cells
• Limiting DNA damage and preventing cell death, both of which are essential for chemotherapy to work

Implications for Cancer Treatment

"Our findings highlight a potentially concerning role for NAD+-boosting supplements in the context of an active cancer, especially when used in conjunction with chemotherapy," said study lead Jordan Winter, Case Western Reserve School of Medicine professor and co-leader of the developmental therapeutics program at the National Cancer Institute-designated Cancer Comprehensive Cancer Center. "Our discovery is a call to action for the medical community."

The researchers emphasized that the study does not show these supplements are harmful for healthy individuals. However, for people with active cancer, especially those receiving chemotherapy, the potential risks may be significant.

"This research is a critical reminder that 'natural' doesn't always mean safe," Winter said, "especially in the complex biology of cancer treatment."

The team recommends routine screening of supplement use among cancer patients and calls for further clinical studies to better understand how NAD+ supplements interact with cancer therapies.

For now, Winter advises patients to speak with their oncologist and care team about any supplements they are taking.

Reference: "Vitamin B3 derivatives support pancreatic cancer cell survival and chemotherapy resistance" by Faith Nakazzi, Mehrdad Zarei, Mariana Lopes, Hallie J. Graor, William C. Beegan, Eric Gu, Sakineh Rezaei, Peder J. Lund and Jordan M. Winter, 20 February 2026, Cancer Letters.
DOI: 10.1016/j.canlet.2026.218334