Creatine may boost immune cells that help fight cancer

UCLA researchers in Los Angeles have found that creatine, the muscle-building supplement sold over the counter, may also help immune cells inside tumors do a better job of activating cancer-fighting T cells. In a study published in iScience and highlighted on July 8, 2026, the team reported that creatine increased dendritic-cell activity in mouse melanoma models, slowed tumor growth, and boosted human dendritic cells in a lab dish.

The work centers on dendritic cells, the immune system’s sentinels. These cells detect tumors and then switch on killer CD8 T cells, the body’s main cellular weapon against cancer. Inside the nutrient-poor tumor environment, UCLA found, dendritic cells ramped up creatine intake and appeared to depend on it for energy. When the scientists removed the creatine transporter, dendritic-cell function weakened, strengthening the case that the supplement was feeding a real metabolic need rather than merely marking a side effect.

That matters because modern immunotherapy still leaves many patients behind. Treatments designed to unleash T cells help only about 20% to 40% of patients in a meaningful way, which has pushed cancer researchers to look beyond the T cells themselves and toward the cells that prime and coordinate them. Lili Yang, the study’s senior author, has said the goal is to support the larger immune infrastructure those treatments rely on. The UCLA team says the findings could one day inform dendritic cell-based cancer vaccines and complement existing immunotherapies.

The new study also extends a line of research the UCLA lab began in 2019, when it showed that creatine uptake was critical to CD8 T-cell anti-tumor activity. In that earlier mouse work, creatine supplementation improved suppression of skin and colon cancer tumors, using a dose the team described as comparable to what athletes and bodybuilders safely take. The latest study broadens the target from killer T cells to the cells that help wake them up in the first place.

Still, the science is far from routine treatment. The work was preclinical, done in mice and human cells, not in cancer patients. That caution matters because creatine has also shown a darker side in some cancer models. A 2021 PubMed-indexed study found it promoted metastasis in mouse models of colorectal and breast cancer through Smad2/3 signaling. A 2025 review screened 230 articles, included five preclinical studies of creatine with PD-1 blockade, and concluded the supplement may improve anti-tumor effects while also carrying a possible metastasis risk in select tumor types.

For now, the UCLA finding is a mechanistic step forward, not a reason to treat creatine as proven cancer therapy. The data suggest it may eventually become part of a broader immunotherapy toolkit, but cancer patients should not assume an over-the-counter supplement is an evidence-based substitute for treatment.