Arginine-Rich Diet Boosts Immune Response in Mice

A team from Rockefeller University in New York published a paper on July 30 in the journal Cell linking dietary levels of the amino acid arginine to the immune system’s ability to recognize altered and infected cells. Mice fed a diet low in arginine developed more colon tumors, while mice fed an arginine-rich diet developed fewer. The same pattern showed up in flu and SARS-CoV-2 infections. The paper carries the identifier DOI 10.1016/j.cell.2026.07.020.

The work was led by Sohail Tavazoie, professor and head of the Elizabeth and Vincent Meyer Laboratory of Systems Cancer Biology at Rockefeller University, with postdoctoral researcher Qiushuang Wu as first author. The lab has been tracking arginine for years. An earlier finding from 2023 showed that colon cancer cells deprived of arginine accumulate more mutations, meaning the shortage affects the cell itself. This new study describes the other half of the story, the one involving the immune system.

Why MHC-1 production stalls without arginine

The starting point was a cell culture. When arginine levels were lowered in it, 414 proteins dropped to abnormally low levels. Most were tied to the amino acid’s already known roles, but among the most sharply suppressed were three HLA genes that encode MHC-1 proteins.

Those proteins sit on a cell’s surface and show the immune system fragments of what is happening inside, a piece of a viral protein or an altered protein from a tumor cell. When there are fewer of them than there should be, T cells have a harder time spotting what is wrong, and a dangerous cell slips through unnoticed.

The source of the breakdown was traced to the ribosome, the molecular machine that assembles proteins. The genetic blueprint for MHC-1 is packed with codons for arginine, a codon being the triplet of bases that determines which amino acid comes next in the chain. In an environment short on arginine, the ribosome stalls at exactly those spots and the protein is left unfinished.

The same diet was then tested in three mouse disease models:

• colon cancer, where the low-arginine diet produced more tumors
• flu, where mice with little arginine carried a heavier viral load and stronger lung inflammation
• SARS-CoV-2 infection, with the same pattern in lung tissue

The viral portion of the work was carried out by H. Heinrich Hoffmann and Charles Rice from the Laboratory of Virology and Infectious Disease. A finding the authors single out as unexpected is that arginine helped even when given after mice were already infected with flu, improving their outcome and survival. The amount that would correspond to the mouse dose in a human is about 10 grams a day, roughly what two over-the-counter tablets contain.

“Arginine supplementation could easily be tested in patients receiving immunotherapy or given to high-risk populations exposed to viral pathogens.”

That is how Tavazoie described the next step, arguing that arginine is cheap and easy to obtain. No clinical trials of that kind have been launched so far.

Same amino acid, two opposite therapeutic directions

What makes this work more interesting than it looks at first is that oncology has for years been trying the opposite, stripping arginine away from tumors. A drug called ADI-PEG20, pegylated arginine deiminase, was developed to break down arginine in the blood and starve tumors that cannot synthesize it on their own, and it has been tested in mesothelioma and liver cancer.

The two approaches are not necessarily at odds, since they do not target the same thing. One goes after the metabolism of the tumor cell itself, the other after what happens to the immune cells around it. Loss of MHC-1 has long been described as one of the ways a tumor evades immune surveillance, and it is linked to a weaker response to checkpoint inhibitors. If that production can be raised by something as basic as the makeup of a meal, that is a question that can be tested in clinical settings relatively quickly.

There is also an older precedent for manipulating amino acids in therapy. Asparaginase, an enzyme that clears asparagine from the blood, has been part of standard treatment for acute lymphoblastic leukemia for decades. The principle, then, is not new, what is new is going in the plus direction instead of the minus.

Does this mean people should take supplements

No, and the authors themselves say so in the plainest terms. There is no human data, the whole study rests on cell cultures and mouse models, and the dose that worked in mice has not been tested on a single patient.

“I don’t want the message to be that everyone should simply start taking arginine all the time,” Tavazoie said.

The limitations go further than that. The mouse model of colon cancer is not the same disease as human cancer, and tumor counts in a mouse are not the same as a clinical outcome in a person. The study demonstrates a mechanism and shows that diet pushes that mechanism in the intended direction, but it does not show that the supplement prevents cancer, does not show that it treats viral infection, and says nothing about what higher doses do to people already on therapy. Arginine also affects blood vessel dilation, so it is not something to add casually to every treatment regimen.

Pierre Close, a researcher at the University of Liege who was not involved in the study, summed up why findings like this still draw attention: “We’re all looking for new strategies.”

The next step that would actually settle the question is a controlled trial in humans, measuring MHC-1 levels and outcomes, not tumor counts in rodents.