How Arginine Helps the Body Fight Cancer and Viruses

Arginine is a tiny building block that our bodies need. It helps make proteins, which are like tiny machines that run many life processes. We can make arginine inside us, and we also eat it in foods that have lots of protein.

When people have very low arginine, they can become sick. Scientists have found that low arginine is linked to colon cancer.

Dr. Sohail Tavazoie leads a lab at Rockefeller University that studies cancer. In 2023, his team showed that taking away arginine from colon‑cancer cells caused those cells to pick up more mistakes in their DNA.

New work from the same group shows that not having enough arginine also harms the immune system. Cells need arginine to make a protein called MHC‑1. MHC‑1 shows the immune system that something is wrong, such as a virus or a mutated cell.

Arginine Can Boost an Immune Signal

The researchers discovered that a modest amount of arginine – about the amount in a few over‑the‑counter pills – can bring back the genes that make MHC‑1. The results were published in Cell.

"Adding arginine could be tried right away in patients getting immunotherapy, or in people who face viral threats," Dr. Tavazoie said. "Because arginine is cheap and easy to get, we hope doctors will test it soon."

How Cells Read the DNA Code

Proteins are made from amino acids. The DNA code tells the cell which amino acid to add next. Three DNA letters, called a codon, point to one amino acid. Six different codons tell the cell to add arginine, showing how important it is.

Scientists already know that changing the amount of an amino acid can shift how a cell works. But they did not know if it could directly change which genes are turned on.

In the new study, researchers looked at whether diet or disease‑related changes in arginine levels could affect gene activity. Funding came from the Stavros Niarchos Foundation Institute for Global Infectious Disease Research and the Weill Cancer East Hub.

They examined several disease models: colon cancer, flu, and COVID‑19. All three diseases showed unusually low arginine levels.

Low Arginine Hides Cells From the Immune System

Using cell cultures, the team found that 414 proteins dropped when arginine went down. Most of these proteins belong to genes that normally use arginine.

Surprisingly, three HLA genes that make MHC‑1 proteins also fell. MHC‑1 sits on the surface of every cell and shows foreign or abnormal pieces to T‑cells, which then call other immune cells to act.

Making MHC‑1 needs arginine at many spots. When arginine was missing, the cell’s protein factories (ribosomes) got stuck and could not finish MHC‑1. Fewer MHC‑1 pieces meant the immune system saw fewer danger signals, letting bad cells slip by.

"These results show that eating a single amino acid can directly tune gene activity," Dr. Tavazoie explained. "We think many other proteins and amino acids work the same way."

More Arginine Means Fewer Tumors in Mice

The scientists fed mice different amounts of arginine. Mice with a low‑arginine diet grew more colon‑cancer tumors. Mice that ate more arginine had fewer tumors.

They repeated the test with flu‑infected and COVID‑infected mice. The pattern stayed the same. Even giving arginine after a flu infection helped the mice recover faster.

What This Could Mean for Aging and Disease

Arginine levels naturally drop as we get older. This loss might make older people more vulnerable to cancer and viral infections.

"A diet low in arginine could create a perfect storm for colon cancer and severe viral disease," Dr. Tavazoie said. "We are also looking at other amino acids to see if they can help too."