Study Finds Lower Protein Intake May Slow Liver Tumor Growth in Damaged Livers

A new study published in Science Advances suggests that reducing dietary protein may slow the progression of Liver Cancer by limiting ammonia buildup, particularly in individuals with impaired liver function. The findings highlight how a normal metabolic byproduct can become a driver of tumor growth under certain conditions.

In a healthy liver, ammonia-produced during protein breakdown-is converted into urea and safely excreted through the Urea Cycle. However, when this process is disrupted, ammonia accumulates in the liver and bloodstream. Researchers led by Wei-Xing Zong at Rutgers University found that this excess ammonia can be repurposed by tumor cells.

Instead of being eliminated, ammonia provides nitrogen that cancer cells use to produce amino acids and nucleotides—key components required for DNA synthesis and rapid cell division. This effectively turns a toxic waste product into fuel for tumor growth.

To test this mechanism, researchers fed mice prone to liver tumors a low-protein diet. Reduced protein intake lowered ammonia production, which significantly slowed tumor growth and improved survival rates across multiple models. Additional experiments confirmed that disabling ammonia-detoxifying enzymes led to increased tumor progression, reinforcing the role of ammonia in cancer development.

Despite these findings, experts caution that protein restriction is not universally recommended, especially for cancer patients who require adequate nutrition to maintain strength and recovery. The results are most relevant for individuals with compromised liver function, such as those with hepatitis or fatty liver disease.

Overall, the study reveals a critical link between ammonia metabolism and cancer progression, opening new avenues for targeted dietary and therapeutic strategies.

REFERENCE: Xinlu Han, Jianliang Shen, Junrong Yan, Rahul Tacke, Weiwei Dai, Qingqing Mao, Heineken Queen Daguplo, Shuyang Liu, Ariful Islam, Tong Liu, Mark C. Koch, Richard Z. Lin, Hong Li, Tracy Anthony, Ping Xie, Lanjing Zhang, Shenglan Gao, M. Celeste Simon, Xin Chen, Jiekun Yang, Xiaoyang Su, Wei-Xing Zong. Impaired nitrogenous waste clearance promotes hepatocellular carcinoma. Science Advances, 2026; 12 (2) DOI: 10.1126/sciadv.aec0766