Researchers say a simple change in diet might help people with liver problems lower their risk of liver cancer. According to a new study, eating less protein could slow the growth of liver tumours and possibly make patients live longer.
Scientists from Rutgers University led the study and published it in the journal Science Advances. They found that when protein intake was reduced, liver tumours grew more slowly in mice. The researchers also discovered why such an event might happen. When the liver cannot properly remove waste products from the body, certain substances can build up and help cancer cells grow, potentially leading to the progression of liver cancer and worsening survival rates.
Liver cancer is one of the most dangerous forms of cancer in the United States. Survival rates are still quite low compared with many other cancers. Only about 22% of patients survive for at least five years after diagnosis, according to experts. The American Cancer Society projects that the United States will diagnose approximately 42,240 new cases of liver cancer in 2025. Around 30,090 people are also expected to die from the disease that year.
However, the number of people at risk of liver cancer is much larger. Many adults already live with liver conditions that can increase their chances of developing the disease. For example, fatty liver disease affects about one in four adults in the United States. Other conditions such as viral hepatitis and heavy alcohol use can also damage the liver and lead to cirrhosis, which significantly raises the risk of liver cancer.
Wei-Xing Zong, a senior author of the study and a professor at Rutgers, explained that people with damaged livers may benefit from reducing the amount of protein they eat. When the liver is not working properly, it may struggle to process certain waste products created when the body breaks down protein. When people eat protein, the body produces nitrogen, which can be turned into ammonia. Ammonia is harmful to the body and especially dangerous for the brain, as it can lead to neurological issues and cognitive impairment if not properly processed by the liver. In a healthy person, the liver converts ammonia into another substance called urea. The body then removes urea through urine.
But in people with liver disease, this process may not work properly. As a result, ammonia can build up in the body. Scientists have known for many years that liver cancer patients often have problems removing ammonia. However, researchers were unsure whether ammonia buildup helped cause cancer or whether it was simply a result of the disease. To answer this question, the research team conducted experiments using mice. First, they created liver tumours in the animals while keeping their ammonia-processing system normal. After that, they used gene-editing tools to block certain enzymes responsible for removing ammonia in some of the mice.
The results were clear. Mice that could not remove ammonia properly developed bigger tumours. Scientists also found that these mice died sooner than mice with healthy livers. Further studies showed that cancer cells were using the extra ammonia in the body. They changed the ammonia into amino acids and nucleotides, which help tumours grow and multiply. After discovering this, researchers wanted to see if diet could help. They fed one group of mice food with less protein. Another group continued to eat normal amounts of protein.
Mice that ate less protein grew tumours more slowly. They also lived longer. Scientists say these findings could matter for people with liver problems. This group includes those with liver cancer, fatty liver disease, viral hepatitis, or other liver conditions.
Lowering protein intake might help reduce ammonia levels and slow cancer growth in some patients. However, experts warn that people should not change their diets without medical advice. Cancer treatment guidelines often recommend higher protein intake to help patients maintain muscle strength during illness. The right amount of protein may vary depending on a person’s health and the condition of their liver. Still, the researchers say reducing protein could be a simple and practical way to lower ammonia levels in people whose livers cannot process it properly.
