Liver cancer is one of the most dangerous cancers in the world, and doctors have been searching for better ways to prevent it for many years. Now, a new study suggests that a simple dietary change may help people who already have liver disease reduce their risk.
The research shows that lowering protein intake might slow the growth of liver tumors and possibly reduce the chance of developing liver cancer in the first place.
The study was led by scientists at Rutgers University and published in the scientific journal Science Advances. In their research, the team found that mice with liver tumors lived longer and had slower cancer growth when they were fed a diet with less protein.
The results offer new insight into how liver disease can create conditions that help cancer grow and how diet might influence that process.
Liver cancer is a major global health problem. In the United States alone, it is one of the most deadly types of cancer. The five‑year survival rate is only about 22 percent, which means that fewer than one in four patients are still alive five years after diagnosis.
According to the American Cancer Society, more than 42,000 new cases of liver cancer were expected in 2025, and over 30,000 people were projected to die from the disease.
Even more concerning is the growing number of people who have liver diseases that can increase the risk of cancer. One of the most common is fatty liver disease. Studies suggest that about one in four adults in the United States has some form of fatty liver disease.
This condition occurs when too much fat builds up inside liver cells. Over time, it can damage the liver and lead to inflammation, scarring, and eventually cirrhosis.
Other major causes of liver damage include chronic hepatitis infections and heavy alcohol use. All of these conditions can weaken the liver and make it more likely for cancer to develop.
The new study focused on a specific problem that occurs when the liver is damaged: the buildup of a toxic substance called ammonia.
When people eat protein, the body breaks it down into smaller components that it can use for energy and building tissues. During this process, nitrogen is released and converted into ammonia. Ammonia is dangerous to the body, especially to the brain and nervous system, so the body must quickly remove it.
Under normal circumstances, the liver performs this task efficiently. It converts ammonia into a safer compound called urea. The urea then travels through the bloodstream to the kidneys and leaves the body in urine.
However, when the liver is damaged or not functioning properly, this detox process may stop working well. As a result, ammonia levels can rise in the body.
For many years, doctors have known that liver cancer patients often have trouble processing ammonia. What scientists did not know was whether ammonia buildup was simply a result of cancer or whether it might actually help tumors grow.
To answer this question, the Rutgers research team conducted experiments using mice. First, they created liver tumors in the animals while their ammonia processing systems were still working normally.
Next, the scientists used gene‑editing tools to disable certain enzymes that help the liver process ammonia in some of the mice. These enzymes are part of the body’s system for turning ammonia into urea.
The researchers then compared the animals that could no longer process ammonia properly with mice whose ammonia‑handling systems were still functioning.
The results were striking. Mice that could not remove ammonia efficiently developed much larger tumors and died significantly sooner than the other mice. Their bodies accumulated higher levels of ammonia, which appeared to create an environment that helped cancer cells grow faster.
When the researchers looked more closely at what was happening inside the tumors, they discovered something surprising. The excess ammonia was not just building up as waste. Instead, cancer cells were using it as a raw material to support their growth.
The ammonia was being turned into molecules such as amino acids and nucleotides. These molecules are essential building blocks that cells need to multiply. Cancer cells grow rapidly, so they require large amounts of these materials.
In other words, the ammonia that should have been removed as waste was actually feeding the tumor.
After understanding this process, the scientists wanted to test whether lowering ammonia levels could slow tumor growth. Since ammonia is produced when protein is broken down, they decided to reduce the amount of protein in the animals’ diets.
The results were dramatic. Mice that ate a low‑protein diet developed smaller tumors and survived much longer than mice that continued eating a normal amount of protein.
The researchers believe that reducing protein intake lowered the amount of nitrogen entering the body. This meant less ammonia was produced, which limited the supply of materials that cancer cells could use to grow.
However, the scientists emphasized that these findings do not mean everyone should suddenly cut protein from their diet. Protein is an essential nutrient that helps build muscles, repair tissues, and support many important body functions.
For people with healthy livers, the body can safely process ammonia without any problems. In these individuals, eating normal amounts of protein is generally safe.
The findings may be most important for people who already have liver disease or significant liver damage. In those cases, the liver may struggle to remove ammonia effectively. Reducing protein intake could help lower ammonia levels and potentially slow cancer growth.
Even so, experts caution that any major diet change should be discussed with a doctor. Many cancer patients are encouraged to eat enough protein to maintain strength and muscle mass during treatment. The best approach will likely depend on each person’s health condition and liver function.
When reviewing the study findings carefully, the research offers an important new perspective on how metabolism and cancer may be connected.
The study suggests that liver tumors can take advantage of metabolic waste products such as ammonia to fuel their growth. By identifying this hidden pathway, scientists may eventually develop new treatments that target ammonia metabolism or related processes.
At the same time, the results should be interpreted with caution because the experiments were conducted in mice rather than humans. More studies are needed to confirm whether similar effects occur in patients with liver disease. Clinical trials will be necessary to determine whether controlled dietary changes could safely help reduce liver cancer risk.
Overall, the research highlights the complex relationship between diet, metabolism, and cancer development. It also shows how understanding the body’s waste‑processing systems may lead to new strategies for preventing or slowing serious diseases such as liver cancer.
If you care about liver health, please read studies about a diet that can treat fatty liver disease and obesity, and coffee drinkers may halve their risk of liver cancer.
For more information about liver health, please see recent studies that anti-inflammatory diet could help prevent fatty liver disease, and results showing vitamin D could help prevent non-alcoholic fatty liver disease.
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