New research suggests a surprising link between protein intake and liver health, particularly for those with existing liver conditions. A study from Rutgers University detailed in Science Advances indicates that excess protein can contribute to the growth of liver tumors by increasing ammonia levels in the body. While protein is essential for overall health, these findings underscore the importance of personalized dietary recommendations – and possibly reduced protein consumption – for individuals with fatty liver disease, cirrhosis, or cancer, alongside existing guidelines for maintaining muscle mass.
Individuals with fatty liver disease, where fat accumulates in the liver and slows down the body’s metabolic processes, should be mindful of their protein intake. This caution extends to anyone with reduced liver function, as research suggests a link between protein consumption and liver health. Following a doctor’s specific dietary recommendations is crucial for reducing the risk of developing liver cancer or slowing its progression if a tumor is already present. Limiting protein intake may help prevent disruptions in the organ’s waste removal processes, which could potentially fuel the growth of cancerous cells.
Ammonia is Key
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A study published in Science Advances by researchers at Rutgers University, led by Wei-Xing Zong, suggests a potential mechanism explaining how excess protein could contribute to tumor development. The research, conducted on animals, indicates that the breakdown of dietary proteins can lead to the production of ammonia, a toxic compound. While a healthy liver converts ammonia into urea for excretion in urine, this process is impaired in individuals with liver tumors or compromised liver function, leading to ammonia buildup. The study investigated whether this ammonia accumulation is merely a consequence of the tumor or if it actively promotes cancer growth. Researchers induced tumors in animals and then, using genetic editing techniques, deactivated the enzymes responsible for processing ammonia in some animals but not others. The results showed that mice with deactivated enzymes and higher ammonia levels developed larger tumors and experienced a faster rate of mortality compared to those with functioning systems. This is because excess ammonia was found to migrate into molecules that support tumor cell proliferation, transforming into amino acids and nucleotides – essential building blocks for cancer cells.
A Tailored Diet
To test this mechanism, the researchers then explored the impact of a low-protein diet. Animals with tumors that were fed a low-protein diet exhibited significantly slower tumor growth and increased lifespan compared to those consuming standard protein levels. These findings suggest that while a healthy liver can effectively manage high protein intake, a reduced protein diet may be beneficial for individuals with liver cancer, fatty liver disease, viral hepatitis, or other liver conditions. However, any dietary changes should be discussed with a healthcare professional or registered dietitian. Current cancer guidelines generally recommend increased protein intake to help patients maintain muscle mass and strength, combating sarcopenia. Therefore, treatment plans must consider the patient’s overall health and liver function, recognizing that reducing protein intake may be advisable in cases of elevated ammonia levels. “If you suffer from a liver disease or damage that prevents it from functioning properly, you should seriously consider reducing your protein intake to reduce the risk of developing liver cancer,” advises Wei-Xing Zong in a statement from the American university.
What to Do
“The study, conducted on animals, highlights how ammonia buildup, linked to the breakdown of proteins in the diet, isn’t just a consequence of liver tumors but may also fuel their growth,” explains Giammarco Mocci, Head of the Gastroenterology Unit at ARNAS G. Brotzu in Cagliari. “Researchers observed slower tumor growth in animals with liver tumors fed a low-protein diet compared to those with standard protein levels.” These experimental observations underscore the potential risks of excessive protein intake, particularly when liver function is impaired, and emphasize the importance of mindful eating. Mocci notes that research has long demonstrated that a high-protein diet over time can strain the liver, responsible for protein metabolism. This can lead to increased triglyceride deposition within liver cells and a significant increase in a protein used as a marker of liver damage, associated with fatty liver disease and liver cancer. In cases of fatty liver, prioritizing fiber-rich foods like legumes and vegetables, lean protein sources like fish, and limiting simple sugars and saturated fats is recommended. However, self-treating is discouraged; consulting with doctors and nutrition specialists is essential.
Understanding Fatty Liver Disease and Steatohepatitis
Fatty liver disease, now known as MASLD (metabolic dysfunction-associated steatic liver disease), is characterized by an accumulation of fat in the liver. It can progress to MASH (metabolic dysfunction-associated steatohepatitis), where fibrosis may develop, potentially leading to cirrhosis and cancer. The combination of fat accumulation with inflammation is particularly concerning, as it progressively damages liver cells. These processes are exacerbated by alcohol consumption and a diet high in lipids, especially those from animal sources, making it difficult for the liver to process and convert fats into energy. As a result, liver cells become overloaded with fat, rupture, and are gradually replaced by adipose tissue. Evidence of these cellular “explosions” can be observed through a simple blood test, specifically elevated levels of liver enzymes known as transaminases (GOT and GPT).
