New study shows liver patients see benefits after going meatless for one meal

RICHMOND, Va. (May 2, 2024) – Just one meal without meat can lower levels of harmful ammonia in people with advanced liver disease, researchers from Virginia Commonwealth University’s School of Medicine and Richmond VA Medical Center report.

The study, a small clinical trial conducted on adults whose livers are permanently damaged by cirrhosis who eat a Western non-vegetarian diet, explored the effects of substituting one meal with a meatless option, vegan or vegetarian.

High levels of ammonia in the blood are linked to cirrhosis and a type of cognitive decline called hepatic encephalopathy. Ammonia levels are also known to be influenced by factors such as gut bacteria and diet. While earlier studies hinted at the benefits of a vegetarian diet for those with cognitive problems caused by cirrhosis, implementing long-term dietary changes can be challenging for patients to make and sustain. Further research is still needed to investigate the impact of vegan diets on cirrhosis and ammonia.

These factors prompted VCU gastroenterologist Jasmohan Bajaj, M.D., and a team of international colleagues to wonder whether a temporary dietary switch could make a significant impact on the interplay among ammonia levels, diet, and cirrhosis. Among the paper’s authors include Bryan Badal, M.D., a fellow in the VCU Department of Internal Medicine’s Division of Gastroenterology, Hepatology and Nutrition, and associate professor Leroy Thacker, Ph.D., of the VCU School of Population Health’s Department of Biostatistics.

According to the preliminary results published today, May 2, in the journal Clinical and Translational Gastroenterology, even a single meatless meal eaten by patients with cirrhosis generates less harmful ammonia.

“It was exciting to see that even small changes in your diet, like having one meal without meat once in a while, could benefit your liver by lowering harmful ammonia levels in patients with cirrhosis,” said Bajaj, a world-renowned expert in hepatic encephalopathy with the Richmond VA Medical Center, where the study was conducted, and the VCU Stravitz-Sanyal Institute for Liver Disease and Metabolic Health. “We now need more research to learn if consuming meals without meat goes beyond reducing ammonia to preventing problems in brain function and liver disease progression.”

Ammonia is a waste product that bacteria in the intestines make when digesting food. It is normally processed in the liver, sent to the kidneys and then eliminated through urine. Livers severely damaged by cirrhosis, however, can’t process the ammonia, allowing dangerous levels of the toxin to rise and travel to the brain. Once there, the ammonia can impair cognitive function, causing confusion or delirium. This hepatic encephalopathy can lead to coma and can sometimes be fatal without treatment.

Western-style meals, which are high in carbohydrates and red meat while low in fiber, can increase levels of ammonia. Could even a simple, infrequent adjustment in the diet, such as switching to non-meat options for a single meal, reduce ammonia levels and benefit liver patients?

“It can be so hard to make long-term dietary and behavioral changes. We wondered if making an occasional change could be an option for these patients. Liver patients with cirrhosis should know that making positive changes in their diet doesn't have to be overwhelming or difficult,” Bajaj said.

They studied 30 adults (including non-veterans) with cirrhosis who were treated at the Richmond VA Medical Center and who usually ate meat. They split them into three groups of 10 to eat three kinds of burgers: one made of pork/beef, one with a vegan meat substitute, and a vegetarian bean burger. Each burger contained 20 grams of protein, reflecting the amount in a typical Western meal. In addition to the burgers, participants ate low-fat potato chips and a whole-grain bun, along with water. No condiments or toppings were allowed.

Although the patients had similar gut bacteria profiles initially, the type of meal seemed to affect ammonia levels differently. Blood and urine samples taken before and after meals revealed noteworthy differences. Just a few hours after eating, the samples revealed that those who ate a meat burger had higher amino acids associated with ammonia production and hepatic encephalopathy than those who ate the non-meat burgers.

“The main take-home message was that occasionally skipping meat from just a single meal can have benefits for patients with cirrhosis. A simple change to a patient’s diet or substituting some parts of it could be a simple and accessible method to reduce ammonia generation,” Bajaj said.

Although the results are preliminary, the study’s authors suggested that physicians should encourage liver patients who regularly eat meat to try and substitute meat with sources of protein from plant or dairy sources. A nutrition expert could provide valuable insights into the best foods for liver patients with cirrhosis, who still need to eat protein as part of a healthy diet.

The researchers noted that the findings should be confirmed by exploring how changes in diet over time could have an even greater impact on patients with cirrhosis, the ninth-leading cause of death in the United States.

The study was partly funded by grants from the American College of Gastroenterology Clinical Research Award, the Veterans Affairs Merit Review, the Richmond Institute for Veterans Research and the National Institute on Alcohol Abuse and Alcoholism.