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 with adults whose livers are damaged by cirrhosis and who eat a Western non-vegetarian diet, explored the effects of substituting one meal with a meatless option, vegan or vegetarian.

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 and low in fiber, can increase levels of ammonia. 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 to make and sustain.

For the study, researchers split 30 adults with cirrhosis who usually ate meat 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. 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. Just a few hours after eating, blood and urine samples showed 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.

Although the results are preliminary, the study authors suggest that people with liver disease who regularly eat meat try to substitute meat with sources of protein from plant or dairy sources. They note that 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.

To read the abstract of the study, published in Clinical and Translational Gastroenterology, click here