‘Even one meal change’ to vegetarian, vegan can reduce serum ammonia in cirrhosis
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Key takeaways:
- Serum ammonia levels were “significantly elevated” after the meal in the meat group vs. non-meat groups.
- Changes in ammonia and metabolomics were similar in those with and without prior hepatic encephalopathy.
Substitution of just one meat-based meal with a vegetarian or vegan alternative reduced serum ammonia levels for up to 3 hours and improved metabolites in patients with cirrhosis who follow a Western meat-based diet, researchers reported.
“High ammonia generation after a protein load is a harbinger for poor outcomes in cirrhosis, but prior studies have evaluated complete diet change from meat to vegetarian, which is hard to sustain,” Jasmohan S. Bajaj, MD, MS, FACG, study author and professor in the division of gastroenterology, hepatology and nutrition at Virginia Commonwealth University School of Medicine, told Healio. “The aim [of this study] was to see if changing just one meal could alter ammonia generation in patients with cirrhosis and potential mechanisms behind that.”
In a randomized clinical trial, Bajaj and colleagues enrolled 30 men with cirrhosis who were on a stable, Western meat-based diet, 50% of whom had prior hepatic encephalopathy (HE). Patients were fasted overnight and randomly assigned to 20 g of a meat (n = 10), vegan (n = 10) or vegetarian (n = 10) burger meal, which they ate under observation.
Blood samples were collected for analysis of metabolomics and ammonia at baseline and every hour for 3 hours following the meal. At baseline, mean ammonia levels for the three groups were 58.2 µmol/L, 36.1 µmol/L and 52.9 µmol/L, respectively, and stool microbiome composition was similar across groups.
According to study results published in Clinical and Translational Gastroenterology, serum ammonia was “significantly elevated” in the meat group at 1 hour (75.1 µmol/L), 2 hours (76.4 µmol/L) and 3 hours (74.1 µmol/L) after meal consumption compared with the vegan (39.3 µmol/L, 41.2 µmol/L and 41.5 µmol/L) and vegetarian (50 µmol/L, 47.8 µmol/L and 45.5 µmol/L) groups.
“Even one meal change from meat-based to vegetarian or vegan can reduce ammonia generation that is independent of gut microbial change,” Bajaj said. “This was similar regardless of whether a patient had previously been diagnosed with HE.”
He continued: “Moreover, many metabolic processes involving energy generation and fatty acids, which interact with ammonia generation, were changed with one meal.”
Specifically, results demonstrated a reduction in metabolites of branched chain and acylcarnitines as well as alterations in lipid profile — higher sphingomyelins and lower lysophospholipids — in the meat vs. non-meat groups.
“We must not in any circumstance restrict protein intake, but we could ask patients to occasionally substitute red meat with plant proteins of equal amount,” Bajaj told Healio. “This may not require a full-scale switching of diets but reducing meat intake without sacrificing total protein intake.”
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