Hepatic encephalopathy is a neuropsychiatric syndrome. It has various aetiologies and can occur in the clinical course of acute (fulminant) or chronic hepatic failure. Usually this condition is associated with reversible metabolic abnormalities without neuronal structural. The pathogenesis of this syndrome includes high blood ammonia levels, an imbalance between plasma concentrations of branched-chain and aromatic amino acids, false neurotransmitters and neurotransmitters receptor changes in central nervous system. 

Evidences suggest that liver cirrhosis caused due to alcohol is significantly associated with protein malnutrition. However, high protein diets may also worsen hepatic encephalopathy; and first line of management incudes restriction of protein, which in turn causes malnutrition and promotes a negative nitrogen balance. Numerous studies have favoured intervention of vegetable proteins that are well tolerated in comparison to animal protein in patients with liver cirrhosis and chronic portal-systemic encephalopathy. It has been reported that encephalopathy index is lower after vegetable-protein in contrast to animal-protein diet. The potential benefit of vegetable diets on nitrogen metabolism is mainly attributed to the increased intake of dietary fibers and raised absorption and elimination of nitrogen in fecal bacteria. In addition, mixture of amino acids consisting of branched-chain amino-acids may play an active role in maintaining a positive nitrogen balance and minimize muscle wasting in patients with liver cirrhosis.

Source: Zavaglia C, Brivio M, Losacco E, Onida L. Apporto proteico dietetico ed encefalopatia epatica nella cirrosi [The dietary protein contribution and hepatic encephalopathy in cirrhosis]. Recenti Prog Med. 1992 Apr;83(4):218-23. Italian. PMID: 1626117.