[The dietary protein contribution and hepatic encephalopathy in cirrhosis]

Hepatic encephalopathy is a neuropsychiatric syndrome, which can occur in the clinical course of acute (fulminant) or chronic hepatic failure of various aetiology; reversible metabolic abnormalities without neuronal structural changes are frequently found in this condition. High blood ammonia levels, an imbalance between plasma concentrations of branched-chain and aromatic amino acids, false neurotransmitters and neurotransmitters receptor changes in CNS are the commonly recognized pathogenetic mechanism of this syndrome. Protein malnutrition is a frequent occurrence in liver cirrhosis, especially of alcoholic aetiology. High protein diets may precipitate hepatic encephalopathy; protein restriction leads to malnutrition and enhances a negative nitrogen balance. Several clinical studies have shown that vegetable proteins are tolerated better than animal in patients with liver cirrhosis and chronic portal-systemic encephalopathy: encephalopathy index is usually lower after vegetable-protein than animal-protein diet. The favourable therapeutic effect of vegetable diets on nitrogen metabolism can be mainly accounted for by the increased intake of dietary fibers and increased incorporation and elimination of nitrogen in fecal bacteria. Mixture of amino acids enriched with branched-chain amino-acids may contribute to maintain a positive nitrogen balance and minimize muscle wasting in cirrhotics.