Alcohol is one of the predominant causes of liver diseases and liver-related deaths worldwide. 10% of heavy drinkers consuming more than 30g /day of alcohol for 5 years develop alcoholic liver disease (ALD). The liver acts as a major organ in alcohol metabolism. Alcohol is metabolized to acetaldehyde, the key toxin in alcohol mediated liver injury which gets converted to reactive oxygen species (ROS) through oxidative pathway thus leading to hepatocyte injury. Several experimental and human studies have shown that alcohol also causes intestinal bacterial overgrowth, intestinal mucosal damage and enhances intestinal permeability, leading to translocation of bacteria and their by-products (like LPS) in the portal circulation. Bacteria further stimulate the production of ROS and pro-inflammatory cytokines like TNF-alpha, IL-6, \& chemokines, thus further damaging the liver. Alcohol intake not only causes bacterial overgrowth but also brings a qualitative change in the type of bacteria. The number of gram-negative bacteria like Enterobacteriaceae / Proteobacteria - E.Coli, Firmicutes -Enterococcocus, Bacteriodetes- Fusobacteria and Staphylococaceae -Staphylococcus increase whereas the number of gram-positive bacteria viz. Firmicutes -Lactobacillus, Ruminococcaceae, Lachnospiraceae; Actinobacteria -Bifidobacterium decrease. This change is termed dysbiosis. Thus alcohol-related liver injury is potentiated by alcohol-induced gut barrier dysfunction and ensuing cascade of events, involving dysbiosis. Studies suggest that probiotic administration decreased alcohol-induced dysbiosis, TNF- alpha \& IL-6 levels, and improves gut leakiness \& liver inflammation. Probiotics also restore the level of lactobacilli thus creating more acidic environment, lowering the intestinal pH \& stabilizing mucosal barrier, thereby preventing microbial translocation \& blocking TLR-4 signaling cascade and attenuating liver injury. Hence there is evidence that suggests to targeting dysbiosis improves alcohol-related liver disease. Studies have also shown that lactobacilli use saturated fat (SF) for its growth and supplementing SF improves gut lactobacilli levels and subsequently decreases the progression of ALD. Low levels of microbial long-chain saturated fat caused due to alcohol compromise the growth of lactobacillus and hence disrupt gut barrier integrity. A large multicentre epidemiologic study in chronic alcoholics with comparable per capita alcohol intake has shown that intake of saturated fat is associated with lower mortality rates as compared to unsaturated fats (USF) Diet rich in SF has been found to prevent ethanol-induced changes viz. an increase in proteobacteria \& liver steatosis, which were actually increased with the consumption of USF. Yet another study reported that the SF diet improved intestinal tight junction expression and alleviated intestinal inflammation caused due to ethanol intake. Supplementation of long-chain fatty SF to ethanol injured mice with increased intestinal permeability restored metabolic homeostasis with decreased intestinal bad bacteria levels where supposedly saturated fat serves as a vitamin B substitute and promotes the growth of lactobacilli species which ameliorates alcoholic liver injury.
Alcohol induced disruption in the intestinal tight junction protein levels, endotoxemia and hepatic LPS signaling were found to be alleviated by SF in the form of medium chain triglycerides. Dietary SF (e.g., palm oil or MCT oil) reversed the established experimental ALD in rats, and improved liver histological changes despite continued intragastric ethanol administration.
Hence the supplementation of SF in ALD is a logical manoeuvre within the nutritional therapy of this disease, as almost 90% of these patients are malnourished primarily due to a reduced diet intake. Fats are concentrated source of energy which makes the food palatable, hence making the attainment of higher calorie (35-40 kcal/kg body weight/day) target possible. With this background use of SF in ALD is a promising modality in the medical armamentarium, given the fact that nutrition remains the cornerstone of the overall therapy.
