Mediterranean diet and wine polyphenolics may help prevent alcoholic liver disease

A new area of research investigates how the polyphenols in wine may be involved in restoring the microbial balance between detrimental and beneficial bacteria in the gut and thus, can contribute to the lower risk of alcohol-induced liver damage.

Alcohol abuse represents the most common cause of liver disease in Western countries. The so-called Alcoholic Liver Disease (ALD) may progress from steatosis (fatty liver) to steatohepatitis (fatty liver inflammation), liver cirrhosis, and eventually hepatic cancer. The pathogenesis of ALD is still poorly understood, and thus, an effective treatment of the disease is not established yet. Prevention should be the main goal.

In recent years, researchers discovered that the gut flora plays an important role in the pathogenesis of alcoholic liver injury. There are multiple times more microbial cells in the gut than the total number of cells in the human body. The microbes contribute to a complex of biological processes such as digestion, synthesis of vitamins, and regulation of the immune system. A poor diet and other factors of our modern lifestyle can disrupt the intestinal balance by quantitative (bacterial overgrowth) and qualitative (microbial imbalance) alterations. Such a disturbed balance of gut bacteria results in a dysfunction of the intestinal barrier and translocation of bacteria and/or bacterial products. Such a translocation of bacterial products into the portal blood appears to play a key role in alcohol-induced liver damage. Those alterations in the gut microflora that are associated with liver diseases including ALD, are influenced by various lifestyle factors.

The Mediterranean diet (MD) is considered to be one of the healthiest ways of eating. Many of the characteristic components of the MD such as vegetables, fruits and nuts are the most important source of fiber and chemical compounds, like flavonoids, phytosterols, vitamins, terpenes and phenols, which protect against damaging oxidative processes. These plant compounds are also metabolized by gut bacteria and together with a diet, rich in fiber, flavonoids and other polyphenolic substances, stimulate the growth and activity of the gut microflora which is assumed to affect health positively.

Moderate wine consumption with meals is a traditional part of the Mediterranean way of eating. The beneficial effect of wine has been attributed primarily to alcohol per se as well as to its non-alcoholic compounds. These phenolic substances in wine possess antioxidant properties that may prevent or delay the progression of diseases caused by oxidative stress and inflammation. Pre-clinical and clinical studies have shown that wine consumption also affects the amount and composition of gut microbiota. It was observed that wine phenolic compounds can initiate changes in the colonic bacterial population and thus, acting as prebiotics (*).

Several studies show that the modulation of gut microbiota seems to be a promising strategy to reduce alcohol-induced liver injury. The use of natural wine phenolics, by restoring the microbial balance between detrimental and protective luminal bacteria, might reduce the transit time of toxic substances into the portal vein, thus lowering risk of liver injury. So in the last decade, the relationship between dietary intake, alcohol consumption and changes in the gut microbiota and its consequent involvement in the pathogenesis of alcoholic liver disease have become of prime interest. In addition, interventions focusing on the modulation of gut bacteria and/or bacterial products that could change the ALD risk are the focus of research and further larger studies are needed to confirm these preliminary results.

(*) PrebioticsPrebiotics are usually non-digestible carbohydrates oligosaccharides or short polysaccharides (ie. i...: non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth or activity of one or a limited number of bacterial species in the colon, which have the potential to improve the host’s health. Simply speaking, prebiotics are the “food” for beneficial bacteria

1. Zhong W, Zhou Z. Alterations of the gut microbiome and metabolome in alcoholic liver disease. World J Gastrointest Pathophysiol. 2014;5(4):514-22

For more information about this article, read the scientific abstract here.

2. Vassallo G, Mirijello A, Ferrulli A, et al. Review article: alcohol and gut microbiota – the possible role of gut microbiota modulation in the reatment of alcoholic liver disease, Aliment Pharmacol Ther.2015;41(10):917-27.

For more information about this article, read the scientific abstract here.