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Branched-chain amino acids in liver protection

A long-term high alcohol intake leads to severe liver damage and may directly cause liver cirrhosis. Unfortunately, what the word “high” means is not so clear yet. Patients with liver cirrhosis often have protein malnutrition and reduced physical activity. At the same time, they often report high blood levels of ammonia and imbalanced essential amino acids in blood. Practically all findings in cirrhotic patients have documented a dramatic decrease of branched-chain amino acids (BCAA) in plasma and imbalances in circulating levels of other essential amino acids. Considering the overall situation of a patient suffering with a liver damage or cirrhosis; nutritional support based on BCAA makes for a coherent nutritional story.

Indeed, long-term placebo controlled studies have been very supporting for the above concept, both in Japan and Europe. See: www.ncbi.nlm.nih.gov/pubmed/2606303   and www.ncbi.nlm.nih.gov/pubmed/12806613  The mechanism(s) for the beneficial effects of BCAA is probably mediated by their stimulating activity on hepatocyte growth factor, favoring liver regeneration. Some new studies (www.ncbi.nlm.nih.gov/pubmed/26058864 ) have also suggested that BCAA are essential in mediating efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of such channeling could be a significant contributor to mitochondrial dysfunction and liver damage. While major clinical test were conducted only in patients with advanced liver cirrhosis leading to successful development and use of BCAA-based medical foods for alcoholic liver cirrhosis in Japan; one wonders how nutritional supplementation with BCAA (perhaps combined with some nonessential amino acids) could serve to protect liver of otherwise healthy drinkers, especially those who have low protein intakes. In that target group, which is very large world-wide, medical science is less clear.

Unfortunately, such "scientific greyness" for pre-pathologic states is seen frequently in other illnesses since only sick people are sufficiently categorized and clinically researched. Therefore, much better knowledge is available on nutra-pharmaceutical drug treatments than on nutritional prevention. But, before we know more, make sure you have enough BCAA in your food before you go to that party…