Novel metabolic and physiological functions of branched chain amino acids: a review

Abstract

It is widely known that branched chain amino acids (BCAA) are not only elementary components for building muscle tissue but also participate in increasing protein synthesis in animals and humans. BCAA (isoleucine, leucine and valine) regulate many key signaling pathways, the most classic of which is the activation of the mTOR signaling pathway. This signaling pathway connects many diverse physiological and metabolic roles. Recent years have witnessed many striking developments in determining the novel functions of BCAA including: (1) Insufficient or excessive levels of BCAA in the diet enhances lipolysis. (2) BCAA, especially isoleucine, play a major role in enhancing glucose consumption and utilization by up-regulating intestinal and muscular glucose transporters. (3) Supplementation of leucine in the diet enhances meat quality in finishing pigs. (4) BCAA are beneficial for mammary health, milk quality and embryo growth. (5) BCAA enhance intestinal development, intestinal amino acid transportation and mucin production. (6) BCAA participate in up-regulating innate and adaptive immune responses. In addition, abnormally elevated BCAA levels in the blood (decreased BCAA catabolism) are a good biomarker for the early detection of obesity, diabetes and other metabolic diseases. This review will provide some insights into these novel metabolic and physiological functions of BCAA.

Dietary requirements for leucine, isoleucine and valine (branched-chain amino acids) by juvenile red drumSciaenops ocellatus

“…In addition, BCAAs are increasingly recognized as an anabolic nutrient signal, communicating the presence of an ingested protein-containing meal to peripheral tissues, and promoting protein synthesis in fish muscle (Kawanago, Takemura, Ishizuka, Kousaka, & Shioya, 2014;Shioya, 2015 andLansard et al, 2011). In addition, in other monogastric species (i.e., pigs and rats), BCAAs are known to be regulators of lipolysis, enhancing glucose consumption and utilization, promoting improved meat quality, benefitting embryo growth, enhancing intestinal development and intestinal AA transportation, and upregulating innate and adaptive immune responses (Zhang, Zeng, Ren, Mao, & Qiao, 2017).…”

Amino acids metabolism and degradation is regulated during porcine oviductal epithelial cells (OECs) primary culture in vitro – a signaling pathways activation approach

“…BCAA is a group of compounds that are extensively studied in human and animal models. Most of the research conducted focuses on the influence of these amino acids on physical fitness, primarily of men [30]. They are mainly associated with mediation of weight loss [31].…”

Nutrient regulation of pancreatic β-cell proliferation

“…Amino acids, especially branched-chain amino acids (BCAA), including leucine, isoleucine and valine, regulate diverse physiological and metabolic pathways including hormone secretion, lipolysis and glucose metabolism [41]. The study of BCAA is increasingly relevant in the context of T2D since increased levels of plasma BCAA have been reported to lead to insulin resistance, possibly via persistent activation of the mTOR signaling pathway or perturbation of mitochondrial function [41].…”

“…The study of BCAA is increasingly relevant in the context of T2D since increased levels of plasma BCAA have been reported to lead to insulin resistance, possibly via persistent activation of the mTOR signaling pathway or perturbation of mitochondrial function [41]. Although amino acids, in particular BCAA are well known stimulators of insulin secretion [42], very few studies suggest a role of amino acids in β-cell proliferation.…”