The influence of L-valine and intestinal microbiota on host metabolism

L-valine is an important branched-chain amino acid that has complex interactions with intestinal microorganisms, and these interactions have multiple impacts on host metabolism, as follows:

Impact on lipid metabolism: The intake of L-valine can affect the composition and diversity of intestinal microorganisms, thereby regulating the body's lipid metabolism. Beneficial flora, in the process of utilizing it, may produce anti-inflammatory metabolites such as short-chain fatty acids. These metabolites can reduce inflammatory responses, improve intestinal health, and thus have a positive impact on lipid metabolism. However, metabolites produced by certain harmful flora using L-valine, such as some amines or ketone bodies, may promote lipid synthesis and inflammatory reactions, which is detrimental to the normal progress of lipid metabolism.

Impact on blood glucose metabolism: Studies have shown that L-valine can mediate the positive effect between Escherichia coli and fasting blood glucose (FBG). Exposure to moderate altitudes can reduce an individual's serum L-valine content, while decreasing FBG and insulin resistance index. This indicates that intestinal flora may affect blood glucose regulatory homeostasis by regulating L-valine metabolism, and changes in its content may be related to the occurrence and development of metabolic syndromes such as insulin resistance.

Impact on intestinal barrier function: L-valine can be metabolized by intestinal microorganisms to produce isobutyric acid. Isobutyric acid can significantly enhance the intestinal mucosal barrier function, promote the formation of the intestinal barrier, help maintain the normal physiological function of the intestine, reduce the entry of harmful substances into the blood circulation, and thus have a positive impact on the host's metabolic environment.

Impact on inflammatory responses: Studies on weaned piglets have found that dietary L-valine supplementation can reduce plasma interleukin (IL)-1α and IL-1 receptor antagonist concentrations, as well as isovaleric acid and ammonia nitrogen concentrations in the colon. This indicates that L-valine can beneficially regulate inflammatory responses, which may be related to its regulatory effect on intestinal microbial metabolites, thereby affecting the host's metabolic state.

Impact on hepatic lipid metabolism: Studies on laying hens have found that long-term intake of high levels of L-valine can accelerate the development of non-alcoholic fatty liver disease (NAFLD) in laying hens by promoting fat synthesis and inhibiting fatty acid oxidation. This indicates that its intake needs to be appropriately controlled; otherwise, it may have an adverse impact on hepatic lipid metabolism.