Gut microbiota metabolites, amino acid metabolites and improvements in insulin sensitivity and glucose metabolism: the POUNDS Lost trial Gut There's a reason L carnitine keeps showing up in PCOS research Because PCOS is closely tied to insulin resistance, inflammation, and metabolic dysfunctionand L carnitine plays a role in energy metabolism and fat utilization. Case of 24 Acetyl L Carnitine 400 mg Cap 30 By Nature's Bounty USA L carnitine is a naturally occurring amino acid structure that is made in the human brain, liver, and kidneys. L carnitine plays a critical role in energy production, as it converts fat into energy.