Carnosic acid, a major phenolic diterpene found in rosemary (Rosmarinus officinalis), has been investigated in preclinical studies for its potential benefits in managing metabolic syndrome. Metabolic syndrome is characterized by a cluster of conditions, including insulin resistance, hyperglycemia, dyslipidemia, hypertension, and central obesity. Several in vitro and animal studies have demonstrated that carnosic acid exhibits antioxidant, anti-inflammatory, and lipid-lowering properties. For example, research has shown that carnosic acid can improve insulin sensitivity, reduce blood glucose levels, and decrease triglyceride and cholesterol concentrations in rodent models of metabolic syndrome. Mechanistically, these effects are thought to result from modulation of key metabolic pathways, such as activation of AMP-activated protein kinase (AMPK) and inhibition of lipid accumulation in adipocytes.

However, the current evidence is limited to laboratory and animal research. There is a lack of robust human clinical trials directly evaluating the effects of carnosic acid supplementation in patients with metabolic syndrome. While the preclinical data are promising and suggest a potential role for carnosic acid in metabolic health, the overall evidence quality remains low, and its efficacy and safety in humans are not yet established. Therefore, while there is scientific rationale and early evidence, more well-designed human studies are needed before carnosic acid can be confidently recommended for metabolic syndrome.