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BACKGROUND: The major component of lemongrass by weight is dietary fibre (DF), but no literature has been reported on its DF components and fermentation products when ingested. OBJECTIVE: This study analysed DF components of lemongrass, investigated the potential of the major product from total DF (TDF) fermentation to inhibit α-amylase and HMG-CoA reductase, key enzymes of diabetes mellitus and hypercholesterolemia, respectively, and determined the serum glucose- and cholesterol-lowering potential of TDF in an animal model. METHODS: Lemongrass DF components were analysed, TDF was fermented in vitro; the major fermentation product was isolated for enzyme inhibitory assays; and postprandial blood glucose- and cholesterol-lowering potential of TDF was determined in Sprague-Dawley rats. RESULTS: TDF in lemongrass was 65.7 g/100g and soluble DF, 2.8 g/100 g. Significant amount of propionate (10.9 mM/g TDF) was produced after TDF fermentation; propionate inhibited 20.4% α-amylase activity, and 13.1 % HMG-CoA reductase activity in vitro. TDF further exhibited antihyperglycemic and cholesterol-lowering potential in an animal model. CONCLUSIONS: DF from lemongrass was shown to reduce hyperglycemia and hypercholesterolemia in an animal model, through mild inhibition of α-amylase and HMG-CoA reductase. Thus, lemongrass DF may have a significant role in mitigating the risk of type 2 diabetes mellitus and hypercholesterolemia.