Butyrate, carnitine and leucine are dietary ingredients that may be ketogenic but whether they are equally or more ketogenic in humans than medium-chain triacylglycerols is unclear.

Our objective was to compare the ketogenic effect in healthy adult humans of l-leucine, butyrate, octanoyl-monoacylglycerol (O-MAG) and l-carnitine during a 4 h metabolic study period.

Each test substance was taken with a standard breakfast: butyrate (2 or 4 g), O-MAG (5 or 10 g), l-leucine (5 g), or l-carnitine (2 g), and compared to a no treatment Control (n = 13). At the doses provided, butyrate (2 g; 4 g), O-MAG (5 g; 10 g) increased total plasma ketones AUC of 3.5, 5.0, 1.5, and 2.7-fold (P ≤ 0.05), respectively, compared to baseline. l-carnitine did not significantly stimulate ketogenesis relative to Control. Per gram tested, butyrate was the most ketogenic, and has the potential to be an ingredient in a ketogenic functional food or beverage.