Erythropoietin (EPO) is a hormone primarily produced by the kidneys that stimulates the production of red blood cells in the bone marrow, a process known as erythropoiesis.[1][2] This process is typically triggered when oxygen levels in the blood drop, and it helps maintain oxygen delivery throughout the body.[1][2]
Some trials have examined the effect of exogenous ketones on serum EPO concentrations. A small randomized controlled trial in 17 adults found an increase in EPO following an intravenous infusion of beta-hydroxybutyrate administered the morning after an overnight fast (no breakfast).[3] Another randomized controlled trial in 20 recreationally active men found an increase in EPO following 3 weeks of endurance training during which ketone ester was consumed daily after each training session and before sleep.[4] Similarly, a small randomized controlled crossover study in 9 recreationally active men found that consuming a ketone ester after a 1-hour exercise bout without eating breakfast increased EPO for up to 4 hours.[5] However, another trial found that when carbohydrates are consumed before exercise, consuming a ketone ester after exercise does not affect EPO.[6] Because these outcomes are somewhat mixed and because the trials are small, more research is needed to determine whether exogenous ketones have a robust stimulating effect on serum EPO concentrations.
As a side note, EPO is on the World Anti-Doping Agency prohibited list because it is a performance-enhancing drug.[7] So, if consuming an exogenous ketone had a meaningful effect on EPO, we would also expect to see an increase in exercise performance. However, the current evidence shows that supplementation with exogenous ketones does not improve exercise performance (see Do exogenous ketones improve exercise performance?).