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Exogenous ketone drinks may improve athletic performance and recovery, but information on their gastrointestinal (GI) tolerability is limited. Studies to date have used simplistic reporting methodology that inadequately represents symptom type, frequency and severity. Here, GI symptoms were recorded during three studies of exogenous ketone monoester (KME) and salt (KS) drinks. Study 1 compared low and high dose KME and KS drinks consumed at rest. Study 2 compared KME to isocaloric carbohydrate (CHO) consumed at rest either when fasted or after a standard meal. Study 3 compared KME+CHO to isocaloric CHO consumed before and during 3.25h of bicycle exercise. Participants reported symptom type and rated severity be-tween 0-8 using a Likert Scale at regular intervals. The number of visits with no symptoms reported after ketone drinks was n=32/60 in Study 1, n=9/32 in Study 2 and n=20/42 in Study 3. Following KME and KS drinks, symptoms were acute but mild and were fully resolved by the end of the study. High dose KS drinks caused greater total-visit symptom load than low dose KS (13.8±4.3 vs. 2.0±1.0; P<0.05) and significantly greater time-point symptom load than KME drinks 1-2h post-drink. At rest, KME drinks caused greater total-visit symptom load than CHO drinks (5.0±1.6 vs. 0.6±0.4; P<0.05). However, during exercise there was no significant difference in total-visit symptom load between KME+CHO (4.2±1.0) and CHO (7.2±1.9) drinks. In summary, exogenous ketone drinks cause mild GI symptoms that depend on time, the type and amount of compound consumed and on exercise.

Original publication




Journal article


Int J Sport Nutr Exerc Metab

Publication Date



1 - 23


(3 that are not included in the title): ketone ester, ketone monoster, ketone salt