Ketone precursors — sometimes called pre-ketones — include 1,3-butanediol, bis hexanoyl (R)-1,3-butanediol, and bis octanoyl (R)-1,3-butanediol, which are metabolized in the liver to produce the ketone bodies beta-hydroxybutyrate and acetoacetate.[1][2][3][4][5][6][7][8] Therefore, ingesting a ketone precursor increases the concentration of beta-hydroxybutyrate in the blood and mimics ketosis.[9][8][10][11][12] Companies like ketone-IQ (formerly HVMN) sell products containing 1,3-butanediol and claim a wide variety of benefits. However, as described below, there are few clinical studies.
A single dose of 1,3-butanediol increased cardiac output, stroke volume, and the left ventricular ejection fraction in men with heart failure in a small randomized controlled trial.[13] Further larger studies are needed to confirm these effects.
Ingesting a single dose of 1,3-butanediol either before or before and during exercise did not affect aerobic exercise performance during running or cycling, as shown by two small randomized controlled trials.[14][15]
The effects on blood glucose are mixed. One small study found that a single dose of bis octanoyl (R)-1,3-butanediol did not affect fasting blood glucose in older adults.[11] However, this study did not include a control group,[11] so firm conclusions cannot be made. Another study found that a single dose of bis hexanoyl (R)-1,3-butanediol lowered postprandial blood glucose when taken before a carbohydrate-containing meal.[8] However, this study also lacked a control group.[8] A follow-up study that included a control group found no effect on blood glucose.[10]
Generally, there are very few randomized controlled trials on ketone precursors, and much of the existing work is of low quality. Further high-quality research is needed to make firm conclusions about the effects of ketone precursors on health and performance.