Cognitive function
Preclinical studies in rodents have shown that exogenous ketones can enhance cognitive function.[1][2][3][4] Some randomized controlled trials have also found that supplementation with exogenous ketones can improve aspects of cognitive function in people under conditions of metabolic stress (e.g., fasting, exercise, or hypoxia, which is a condition when the body is deprived of an adequate oxygen supply)[5][6][7][8][9][10] and in people with neurodegenerative conditions (e.g., Alzheimer’s disease).[11] However, the effects in humans vary considerably, and some clinical trials have found no benefit of exogenous ketones on cognitive function.[12][13][14] Further high-quality randomized controlled trials are needed to understand the therapeutic efficacy of ketones in people with mild cognitive impairment or Alzheimer's disease.
Glycemic control
Two meta-analyses have found that supplementation with exogenous ketones can lower blood glucose and increase insulin in people with obesity and prediabetes and in people without known health conditions.[15][16] Some,[17][18] but not all,[19][20] randomized controlled trials have found similar effects in people with type 2 diabetes. More research is needed to determine the efficacy of exogenous ketones in treating diabetes.
Heart failure
One meta-analysis has shown that exogenous ketones can increase the left ventricular ejection fraction, cardiac output, and stroke volume — signs of improved cardiac function — in people with heart failure, without influencing the heart rate or blood pressure.[21] A subgroup analysis in that study found that exogenous ketones can also enhance cardiac function in people without heart failure.[21] However, there was a high risk of bias among the included studies, and the analysis combined different types of ketone delivery: intravenously infused beta-hydroxybutyrate and orally administered ketone esters. That said, two further randomized controlled trials that used an orally ingested ketone ester have confirmed the findings of the meta-analysis described above in heart failure patients and people with type 2 diabetes.[22][23]