Beta-hydroxybutyrate — The Signaling Ketone
Beta-hydroxybutyrate (BHB) is the primary ketone body produced during fasting or carbohydrate restriction, serving not only as an energy substrate but as a potent signaling metabolite. By acting as an endogenous inhibitor of histone deacetylases (HDACs), BHB links metabolic state to gene expression, promoting cellular resilience and longevity pathways.
Mechanism of Action
BHB acts as an endogenous inhibitor of class I and IIa histone deacetylases (HDAC1, HDAC3, HDAC4), leading to histone hyperacetylation and the transcriptional activation of stress-resistance genes. This HDAC inhibition directly induces the expression of Foxo3a, a key transcription factor in longevity, and upregulates brain-derived neurotrophic factor (BDNF). Furthermore, BHB metabolism increases the NAD+/NADH ratio, which in turn activates sirtuins and AMPK. It also suppresses the activity of the mechanistic target of rapamycin (mTOR) complex and mitigates inflammation by inhibiting the NLRP3 inflammasome.
Human Trial Evidence
No published human longevity trials. Animal/in-vitro evidence only. Short-term human trials have primarily focused on the safety, tolerability, and acute metabolic effects of exogenous ketone esters and salts, demonstrating their ability to safely induce therapeutic ketosis without severe adverse effects.
Dosing Protocol
Exogenous ketone esters are typically dosed between 10–25 g per serving, while ketone salts range from 10–15 g of BHB. These are often taken acutely for cognitive or physical performance, or to sustain ketosis. Optimal dosing for long-term longevity benefits in humans remains unestablished.
Safety & Contraindications
Exogenous BHB supplements are generally safe and well-tolerated in healthy adults. The most common adverse effects are gastrointestinal, including stomach upset, diarrhea, and constipation, particularly at higher doses or with ketone salts due to the high mineral load (sodium, calcium, or magnesium). Caution is advised for individuals with impaired renal function or those prone to electrolyte imbalances.