Beta-hydroxybutyrate (BHB) is a ketone body your body produces during fasting or a very low-carb diet. Supplement forms are mineral salts, such as sodium, potassium, magnesium, or calcium, designed to increase blood ketones without changing what you eat.
People take BHB to support mental focus and physical energy while in ketosis, or to ease the shift into a ketogenic diet. The evidence for meaningful performance or cognitive improvements in people not in ketosis is limited and mixed.
Dosage and timing vary widely across products. Most come as powders or capsules and are taken with water, either on an empty stomach or with meals. The effects are temporary, lasting only a few hours.
Key cautions: It may cause digestive upset, including diarrhea and cramping, and can disrupt electrolyte balance. Do not use it if you have kidney disease, heart conditions, or diabetes unless a doctor supervises. Excess intake can lower blood pH.