SMIT1 both alters KCNQ selectivity for BHB, and also amplifies the effects of clinically relevant concentrations of BHB on KCNQ2/3, suggesting we should consider KCNQ2/3–SMIT1 complexes when evaluating the mechanisms underlying the therapeutic action of the ketogenic diet and fasting in epilepsy. The gene discussed is KCNQ2; the disease is epilepsy.