Myo-Inositol — The Insulin Sensitiser
Myo-inositol is a naturally occurring sugar alcohol that serves as a key structural basis for secondary messengers in eukaryotic cells. In the context of longevity, it is primarily valued for its ability to improve insulin sensitivity, regulate glucose metabolism, and mitigate metabolic syndrome, which are critical factors in healthspan extension.
Mechanism of Action
Myo-inositol functions as a precursor to inositol triphosphate (IP3) and phosphatidylinositol (PI), which are essential intracellular secondary messengers. It plays a crucial role in insulin signalling by facilitating the translocation of GLUT4 transporters to the cell membrane, thereby enhancing cellular glucose uptake. Additionally, myo-inositol modulates intracellular calcium release and influences the activity of various kinases, including AMPK, which promotes metabolic homeostasis and reduces oxidative stress.
Human Trial Evidence
Extensive human trials have demonstrated the efficacy of myo-inositol in improving metabolic parameters, particularly in women with polycystic ovary syndrome (PCOS) and individuals with metabolic syndrome. Clinical studies consistently show significant reductions in fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and serum triglycerides. Evidence for direct lifespan extension in humans is lacking, but its benefits on metabolic healthspan are well-documented.
Dosing Protocol
2,000 to 4,000 mg per day, typically divided into two doses. It is often taken in powder form dissolved in water. For optimal absorption, it is frequently administered away from meals, though taking it with food is acceptable to minimise gastrointestinal discomfort.
Safety & Contraindications
Myo-inositol is generally recognised as safe (GRAS) and is well-tolerated at standard doses. Mild adverse effects may include gastrointestinal distress, such as nausea, flatulence, or diarrhoea, particularly at higher doses (above 12 g/day). It should be used with caution in individuals taking hypoglycaemic medications, as it may have an additive effect on lowering blood glucose levels.