inositol

Inositol refers to a family of nine stereoisomers of the cyclohexanehexol molecule, the best known and most abundant being myo-inositol. It is a polyol related to glucose and occurs naturally in a wide range of foods, including fruits, beans, grains, and nuts. In plants and animals, inositol is also produced biologically from glucose-6-phosphate through the myo-inositol phosphate pathway.

Biological role and metabolism include its key function as a structural component of phosphatidylinositol lipids in cell membranes. These lipids are precursors to phosphoinositide signaling molecules such as PIP2, IP3, and DAG, which regulate calcium signaling, vesicle trafficking, and various cellular processes. Inositol phosphates also participate in nuclear signaling and osmoregulation in some organisms. The most common natural form, myo-inositol, serves as the reference stereoisomer for biological activity in humans.

Uses and clinical evidence show that myo-inositol is widely used as a dietary supplement. It has been studied for polycystic ovary syndrome (PCOS), where several randomized trials report improvements in ovulatory function, insulin sensitivity, and androgen levels, particularly when myo-inositol is combined with D-chiro-inositol in specific ratios. Evidence for myo-inositol’s effects on mood disorders or anxiety is less consistent and not yet conclusive. Other proposed uses exist, but robust clinical data are limited.

Safety and intake: there is no official daily requirement for inositol, and dietary intake typically contributes most of the body’s inositol. Supplements are generally well tolerated; high doses can cause gastrointestinal symptoms in some individuals, and caution is advised for people with certain psychiatric conditions.