MyoInositol

Myoinositol is a naturally occurring stereoisomer of inositol, a cyclohexanehexol. It is the most abundant form of inositol in humans and in nature and is found in cells as part of phosphatidylinositol and related phosphates. In humans, myoinositol is produced from glucose and is also obtained from dietary sources such as fruits, beans, grains, and nuts.

Biological roles of myoinositol include its function as a precursor for phosphatidylinositol, which can be phosphorylated to form inositol phosphates that act as intracellular second messengers. These signaling molecules, including IP3, participate in calcium signaling and other pathways essential for cellular processes. Myoinositol is implicated in membrane biology, insulin signaling, and osmoregulation in certain tissues, with its exact functions varying by context.

Clinical use and research of myoinositol focus largely on polycystic ovary syndrome (PCOS). It is marketed as a dietary supplement and has been studied for potential benefits on ovulatory function and insulin sensitivity. Some trials report improvements, especially when myoinositol is used in combination with D-chiro-inositol in specific ratios (commonly discussed as around 40:1 MI:DCI), but results are heterogeneous and guidelines vary. Typical supplemental dosages range from about 2 to 4 grams per day, divided into multiple doses; higher doses may cause gastrointestinal discomfort. Myoinositol is generally considered safe for short-term use, though individuals with certain medical conditions or those taking medications should consult a clinician.

Dietary sources include fruits, beans, grains, and nuts, but the body also synthesizes myoinositol endogenously. It is not classified as an essential nutrient, yet it serves important roles in cellular signaling and metabolism.