Inositol

Overview

Inositol is a compound that has been known for a long time, but in 1940 scientists first realized that it was an essential nutrient. It is a sugar-like substance and is part of the water-soluble B vitamin complex. It is found in the liver, kidney, skeletal and heart muscle. It is also present in the leaves and seeds of many plants. In animal tissues inositol occurs as a component of phospholipids and in plants it usually occurs as phytic acid, which is the hexaphosphate ester of inositol. In humans, inositol is synthesized in the intestinal tract by the beneficial or “friendly” bacteria.

Dosage Info

Dosage Range

100-1,000mg daily. Dosages in the range of 12-18 grams daily have been used for certain conditions such as panic disorder. (1)

Most Common Dosage

250mg, 2 times a day.

Dosage Forms

Tablets and capsules.

Adult RDI

None established

Adult ODA

None established

RDA

Interactions and Depletions

Interactions

Depletions

Active Forms

Inositol monophosphate, inositol hexaniacinate.

Absorption

Myo-inositol is efficiently absorbed from the small intestine.

Toxicities & Precautions

General

No toxicity has been reported or observed with inositol.

Functions in the Body

Essential Component of Phospholipids:

In cellular membranes of animals and humans.

Cellular Response:

As part of phospholipids in cellular membranes, phosphatidylinositol helps to mediate cellular responses to external stimuli.

Arachidonic Acid Production:

Phosphatidylinositol also facilitates the production of arachidonic acid.

Diabetes:

Myo-inositol may be helpful in the treatment of diabetic neuropathy.

Mental Illness:

Several studies have reported that inositol can be effective in treating depression, panic and obsessive-compulsive disorders.

Clinical Applications

Raynaud’s Disease

Inositol hexaniacinate reduces peripheral vasospasms during cold weather. (2)

Panic Attacks

Inositol has been shown to be an effective treatment for this disorder. (3)

Obsessive-Compulsive Disorder

Inositol provided significant improvement in patients with this condition. (4) , (5)

Depression

Some studies have shown that inositol is as effective as imipramine in treating depression. (6)

Diabetic Neuropathy

In post-mortem studies, the sciatic nerves of diabetic individuals were found to contain significantly lower concentrations of inositol compared to controls. (7) Inositol is useful in the prevention and treatment of diabetic neuropathy. (8)

Symptoms and Causes of Deficiency

No inositol deficiency has been identified in humans, and a deficiency is not likely because of its widespread occurrence in foods.

Dietary Sources

Inositol occurs in foods in three different forms: as free myo-inositol, phytic acid, and inositol-containing phospholipids. The richest plant sources of myo-inositol are seeds such as beans, grains, and nuts. The richest animal sources are organ meats. Free myo-inositol predominates in brain and kidney, whereas phospholipid-inositol is concentrated in skeletal muscle, heart, liver, and pancreas.

References

  1. View Abstract: Palatnik A, Frolov K, Fux M, Benjamin J. Double-Blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol. Jun2001;21(3):335-9.
  2. View Abstract: Sunderland GT, et al. A Double-blind Randomised Placebo Controlled Trial of Hexopal in Primary Raynaud’s Disease. Clin Rheumatol. Mar1988;7(1):46-49.
  3. View Abstract: Benjamin J, et al. Double-blind, Placebo-controlled, Crossover Trial of Inositol Treatment for Panic Disorder. Am J Psychiatry. Jul1995;152(7):1084-86.
  4. View Abstract: Fux M, et al. Inositol Treatment of Obsessive-compulsive Disorder. Am J Psychiatry. Sep1996;153(9):1219-21.
  5. View Abstract: Carey PD, Warwick J, Harvey BH, Stein DJ, Seedat S. Single photon emission computed tomography (SPECT) in obsessive-compulsive disorder before and after treatment with inositol. Metab Brain Dis. Jun2004;19(1-2):125-34.
  6. View Abstract: Benjamin J, et al. Inositol Treatment in Psychiatry. Psychopharmacol Bull. 1995;31(1):167-75.
  7. View Abstract: Mayhew JA, et al. Free and Lipid Inositol, Sorbitol and Sugars in Sciatic Nerve Obtained Post-mortem from Diabetic Patients and Control Subjects. Diabetologia. Jan1983;24(1):13-15.
  8. View Abstract: Salway JG, et al. Effect of Myo-inositol on Peripheral-nerve Function in diabetes. Lancet. Dec1978;2(8103):1282-84.