Inositol as a treatment for psychiatric disorders: a scientific evaluation of its clinical effectiveness

Townsend Letter for Doctors and Patients, Oct, 2004 by Gina L. Nick

Not for Use During Pregnancy

Researchers have documented the preventive effect of inositol in folate-resistant neural tube defects in rats and mice, (16,17) as well as its positive effect in treating hyperglycemia-induced embryopathy. (18) However, inositol may cause dose-related uterine contractions because it has an intimate relationship with oxytocin, a key uterine stimulator. Oxytocin activates phospholipase C to produce inositol-1,4,5-triphosphate, which causes the release of calcium from intracellular stores and stimulates uterine contractions. (19,20) Thus, it is possible that inositol in high doses may stimulate uterine contractions via its role in the oxytocin stimulatory pathway, making it potentially dangerous for pregnant women.

Inositol in Food

Inositol in the form of phytic acid has been proposed as a possible agent in the cancer-fighting potential of whole grains. (21) The compound is heat- and acid-stable and is found in high concentration in many food items, including cereal grains, nuts, and seeds. Phytic acid is a metal chelator that can suppress damaging metal-catalyzed redox reactions, making it a natural antioxidant. Indeed, a high concentration of phytic acid in fruits and vegetables prevents oxidative browning and putrefaction by inhibiting polyphenol oxidase. (22)

The foods in which phytic acid is found are typically high in numerous other antioxidants, including quercetin and flavonoids. Phytic acid is also a major source of dietary phosphorus. (23) It is unclear if physiologically effective doses of inositol for treating mood can be achieved through diet alone.

In the Lab

Carey (24) has recently demonstrated in 14 patients with OCD that improvement during inositol treatment parallels specific single photon emission computed tomography (SPECT) changes in certain areas of the brain. These findings suggest inositol's clinical effects are mediated through neuronal circuitry that is different from those involved with the SSRIs, implying an "overlapping but distinct mechanism of action."

Brink et al., (25) exploring the mechanism of action of mI in depression and related anxiety disorders, found both similarities and differences in the effects of myo-inositol (mI), fluoxetine and imipramine on serotonin 5HT2A and muscarinic acetylcholine receptors in human neuroblastoma cells. These findings may help to explain why mI seems to be effective exclusively in selective serotonin reuptake inhibitor-sensitive disorders.

Conclusion

Inositol's clinical efficacy coupled with the absence of significant side effects suggests that this nutrient may be an attractive addition to treatment plans for patients suffering from panic disorder, clinical depression, and/or obsessive-compulsive disorder. While inositol has shown benefit in some SSRI responsive conditions, it is not indicated as a replacement for SSRIs or as a treatment for all SSRI responsive conditions. Further research is necessary to elucidate the full potential of this natural compound in the treatment of mental illnesses and other conditions.