Inositol, unofficially referred to as "vitamin B 8 ," is present in all animal tissues, with the highest levels in the heart and brain. It is part of the membranes (outer coverings) of all cells, and plays a role in helping the liver process fats as well as contributing to the function of muscles and nerves.
Inositol may also be involved in depression. People who are depressed may have lower than normal levels of inositol in their spinal fluid. In addition, inositol participates in the action of serotonin , a neurotransmitter known to be a factor in depression. (Neurotransmitters are chemicals that transmit messages between nerve cells.) For these two reasons, inositol has been proposed as a treatment for depression, and preliminary evidence suggests that it may be helpful.
Inositol has also been tried for other psychological and nerve-related conditions.
Inositol is not known to be an essential nutrient. However, nuts, seeds, beans, whole grains, cantaloupe, and citrus fruits supply a substance called phytic acid (inositol hexaphosphate, or IP6), which releases inositol when acted on by bacteria in the digestive tract. The typical American diet provides an estimated 1,000 mg daily.
Experimentally, inositol dosages of up to 18 g daily have been tried for various conditions.
Inositol has also been studied for
Inositol is sometimes proposed as a treatment for
Small double-blind studies have found inositol helpful for
However, a double-blind study of 42 people with severe depression that was not responding to standard antidepressant treatment found no improvement when inositol was added.
A double-blind, crossover study of 20 individuals compared inositol to the antidepressant drug fluvoxamine (Luvox), a medication related to Prozac.
In a 6-week, double-blind study, 24 individuals with
No serious ill effects have been reported for inositol, even with a therapeutic dosage that equals about 18 times the average dietary intake. However, no long-term safety studies have been performed.
Although inositol has sometimes been recommended for bipolar disorder, there is evidence to suggest inositol may trigger manic episodes in people with this condition. 29
Safety has not been established in young children, women who are pregnant or nursing, and those with severe liver and kidney disease. As with all supplements used in very large doses, it is important to purchase a reputable product, because a contaminant present even in small percentages could add up to a real problem.
10. Fux M, Benjamin J, Belmaker RH. Inositol versus placebo augmentation of serotonin reuptake inhibitors in the treatment of obsessive-compulsive disorder: a double-blind cross-over study. Int J Neuropsychopharmcol. 1999;2:193-195.
14. Gregersen G, Bertelsen B, Harbo H, et al. Oral supplementation of myoinositol: effects on peripheral nerve function in human diabetics and on the concentration in plasma, erythrocytes, urine and muscle tissue in human diabetics and normals. Acta Neurol Scand . 1983;67:164-172.
31. Gerli S, Mignosa M, Di Renzo GC. Effects of inositol on ovarian function and metabolic factors in women with PCOS: a randomized double blind placebo-controlled trial. Eur Rev Med Pharmacol Sci . 2003;7:151-9.
33. Gerli S, Papaleo E, Ferrari A, et al. Randomized, double-blind, placebo-controlled trial: effects of myo-inositol on ovarian function and metabolic factors in women with PCOS. Eur Rev Med Pharmacol Sci. 2007;11:347-354.
Last reviewed April 2009 by EBSCO CAM Review Board
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