Inositol as a dietary supplement
Inositol, often referred to as vitamin B8, is a naturally occurring substance found in animal tissues, particularly in the heart and brain. As a dietary supplement, it is promoted for various health benefits, primarily for its potential role in alleviating conditions such as depression, panic disorder, and anxiety. There is preliminary evidence suggesting that inositol may support mental health, as individuals with depression can have lower levels of inositol in their spinal fluid.
Inositol exists in several forms, with Myo-inositol and D-chiro-inositol being the most common in supplements. While it is not classified as an essential nutrient, dietary sources include nuts, seeds, beans, whole grains, and certain fruits. Typical intake from a standard diet is around 1,000 mg daily, while therapeutic dosages can range from 1 to 60 grams, depending on the condition treated.
Research has explored inositol's efficacy for various disorders, including bipolar disorder, polycystic ovary syndrome (PCOS), and diabetic neuropathy, with mixed results. While some studies indicate potential benefits, particularly for PCOS and panic disorders, evidence remains inconclusive for many uses. Generally, inositol is considered safe for short-term use, but caution is advised for specific populations, such as individuals with bipolar disorder or diabetes. As with any supplement, it is important to consult healthcare professionals before starting inositol, especially at therapeutic dosages.
Inositol as a dietary supplement
- DEFINITION: Natural substance promoted as a dietary supplement for specific health benefits.
- PRINCIPAL PROPOSED USES: Depression, panic disorder, anxiety
- OTHER PROPOSED USES: Alzheimer’s disease, attention deficit hyperactivity disorder, bipolar disorder, bulimia, cancer prevention, diabetic neuropathy, obsessive-compulsive disorder, premenstrual syndrome, polycystic ovarian syndrome, psoriasis caused by treatment with lithium, post-traumatic stress disorder, insomnia, metabolic syndrome, insulin resistance, cholesterol
Overview
Inositol, unofficially referred to as vitamin B8, 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. It plays a role in helping the liver process fats and in 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 also has been tried for other psychological and nerve-related conditions.
There are nine forms of inositol, but Myo-inositol and D-chiro-inositol are the most common forms found in supplements.
Sources
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 milligrams (mg) daily.
Therapeutic Dosages
Experimentally, inositol dosages of up to 60 grams (g) daily have been tried for various conditions, but doses usually fall between 1 and 4 g daily. It has been shown to be safe for up to ten weeks. Some uses have relatively well-established doses, including 2 g for metabolic syndrome, 2 g for PCOS, 6 g for lithium-related psoriasis, and 12 g for panic and anxiety disorders.
In pregnant women, 4000 mg of inositol has been successfully used. It is commonly taken with folic acid supplements between 200 and 400 micrograms.
Therapeutic Uses
Inositol has been studied for depression, bipolar disorder, panic disorder, bulimia, and obsessive-compulsive disorder, but the evidence remains inconclusive. Other potential uses include Alzheimer’s disease and attention deficit hyperactivity disorder.
According to two double-blind studies enrolling almost four hundred people, inositol may help improve various symptoms of polycystic ovary syndrome, including infertility and weight gain. Another small double-blind study found that inositol supplements could help reduce symptoms of psoriasis triggered or made worse by the use of the drug lithium. A small double-blind study failed to find inositol helpful for premenstrual dysphoric disorder, a severe form of premenstrual syndrome.
Other uses supported by research include treating panic disorder. In one study, four weeks of 18 g of Myo-inositol was more effective than serotonin reuptake inhibitors or benzodiazepines in preventing panic episodes, and it caused fewer side effects.
Inositol is sometimes proposed as a treatment for diabetic neuropathy. Inositol has also been investigated for potential cancer-preventive properties.
Scientific Evidence
Depression. Small double-blind studies have found inositol helpful for depression. In one such trial, twenty-eight depressed persons were given a daily dose of 12 g of inositol for four weeks. By the fourth week, the group receiving inositol showed significant improvement compared with the placebo group. However, a double-blind study of forty-two people with severe depression that was not responding to standard antidepressant treatment found no improvement when inositol was added.
Panic disorder. People with panic disorder frequently develop panic attacks, often with no warning. The racing heartbeat, chest pressure, sweating, and other physical symptoms can be so intense that they are mistaken for a heart attack. A small double-blind study (twenty-one participants) found that people given 12 g of inositol daily had fewer and less severe panic attacks compared with the placebo group.
A double-blind, crossover study of twenty people compared inositol to the antidepressant drug fluvoxamine (Luvox), a medication related to Prozac. The results of four weeks of treatment showed that the supplement was, at minimum, just as effective as the drug. Small studies did show inositol to be effective in treating obsessive-compulsive disorder; however, similar research on its ability to treat post-traumatic stress disorder was inconclusive.
Bipolar disorder. In a six-week, double-blind study, twenty-four people with bipolar disorder received either placebo or inositol (2 g three times daily for a week, then increased to 4 g three times daily) in addition to their regular medical treatment. The results of this small study failed to show statistically significant benefits; however, promising trends were seen that suggest a larger study is warranted.
Polycystic ovary syndrome. Polycystic ovary syndrome (PCOS) is a chronic endocrine disorder in women that leads to infertility, weight gain, and many other problems. In a double-blind, placebo-controlled trial, 136 women with PCOS were given inositol at a dose of 100 mg twice daily, while 147 were given placebo. During the fourteen-week study, participants given inositol showed improvement in ovulation frequency compared with those given placebo. Benefits were also seen regarding weight loss and HDL (good) cholesterol levels. A subsequent study of ninety-four women found similar results. However, both of the studies were performed by the same research group. Independent confirmation is necessary before inositol can be considered an effective treatment for PCOS.
As studies on inositol continued in the twenty-first century, researchers continued to see promising results concerning ovulation and fertility. Inositol also appeared to be effective in treating gestational diabetes in pregnant women. It also showed promise for preventing preterm birth. One study of postmenopausal women found that supplementation with inositol improved insulin sensitivity, blood pressure, and cholesterol. For this reason, inositol remained an effective natural treatment for metabolic disorders.
Safety Issues
No serious side effects have been reported for inositol, even with a therapeutic dosage that equals about eighteen 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. Persons with bipolar disorder should not take inositol unless under a doctor’s supervision. Individuals with diabetes should also avoid inositol unless instructed by a physician because it can impact blood sugar.
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 be harmful.
Bibliography
Allan, S. J., et al. “The Effect of Inositol Supplements on the Psoriasis of Patients Taking Lithium.” British Journal of Dermatology, vol. 150, 2004, pp. 966-69.
Cherry, Kendra. “Inositol: Benefits, Side Effects, Dosage, Interactions.” Verywell Mind, 24 June 2024, www.verywellmind.com/inositol-what-should-i-know-about-it-89466. Accessed 24 Sept. 2024.
Gerli, S., et al. “Randomized, Double-Blind, Placebo-Controlled Trial: Effects of Myo-Inositol on Ovarian Function and Metabolic Factors in Women with PCOS.” European Review for Medical and Pharmacological Sciences, vol. 11, 2007, pp. 347-54.
“Inositol: Benefits & Side Effects.” Cleveland Clinic, 6 Aug. 2023, my.clevelandclinic.org/health/drugs/25173-inositol. Accessed 24 Sept. 2024.
Nemets, B., et al. “Myo-Inositol Has No Beneficial Effect on Premenstrual Dysphoric Disorder.” World Journal of Biological Psychiatry, vol. 3, 2002, pp. 147-49.
Owczarczyk-Saczonek, Agnieszka, et al. “D-chiro-inositol as a Treatment in Plaque Psoriasis: A Randomized Placebo-Controlled Clinical Trial.” DermatologicTherapy, vol. 34, no. 1, 2021, p. e14538, doi:10.1111/dth.14538.
Palatnik, A., et al. “Double-Blind, Controlled, Crossover Trial of Inositol versus Fluvoxamine for the Treatment of Panic Disorder.” Journal of Clinical Psychopharmacology, vol. 21, 2001, pp. 335-39.
Zulfarina, Mohamed S., et al. “Pharmacological Therapy in Panic Disorder: Current Guidelines and Novel Drugs Discovery for Treatment-Resistant Patient.” Clinical Psychopharmacology and Neuroscience: The Official Scientific Journal of the Korean College of Neuropsychopharmacology, vol. 17, no. 2, 2019, pp. 145-54, doi:10.9758/cpn.2019.17.2.145.