Myo-inositol is a vitamin-like nutrient produced by the body and found in many foods. It’s gained a growing appreciation for its purported benefits in women with PCOS. But myo-inositol is also being researched for reducing anxiety, improving diabetes, and enhancing fertility in men. We will explore why myo-inositol might be important and ways to naturally boost it in the body.
What Is Myo-Inositol?
Overview
Myo-inositol is the most common form of inositol found in nearly all plants and animals [1].
It plays so many roles, that it – specifically, inositol – was unofficially classified as a B vitamin (vitamin B8). However, generally, it is referred to as a vitamin-like substance instead [2].
On the other hand, myo-inositol supplements have not been approved by the FDA for medical use. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
Role in the Body
All cells need myo-inositol to survive. Once they take it in, they transform it to phosphatidylinositol, a crucial component of cell membranes. Myo-inositol also helps orchestrate the activity of hormones [3, 4].
It affects the very structure of cells, metabolism in brain cells, fat burning and storage, energy use, and the stress response. It is equally important for the brain, as it protects neurons and nerves [5, 6, 7, 8, 9].
Myo-inositol is also used by the ovaries to make hormones that affect fertility and ovulation (such as FSH) [10].
The second most abundant inositol after myo-inositol is D-chiro-inositol. It acts as an antioxidant and studies suggest it helps improve PCOS and hormonal imbalance in women [10, 11].
Levels of myo-inositol are especially high in the brain. In fact, the brain can make large amounts of myo-inositol from the products of glucose breakdown. Myo-inositol levels in brain cells are a measure of the “energy charge” of cells. Scientists believe that the more inositol brain cells have, the better they’re protected and the greater the overall energy in the brain [12].
Myo-inositol also increases from any kind of brain damage, as a way to compensate for injury and heal. But this increase in brain myo-inositol is also linked to scar tissue in the brain and cognitive problems [13, 14].
Having balanced levels of myo-inositol in the body may be key. Low levels are linked to infertility, anxiety, and metabolic and hormonal problems. But extremely high levels are linked to brain damage and mania.
Genetics
Two genes are very important for inositol production:
You can get a comprehensive genetics test and upload the results to SelfDecode to analyze your genome for these genes.
Snapshot
Proponents
- Essential nutrient
- Helps with diabetes and metabolic syndrome
- Increases fertility and reduces PCOS symptoms in women
- Protects the brain and nerves
- May improve mental health (mood and anxiety)
Skeptics
- May not be beneficial for men with diabetes
- Can cause nausea, digestive problems, and tiredness
- Doesn’t improve autism, cognitive problems and mania
- Large-scale, multi-center clinical trials are lacking
- Long-term safety unknown
Potential Health Benefits and Uses of Myo-inositol
Possibly Effective:
1) PCOS
Polycystic ovarian syndrome (PCOS), a common hormonal disorder in women, causes ovulation problems, weight gain, insulin resistance, and increased male hormone levels [15].
Solid evidence (40 clinical studies) support the benefits of myo-inositol for PCOS.
According to a review of studies with over 800 women undergoing in vitro fertilization (IVS), myo-inositol improves fertility by lowering male sex hormones in both women with and without PCOS. But it could also improve ovulation in women with PCOS [16].
Myo-inositol also reduces insulin resistance and increases estrogen levels, according to a review of studies on over 500 women with PCOS [17].
In one large study of over 3,500 women with PCOS (observational), myo-inositol was used together with folic acid for 2-3 months to improve symptoms [18].
Some scientists consider that myo-inositol can be combined with small amounts of D-chiro-inositol to balance hormones, improve insulin resistance, and fertility in women with PCOS [10, 11].
D-chiro-inositol is the second most abundant inositol in the body. Limited evidence suggests this combination may be better for improving the quality of immature eggs than myo-inositol alone [10, 11].
In one clinical trial of 50 women with PCOS, myo-inositol reduced testosterone, luteinizing hormone (LH), and insulin levels after 3 months. After 6 months, it also reduced acne and unwanted, male-like, hair growth [19].
A dose of 4 g/day of myo-inositol was used in most studies to increase fertility and reduce PCOS symptoms over 1-6 months [18, 20, 21, 19].
2) Diabetes Prevention During Pregnancy
Myo-inositol mimics the effects of insulin. Studies suggest it enhances insulin sensitivity. Based on the studies so far, it seems better suited for overweight women [22].
Myo-inositol reduced diabetes during pregnancy (gestational diabetes mellitus) by 50% in 4 trials. The effect was the strongest in overweight pregnant women, who are at highest risk [22, 23].
In a trial of 69 women with diabetes in pregnancy, myo-inositol reduced fasting glucose levels and insulin, beneficially impacting insulin resistance. It was used together with folic acid for 8 weeks [24].
One study looked at 98 pregnancies achieved by women with PCOS who either used myo-inositol or the standard drug, metformin. Over half of the women who took metformin had diabetes during pregnancy, compared to only one-fifth of the women who used myo-inositol. Studies would need to replicate this finding [25].
Urine myo-inositol levels are often high in people with diabetes and glucose intolerance. In fact, myo-inositol levels in the urine are very useful for early detection of diabetes, more convenient and less time-consuming than blood tests [26].
Insulin resistance and diabetes complications may result from a myo-inositol deficiency, according to human and animal studies. This lack of myo-inositol can further reduce phosphatidylinositol, which worsens nerve damage and neuropathies [27].
The dose in these studies varied, but 4g/day was most common.
Erectile Dysfunction in Diabetes
Diabetes can cause erectile dysfunction in men. A combination of myo-inositol and folic acid improved erectile dysfunction in 176 men with type 2 diabetes. All men took 4 g/day of inositol and 400 μg/day of folic acid [28].
Animal Studies & Mechanisms
Myo-inositol given to rats reduces glucose and insulin levels by making muscles take in more glucose from the bloodstream. It increased receptors that help remove glucose from the blood (GLUT4) [29].
Myo-inositol added to the diet reduced blood glucose in obese insulin-resistant monkeys. It may help prevent a rise in blood sugar levels after meals in the presence of insulin resistance [30].
In animals, myo-inositol could reduce stomach fat and protect embryos from defects caused by diabetes in pregnancy. In rats with diabetes, it also protected the nerves, their insulation (myelin), and prevented diabetic neuropathy [22, 31].
3) Weight Loss (in Women with PCOS)
Weak evidence supports the use of myo-inositol for weight loss in moderately-overweight women with PCOS. On the other hand, myo-inositol likely doesn’t contribute to weight loss in postmenopausal women. Further studies are needed in more diverse populations.
Women with PCOS struggle to lose weight. Supplemental myo-inositol reduced body mass and leptin levels in clinical trials of over 300 women with PCOS. In one of the studies, myo-inositol was used at a lower dose of only 200 mg/day [32, 33].
In one study of 92 women with PCOS, myo-inositol combined with folic acid normalized ovulation and increased weight loss. It also reduced leptin levels, which may help also lower inflammation and fatigue [34].
In another study, myo-inositol alone increased weight loss at 2 g/day in 43 obese women with PCOS [33].
In 69 women with diabetes in pregnancy, myo-inositol together with folic acid could also increase adiponectin, a hormone that helps burn fats and reduces inflammation [24].
However, it didn’t help 80 postmenopausal women lose weight in one study – it only reduced blood fats [35].
The dose varied between 200 mg and 4 g/day, but does not seem to affect very obese women (BMI > 37). It probably only helps moderately overweight premenopausal women with PCOS lose weight, based on the clinical studies so far [36].
Myo-inositol worked as a “lipotropic” in animal studies – it increased the breakdown of fat deposits and reduced liver fats better than choline [37].
4) Panic Disorder
In 20 people with panic disorder, high doses of myo-inositol (17 g/day) reduced panic attack and anxiety symptoms better than the typical SSRI (fluvoxamine) after a month. Myo-inositol reduced the number of panic attacks per week by 4, whereas the SSRI only reduced them by 2 [38].
When given to 21 people with panic disorder, high doses of myo-inositol (12 g/day) reduced the severity and frequency of panic attacks [39].
Large-scale trials are needed to confirm these findings.
5) Lithium Side Effects
Lithium is commonly used to treat bipolar disorder. Lithium can deplete inositol levels and cause psoriasis and dry scaly skin. In one clinical trial, inositol supplementation reduced these side effects in 15 patients taking lithium. We can’t draw any reliable conclusions from a single, small clinical trial [40].
Possibly Ineffective:
6) Autism
According to the evidence, myo-inositol is not beneficial for children with autism or ADHD. It may even worsen symptoms, studies show [41].
7) Alzheimer’s Disease
Clinical studies suggest that taking inositol by mouth likely doesn’t improve symptoms of Alzheimer disease [42].
The Function of Myo-Inositol in the Brain
Myo-inositol is found in high concentrations in the brain where it influences brain plasticity and signaling [8].
People with anorexia and depression have low brain levels of myo-inositol [8].
In a human brain imaging study, inositol levels increased in people who survived a fatal viral infection that attacks the white matter in the brain. This suggests that myo-inositol may help the brain recover from attack [43].
Monitoring levels of inositol in various parts of the brain may help detect and prevent seizures. People with epilepsy had higher myo-inositol in the parts of the brain where seizures occurred and lower levels in other parts of the brain. This is because the brain tries to protect itself from damage caused by seizures by increasing myo-inositol [44].
Liver disease leads to a buildup of toxic metabolites that can damage the brain. Myo-inositol increases as a way to reduce brain damage in liver diseases. In one brain imaging study of 36 people, those with liver disease had lower myo-inositol brain levels, which points to poor brain protection [45].
Very low blood sodium levels can destroy myelin, the brain cell’s protective sheathing. Myo-inositol protected myelin in brain cells, reduced brain damage, and increased survival in rats with low blood sodium [46].
Myo-Inositol in the Brain – it’s not that simple
Although myo-inositol protects the brain overall, increased myo-inositol has also been linked to poor cognitive function. People with mild cognitive impairment and Alzheimer’s disease have increased myo-inositol in some regions in the brain, which can now be detected with brain imaging [47, 48].
Increased myo-inositol levels can signal the beginning of a cognitive decline in inflammatory brain diseases, Alzheimer’s disease, and HIV. In a brain imaging study of 36 people, the inflammatory marker CRP in the blood was linked to increased myo-inositol in the brain [49].
It seems that people with the APOE4/E4 genotype are more likely to have high myo-inositol in the brain, which predisposes them to cognitive impairment [50].
Myo-inositol is also increased in the brain in people with mania and brain injury [47].
Myo-inositol Increases During Brain Inflammation
When the brain is attacked in any way, the brain’s support and immune cells – called the glia – start dividing to try to compensate for the damage and inflammation [13, 14].
This creates a sort of dense “scar” tissue in the brain, which leads to cognition problems in many diseases. It is also the reason brain myo-inositol is usually increased after any brain injury, as it’s the brain’s mechanism for protecting itself and attempting to recover [13, 14].
Research suggests that the rise in myo-inositol could signal brain vulnerability and that these scar tissues are being formed, even before symptoms appear [13, 14].
Insufficient Evidence:
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of myo-inositol for any of the below-listed uses.
Remember to speak with a doctor before taking myo-inositol supplements. Myo-inositol should never be used as a replacement for approved medical therapies.
8) Effects on Serotonin and PMS
Some researchers have posited that myo-inositol may act similar to commonly used antidepressants (SSRIs) since it increases serotonin activity in the brains of rats. However, proper clinical data are lacking to support such claims [51, 52].
In one study of 30 women with a PMS mood disorder, myo-inositol reduced symptoms and improved mood given over 6 menstrual cycles. A lower dose of myo-inositol softgels (3.6 g/day) had the same effects as a higher dose of the powder (12 g/day), and neither caused side effects [53].
By increasing serotonin, myo-inositol could potentially help with insomnia, though this hypothesis remains unproven. In one brain imaging study of 19 teenagers, low brain myo-inositol was linked to depression, insomnia, and tiredness [54].
Additionally, prescription lithium can deplete inositol and cause serotonin syndrome. In animals, myo-inositol could prevent serotonin toxicity from lithium, probably by restoring normal brain levels [55].
9) Mental Health
Limited evidence suggests that myo-inositol shows some promise as a complementary approach to mental health disorders where serotonin-boosting drugs (SSRIs) are used – such as depression, anxiety, and OCD – but clinical data are limited. The typical dose from these studies was high: 12-17 g/day for at least 4 weeks [39].
However, there’s still insufficient evidence to rate the effectivenes of myo-inositol on mental health. We’ve outlined some studies that focused on either inositol or myo-inositol below.
Anxiety
According to a meta-analysis of clinical trials, taking inositol by mouth doesn’t improve symptoms of anxiety disorders [56].
Depression
People with depression and anxiety may have low brain inositol levels (according to brain imaging studies), which may contribute to decreased serotonin activity in the brain [8].
According to a review of 7 studies, myo-inositol may be beneficial for people with mood problems, especially well for women with PMS-related low mood and anxiety [57, 58].
However, the authors concluded that the impact of inositol on symptoms of depression is likely not significant enough [59].
In a study of 28 people with depression, high doses of myo-inositol (12 g/day) improved mood and all symptoms after 4 weeks. Myo-inositol (18 g/day) also reduced OCD symptoms in 13 people after 6 weeks [39].
Large-scale clinical trials are needed.
Bipolar Disorder
Myo-inositol may play a role as a complementary strategy in children with bipolar disorder, who are especially sensitive to the side effects of SSRIs and other medications. Myo-inositol is well tolerated and safe, but no studies have confirmed these benefits in children yet [60].
Obsessive Compulsive Disorder (OCD)
According to one unproven hypothesis, long-term inositol administration may positively impact OCD. The exact mechanism of this purported effect is not known but is thought to involve the upregulation of striatal dopamine (D2) receptors [61].
Eating Disorders
Myo-inositol reduced overall bulimia symptoms, binge eating, and purging in 12 patients. High doses (18 g/day) were used for 6 weeks. Additional trials are needed [62].
10) Metabolic Syndrome
Scientists believe that myo-inositol’s insulin-sensitizing effects might help prevent or reduce metabolic syndrome, especially in women. Though early studies show promise, there is insufficient evidence to support the use of myo-inositol for metabolic syndrome.
Myo-inositol over 1 year improved metabolic syndrome in a clinical trial of 80 postmenopausal women. It improved insulin resistance, reduced blood glucose, insulin, triglycerides, total cholesterol, and raised HDL (the “good” cholesterol) [63].
Several other clinical studies in women with PCOS have shown the same benefits, plus reducing triglycerides and blood pressure. Large-scale trials are needed [64, 65, 66].
11) Cancer Prevention Research
Researchers are exploring whether myo-inositol has anti-inflammatory and cancer-fighting properties. The existing evidence is weak and inconclusive [67].
When given to 21 heavy smokers, myo-inositol reduced pre-cancerous lung damage, which could help prevent lung cancer. In airway cells exposed to tobacco, myo-inositol could block the pathways that cause uncontrolled cell division and cancer growth (such as MAPK) [68].
It also reduced the development of lung cancer in mice exposed to tobacco smoke [69].
A combination of carotenoids and myo-inositol prevented liver cancer in people with viral hepatitis and cirrhosis [70].
In mice, inositol stopped the spreading of colon cancer to the liver [71].
12) Effects on Fertility in Men
The fertility-enhancing effects of myo-inositol are also being researched in men, though it’s too early to draw any conclusions. Additional clinical research is needed to determine if myo-inositol is safe and effective for male infertility.
In 194 men with infertility due to an unknown cause, myo-inositol improved sperm quality, sperm count, and fertility after 3 months. It balanced reproductive hormone levels, reducing LH and FSH, and slightly increasing testosterone. All men took 2 g/day of myo-inositol and 200 μg/day of folic acid [72].
In one study, myo-inositol was added to sperm from 40 men. Myo-inositol increased sperm motility and sperm count in samples from all men. It also increased the mitochondrial function in sperm from men with low sperm count [73].
Thus, myo-inositol shows some potential either as a supplement in men with fertility problems or as a compound that might improve success rates of in vitro fertilization (IVF).
13) Lung Health
In preterm babies with lung problems, myo-inositol protects the lungs and helps them develop properly. A drop in myo-inositol may prevent the healing of lung tissue in preterm babies, according to a study of 47 babies [74].
Researchers are investigating whether myo-inositol can aid lung healing and decrease precancerous lesions. One study in 21 heavy smokers had promising results, but much more research is needed [68].
14) Heart Health
Limited evidence suggests that myo-inositol may contribute to heart health and heart disease prevention in people who are overweight, particularly women.
In several clinical studies, myo-inositol supplementation reduced heart disease risk factors in people with metabolic syndrome. It reduced blood pressure, total cholesterol, and triglycerides while increasing HDL cholesterol [75, 76].
A combination supplement with myo-inositol, soy isoflavones, and cocoa polyphenols reduced heart disease risk in 60 postmenopausal women after 6 months. Aside from improving blood fat measurements, it also improved levels of metabolic hormones (resistin and visfatin). Further research is needed [77].
15) Prenatal Development
Pregnant and breastfeeding women may want to eat enough healthy inositol-rich foods such as fruits, beans, grains, and nuts [78].
Myo-inositol is crucial during pregnancy for prenatal growth. The fact that newborns have higher concentrations of it than in adults speaks to its importance for healthy development, especially in preterm babies [79, 80].
Inositol levels start to decline within the first 3 weeks after birth in babies who are not breastfed. In one study of 65 babies, babies who were breastfed had higher myo-inositol levels. Levels decreased in babies who were fed with a formula [80].
Small amounts of inositol are sometimes added to prenatal supplements. However, proper trials need to determine the safety of varying inositol doses in pregnant women and children [81, 82].
16) Antioxidant Defense
Myo-inositol boosted the master antioxidant glutathione in blood cells and reduced oxidative stress in 26 women with PCOS [83].
Buckwheat and squash, rich in D-Chiro-Inositol, are antioxidants, according to several animal and cellular studies [84, 85].
More research is needed.
17) Skin Health
Myo-inositol supplementation reduced severe to moderate acne in women with PCOS [86].
It could also reduce unwanted, masculine hair growth in women with high male sex hormones and insulin resistance [87].
Further trials are needed.
Lacking Evidence:
No clinical evidence supports the use of myo-inositol for any of the conditions listed in this section.
Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
18) Inflammation
Clinical data are lacking to support this purported benefit.
In a study with mice, phosphatidylinositol reduced inflammation and liver damage from lectins. It suppressed inflammatory cytokines and normalized the immune response [88].
A squash extract rich in D-Chiro-Inositol, the second most abundant inositol, reduced inflammatory markers such as TNF-alpha and IL-6 in fat cells. It also acted as an antioxidant, increasing glutathione levels [84].
19) Anti-Aging Potential
Since inositol plays so many roles in the body, scientists decided to see if it could also reverse aging in the lab. The findings are limited to fruit flies, though, in which D-chiro-inositol protected from oxidative stress and extends the life span. Clinical trials are lacking [89].
Inositol and Cannabinoids
Myo-inositol can be converted to more complex phospholipids in the body (such as IP3 and PIP2). These substances act as powerful messengers and can boost cannabinoid production. They may increase the body’s natural feel-good cannabinoid 2-AG [90].
Supplementing Myo-inositol
Food Sources
Myo-inositol can be found in the following food sources [91]:
- Meat and seafood (beef, chicken breast, pork, tuna, crabs, clams)
- Various fresh fruit (cantaloupe, citrus fruits, cherries, peaches, etc.)
- Vegetables (artichoke, okra, cabbage, spinach, beans.)
- Dairy
- Dried prunes
- Grains
Myo-inositol is much higher in fresh fruits and vegetables than in dried or canned ones.
Phosphatidylinositol is also found in lecithin, so all lecithin-rich foods such as the following are good sources:
- Meat and fish: chicken liver, chicken kidney, pork, and beef liver
- Egg (yolk)
- Vegetable oil
- Cruciferous vegetables
- Dairy
Animal sources generally provide a larger source of lecithin than plant-based ones [92, 93, 94].
The best source of D-chiro-inositol (used as an antioxidant and for PCOS in combination with myo-inositol) is buckwheat. It’s also found in a type of squash (fig leaf melon) [95, 96].
Dosage
- Higher doses (12-18 g/day) were used for depression, anxiety, OCD, and eating disorders in clinical studies. Scientists hypothesize that these higher doses may be needed to raise serotonin and inositol in the brain.
- For fertility, PCOS, weight loss, and increasing sensitivity to insulin, lower doses (2-4 g/day) were used.
- When combined with D-chiro-inositol for women with PCOS, D-chiro-inositol is used only at 1/40 of the dose of inositol. For example, 4 g/day inositol, 100 mg/day of D-chiro-inositol.
- Softgels are absorbed much better than powder. Only about 30% of the dosage is needed to achieve the same effects. In one study, 3.6 g/day of softgels worked as well as 12 g of the powder for women with PMS mood disorder [53+].
- A diet rich in myo-inositol can make up for up to 1.5 g/day. However, if you also include lecithin foods rich in phosphatidylinositol, you may get more inositols overall from food [78].
Caution and Side Effects
Overall, myo-inositol is considered to be safe with few side effects. However, proper safety trials in different populations are needed.
High doses can cause some stomach upset. Typical side effects reported in some of the studies were mild and include digestive problems, nausea, and tiredness.
Studies suggest there are certain states when increasing myo-inositol in the body is not beneficial (and can even be harmful), such as in people with:
- End-stage kidney disease, myo-inositol can worsen the immune response. Since people with serious kidney disease may have raised myo-inositol levels even without supplements, taking myo-inositol supplements can be especially harmful [97].
- Cognitive impairment and neurological diseases like Alzheimer’s Disease. Other inositols (not myo-inositol) are being researched, but no benefits have been proven yet [98].
- Any kind of brain injury, such as traumatic brain injury [99].
- Myo-inositol is increased in people with lymphomas, brain, and spinal cord tumors. Supplementing is probably not beneficial [100].
- Schizophrenia (no benefits) [41].
- Myo-inositol may be increased in mania, and since lithium decreases it, supplementing is probably not a good idea [101, 102].
- Children with autism (no benefits) or ADHD (can even worsen symptoms) [41].
Takeaway
Myo-inositol is a vitamin-like compound that cells in the body require to generate energy and burn fat.
This nutrient is best known for its impact on PCOS. Solid evidence supports the use of myo-inositol for improving fertility, weight control, metabolic health, and hormonal balance in women with PCOS.
Studies also show that myo-inositol may help reduce symptoms of panic disorder and lessen the side effects of prescription lithium.
On the other hand, there’s not enough evidence to support its use for anxiety, depression, or other mental health problems.
Although more research is needed, studies reveal that higher brain myo-inositol may signal cognitive decline. Based on the exisiting evidence, experts caution against supplementation in people with autism, cognitive impairment, or any kind of brain damage.
