Myo-Inositol for PCOS 

Myo-Inositol for PCOS 

Polycystic ovary syndrome (PCOS) is a condition that is thought to affect 10% of women of childbearing age. It impacts everyday life and the most common symptoms are irregular periods or the complete loss of the menstrual cycle, difficulties with conception, skin issues, hormonal irregularities and even psychological issues such as depression, anxiety and low mood. The good news is that there are natural remedies that can help to control these symptoms. One of these is myo-inositol, an ingredient you may not have heard of, but will know very well by the end of this article.

What is Myo-inositol?

Often (wrongly) referred to as vitamin B8, inositol isn’t an essential micronutrient like the B vitamins. However, it is known as a ‘pseudovitamin’ in nutrition circles because it isn’t essential for health but nevertheless has important functions in the body. Coenzyme Q10, alpha-lipoic acid and L-carnitine are other examples of pseudovitamins.

Inositol is actually a group of 9 molecules, but myo-inositol is by far the most abundant, making up around 90% of the body’s total inositol reserves. It is also the most heavily researched. Inositol can be found in a variety of foods such as dairy produce, fruit, vegetables, wholegrains, meat and eggs. Typically, adults get between 600-900mg of inositol a day through food, but taking higher doses through myo-inositol supplements can have some impressive benefits.

Myo-inositol for PCOS

Polycystic ovary syndrome is characterised by insulin resistance which leads to elevated blood sugar levels and androgens (steroid hormones like testosterone). These hormonal irregularities are behind the aforementioned menstrual cycle disturbances which can lead to infertility. Impressively, myo-inositol has not only been shown to normalise ovulation, it has been shown on numerous occasions to increase pregnancy rates.

One study of note published in 2008 recruited 20 women with PCOS and randomly assigned them to two groups. Group A received 2g of myo-inositol per day whereas group B took 200 micrograms of folic acid daily. After 12 weeks of this therapy, the women taking myo-inositol saw improvements to insulin function, blood sugar, and levels of testosterone, luteinising hormone (LH), follicle stimulating hormone (FSH) and prolactin. Most impressive though was the restoration to the menstrual cycle in all of the participants. No changes occurred in the group of women taking folic acid.

Many women with PCOS who are looking to conceive go down the IVF route. A study from 2013 showed that taking myo-inositol alongside D-chiro-inositol improved egg and embryo quality as well as pregnancy rates in women with PCOS undergoing IVF.

However, many can’t or don’t want to conceive through IVF and myo-inositol supplements can be of help to these women too. One of the landmark studies in this area compared the effects of myo-inositol to metformin, which is a primary treatment for both PCOS and type 2 diabetes due to its insulin-sensitising effects in the body. For this study, 100 women were randomly assigned to receive either 1500mg of metformin per day or 4g of myo-inositol alongside 400 micrograms of folic acid.

It was found that in the metformin group, 50% of the women restored normal ovulation and 18.3% of these women became pregnant. In the group of women receiving myo-inositol and folic acid, 65% of them saw a return of their menstrual cycle and 30% of them conceived. So, myo-inositol led to nearly double the amount of pregnancies when compared to the reference drug metformin. Extremely impressive and clinically relevant findings.

The critical thinkers upon us may question how much of a role folic acid played in these results, given its well-known role in healthy pregnancy. However, the researchers confirmed that the folic acid had no impact on the return of the menstrual cycle and conception, nor did it affect the mechanisms in which myo-inositol works. It was included because of its ability to support the production of maternal tissues and reduce the risk of neural tube defects during pregnancy. The European Food Safety Authority recommends 400 micrograms of folic acid daily while trying to conceive and during the first trimester of pregnancy.

As PCOS is caused by hormone imbalance, it comes as no surprise that one of the most common symptoms is acne. One study of 50 women with PCOS who had mild to moderate acne saw large benefits over the 6 month research period. When compared to the measurements taken at the beginning of the study, 6 months of taking 4g of myo-inositol per day led to significant improvements in insulin sensitivity and hormone balance as well as acne. Specifically, the myo-inositol supplement led to 53% of participants totally eradicating their acne.

So, how does myo-inositol actually work? Well it is well understood that it is beneficial for PCOS and the associated symptoms because of its influence on hormone signalling. Myo-inositol is stored in our cells and used as a precursor to inositol triphosphate, which acts as a messenger for insulin and other hormones (including those involved in fertility) to ensure they function as they should. It is not fully understood why people with PCOS and type 2 diabetes excrete more inositol than normal, but it is clear that increasing inositol stores though supplementation helps to manage their condition.

Myo-inositol for Depression and Anxiety

As myo-inositol is most abundant in the brain, this provides a clue that it could provide benefits to cognitive function or psychological wellbeing too. This is an area that has been researched well and some of these studies were published 25 years ago, showing that myo-inositol is far from a novel, unproven supplement.

After it was discovered that inositol levels are often lower in people with depression, Levine and colleagues (1995) wanted to assess whether increasing levels through supplementation would improve the symptoms. The 28 participants were randomly divided into 2 groups and either given a placebo or 12g of myo-inositol daily. After just 4 weeks, it was reported that those receiving the myo-inositol supplement saw a significant improvement in symptoms. Just as importantly, no adverse reactions were reported and there were no changes to haematology or liver and kidney function, indicating that myo-inositol supplements are safe and well tolerated. 

Equally impressive results have been seen in those with panic disorders and anxiety. As the prescription medication for these conditions are unreliable and are often discontinued due to side effects, the researchers wanted to compare the efficacy of myo-inositol to the reference drug fluvoxamine.

Similar to the above study, the researchers randomly split the twenty participants into two groups and gave one group the fluvoxamine, while the other group received 18g of myo-inositol daily for 4 weeks. This study was double-blind, meaning neither the participants nor the researchers knew who had which treatment.

Before the study and after the 4 week intervention, the participants completed the Hamilton Rating Scale for Anxiety, provided scores for agoraphobia and noted the number of panic attacks they experienced. It was reported that both groups saw significant improvements to their anxiety levels and agoraphobia. However, it was found that the group receiving the myo-inositol saw a reduction in the number of panic attacks by 4 on average, compared to an average of 2.4 in the fluvoxamine group.

With regards to adverse reactions, the group receiving fluvoxamine reported significantly more episodes of nausea and tiredness when compared to those taking myo-inositol. The researchers concluded that: “Because inositol is a natural compound with few known side effects, it is attractive to patients who are ambivalent about taking psychiatric medication”.

Psychological disturbances can be expressed through disordered eating and there is also published evidence to show it can help in this regard too. Again using 18g of myo-inositol, researchers wanted to investigate the effects of this supplement regime on bulimia nervosa and binge eating. After 6 weeks of myo-inositol supplementation the participants saw a significant improvement in their condition.

The above benefits are certainly impressive, but how do they occur? It is thought that inositol supports the production of neurotransmitters – the chemical messengers that relay information across our brain. One of these is serotonin, which when functioning normally, helps to control feelings of anxiety, depression, stress and our sleeping patterns. What’s interesting is 90% of the body’s serotonin is produced in the gut and through the gut-brain axis it can help to regulate appetite and food cravings as well as digestion and nutrient absorption. 


Although not a vitamin, hopefully this article has made it clear that myo-inositol is an important nutrient for health and wellbeing. Despite being available in a wide variety of foods, the only way to obtain a therapeutic dose is through supplementation. Myo-inositol is a flavourless powder that mixes effortlessly into drinks and can even be incorporated into food. For benefits to PCOS, it is clear that 4g (~1 teaspoon) per day is all that is required, whereas a significantly higher amount of 18g per day (~2 desert spoons) is needed for benefits to mental health. As this heavily researched nutrient has shown to be beneficial and safe time and time again, it is definitely worth considering if you are looking for natural support for PCOS or depression and anxiety.