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Inositol, especially its most popular form, myo-inositol, has gained a firm place in the world of women’s health. You may be familiar with it as part of the dietary supplements often used for polycystic ovary syndrome (PCOS) or in connection with elevated blood sugar, hormonal imbalances or irregular menstrual cycles. But in addition, it also surprises with other benefits. In this article, we’ll look at who inositol can help, when it’s worth supplementing, or whether it may be lacking in our bodies.
In the article, you will read about the influence of inositol on these areas:
What is inositol?
Inositol is a cyclic alcohol, which resembles vitamins in structure. That is why it was also referred to as vitamin B8 in the past. Today, however, we know that it is not a vitamin. Our body can make it itself, specifically in the kidneys.
Every day our body produces approximately 4 g of inositol. However, dietary intake cannot be overlooked either, as it accounts for up to a quarter of this amount. So, if we have a normal mixed diet, we take in an average of 1 g of inositol every day, mainly through plant-based foods.
When we are healthy without increased nutrient requirements, this amount is usually sufficient for us. However, we go through periods in our lives when the need for inositol increases or the level of inositol in the body decreases. And that’s when it can make sense to reach for a nutritional supplement to help your body replenish what it needs at the moment. [2]
What does inositol do in the body?
This substance is not just a silent inconspicuous inhabitant of the human body. On the contrary, it plays key roles in many processes that are constantly going on inside of us. First of all, it is part of cell membranes, specifically structural fat molecules called phospholipids (like choline). Thanks to this, it helps the cells maintain their shape, flexibility and ability to communicate with each other.
But this is just the beginning. Inositol is also an essential player in several metabolic processes.
4 functions of inositol in the body:
- It helps cells to communicate. It is involved in the transmission of signals and information between them. This allows, for example, nerve transmissions to work or the contraction of muscles that is necessary for movement, including in gymnastics and other sports.
- It is involved in glucose metabolism and the insulin sensitivity of cells. Inositol in cell membranes binds to insulin and forms a signalling complex with it that activates the so-called GLUT-4 transporters. These then allow glucose (sugar) to enter the cells from the blood, where it can be further converted into energy. [12]
- It is involved in serotonin metabolism, dopamine and GABA, which are the main neurotransmitters in the brain that affect our mood or memory, for example.
- It also plays a role in hormonal balance, especially in the production of female sex hormones and the proper course of ovulation.
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What forms does inositol take?
You may have already wondered why people sometimes talk about inositol and sometimes about myo-inositol. What is the difference between them? In simple terms, we can say that myo-inositol is one form of inositol, and because it is the most well-known and used in dietary supplements, these names are often confused.
However, if we take a closer look at inositol, we find that there are 9 different forms, called isomers. You can think of them as one building set that can be put together in nine different ways. All versions have the same building blocks (chemical composition), but they differ in their arrangement in space.
Of these nine forms, eight are found in nature, but in the human body, three are of particular importance:
- myo-inositol
- D-chiro-inositol
- scyllo-inositol [8]
In the following sections, we will focus on myo-inositol in particular, as it is the most abundant in foods, the best studied, and the most commonly used in dietary supplements.
What are the health effects of inositol?
1. May help in PCOS therapy
Inositol is quite unique among supplements because it has found its place in therapy for polycystic ovary syndrome (PCOS). This is the most common female hormonal disorder, which is also one of the most common causes of female infertility.
The exact cause of PCOS is not yet known. However, we do know that it is a complex set of symptoms and health problems that affect approximately 6 to 13% of women of reproductive age.
What problems can plague women with PCOS?
- irregular menstrual cycles, infrequent or completely absent bleeding (amenorrhoea)
- insulin resistance – Affects up to 75% of thin women with PCOS and up to 95% of women who are overweight or obese
- overweight and obesity – It is estimated that up to around 60-70% of women with PCOS are overweight or obese
- ovarian cysts – However, it is important to mention that ovaries with numerous cysts do not automatically mean that a woman has PCOS
- acne, hirsutism (excessive body hair)
- impaired glucose tolerance or type 2 diabetes (type 2 diabetes mellitus)
- elevated cholesterol, cardiovascular problems
- increased risk of endometrial (inner lining of the uterus) tumours [7,16]
So PCOS is much more than just cysts on the ovaries – it is a condition that affects a woman’s metabolism, hormonal balance and overall health. That’s why inositol is increasingly coming to the fore as a promising part of PCOS therapy.
How does inositol work in PCOS?
In the context of polycystic ovary syndrome, scientists are mainly studying myo-inositol – and not by chance. It is the one that shows the most pronounced effects, especially in women whose PCOS is accompanied by insulin resistance (which is true for most women).
Myo-inositol acts as an insulin-sensitiser – a substance that improves the sensitivity of cells to insulin. This means that the cells are better able to respond to the presence of insulin and process glucose more efficiently. As a result, insulin resistance, which is closely linked to many of the problems typical of PCOS, is alleviated. [6]
- higher levels of androgens (male sex hormones) and associated acne or hirsutism
- irregular menstrual cycles or lack of ovulation
- weight gain
- higher risk of type 2 diabetes
Thus, insulin resistance complicates the course of PCOS and also increases the risk of other health complications. Inositol may be particularly helpful in the treatment of PCOS in that it may help to improve insulin sensitivity and consequently reduce the occurrence of both hormonal and metabolic difficulties. In this way, it can have a positive effect on the menstrual cycle, ovulation, as well as a woman’s overall health.
For many women with PCOS, inositol can be a welcome part of taking care of their health. However, it is important to remember that every body is different and taking inositol should be discussed with a doctor or specialist, especially if you are taking medication or have other health conditions.
Also, remember that the foundation of managing PCOS remains a healthy lifestyle – i.e. a balanced diet, exercise, stress management and quality sleep. No nutritional supplement on its own can replace this foundation, but it can be a valuable aid on the road to feeling better and finding balance in the body.
Scientific view on inositol: What effect does it have on PCOS?
Metformin is commonly used in the treatment of polycystic ovary syndrome. However, this is a drug primarily intended for the treatment of diabetes mellitus (diabetes), and in PCOS, it is used so-called off-label (it is not officially prescribed for its treatment). In addition, it is associated with frequent digestive problems. Therefore, alternatives are being sought and tried for women with PCOS who do not have diabetes. [6]
It was the effect of metformin and inositol that was compared in a high-quality Italian semi-randomised study that observed 46 women with PCOS aged 18-28 years for 6 months. All the women had insulin resistance and were not taking any medications. Thirty healthy women also participated in the study as a control group. [6]
Women with PCOS were randomly divided into two groups. One of them took 1500 mg of metformin daily (standard dose), while the other was prescribed 4 g of myo-inositol and 400 μg of folic acid. Folic acid is traditionally added to supplements with myo-inositol because their combination is shown to be effective in promoting women’s health. [6]
The researchers looked at a number of parameters, for example:
- Body Mass Index (BMI), which is used to assess body weight
- the length of the menstrual cycle
- HOMA-IR index, which assesses the severity of insulin resistance
- concentration of sex hormones [6]
These parameters were measured in women at the beginning of the research and then after 6 months of treatment. It turned out that inositol was as effective as metformin, sometimes even surpassing it. Their effect was shown, for example, when monitoring BMI, HOMA-IR or cycle length.
- BMI decreased in the studied women by 5.63% with metformin and by 7.32% with inositol.
- Cycle length was reduced by 45% for metformin and by 38.7% for inositol.
- HOMA-IR index decreased by 16.7% after metformin and by 28.6% with inositol. [6]
2. May help prevent gestational diabetes
Gestational diabetes mellitus (GDM) is a form of diabetes that occurs during pregnancy. It occurs when a woman’s body cannot process glucose efficiently – usually because of insulin resistance, which naturally increases during this period. After childbirth, in most cases, it will resolve spontaneously, but if it is not controlled, it can increase the risk of developing type 2 diabetes in the future.
Women with gestational diabetes experience unstable blood sugar levels (glycaemia) and, therefore, a risk of hyperglycaemia (too high sugar) or hypoglycaemia (too low sugar). Keeping glycaemia as close to normal as possible is important not only for the health of the mother but also for the proper development of the baby and a smooth pregnancy. [1]
How does inositol work in gestational diabetes?
In gestational diabetes, inositol may work similarly to PCOS through its effect on insulin sensitivity. It has been shown that it may help with glycaemic control in already developed GDM, but is also useful in its prevention. For example, in one review study, taking 4 g of inositol daily was shown to reduce the risk of GDM by 40%. [2,5]
These results are promising, but it is also important to add that inositol supplementation should always be part of a comprehensive approach – that is, along with dietary modification, appropriate exercise and regular glycaemic control. And, as always, in pregnancy, the key is to work with a doctor who can best assess what is safe and appropriate for a particular woman and her baby.
Scientific view on inositol: What effect does it have on gestational diabetes?
Italian researchers observed 220 pregnant women without a diagnosis of GDM. In the first trimester, they measured their blood sugar levels (glycaemia), HOMA-IR index (an index for assessing insulin resistance), and other parameters. They were then prescribed a supplementation routine—half of the women took 4 g of myo-inositol and 400 μg of folic acid, while the rest received a daily placebo.
They were then measured again before the end of the pregnancy. It showed that the group taking daily myo-inositol had a 3% lower fasting glycaemia level at the end of pregnancy compared to the first trimester. Conversely, women in the placebo group had it even higher on average than at baseline. Further, the HOMA-IR index fell by an average of 30% in the myo-inositol group. [3]
3. Reduces the risk of metabolic syndrome and type 2 diabetes
In recent years, inositol has been coming into the spotlight as an interesting helper in the fight against metabolic syndrome and type 2 diabetes, and not by accident. The key problem in these diseases is insulin resistance, which we have already mentioned above. And since inositol helps to increase insulin sensitivity, it can help fight it, improving the movement of glucose from the blood into the cells to help control glycaemia.
For example, study results suggest that inositol supplementation can reduce both fasting glycaemia and glycated haemoglobin levels, which are key indicators of long-term diabetes control. This makes it a suitable adjunct to standard antidiabetic treatment. It is even more interesting that its mechanism of action resembles that of metformin, the drug of first choice for the treatment of diabetes. [2,14]
Therefore, inositol appears to be a suitable adjunct to standard antidiabetic treatment. Interestingly, its mechanism of action in many ways resembles that of metformin – the drug of choice in the treatment of type 2 diabetes.
Of course, in this case too, nutritional supplements are not a substitute for medication or medical guidance, but they can be a valuable supportive tool.
Scientific view on inositol: What effect does it have on type 2 diabetes?
In the research, scientists observed 20 participants with type 2 diabetes. Each of them was taking antidiabetic drugs and the effect of myo-inositol was monitored only as an adjunctive therapy. All study participants took 1100 mg of myo-inositol, 27.6 mg of d-chiro-inositol and 400 μg of folic acid daily for 3 months.
After three months, the group showed an average drop in glycated haemoglobin of 10%. This parameter tells us how high a person’s blood sugar has been on average over the last three months. If the value has decreased after three months of follow-up, it means that during this time, they have managed to keep it under control better than before. Fasting glycaemia levels also decreased by up to 16% on average. [17]
4. Benefits mental health
Inositol is quite a versatile supplement, and with its impact on metabolic health, it is finding an increasingly strong place in the area of mental health as well. Clinical studies show, for example, that it can help alleviate symptoms of depression, anxiety, panic disorder or even obsessive-compulsive disorder (OCD).
How does inositol work in mental illness?
The effects of inositol on the psyche are complex, but a key role is played by its influence on the metabolism of neurotransmitters – substances that ensure communication between brain cells. Studies suggest that inositol may influence the activity of serotonin receptors, thereby influencing the activity of serotonin – a neurotransmitter that affects mood, sleep, appetite and stress management. [2]
5. Can improve reproductive health
Myo-inositol plays an important role in the proper functioning of the reproductive system – in both women and men. In the body, it is involved in many processes related to hormonal balance, maturation of sex cells, and overall cell metabolism.
In women, it is studied in relation to egg quality and assisted reproduction, such as artificial insemination, including IVF. Research shows that having enough myo-inositol in the follicular fluid (the fluid around the egg) is associated with better egg quality and a higher chance of fertilisation. It is similarly important in men – low levels of inositol in the semen are often associated with reduced sperm quality.
Myo-inositol is also proving useful in preparation for IVF, where it can promote egg maturation and increase the chance of fertilisation. It also helps with ovulation problems that are typical for women with PCOS, for example.
Inositol may not be a miracle supplement, but when trying for a baby, it can be part of the natural support that helps the body function as it should. [11]
Scientific view on inositol: What effect does it have on fertility?
The research observed 60 female participants who had been diagnosed as infertile. They all underwent fertility therapy and were also given 4 g of myo-inositol and folic acid powder to take. In addition to these, the study also included a control group of 30 women who received a placebo in the form of folic acid (400 mg per day) in addition to the standard treatment. After 12 weeks of treatment, the women were assessed using indicators such as fertilisation rate or the ovarian stimulation index, which evaluates how well the ovaries respond to hormonal stimulation.[10]
The results showed that the group that took myo-inositol in addition had a significantly higher ovarian stimulation index than the placebo group, and there was also a higher fertilisation rate.[10]
6. Other effects of inositol
The effects of inositol mentioned above are the ones that are best studied so far. However, in addition to these, promising benefits in other health areas are also being shown.
- Inositol can help lower cholesterol and blood pressure.
- It also shows an effect in weight loss. [13]
- It can also be useful in the treatment of panic attacks, bipolar disorder and other psychological problems.
- It could even have the effect of improving the quality of sleep. [9]
Can we have inositol deficiency?
Although the body can make inositol on its own to a certain extent, several factors can reduce its levels. Lower levels may then be associated with mood disorders, PCOS, insulin resistance and other complications.
Inositol deficiency can occur in several ways
- reduced intake in food
- increased excretion of inositol
- lower creation in the body
- taking certain medicines, such as hormonal contraceptives [4]
In which foods can we find inositol?
If we want to increase the intake of inositol with food, we need to reach for plant-based ones. They are the ones that are rich in inositol, while animal products contain only very low amounts. Most inositol is found in the following foods.
Inositol content in specific foods
| sugar melon | 355 mg |
| orange | 307 mg |
| grapefruit | 199 mg |
| kiwi | 118 mg |
| red beans | 60 mg |
| wholemeal bread | 142 mg |
| oatmeal | 42 mg |
| green beans | 105 mg |
| zucchini | 53 mg |
| tomatoes | 54 mg |
| almonds | 278 mg |
| peanuts | 134 mg |
[15]
Who is suitable to take inositol?
You read a while ago that inositol is also in the foods we eat daily. However, if we want to reap its benefits, it’s a good idea to supplement it. Especially when we are dealing with a problem for which inositol could be helpful. Who can benefit from the health benefits of inositol?
- People with inadequate dietary intake of inositol. These are especially those who have few plant-based foods in their diet.
- Women with PCOS, as it can help them relieve insulin resistance and thus improve other symptoms of this syndrome.
- People with metabolic syndrome or type 2 diabetes who also need to improve insulin sensitivity.
- People with mental health problems such as anxiety or depression.
Inositol may also benefit pregnant women, as it has been shown to help prevent gestational diabetes, but it is always important to consult a doctor first. Research shows that pregnant women tolerate doses of up to 4g per day well. [3,14]
How much inositol to take daily?
The appropriate daily dose of inositol depends on what we want to achieve with its supplementation.
- For preventive use, it is advisable to start with a lower dose of around 500-1000 mg per day.
- In the case of PCOS or metabolic syndrome, the effective dose appears to be around 1-4 g of inositol per day. [14]
- Pregnant women may benefit from inositol at a dose of 2-4 g per day. [2]
- If we expect beneficial effects on mental health, research suggests that higher doses of up to around 12 g of inositol per day, divided into several doses per day, are appropriate.
Can inositol have side effects?
Inositol is one of the supplements that usually get along very well with the body. Even in higher doses, it is considered safe, and if side effects do occur, they are mostly only mild indigestion. However, even these have only been observed at excessive doses of around 12 g of inositol per day. In normal doses, however, inositol is considered safe. [14]
What Should You Remember?
Inositol is one of the lesser-known substances, but it is involved in a surprising number of important processes in the body – from metabolism and hormone balance to neural connections in the brain. Research suggests that supplementation may be helpful for conditions such as polycystic ovary syndrome (PCOS), where the body is struggling with hormonal imbalances, insulin resistance or psychological stress. However, it is not a quick fix or a substitute for a healthy lifestyle – rather, it is a support that can appropriately complement an overall approach to self-care.
[1] CDC Gestational Diabetes. – https://www.cdc.gov/diabetes/about/gestational-diabetes.html
[2] CONCERTO, C. et al. Neurobiology and Applications of Inositol in Psychiatry: A Narrative Review. – https://www.mdpi.com/1467-3045/45/2/113
[3] D’ANNA, R. et al. Myo-inositol Supplementation for Prevention of Gestational Diabetes in Obese Pregnant Women: A Randomized Controlled Trial. – https://pubmed.ncbi.nlm.nih.gov/26241420/
[4] DINICOLA, S. et al. Nutritional and Acquired Deficiencies in Inositol Bioavailability. Correlations with Metabolic Disorders. – https://www.mdpi.com/1422-0067/18/10/2187
[5] DINICOLANTONIO, J.J. - H O’KEEFE, J. Myo-inositol for insulin resistance, metabolic syndrome, polycystic ovary syndrome and gestational diabetes. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8896029/
[6] FRUZZETTI, F. et al. Comparison of two insulin sensitizers, metformin and myo-inositol, in women with polycystic ovary syndrome (PCOS). – https://pubmed.ncbi.nlm.nih.gov/27808588/
[7] GREFF, D. et al. Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9878965/
[8] LÓPEZ-GAMBERO, A.J. et al. The Biomedical Uses of Inositols: A Nutraceutical Approach to Metabolic Dysfunction in Aging and Neurodegenerative Diseases. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7554709/
[9] MASHAYEKH-AMIRI, S. et al. The impact of myo-inositol supplementation on sleep quality in pregnant women: a randomized, double-blind, placebo-controlled study. – https://pubmed.ncbi.nlm.nih.gov/32933356/
[10] MOHAMMADI, S. et al. The effect of Myo-inositol on fertility rates in poor ovarian responder in women undergoing assisted reproductive technique: a randomized clinical trial. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8063404/
[11] RUSSO, M. et al. Melatonin and Myo-Inositol: Supporting Reproduction from the Oocyte to Birth. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8395120/
[12] TAHIR, F. - MAJID, Z. Inositol Supplementation in the Prevention of Gestational Diabetes Mellitus. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823013/
[13] ZAREZADEH, M. et al. Inositol supplementation and body mass index: A systematic review and meta-analysis of randomized clinical trials. – https://pubmed.ncbi.nlm.nih.gov/35664247/g
[14] Inositol benefits, dosage, and side effects. – https://examine.com/supplements/inositol/
[15] Myo-inositol content of common foods: development of a high-myo-inositol diet. – https://www.researchgate.net/publication/15783165_Myo-inositol_content_of_common_foods_development_of_a_high-myo-inositol_diet
[16] Polycystic ovary syndrome. – https://www.who.int/news-room/fact-sheets/detail/polycystic-ovary-syndrome
[17] The Effectiveness of Myo‐Inositol and D‐Chiro Inositol Treatment in Type 2 Diabetes – https://onlinelibrary.wiley.com/doi/10.1155/2016/9132052
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