Inositols are a chemical compound found in the body which belong to the same family as sugars. It has 9 different forms but the main two are myo-inositol (MI) and D-chiro-inositol (DCI). In this article we take a deep dive into inositols and PCOS and how supplementation can influence fertility outcomes.
What do Inositols do?
Inositol has been linked to a number of important functions in the body, including our mood. They are involved in the production of neurotransmitters such as dopamine and serotonin, our happy hormones.
In fact, decreased levels of inositols in the body have been linked to conditions such as depression, anxiety, OCD and PTSD.
Inositols and insulin
One of the main functions of inositols are their role in the activity of insulin. Insulin is an important hormone in the body that plays an essential role in controlling our blood sugar levels.
DCI and MI play important roles by helping to produce factors necessary for insulin to work effectively.
If the body is unable to respond effectively to insulin, this is known as insulin resistance. This means it is more difficult for the body to process carbohydrates in the diet and leads to poor blood-sugar control.
Inositols and PCOS
When we look at the research around inositols and PCOS, there is an increasing amount of evidence showing supplementation may be beneficial.
PCOS (polycystic ovarian syndrome) is an endocrine, reproductive and metabolic disorder that affects at least 5-10% of women. This number is most likely much larger as many go undiagnosed.
Symptoms that individuals with PCOS may experience include:
- irregular menstrual cycles (including amenorrhoea – absence of a cycle and oligomenorrhoea – infrequent cycles)
- hyperandrogenism (excess androgen – male hormone production) and hirsutism (abnormal hair growth)
- unexplained weight gain
- polycystic ovaries
It is estimated that around 80% of obese and 30-40% of lean women who have PCOS also suffer from insulin resistance.
There is now an increasingly large amount of evidence supporting a central role of insulin resistance in the development of many PCOS symptoms. This includes hyperandrogenism, where insulin directly stimulates the ovaries to produce more androgens (more male hormones).
It is suggested that reducing insulin resistance is a key therapeutic strategy when treating PCOS.
Inositols, in particular MI and DCI, are thought to be beneficial in targeting insulin resistance as they act as insulin-sensitising agents. This is where they improve the body’s ability to respond correctly to insulin.
This theory has been supported by recent research which has found supplementation to be an effective treatment strategy alongside other nutrition and lifestyle interventions.
Not only does supplementation appear to improve insulin sensitivity, but studies have suggested that supplementation is also able to assist in improving many of the other metabolic and hormonal side effects of PCOS such as reducing hyperandrogenism and improving blood lipid profiles (Pizzo et al., 2013) (Iuorno et al., 2002) (Tabrizi et al., 2018).
When we look at Inositols and PCOS cravings – one study even found that supplementation may also help to reduce sugar/carbohydrate cravings which are commonly experienced by individuals with PCOS.
Can inositol help with infertility?
Unfortunately, one of the many symptoms of PCOS is infertility. The exact link between PCOS and infertility is still unknown however research suggests that insulin resistance is the underlying mechanism.
One study has showed that in women with PCOS, there is an imbalance in the ratio of MI:DCI in the ovaries. It found that MI levels are much lower than normal. The cause of this MI deficiency is thought to be linked to abnormally high levels of insulin.
MI is necessary in the regulation of follicle stimulating hormone (FSH). This plays a crucial roles in regulating ovulation and egg quality thus contributing to fertility outcomes.
This supports the concept that maintaining normal levels of MI and DCI are essential for supporting normal ovarian function.
- improve ovarian function
- promote ovulation
- improve menstrual regularity
- Potentially benefit egg and embryo quality thus enhancing fertility outcomes
Additionally, high androgen (male hormone) levels, which are common in PCOS, have further impacts on fertility and this may also be corrected with supplementation.
One study which involved women with PCOS who also had ovulatory dysfunction (PCOS was the only apparent cause of their infertility), found that 6 months of supplementation with MI alongside folic acid was able to restore at least one spontaneous menstrual cycle in 22 of the 25 women. When followed up, 18 of these women had maintained normal ovulation and 10 had successful pregnancies.
A systematic review of randomised controlled trials found that MI supplementation in women with PCOS may lead to improved insulin sensitivity, restoration of normal ovulation, improved egg quality and a reduction in hyperandrogenism which may in turn help increase fertility.
Inositol and PCOS – the ideal supplementation ratio
Many of the studies into inositol supplementation, have found there is an ideal ratio of myo-inositol to D-chiro-inositol needed for optimal outcomes.
A review investigating the ideal ratio concluded that a MI:DCI ratio of 40:1 is most effective for managing insulin resistance and restoring ovulation.
How effective is it?
A Cochrane review into the effectiveness and safety of oral inositol supplementation for reproductive outcomes in women with PCOS, found that although there is some compelling research to support the benefits of supplementation, the evidence is still limited.
As such, the authors concluded they were not able to definitively show that supplementation will increase the chances of falling pregnant and maintaining pregnancy.
However, this does not mean that inositol supplementation isn’t an effective strategy to improve your chances of fertility, only that more research is still required.
Sources of inositol
Inositols are found naturally in many plant-based foods including some wholegrains, fruits and vegetables, nuts and beans.
It is estimated, that the average person consumes approximately 1g of inositol in their diet, however, this is not well taken up by the body. As such, these natural sources don’t contain the specific doses and amounts necessary to produce the desired effects.
Therefore, whilst as dietitians, we usually promote food first over supplementation, this is one instance in which supplementation is preferred.
A review into potential side effects of supplementation with inositol found little reported adverse side effects. Mild side-effects such as nausea, gas and diahorrea were only observed with a high dose of the supplement (12g). This is much greater than the doses that are used in the majority of clinical studies which usually supplement with around 2-4g/day. Despite the lack of reported negative side-effects, it should be noted that there is still very little information available regarding the safety and/or side effects of inositol supplementation and more research is still required.
Is inositol supplementation right for me?
Inositol supplementation is not essential for PCOS management, however, it may be potentially beneficial alongside other medical, dietary and lifestyle interventions in some individuals. As with all supplements, it is recommended you speak with a healthcare practitioner before commencing any new supplements. This is particularly important if you are currently taking medications such as Metformin to ensure blood sugar levels don’t drop too low.
Inositols and PCOS, the research may might not be as clear as we would like it to be. However, a growing amount of data is showing this supplement may be promising in helping many common PCOS symptoms. Resultantly, this may have many positive outcomes in assisting with fertility, however more research is needed in this area. For more advice on how your nutrition can help with PCOS symptom management – book in for a consultation with one of our dietitians here.
This article was written by Plant Nutrition and Wellness’s fertility dietitian Georgia D’Andrea.