What is inositol and do I need it to help manage my PCOS?

You probably have heard of inositol if you’ve been diagnosed with PCOS. It is a supplement that has many beneficial claims, but is inositol helpful for the management of PCOS?

What is inositol?

Inositol is a type of sugar alcohol that helps your body process insulin (a key hormone) and influences several other hormones in the body. Inositol also has some antioxidant properties to help free radical damage in the body.

What are the different types of inositol?

When talking about inositol we really are talking about nine different stereoisomers (the same parts but in a different chemical configuration). Although there are two inositol isomers that are of particular interest for PCOS management.


Myo-inositol was considered a member of the B-vitamin complex. It was known as Vitamin B8 despite not being an essential nutrient, as it can be produced by the body from glucose (sugar). As myo-inositol is an FSH (follicle-stimulating hormone) secondary messenger, it is effective in optimising the FSH/LH ratio and regulating the menstrual cycle. This link to FSH may also lead to improved ovarian follicle maturation and higher egg cell quality – potentially increasing reproductive success.


D-chiro inositol is involved in the synthesis of androgens, is dependent on insulin, and promotes glucose storage. D-chiro-Insoistol is converted from Myo-Insoistol through insulin-stimulated NAD-dependent epimerase. Interestingly, D-Chiro-Inositol can impair egg cell quality if it is administered in high doses.

What are the benefits of inositol?

A systematic review of twelve randomised controlled trials found that the oral administration of Myo-inositol, alone or in combination with D-chiro-inositol, “is capable of restoring spontaneous ovulation and improving fertility in people with PCOS”.

This may be because inositol is considered an insulin sensitiser. This means that it helps the cells in the body be more responsive to insulin, and therefore lets more glucose into the cells, reducing blood glucose levels. This reduction in insulin lowers testosterone levels and restores the FSH/LH ratio in the body.

Inositol may also help to reduce the risk of metabolic disorders associated with PCOS such as high cholesterol and blood pressure.

How much inositol do I need per day?

Interestingly, there is no recommended daily allowance for inositol. The body can make inositol itself and get inositol from various food sources.

Within the body, the kidneys and liver produce about 1-2g of inositol from glucose per day.

It is hypothesised that people with insulin resistance, commonly seen in people with PCOS, may have an inositol deficiency.

Is inositol in foods?

Yes, inositol is found in foods. Inositol is found in melons, citrus fruit, beans, brown rice, corn, sesame seeds, and wheat bran.

Should I take an inositol supplement?

Inositol supplementation as a treatment for PCOS is still experimental, which means more research is needed to conclusively recommended it for PCOS. If you do choose to supplement with inositol, you may want to consider informing your doctor, healthcare or nutrition professional.

Are there any side effects of taking too much inositol?

Although inositol is generally considered safe in adults, there are some potential side effects if too much is taken. These include headaches, tiredness, dizziness and nausea. This tends to occur when high dosages of inositol are taken (12 g plus per day).

Overuse of inositol may lead to hypoglycemia (low blood sugar), although this is considered rare.

How quickly does inositol work?

Most inositol supplement trials are at least 12 weeks (3 months) and often up to 6 months. If you decide to supplement with inositol, ensure you are taking it for at least 3-6 months to be able to see if it has an effect on your PCOS symptoms.

What type of inositol should I take?

Although theoretically, it seems that increasing myo-inositol would improve PCOS symptoms, administering inositol in the physiological ratio of 40:1 Myo-inositol to D-Chiro-inositol seems to be more effective. The use of the 40:1 ratio shows the same efficacy as myo-inositol alone, but in a shorter time.

In summary, inositol may be a helpful supplement for people with PCOS but it should be considered an experimental therapy in PCOS, with emerging evidence on efficacy highlighting the need for further research.

Where can I buy inositol in the UK?

There are plenty of places to purchase inositol in the UK including Time Health, Free Soul and MyOva.

It is important to note that inositol is an experimental therapy for PCOS. It is being recommended because of emerging evidence and requires further research.

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