Inositol for PCOS: benefits, evidence and dosage

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 PCOS?

PCOS (polycystic ovary syndrome) is an endocrine (hormonal) condition that impacts people assigned female at birth (AFAB). It is thought to affect approximately 1 in 10 people AFAB and has various symptoms such as carbohydrate cravings, fatigue, hirsutism, alopecia, irregular periods, difficulty conceiving and skin tags known as hidradenitis suppurativa.

As PCOS doesn’t have a cure, many turn to lifestyle changes such as supplements to help with symptom management. One of these supplements is inositol.

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 for PCOS?

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

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

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 for PCOS?

Inositol has been researched in people with and without PCOS due to its interesting benefits on insulin resistance, ovulation, fertility, testosterone levels and metabolic disorder risk. Let’s take a closer look at the evidence.

Improves insulin resistance

People with PCOS tend to have higher rates of insulin resistance than people without PCOS. Insulin resistance is when the body’s cells are resistant to the effects of insulin. 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.

Studies have found that supplementing with a combination of myo-inositol and D-chiro-inositol improves insulin resistance in people with PCOS. A 2016 study found that six months of supplementation significantly reduced LH, free testosterone, fasting insulin, and HOMA index (an index estimating insulin resistance) compared to controls.

May improve ovulation and fertility outcomes

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”.

May reduce testosterone levels

As well as circulating glucose levels, inositol supplementation has been seen to reduce testosterone levels in people with PCOS. A 2009 study found that supplementing with myo-inositol decreased circulating insulin and serum total testosterone levels.

May reduce the risk of metabolic disorders

Inositol may also help to reduce the risk of metabolic disorders associated with PCOS such as high cholesterol and blood pressure. A 2012 randomised control trial found that supplementing with combined myo and D-chiro-inositol reduces the risk of metabolic disease in people with PCOS.

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. Inositol supplements tend to contain 1-4 grams of inositol, to be taken by mouth daily. If you choose to take inositol supplements then make sure you follow the manufacturer’s instructions.

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 inositol for PCOS?

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

What are the 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.

Best inositol for PCOS

There are plenty of places to purchase inositol in the UK including Time Health and MyOva. Here are some of the best inositol supplements for PCOS, including ones available with worldwide shipping.

Key takeaways: inositol for PCOS

There is emerging evidence that inositol can improve symptoms of PCOS such as anovulation, high testosterone, insulin resistance and metabolic syndrome risk. 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. Always consult with your healthcare professional before taking inositol.