What We Know About Inositol and Fertility

There is no shortage of supplements on the market that claim to “naturally improve your fertility” or even “cure infertility.” But do they actually work? Today we’re looking at the evidence on inositol and fertility. Inositol is a popular supplement that is advertised for its effects on both fertility and insulin resistance in people with and without polycystic ovarian syndrome (PCOS). 

What is Inositol?

Inositol is sugar compound and nutrient similar to a B vitamin. It’s naturally found in the brain and our tissues. There are two main types:

1. Myo-inositol
2. D-chiro-inositol 

How May Inositol Assist Fertility?

Inositol may help to normalise hormone levels, in addition, to helping regulate ovulation in people with insulin sensitivity, particularly those with PCOS. We know that regular ovulation and balanced hormones are two key components when it comes to optimising our chances of conceiving! 

What connection does insulin have to fertility?

• We have insulin receptors on our ovaries that can at times overproduce the hormone testosterone, making falling pregnant difficult in some people (particularly those with PCOS).
• Insulin is also involved in creating sex hormone binding globulin, or SHBG for short. When we see a spike in our insulin levels, the level of SHBG will decrease leading to several PCOS symptoms and often difficulty conceiving as a result.

What does the research say?

There are several studies that we can look at to see how myo-inositol may benefit those both with and without PCOS.

A literature review of 197 articles found that myo-inositol (in those with PCOS):

• Improved ovarian function
• Enhanced fertility 
• Reduced the severity of acne and excess hair growth
• Improved spontaneous ovulation
• Induced ovulation

A 2015 study of 137 women with PCOS found that:

• Those who took myo-inositol were more likely to have regular menstrual cycles (and thus more likely to ovulate regularly), improved acne and overall insulin function.  

A 2016 study of 50 women with PCOS found that:

• Both myo-inositol and Metformin (a first-line medication used in the treatment of Type 2 Diabetes, also used in women with PCOS) were equally effective in terms of their ability to regulate the menstrual cycle 
• They observed no changes in acne or excess hair growth in either treatment group (myo-inositol or Metformin)

A 2018 Cochrane review looked at the link between inositols and fertility in women with PCOS and found that based on the available evidence they were unsure whether myo-inositol:

• Improved live birth rates or clinical pregnancy rates in sub-fertile women with PCOS undergoing IVF
• Decreased miscarriage rates or multiple pregnancy rates

A 2019 review article found that myo-inositol may positively impact sperm quality and quantity based on early research, but that further studies were needed to confirm this and understand the mechanism through which myo-inositol may have on male fertility.

In people without PCOS or insulin resistance, there is no real evidence that inositols will have any positive effect on fertility in people trying to conceive without medical intervention. There are currently no quality (placebo-controlled) studies that have looked at the potential impact of myo-inositol on pregnancy rates, ovulation, or menstrual cycle regularity in women without PCOS.

So is myo-inositol worth a try when it comes to infertility?

While the research shows promising results in terms of myo-inositols ability to regulate ovulation and our menstrual cycle in women with PCOS, there is no real evidence to say that this has any benefit in women without PCOS or when compared with the use of other medications like Metformin. 

Despite there being no negative side effects of taking myo-inositol, it would be worth consulting your fertility specialist for individualised advice before commencing on a supplement protocol of any kind.