Inositols & Fertility
You’ve read about them on the internet, you’ve heard chatter about them among friends, you’ve even picked up a bottle of them in Holland & Barrett… but what is an Inositol? And why might they be helpful for your fertility journey?
Inositols are naturally occurring sugars that are found in cereals, corn, legumes and some meat. There are various types of inositol, but myoinositol and D-chiroinositol are the most researched and are most commonly found as supplements. For a long time, it was thought that inositols were a type of B Vitamin, but it is understood now that they are not. They have many different functions within the body, many of which play a role in fertility. Inositols are used as the base or framework for many different hormone messengers, which means when there is a lack of inositols in the body, the cells and tissues cannot communicate very well.
Myoinositol is an important base for internal cell messengers that help take glucose out of the blood (where it circulates after being absorbed from food) and into the cells that need it. This means that having enough myoinositol in your body can help maintain healthy blood glucose levels.
Myoinsitol can also be turned into D-chiroinositol by the body. Again, it is used by the body to let glucose into the cells, and store it until it needs to be used. Unfortunately, the changing of myoinositol to D-chiroinositol is dependent on the amount of insulin in the tissue: if there is too much insulin, less is converted. This can become a vicious cycle, as then less D-chiroinositol means even less glucose uptake by the cells, which causes the pancreas to release even more insulin.
It has been found that if the ovaries are exposed to a lot of insulin, they may produce too much testosterone. This high level of testosterone is often found in women with PCOS. D-chiroinositol regulates the insulin sensitive testosterone production, and it has been found in several studies that having a myoinositol or D-chiroinositol supplement could help reduce testosterone levels in women. This is important because having too much testosterone can inhibit FSH, which is the hormone that helps follicles to grow, mature and release eggs in ovulation.
That might all be a bit confusing, so to summarise:
not enough inositol = too much insulin = too much testosterone = not enough egg maturing = poor ovulation
Several studies have shown that appropriate supplementing of myoinositol can improve egg maturation, pregnancy rates and testosterone levels. Some studies have also found that supplementing myoinositol alongside D-chiroinositol was helpful for restoring regular ovulation in women with PCOS.
However, it is important to supplement inositols appropriately: they are found in different ratios in the body naturally, at the ratio of myoinositol 40:1 d-chiroinositol. Some studies have noted that supplementing too much D-chiroinositol especially can be detrimental to health. Therefore, if you are considering a supplement, look for a 40:1 ratio (it will often say this on the packaging).
The evidence base and scientific understanding of inositols is improving all the time, and there is an abundance of information about them on the internet. However, there is not enough substantial evidence on large enough study groups for it to be recommended as a supplement by the National Institute of Care Excellence (who regulate a lot of prescribing and medical care pathways in the UK). So the purpose of this blog is not to recommend the supplement as such, but to inform you of the science behind the trend. If you have questions about inositols or other supplements that may impact your fertility, you can contact us via the website or social media.
References -
DOI: 10.1136/openhrt-2022-001989
PMID: 21744744
DOI: 10.3390/ph14060504
DOI: 10.1515/hmbci-2017-0067
DOI: 10.1007/s12291-014-0447-z
DOI: 10.1155/2020/6461254.