New research indicates that a natural compound found in the skin of grapes, blueberries and raspberries has the potential to improve female fertility.
The systematic review into resveratrol, which is a polyphenolic compound known for its antiaging, anti-inflammatory and antioxidant properties, is published in the International Journal of Molecular Sciences.
Researchers from Anglia Ruskin University (ARU) in Cambridge, England, alongside colleagues from Italy, South Korea and the Queen Elizabeth Hospital King's Lynn NHS Foundation Trust, examined all previously published research on resveratrol and female reproductive health.
By collating and reviewing results from 24 in vitro and in vivo studies, involving a total of 9,563 human participants, they found evidence to suggest resveratrol can improve the quantity and quality of egg cells, called oocytes.
Four studies specifically investigated resveratrol in connection with the quantity of matured oocytes. Two of these reported an increase, while two found no significant differences. Additionally, two studies assessed the quality of matured oocytes and both reported an improvement amongst women who took resveratrol.
A possible explanation is that resveratrol reduces oxidative stress, helping to protect mitochondrial DNA from damage and enhance telomerase activity, to reduce cellular aging. Resveratrol also activates the molecule sirtuin 1 (SIRT1), which is typically reduced in aged oocytes, therefore potentially slowing cell aging and extending ovarian lifespan.
The review also found evidence that resveratrol could potentially treat infertility associated with endometriosis, and have positive effects on polycystic ovary syndrome and obesity-related infertility, by inhibiting pathways involved in androgen production and reducing inflammation and oxidative stress.
Crucially, the review found mixed results regarding miscarriage and pregnancy data. Five studies reported on pregnancy rates, with two indicating an increase, two found no difference, and one reporting a decrease amongst those taking resveratrol. The same study that noted a decrease in pregnancy rates also reported an increase in miscarriage rates, while a second study found no difference.
Resveratrol is generally considered safe when consumed in moderate amounts through diet and through supplements, in doses up to five grams a day for a month, although the safety of high-dose supplementation, particularly over long periods, remains unclear.
Lee Smith, Professor of Public Health at Anglia Ruskin University (ARU) and senior author of the paper, said: "Our systematic review on resveratrol and female fertility is a comprehensive overview of all current research, and it highlights the compound's potential to improve reproductive outcomes and possibly pave the way for new, less invasive treatments, using natural substances.
"However, our findings are based on a number of limitations, including the limited number of human studies, the different parameters of each study and the lack of robust data on dosage and side effects, particularly related to birth defects or foetal abnormalities.
"Therefore, there is a need for further clinical trials, involving human participants, in order to translate these promising results into practical recommendations for women looking to improve their fertility, including guidance on the safe and effective dosage of resveratrol."
