Can probiotics boost male and female fertility?

Benefits beyond the gut: The role of probiotics in improving male and female infertility.

Infertility affects millions globally and has become a common problem in recent decades. According to recent estimates, around 48 million couples and 186 million individuals live with infertility worldwide Around 48 million couples and 186 million individuals live with infertility worldwide. In males, infertility is commonly caused by ejection problems, absence or low levels of sperm, or abnormal shape or movement of the sperm. Infertility in females, on the other hand, is caused by a range of abnormalities of the uterus, ovaries, fallopian tubes, and the endocrine system. It has been recently discovered that microbiological factors could be related to the pathogenesis.¹ 

The link between dysbiosis and infertility

The microbiome, which consists of millions of microorganisms acts as an important mediator of reproductive health. It is observed in the semen and the entire reproductive tract in women. These microorganisms aid in maintaining an ecological balance in the reproductive tract and contribute toward host fertility and fitness.² 

Dysbiosis is the reduction in microbial diversity and a combination of the loss of friendly bacteria and a rise in pathogenic bacteria. Dysbiosis in the reproductive tract may result in the malfunction of the reproductive system, associated physiological diseases, and poor pregnancy outcomes.² 

Several clinical studies have proposed that gut microbiota plays a significant role in maintaining a healthy state of the reproductive tract Clinical studies have proposed that gut microbiota plays a significant role in maintaining a healthy state of the reproductive tract and the development of some associated diseases.² 

Male infertility is connected to inadequate testosterone levels and other sex hormones, increased inflammatory reactions, and oxidative stress. Dysbiosis in males may result in numerous inflammatory diseases like epididymitis, orchitis, prostatitis, decreased fertility, and inferior semen quality.³ 

The biodiversity of microbiota in the reproductive tract is quite dynamic in women and is dependent on several factors including hormonal changes occurring at different stages of the reproductive cycle.³ 

Lower levels of estrogen and an increase in pH around the menstrual period can shift the balance towards dysbiosis. These factors can decrease the population of lactobacilli and increase the growth of opportunistic, pathogenic microorganisms. Bacterial vaginosis is the most common type of vaginal dysbiosis which can lead to gynaecological complications including spontaneous preterm birth, abortion, and endometritis. Dysbiosis of the endometrial microbiome is responsible for gynaecological complications including chronic endometriosis, dysfunctional endometrial bleeding, endometrial polyps, endometrial cancer, and preterm delivery.³ 

Benefits of the dietary supplementation of probiotics in infertility

The administration of live microorganisms in the form of probiotics may aid in the maintenance of reproductive health in both males and females. Clinical studies that were conducted with probiotics demonstrated that Lactobacillus species (L. `fermentum, L. reuteri RC-14, L. gasseri, L. casei, L. rhamnosus, L. crispatus, L. acidophilus, and L. salivarius), Bifidobacterium species, and Bacillus species are beneficial in moderating fertility dysbiosis.^3,4,5 

Data shows that probiotics can enhance male fertility by improving testosterone levels Data shows that probiotics can enhance male fertility by improving testosterone levels, weakening inflammatory responses, and reversing the hostile effects of oxidative stress. Probiotic supplementation is found to have positive effects on testicular performance and semen quality. Probiotics alone or in combination with other treatment is found to improve infertility due to age, obesity, prostate dysfunction, environment, physiological stress, and idiopathic infertility.³ 

In a study carried out on 21 male patients with Idiopathic asthenozoospermia, a 2 × 1011 CFU of Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus rhamnosus, Lactobacillus acidophilus, Bifidobacterium longum, Bifidobacterium breve, and Streptococcus thermophil led to improvement in testosterone levels, ejaculation volume, sperm concentration, and motile sperm percentage.³ 

Benefits of the dietary supplementation of probiotics in female infertility

Probiotic supplements can modify the composition of microbiota in the gut and regulate the metabolism in women. This can impact the configuration of the microbiome, integrity of the biofilms, and the immune response. Probiotics may also act by altering the composition of the microbiota in the vagina thereby balancing the microbial ecology and improving reproductive health. Similar to the probiotics for male infertility management, Lactobacillus, Bifidobacterium, and Bacillus species are the most adapted probiotic candidates for positively modifying reproductive tract dysbiosis.³ 

Scientific evidence supports the potential role of probiotics in infertility conditions as well as hormonal disorders; like Polycystic Ovarian Syndrome (PCOS). In a study conducted by Zhang et al (2019), the administration of 1 × 106 CFU/day of Bifidobacterium lactis V9 for 10 weeks in PCOS patients showed a positive effect on the modulation of sex hormone levels and regulation of LH and LH/FSH hormones through the gut-brain axis. Anukam et al. (2009) carried out a study on 59 women with vaginal dysbiosis who were administered 5 × 109 CFU/day of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 for 24 weeks. Administration of probiotics led to the restoration of the normal vaginal flora, acidic pH, and fewer vulvovaginitis recurrences with long-term use.³ 

Recent studies have suggested that the gut microbiota can be a potential pathogenic factor in the development of PCOS, explaining why probiotic usage could be a nutritional intervention to help prevent or manage PCOS. A meta-analysis in 2020 concluded that synbiotics and probiotics can improve hormonal and inflammatory indices in this population. Such inflammatory indices typically contribute to impaired glucose tolerance, insulin sensitivity and other complications. Synbiotic and probiotic administration can modulate glucotoxicity and manage the pathophysiological complications that come with PCOS.⁵ 

Interventions with probiotics indicate an effective improvement in male and female infertility. Further investigations can help in understanding additional opportunities with probiotics on reproductive health and the offspring.^2,3,6 

References: 

1. Infertility. Available at:
   https://www.who.int/news-room/fact-sheets/detail/infertility#:~:text=In…. Accessed 30 May 2022.  
2. Feng T, Liu Y. Microorganisms in the reproductive system and probiotic's regulatory effects on reproductive health. Computational and Structural Biotechnology Journal. 2022 March 20;1541–1554. 
3. Hashem NM, Gonzalez-Bulnes A. The Use of Probiotics for Management and Improvement of Reproductive Eubiosis and Function. Nutrients. 2022 Feb 21;14(4):902. 
4. Zhang F, Dai J, Chen T. Role of Lactobacillus in Female Infertility Via Modulating Sperm Agglutination and Immobilization. Front Cell Infect Microbiol. 2021 Jan 25;10:620529. doi: 10.3389/fcimb.2020.620529. 
5. Kwok KO, Fries LR, Silva-Zolezzi I, Thakkar SK, Iroz A, Blanchard C. Effects of Probiotic Intervention on Markers of Inflammation and Health Outcomes in Women of Reproductive Age and Their Children. Front Nutr. 2022;9:889040. Published 2022 Jun 6. doi:10.3389/fnut.2022.889040 
6. López-Moreno A, Aguilera M. Probiotics dietary supplementation for modulating endocrine and fertility microbiota dysbiosis. Nutrients. 2020 Mar;12(3):757.