A new study reveals that increasing vitamin B12 levels may reduce testosterone deficiency in men struggling with infertility, offering hope for improved reproductive health through simple dietary changes.
Study: Vitamin B12 Is Associated with Higher Serum Testosterone Concentrations and Improved Androgenic Profiles Among Men with Infertility. Image Credit: Tatjana Baibakova / Shutterstock
In a recent study published in The Journal of Nutrition, researchers examined the cross-sectional associations between serum levels of vitamin B12 and male reproductive hormones. The study provides new insights into how micronutrients may influence hormonal profiles in men with infertility.
Infertility is the inability to achieve pregnancy following one year of consistent unprotected sexual intercourse. It affects around 16% of North American couples; male factor infertility accounts for about 30% of cases. Male fertility decline, characterized by hypogonadism and diminished sperm quality, has become a serious concern. Studies have identified significant reductions in testosterone levels in males over the past few decades, independent of age.
Genetic polymorphisms, endocrine dysfunction, and physical impairments have traditionally been deemed the primary causes of male infertility. However, recent studies have highlighted the role of lifestyle factors, including smoking, nutrition, environmental toxins, and sleep disruptions. Diets with more vegetables and fruits and less fat, meat, processed foods, and refined sugars can positively impact sperm parameters.
Vitamin B12 has received attention for its impact on reproductive function in males, with studies suggesting it as an adjuvant therapy for infertility. A recent study also highlighted positive associations between vitamin B12 and enhanced sperm motility, sperm count, and DNA integrity. Nonetheless, conflicting evidence from other studies has suggested no significant link between vitamin B12 and semen quality.
About the study
In the present study, researchers examined the relationship between serum vitamin B12 levels and reproductive hormones in 303 men diagnosed with infertility, recruited from Mount Sinai Hospital in Toronto, Canada, between June 2019 and August 2021. Individuals were excluded if they had a vasectomy, Y-chromosome microdeletions, Klinefelter syndrome, cystic fibrosis, physical impairments leading to infertility, or used fertility-related medicines in the past six months.
Participants completed a personal health questionnaire that collected data on demographics, medical history, anthropometrics, lifestyle, and female partner’s medical history. Venous blood samples were collected to measure serum concentrations of reproductive hormones and vitamin B12. The following hormones were assessed: total testosterone (TT), follicular stimulating hormone (FSH), prolactin, luteinizing hormone (LH), and estradiol.
The monotonic relationship between vitamin B12 levels and reproductive hormones, except estradiol, was assessed using Spearman’s rank correlation analyses. Both univariate and multivariate linear models were employed to assess associations between vitamin B12 levels and reproductive hormones, and logistic regression examined associations between tertiles of vitamin B12 levels and the clinical status of reproductive hormones.
Findings
Overall, 303 participants were recruited. Their mean age and body mass index were 36.5 years and 28 kg/m2, respectively. Approximately 44% were Caucasian, 19.1% were Asian, 4.3% were Indo-Canadian, 8.9% were African-Canadian, and 2.3% were Hispanic. Most subjects were non-smokers (86%). About 0.7% of the sample had vitamin B12 deficiency, while 12.2% had elevated levels.
The average serum vitamin B12 concentration was 446 pmol/L. The mean concentrations of prolactin, TT, LH, and FSH were 8.8 ng/ml, 13.3 ng/dL, 7.2 IU/L, and 9.7 IU/L, respectively. A large proportion of participants exhibited hormonal imbalances, with one-fourth of participants having elevated FSH, one-third elevated LH, and 74.9% increased estradiol. Elevated prolactin and testosterone levels were observed in 2.6% and 30% of the sample, respectively.
Spearman’s rank correlation analyses suggested a significant, positive monotonic association between vitamin B12 levels and TT. In crude univariate linear regression models, vitamin B12 levels were positively associated with TT. In adjusted multivariate models, this association was sustained. No significant associations were evident with other hormones.
In crude logistic regression analyses, persons in the highest tertile of vitamin B12 levels had lower odds of having elevated LH than those in the lowest tertile. Nevertheless, the association diminished in adjusted models. Individuals in the mid-and highest tertiles of vitamin B12 levels had lower odds of TT deficiency compared to those in the lowest tertile.
Conclusions
The findings reveal a positive, linear association between serum vitamin B12 and TT levels. Individuals in the highest and mid-tertiles of vitamin B12 levels had significantly reduced odds of TT deficiency relative to those in the lowest tertile. This suggests that even moderate increases in vitamin B12 levels can reduce the likelihood of testosterone deficiency in men with infertility. There was no evidence of associations with other hormones.
The study’s limitations include the cross-sectional nature, which precludes establishing causality, self-reporting of anthropometric and demographic data, which might lead to bias, and unidentified confounding. Further, the study was only designed to assess vitamin B12; however, several macronutrients and micronutrients could influence reproductive hormones. Future research should examine the combined effects of multiple nutrients on male fertility and reproductive hormones.