Declining Testosterone and Fertility Rates

The average male fertility and testosterone levels across global populations have been noticing a decline for the past several decades. Plastics and other oil derived compounds have become materials in our manufacturing processes since the turn of last century. Many of these compounds contain xenoestrogens, which despite the name, are not estrogenic compounds, they are rather compounds that mimic oestrogen in the body. This is a large component in the lowered testosterone levels we have come to expect as exposure to oestrogen in males is associated with lower testosterone levels [1]. Alarmingly, total testosterone levels have been consistently declining by around 1% a year [2]. This decline seems to follow the trend of decreasing fertility (sperm count) rates, which declined 52% between 1973 and 2011 (39 years) at a rate just faster than 1% per year [3].

Normal Testosterone Levels and TRT

Men’s testosterone levels normally range from the lower side of 265ng/dl to the higher end of 923ng/dl [4] and levels peak around 18 years. This level declines as we age. Another component leading to lower testosterone levels as we age, is the increase of sex hormone binding globulin (SHBG). SHBG does not actually reduce total testosterone, rather free testosterone, which is the testosterone that is free for our tissues to use. SHBG is essential and carries testosterone around our bodies, but higher levels leave less testosterone available for its intended use.

TRT (testosterone replacement therapy) is fast becoming a popular trend amongst aging males to return their testosterone levels to within normal measurements seen in their age group. The therapy involves administering synthetic testosterone to boost the levels. Intervals between administration vary between doctors. Intervals between dosages are often around the two-week mark. The increased intervals between administration result in higher doses being required at each administration. This dosage does not follow the body’s natural testosterone cycle and is seen by the body as an excess of testosterone. Excess testosterone is converted into oestrogen in the male body and can lead to its own set of side effects (such as gynecomastia) [5].

Herbal Testosterone Therapies

Herbal testosterone therapies have been gaining in popularity, with compounds such as Tongkat Ali and Fadogia Agrestis. These substances do not come with the same set of side effects associated with synthetic testosterone. They achieve increased testosterone levels by two mechanisms. The first is to increase your total testosterone levels. Tongkat Ali is a source of compounds known as quassinoids, which instruct the pituitary gland in the brain to release luteinizing hormone. Luteinizing hormone instructs the testes to produce, amongst other things, more testosterone.

There are two theories in circulation as to how Fadogia Agrestis increases total testosterone, the first being that it works in a similar method to Tongkat Ali, instructing the release of more luteinizing hormone. The second being that it mimics the hormone, but still gets the same response out of the testes. The second mechanism comes from the use of Tongkat Ali, which lowers SHBG levels in the body, allowing for more testosterone to be used by the required tissues.

The two compounds synergistically have quite an outstanding effect on total testosterone levels. Dr Andrew Huberman reports on a case where he noticed an increase of levels just above 200ng/dl to 700ng/dl. This is reported as an outlier though and most individuals are likely to report a 300-400ng/dl increase in testosterone when using both compounds [6].

Tongkat Ali Misconception

There seems to be a bit of misinformation circulating that Tongkat Ali exclusively increases testosterone levels in individuals with low baseline testosterone. A study looking into the data from 5 other RCTs (randomised control trials) debunked this, confirming that Tongkat Ali will not only increase testosterone in men with hypogonadism, but significant increases were likely to be seen in healthy individuals as well [7].

References

[1] – Kalla N.R., Nisula B.C., Menard, R.D., Loriaux L. (1980). The Effect of Estradiol on Testicular Testosterone Biosynthesis, Endocrinology, 106(1), 35–39. https://doi.org/10.1210/endo-106-1-35

[2] – Harding, A. (2007, January 19). Men’s Testosterone Levels Declined in Last 20 Years. Retrieved from Reuters Health: https://www.reuters.com/article/health-testosterone-levels-dc-idUKKIM16976320061031

[3] – Swan, S. (2022, July 12). Plastic “Tox” EP 1: Plastics & Health – Are Phthalates Making Us Infertile? With Dr. Shanna Swan. (D. Cohen, Interviewer)

[4] – Sissions, C. (2023, January 06). Typical Testosterone Levels in Males and Females. Retrieved from Medical News Today: https://www.medicalnewstoday.com/articles/323085

[5] – Osterberg, E. C., Bernie, A. M., & Ramasamy, R. (2014). Risks of testosterone replacement therapy in men. Indian journal of urology : IJU : journal of the Urological Society of India, 30(1), 2–7. https://doi.org/10.4103/0970-1591.124197

[6] – Huberman, D. A. (2021, July 14). Andrew Huberman Talks About Testosterone Optimization. (J. Rogan, Interviewer)

[7] – Leisegang, K., Finelli, R., Sikka, S. C., & Panner Selvam, M. K. (2022). Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials. Medicina (Kaunas, Lithuania), 58(8), 1047. https://doi.org/10.3390/medicina58081047