Effect Of Caffeine On Serum Testosterone Levels

Coffee, as we all know is an excellent source of caffeine. When consumed in moderate doses, caffeine intake directly results in dose dependent elevation of cortisol levels by activating adrenal cortex, while improving attention span, alertness and basal activity of brain. However, it is imperative to keep in mind that elevated cortisol secretion has been associated with reduced levels of testosterone.

Did it sink in? But it must have popped a question about how cortisol manages to lower the testosterone levels? Here’s how the whole mechanism works in the background:

Testicles are known to produce an enzyme (11ßHSD-1) that under normal circumstances shields the testosterone against the harmful effects of cortisol. However, when the stress hormones undergo a drastic elevation, the enzyme fails to protect testosterone from the deleterious effects of cortisol. With prolonged high levels of cortisol, the cholesterol present within the body begins to elevate the synthesis of cortisol; thereby resulting in poor synthesis of testosterone.

Seemingly what causes cortisol elevation should inversely affect the testosterone, and therefore caffeine must act no differently. But on the contrary, there are studies that suggests a positive effect of caffeine on elevating the basal testosterone levels.

How Does Caffeine Affect The Serum Testosterone Levels?

Research and clinical study indicates that consuming moderate doses of caffeine assists in enhancing muscle endurance and anaerobic performance and if consumed prior to the workout, it boosts the muscular strength to far greater extent on leg press and bench press when compared to placebo. So, with its cortisol elevating effect how can it positively influence and maximize the muscular strength?

Well, studies are here to answer that for you:

A study proposed that compared to placebo, caffeine consumption in doses 4mg/kg or higher prior to engaging in exercise boosts testosterone levels by up to 12% in athletes. It also showed elevation of cortisol levels in serum by up to 21.3%.
Another study revealed that testosterone secretion can be escalated by up to 14% by chewing a caffeine containing gum (or a dose of 240mg) prior to exercise or workout. However, it also showed a notable decline in the serum cortisol levels which may be due to chewing as chewing is known to alleviate stress (3).
A study based on consumption of caffeine prior to workout, in doses of 200, 400, 600 and 800mg, showed a significant boost in the levels of testosterone. The results were more evident in the group of subjects who consumed 800mg (i.e. testosterone boost by 19%) whereas cortisol levels rose by up to 44%.
A recent study further confirmed the testosterone boosting effects of caffeine, even on sleep deprived men. When sleep deprived men were given caffeine in the dose of 6mg/kg prior to aerobic exercise, their T/C ratio (testosterone to cortisol ratio) improved eminently.

Caffeine is known to be a non-selective PDE inhibitor. In simple terms, it has an ability to block an enzyme called PDE-4 that causes the breakdown of cyclic adenosine monophosphate (cAMP). Elevated levels of cAMP within the cells lead to elevated levels of testosterone as cAMP serves as a secondary messenger between hormones and cells. So, tossing caffeine in the given picture, the PDE-4 enzyme gets inhibited resulting in unaltered cAMP. That said, theoretically this maybe the reason behind the direct relationship rather than the inverse relationship between the levels of cortisol and that of testosterone.

To sum it all up, yes it does elevate cortisol and yes cortisol does lower the levels of testosterone but caffeine somehow exhibits testosterone boosting effects if taken prior to the workout. In short caffeine isn’t really a no-go after all if you are looking to boost testosterone levels with exercise and physical activity.

References

Wu, B. H. (2015). Dose effects of caffeine ingestion on acute hormonal responses to resistance exercise. The Journal of sports medicine and physical fitness, 55(10), 1242-1251.
Beaven, C. M., Hopkins, W. G., Hansen, K. T., Wood, M. R., Cronin, J. B., & Lowe, T. E. (2008). Dose effect of caffeine on testosterone and cortisol responses to resistance exercise. International journal of sport nutrition and exercise metabolism, 18(2), 131-141.
Paton, C. D., Lowe, T., & Irvine, A. (2010). Caffeinated chewing gum increases repeated sprint performance and augments increases in testosterone in competitive cyclists. European journal of applied physiology, 110(6), 1243-1250.