Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s), and is presented for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to medical devices.
There's been a ton of controversy recently about a term coined by Tucker Carlson called “testicular tanning.” He’s referring to the use of red light therapy applied to the testicles to stimulate testosterone. Carlson claims that this is a miracle cure for male testosterone, while mainstream media outlets are nearly unified in claiming that this is unscientific.
In this article we’ll analyze what the research actually says about whether red light therapy can promote testosterone production, and whether it even matters.
Is Male Testosterone Dropping?
Male testosterone is dropping precipitously in industrialized societies. A medical review published in the Journal of Clinical Endocrinology & Metabolism in 2007 analyzed serum testosterone levels across nearly two decades of data collection.
The researchers found that there was an “age-independent decline” in testosterone that remained even when factors known to lower testosterone like obesity were adjusted for. This suggests that there are environmental factors causing the decline.
A more recent study, published in 2021, found that adolescent and young adult men in the US experienced a statistically significant decrease in testosterone between the years 2000 and 2016.
In less than two decades, the study authors noted that the average testosterone level in the young adults tested dropped from around 600 nanograms per deciliter (ng/dl) to around 450 ng/dl. This is a drop of around 25% which is significant.
This trend isn’t unique to American men. An extremely thorough medical study published in 2020 in the Reproductive Biology and Endocrinology Journal examined data from over 100,000 patients in Israel. The researchers found a “highly significant age-independent decline in total testosterone” over the 13 years of the study.
We’ve noted similar results in many other population studies we’ve reviewed from other industrialized nations. Thus we can conclude that male testosterone levels do appear to be dropping across the industrialized world.
Why Is Male Testosterone Dropping?
There are many theories as to why male testosterone is declining so significantly. The answer is likely multifactorial, but one of the theories backed by scientific research is the influence of hormone-disrupting chemicals in our environment.
The class of chemicals that make plastics soft, called “plasticizers,” disrupt endocrine function and appear to bio-accumulate in the tissue of mammals.
Researchers are still yet to uncover the exact biochemical mechanisms that cause this class of chemicals to interfere with male hormone metabolism, but the fact that the trend of lowered testosterone remains constant even when adjusting for factors like obesity and exercise suggests that most of the cause is environmental.
Does Testicular Tanning Increase Testosterone?
There isn’t much medical research suggesting that red light therapy applied to the testicles (or to the body generally) improves testosterone levels.
One clinical trial examined the effects of full-body red light therapy treatment on a variety of health parameters in healthy young athletes, including heart rate variability, cortisol levels, and testosterone.
The researchers found that the treatment had no effect on testosterone levels, though it should be noted that the participants were young (aged 18) male professional athletes, which is a group less likely to have issues with testosterone metabolism than the average patient.
An animal study found that red light therapy increased sperm damage and had no impact on testosterone levels in rams.
We can’t locate any medical studies that suggest red light therapy is effective for improving testosterone levels, so we will conclude that “testicular tanning” is ineffective for boosting T at this point in time.
Unscientific Mainstream Press Coverage of This Topic
We’ve been disappointed by the coverage of this topic in mainstream media. Rather than analyzing the health claim based on medical data to provide consumers with valuable information, most of the coverage has been emotionally-driven rhetoric without a shred of evidence.
An InsideHook article written by a man named Kirk Hook on the topic of testicular tanning stated the following “‘Red light therapy’ doesn’t appear to be a thing anyone is talking about professionally or medically, basically because the idea makes no sense.”
Kirk Hook has no medical credentials and this conclusion is totally unscientific and false. Red light therapy (medically termed “low level light therapy”) returns 6,950 results in PubMed, the leading resource for medical studies.
While it may not be effective for improving testosterone, it has promising early results for other health outcomes. As one randomly selected example, a meta-study published in 2021 found that red light therapy is effective in early research as a side-effect-free treatment for fibromyalgia pain.
A piece on The Guardian about this topic claims that “most men have far more testosterone than they need,” suggesting that the population-level decline in testosterone has no negative effects on male health. The author is named Sam Wolfson and he describes himself as a “freelance music writer” on his author bio. He has no apparent medical credentials and it’s concerning that a major publisher is allowing him to give medical advice to the masses.
This commentary is uncited and demonstrably false, as optimal testosterone levels in men are associated with physical and mental wellbeing. A thorough medical review of testosterone levels and psychological health status found that men with lower testosterone (in the normal range) had higher levels of anxiety and depression than men with average to above-average testosterone.
Testosterone therapy is incredibly effective at treating depression in men with low testosterone, as documented by a meta-review on the topic.
We find it unfortunate that many mainstream journalists are not fulfilling their basic research obligations to help inform the public in an objective manner, and we hope that publishers hire more medically-credentialed writers in the future.