Testosterone, also known as the male sex hormone, is important for the health of both men and women. This steroid hormone is produced primarily in the testes of men, with smaller amounts also produced by the ovaries in women. It is responsible for the development of male secondary sexual characteristics, muscle mass and strength, bone density, and red blood cell production.1
It also affects mood, energy levels and cognitive function in both men and women.2 However, testosterone levels in men naturally decline as they age. Previous research3,4 This decline in testosterone has been suggested to affect the risk of severe COVID-19 in older men.
A study published in July 2024 in the journal Andrology sought to further investigate the link between testosterone levels and COVID-19 severity.5 Testosterone-dependent finger length patterns in hospitalized COVID-19 patients were investigated compared with controls. Their findings revealed important insights into the protective role of testosterone against severe COVID-19 outcomes.
Additional evidence for testosterone’s role in coronavirus severity
The main research is,6 The study, conducted at the University of Łódź Medical School in Poland, examined two competing theories regarding the impact of testosterone on COVID-19 prognosis. The first, known as the high androgen-centric theory, suggests that higher testosterone levels allow viruses to infect cells more effectively.
Conversely, a second theory argues that lower testosterone levels, especially common in older men, lead to a heightened immune response to COVID-19, leading to worse outcomes. To investigate this theory, researchers compared finger length ratios, specifically the index and pinky fingers, in hospitalized COVID-19 patients and healthy controls.
This approach is based on the theory that digit proportions are influenced by testosterone and estrogen exposure during fetal development and puberty. Longer index fingers are associated with lower testosterone or higher estrogen exposure, while longer little or pinky fingers are associated with higher testosterone or lower estrogen exposure.
The study results showed that hospitalized COVID-19 patients had consistently shorter pinkies compared to the other fingers compared to the control group. This is a “feminized” pattern, indicating low testosterone levels. This supports the low androgen-driven theory, which suggests that decreased testosterone contributes to more severe COVID-19 outcomes.
Lead researcher Professor John Manning, from the Applied Sport, Technology, Exercise and Medicine (A-STEM) research team at Swansea University, explained:7
“Patients had digit ratios that indicated low testosterone before and after birth. This pattern emerged early in the pandemic and after widespread vaccination, which means we can conclude that testosterone is protective against severe COVID-19.” The effects may occur because: This hormone reduces inflammation in the lungs and other organs. These findings have implications for public health and treatment.
Key genes in testosterone metabolism influence coronavirus severity
A previous study published in Cell Reports Medicine found that8 Researchers discovered another testosterone-related factor that affects COVID-19 severity in men: a gene called CYP19A1. The study, led by Gülsah Gabriel of the Leibniz Institute of Virology, builds on a decade of research looking at similar patterns in avian influenza.
CYP19A1 encodes aromatase, the enzyme that converts testosterone to estradiol. Researchers found that a specific mutation in this gene, although rare in the general population, was present in 68.7% of men hospitalized with COVID-19. This mutation is known to increase aromatase activity, lowering testosterone and increasing estradiol levels.
Moreover, the researchers found that SARS-CoV-2 infection itself dramatically increased aromatase expression in lung cells, much more than other respiratory viruses. These findings were confirmed through various methods, including analysis of human COVID-19 patients, lung tissue examination of deceased patients, and golden hamster experiments.
In infected male hamsters, CYP19A1 expression was significantly increased in the lungs, resulting in decreased testosterone and increased plasma estradiol levels. This hormonal imbalance appears to lead to more severe COVID-19 outcomes in men.
Interestingly, the researchers found that treating infected male hamsters with the aromatase inhibitor letrozole partially restored hormonal balance and improved lung health. These findings not only provide insight into why men face a higher risk from COVID-19, but also highlight the often overlooked role of hormones in respiratory infections.
As Gabriel points out, “This is one of the first studies to show that the lungs, which are not a classic or typical endocrine organ, can suddenly become an endocrine organ when infected. It appears that (respiratory viruses) can have long-lasting effects if they lose control of the enzymes.” appears.”9
What causes decreased testosterone production?
Testosterone production in men is regulated by signals that pass from the brain to the pituitary gland. The pituitary gland then signals the testes to produce testosterone, and a “feedback loop” continuously monitors levels of this hormone in the blood. When this system is disrupted, testosterone levels decrease.10
In healthy adult men, testosterone levels typically range from 300 to 1,000 nanograms per deciliter (ng/dL).11 Age-related decline in testosterone production, also known as andropause, begins around age 30, with testosterone decreasing by an average of about 1% per year.12 By the time men reach their 70s, many men’s testosterone levels are 30% lower than they were at their peak.13
In addition to aging, genetic disorders and other diseases also contribute to decreased testosterone levels. These include:14,15
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Chronic conditions such as diabetes, obesity, liver or kidney disease |
Lifestyle factors such as stress, poor eating habits, and lack of exercise |
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Drugs that disrupt hormonal balance |
Congenital diseases such as Klinefelter syndrome and Turner syndrome |
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sleep apnea |
Exposure to Endocrine Disrupting Chemicals (EDCs) |
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Consumption of polyunsaturated fats (PUFA) and phytoestrogens |
environmental pollutants |
Symptoms of Low Testosterone Levels
Low circulating testosterone levels result in symptoms of androgen deficiency. Androgens are a group of sex hormones that include testosterone. Clinical symptoms of low testosterone can vary greatly depending on the onset of androgen deficiency, whether the problem is with sperm production or testosterone synthesis, whether it is related to underlying genetic factors, and whether there is a history of androgen treatment.16 Symptoms of androgen deficiency include:17
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fatigue |
hypersensitivity |
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infertility |
poor feeling of well-being |
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decreased libido |
Decreased frequency and quality of erections |
Men may also experience gynecomastia (enlarged breast tissue), hot flushes, sweating, fatigue, loss of muscle mass, and increased body fat.18 In some cases, unrelated problems exist, such as a history of type 2 diabetes, obesity, metabolic syndrome, or other systemic diseases that affect testosterone physiology.19 Study published in the journal Molecular Psychiatry20 It also links testosterone deficiency to anxiety disorders.
Niacinamide naturally increases testosterone levels
One way to boost your testosterone levels naturally is to take niacinamide (aka nicotinamide, a form of vitamin B3 or niacin), which is important for healthy mitochondrial function and cellular energy production. February 2022 study published in the journal Nature Aging21 Niacinamide has been proven to treat problems associated with age-related decline in testosterone levels.
They found that niacinamide improved local testosterone distribution by increasing NAD+. This is essential to support tissues and organs affected by reduced testosterone levels. These findings confirm that niacinamide is a necessary cofactor to address the nearly universal decline in testosterone in both men and women. Bioenergetic medicine expert Georgi Dinkov explained:22
“(T)he discovery that androgen (in this case testosterone) deficiency, which is almost universal with age, is primarily due to a deficiency of the cofactor NAD+, which can be improved by supplementing with NAD+ precursors such as niacinamide.
The rate-limiting step in androgen (testosterone) synthesis appears to be enzyme 3b-HSD, with NAD+ as the major cofactor. Therefore, the decline in NAD+ that occurs in aging (and disease) leads to a decrease in 3b-HSD activity, which results in decreased androgen (testosterone) levels.”
To address testosterone loss, you may want to consider taking:
- Niacinamide 50 mg three times a day
- DHEA 5mg to 10mg orally administered once a day
- Oral pregnenolone 50 mg once daily
Ideally, take the hormone supplements DHEA and pregnenolone with saturated fat, such as a teaspoon of butter, to bypass liver metabolism. Then the effectiveness decreases drastically.
Additional Ways to Optimize Testosterone Production
In addition to taking niacinamide, some additional strategies to increase testosterone naturally include:
• Exercise regularly — A comprehensive meta-analysis published in the Journal of Endocrinological Investigation23 Moderate and high-intensity exercise resulted in significant increases in testosterone in men, with an average increase of 0.74 nmol/L (21.3 ng/dL). Testosterone increases were most pronounced immediately after exercise and within the first 30 minutes after exercise, and typically returned to baseline after 30 minutes.
Moderate exercise, such as walking, cannot be considered excessive exercise, so it is recommended to do so. Study published in the journal Endocrinology24 They found that men who walked less than 4,000 steps a day were more likely to have low testosterone levels. Conversely, men who walked 4,000 to 8,000 steps a day had a significantly lower risk of being deficient.
The study also found that for every 1,000 additional steps taken each day, testosterone levels increased by an average of 7 ng/dL.25 Turkish study further supports the benefits of exercise26 In Japan, continuous and intermittent blood flow restriction (BFR) training, also known as KAATSU, and resistance training have been shown to increase testosterone levels in young men.
• Get adequate sunlight exposure — Sufficient exposure to sunlight creates an excess of cellular energy and increases testosterone production. It also optimizes vitamin D levels, which supports healthy testosterone production.
A study published in the Asian Journal of Andrology found that lower serum vitamin D levels were associated with decreased total testosterone levels in men. Additionally, higher serum vitamin D levels were positively associated with better semen parameters, including sperm concentration, motility, and morphology.
“(These findings) clearly demonstrate a direct, positive relationship between serum vitamin D levels and overall semen quality, male reproductive potential, and testosterone levels,” the authors noted.
However, keep in mind that if your diet is high in seed oils (rich in linoleic acid), you need to be careful about sun exposure. These oils oxidize in sunlight, causing inflammation and DNA damage. This is why you experience rapid sunburn when your diet is high in seed oils. I recommend avoiding high intensity sun exposure until you have not used this oil for about 6 months.
At that point, you can gradually increase your sun exposure. Eventually, you will be able to enjoy an hour or more of peak sunlight without getting burned.
• Consider herbal remedies — One herb that has gained attention for its ability to increase testosterone levels is fenugreek. Study published in Journal of Personalized Medicine27 Fenugreek has been shown to increase serum testosterone levels by inhibiting enzymes such as aromatase and 5-alpha reductase, which are involved in testosterone metabolism. Fenugreek also contains sapogenins and saponins, which have anabolic and androgenic activities.
Another herb I recommend is ashwagandha. Known for its adaptogenic properties, ashwagandha has been shown to support overall hormonal balance and reduce stress. Studies have shown that increased testosterone levels increase testosterone levels by reducing cortisol, a hormone that negatively affects testosterone production.28
