Summary
Highlights
Testosterone is a steroid hormone belonging to the androgen group, acting as a chemical messenger in the bloodstream. Primarily produced in the testicles of males and smaller amounts in the ovaries of females, with tiny amounts from the adrenal glands. It is crucial for male puberty, driving physical transformations like increased muscle mass, voice deepening, and reproductive organ maturation. In adulthood, it maintains bone density, regulates mood, supports cognitive function, and plays a key role in cardiovascular health and sexual function.
Testosterone levels in men gradually decline around age 30 at a rate of 1-2% per year due to decreased testicular efficiency, weaker brain signaling, and increased sex hormone-binding globulin (SHBG), which reduces available testosterone. Symptoms of low testosterone (hypogonadism) include fatigue, difficulty concentrating, mood changes, reduced sex drive, decreased muscle mass, and increased body fat. Chronically low testosterone is linked to increased risks of obesity, type 2 diabetes, cardiovascular problems, and premature death.
To check testosterone levels, a healthcare professional can perform a blood test, ideally in the morning. A general normal range is considered 300 nanograms per deciliter or higher, but optimal levels are personalized based on age, symptoms, and health. Prioritizing lifestyle modifications is recommended before medical interventions. Exercise, especially resistance training with compound movements, and weight management are highlighted as effective ways to support healthy testosterone levels. Excess body fat converts testosterone into estrogen. A balanced diet with healthy fats, protein, and complex carbohydrates is important.
Excessive alcohol consumption and smoking negatively impact testosterone levels and male reproductive health. Environmental toxins like BPA can disrupt hormones. Low energy availability (burning more calories than consumed), common in athletes and those dieting, can significantly lower testosterone levels as the body conserves energy by reducing non-essential functions like hormone production. Studies show that large calorie deficits and intense exercise increase cortisol and decrease testosterone.
Zinc is crucial for testosterone production, acting as a co-factor for enzymes and supporting luteinizing hormone (LH) synthesis which signals the testicles to produce testosterone. It is also involved in converting testosterone to DHT, a more potent form of androgen. Deficiency can impair testosterone synthesis, and athletes may be at higher risk for deficiency. Supplementation can restore levels in deficient individuals, but extra zinc likely won't supercharge levels that are already normal.
A systematic review of 50 popular testosterone booster supplements revealed that only 24.8% of their individual components had published data showing an increase in testosterone. 10.1% had data showing a decrease, 18.3% showed no change, and 61.5% had no data at all. Even among the components with positive data, over half had conflicting data. Fenugreek and ashwagandha showed some positive findings, but the overall evidence for herbal supplements is weak and inconsistent.
Fenugreek showed the most consistent positive findings, with some studies reporting increases in total and free testosterone. Ashwagandha also showed positive effects in some studies. Asian ginseng mostly showed no effect, and tribulus terrestris was deemed ineffective. Maca root also does not affect testosterone. Many other common herbs have little to no testosterone-boosting evidence.
Major limitations in research on herbal supplements include a lack of high-quality, well-designed randomized controlled trials, heterogeneity (variation) across studies, and questionable applicability to the general population. Dietary supplements are poorly regulated, with manufacturers primarily responsible for safety and labeling accuracy. Some supplements contain super-therapeutic doses of vitamins and minerals, exceeding safe upper limits. Specific safety concerns include one case report linking fenugreek extract to pulmonary embolisms and liver stress.
Testosterone is vital for male health, impacting muscle mass, energy, mood, and bone health. However, levels decline naturally with age. Consult a doctor for blood tests, keeping in mind that interpreting the results involves considering health context and symptoms. Prioritize lifestyle habits such as maintaining a healthy weight, reducing abdominal fat, regular exercise, and a balanced diet. Be aware of the impact of low energy availability due to intense training.