In males, testosterone is synthesized primarily in Leydig cells. The number of Leydig cells in turn is regulated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In addition, the amount of testosterone produced by existing Leydig cells is under the control of LH, which regulates the expression of 17β-hydroxysteroid dehydrogenase.
Pregnant or nursing women who are exposed to EDCs can transfer these chemicals to their child. Exposure to EDCs during pregnancy affects the development of male fetuses. Fewer boys have been born in the United States and Japan in the last three decades. The more women are exposed to these hormone-disrupting substances, the greater the chance that their sons will have smaller genitals and incomplete testicular descent, leading to poor reproductive health in the long term. EDCs are also a threat to male fertility, as they contribute to testicular cancer and lower sperm count. All of these birth defects and abnormalities, collectively referred to as Testicular Dysgenesis Syndrome (TDS), are linked to the impaired production of testosterone.5
Testosterone retains nitrogen and is an essential ingredient in the development and maintenance of muscle mass (Sinha-Hikim et al 2006). With a diminution in testosterone, muscle mass diminishes as does strength. Weakness and fatigue result. A number of studies have demonstrated the ability of testosterone to restore lean body mass (muscle) in hypogonadal men, while at the same time causing a reduction in fat mass (Wang et al 2004). Treatment of hypogonadal men with testosterone results in improvement in overall physical performance as well as strength as assessed by, eg, hand grip power (Page 2005). Because of decreased muscle strength and impaired balance, older hypogonadal men are susceptible to falling and since they may already be osteopenic or osteoporotic as a consequence of hypogonadism, they are at increased risk for fracture as a result of the fall (Szulc et al 2003). Men with low levels of testosterone as in androgen deprivation therapy for prostate cancer, have a significant decrease in lean body mass and hemoglobin, while at the same time they experience an increase in weight, body fat and body mass index (Smith et al 2002). Treatment of frail hypogonadal men with testosterone, therefore, can result in changes in muscle gene expression, increased muscle mass, improvements in strength, power and endurance and improved physical function.
Men's levels of testosterone, a hormone known to affect men's mating behaviour, changes depending on whether they are exposed to an ovulating or nonovulating woman's body odour. Men who are exposed to scents of ovulating women maintained a stable testosterone level that was higher than the testosterone level of men exposed to nonovulation cues. Testosterone levels and sexual arousal in men are heavily aware of hormone cycles in females. This may be linked to the ovulatory shift hypothesis, where males are adapted to respond to the ovulation cycles of females by sensing when they are most fertile and whereby females look for preferred male mates when they are the most fertile; both actions may be driven by hormones.
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A 46 XY fetus is destined to become a male because the Y chromosome carries testicular determining gene which initiates transformation of the undifferentiated gonad into testes (Töhönen 2003). The testes subsequently produce both Mullerian Inhibiting Factor (to induce degeneration of the Mullerian system, the internal female ductal apparatus) and testosterone (to stimulate growth and development of the Wolffian system – epididymus, vas deferens, seminal vesicle and, after conversion to dihydrotestosterone (DHT) by the enzyme 5-α-reducase, the prostate gland). DHT is also the primary androgen to cause androgenization of the external genitalia.
There are the testosterone deficiency signs, such as loss of sexual desire, erectile dysfunction, impaired fertility, chronic fatigue, etc. But it’s not always possible to understand which medical condition caused the decrease in testosterone levels. For example, if you always feel exhausted and have no sexual desire, it may provide evidence of depression.
Hypogonadism (as well as age-related low testosterone) is diagnosed with blood tests that measure the level of testosterone in the body. The Endocrine Society recommends testing for suspected low T with a total testosterone test. It may be performed in the morning when testosterone levels tend to be highest in young men, although this isn't necessarily the case in older men. The test may be repeated on another day if the results show a low T level. (5)
When you’re under stress (be it from lack of sleep, workplace stress, emotional stress, stress from a bad diet, overtraining etc.), your body releases cortisol. Cortisol blunts the effects of testosterone (47), which makes sense from an evolutionary point of view – if we were stressed as cavemen chances are it was a life or death situation – not running late to a meeting - in this state (i.e. running from a lion) the body wouldn’t care if you couldn’t get it up, there was more to worry about!
Dobs and colleagues found that men with an increased body mass index had both reduced testosterone and reduced high density lipoprotein (HDL) levels. Treatment with testosterone increased the levels of HDL (Dobs et al 2001). Rising levels of HDL are not a consistent finding with TRT. More often, however, one finds reduced total cholesterol, low density lipoprotein (LDL) cholesterol and triglyceride levels with TRT (Zgliczynski et al 1996; Whitsel et al 2001).
Testosterone is a vital hormone for men, but just like estrogen in women, it goes down as you age. This is a natural process that has many drawbacks. In men, testosterone is responsible for hair growth, bone density, proper weight distribution, sex drive, muscle mass, red cell production, and so much more. But did you know that you can actually increase your testosterone levels as opposed to letting them dwindle?
Conflicting results have been obtained concerning the importance of testosterone in maintaining cardiovascular health. Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve many parameters that are thought to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, decreased total cholesterol, and glycemic control.
High vitamin D intake (via D3) is helpful to low D3 tested people. However, if your D3 is already sufficient then thos dosages you advocate can lead to toxicity and the high intake of D3 must be accompanied by a lower level of calcium intake daily or it will affect your bones and loss of bone calcium. One you get to a sufficient level of D3 via blood test results you only need to get a smaller level of D3 supplements to retain that level.
Yeah a lot of information has come out in the last decade or so proving that cholesterol is in fact good for you, and actually has no correlation to heart disease. But I think it will be a few more years until the world will shift such a strong belief that cholesterol is the enemy. If you are interested in this you should read grain brain. It talks all about (and proves) how high carbohydrates are actually the reason for “high cholesterol” and a high fat low carb diet is great for your body, and more importantly your brain.
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If you’re a frequent reader here in AM, you already know that increased dietary fat intake is directly correlated with increased testosterone production. And not only that, but the types of fat that increase T seem to be saturated fats (SFAs) and monounsaturated fats (MUFAs), while polyunsaturated (PUFAs) actually tend to lower testosterone (more here).
If testosterone deficiency occurs during fetal development, then male characteristics may not completely develop. If testosterone deficiency occurs during puberty, a boy’s growth may slow and no growth spurt will be seen. The child may have reduced development of pubic hair, growth of the penis and testes, and deepening of the voice. Around the time of puberty, boys with too little testosterone may also have less than normal strength and endurance, and their arms and legs may continue to grow out of proportion with the rest of their body.