In addition to conjugation and the 17-ketosteroid pathway, testosterone can also be hydroxylated and oxidized in the liver by cytochrome P450 enzymes, including CYP3A4, CYP3A5, CYP2C9, CYP2C19, and CYP2D6.[155] 6β-Hydroxylation and to a lesser extent 16β-hydroxylation are the major transformations.[155] The 6β-hydroxylation of testosterone is catalyzed mainly by CYP3A4 and to a lesser extent CYP3A5 and is responsible for 75 to 80% of cytochrome P450-mediated testosterone metabolism.[155] In addition to 6β- and 16β-hydroxytestosterone, 1β-, 2α/β-, 11β-, and 15β-hydroxytestosterone are also formed as minor metabolites.[155][156] Certain cytochrome P450 enzymes such as CYP2C9 and CYP2C19 can also oxidize testosterone at the C17 position to form androstenedione.[155]
We’ll be honest. Testosterone boosters don’t really boost. The best testosterone booster is like taking a multivitamin with extra herbs that might slightly and temporarily increase your testosterone levels. Like all supplements, finding the right testosterone booster means wading into a sea of ingredients, all promising to help. Of 133 testosterone boosters, we found only one with the right ingredients to help raise your testosterone levels: Beast Sports Nutrition - Super Test ($45.88 for 180 capsules, or $2.04 per day).
During the month before my experiment, I was definitely sleep deprived. Some nights I was only getting 4 to 5 hours. Testosterone killer! During my experiment I tried to get 8 to 9 hours of sleep at night as consistently as possible. I had to go to bed earlier, but I was only cutting into time that I would have been using to mindlessly surf the net anyway.

A diagnosis of low testosterone is typically made if a man’s free testosterone hormone level is below 300 ng/dL. But as a doctor specializing in sexual health, I typically consider optimized male testosterone levels somewhere between 600 to 800 ng/dL—rarely above or below those numbers. The tests that I routinely recommend to my male clients can be found in this test panel and include biomarkers associated with testosterone, free and total (this includes sex-hormone binding globulin [SHBG]), estradiol, estrogen (total and serum), cortisol, DHEAs, thyroid-stimulating hormone (TSH), hemoglobin A1C, and vitamin D.

There are supplements out there that promise to increase your libido while also upping your testosterone. There are over the counter testosterone supplements and prescription supplements. There are supplements that market themselves as T-boosters, while also touting themselves as an aphrodisiac. And then there are companies that claim to have developed a testosterone pill that contains the triumvirate of male-enhancing properties: T-boosting, libido-enhancing, and even fertility-increasing. These supplement makers sometimes throw in an additional claim of muscle gain as well.
There is increasing interest in the group of patients who fail to respond to treatment with PDE-5 inhibitors and have low serum testosterone levels. Evidence from placebo-controlled trials in this group of men shows that testosterone treatment added to PDE-5 inhibitors improves erectile function compared to PDE-5 inhibitors alone (Aversa et al 2003; Shabsigh et al 2004).

Like other supplements and medication, testosterone therapy comes with risks and possible side effects. This is particularly true if you try to take it for normal aging rather than for treatment of a condition. Also, the Cleveland Clinic points out that the effects that these supplements may have on your heart and prostate can lead to a number of potential issues. Complications include:
In general, the normal range in males is about 270 to 1070 ng/dL with an average level of 679 ng/dL. A normal male testosterone level peaks at about age 20, and then it slowly declines. Testosterone levels above or below the normal range are considered by many to be out of balance. Moreover, some researchers suggest that the healthiest men have testosterone levels between 400 - 600 ng/dL.
Vitamin D supplementation may potentially boost testosterone levels, but further research is needed to determine if it really has an effect on the testosterone levels of young people and athletes. The truth is likely similar to zinc and magnesium — being in a deficient state causes your testosterone levels to drop below baseline, and supplementing it just takes you right back to baseline (but not any higher).
While I do have a pretty manly mustache, I’m not a doctor or a medical expert. I’m a guy with a law degree he’s never used who blogs about manliness. What I’m about to share shouldn’t be taken as a substitute for qualified medical expertise. It’s simply my experience and views on the subject. Before you make any changes in lifestyle or diet, talk to your doctor or healthcare provider. Be smart.
This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.
Low testosterone levels may contribute to decreased sex drive, erectile dysfunction, fragile bones, and other health issues. Having low testosterone levels may also indicate an underlying medical condition. See your doctor if you suspect you have low testosterone. A simple blood test is all it takes to check if your testosterone falls within the normal range.
Testosterone is a steroid from the androstane class containing a keto and hydroxyl groups at the three and seventeen positions respectively. It is biosynthesized in several steps from cholesterol and is converted in the liver to inactive metabolites.[5] It exerts its action through binding to and activation of the androgen receptor.[5] In humans and most other vertebrates, testosterone is secreted primarily by the testicles of males and, to a lesser extent, the ovaries of females. On average, in adult males, levels of testosterone are about 7 to 8 times as great as in adult females.[6] As the metabolism of testosterone in males is more pronounced, the daily production is about 20 times greater in men.[7][8] Females are also more sensitive to the hormone.[9]
There are numerous studies that show that Tribulus does not increase testosterone levels, and provides no assistance in increasing muscle mass or strength. I one of the two group of rugby players were put on the herb or a placebo. At the end of the experiment, there were zero changes in testosterone levels in the Tribulus group. Says a lot. [Source]

There are studies that show Soy consumption in humans leads to lower sperm count, but unfortunately they did not look at testosterone levels in the study (40). This (41) particular study compared the estrogen production of men drinking soy protein to those drinking whey. After two weeks they found the estradiol levels were equal, however soy drinkers had LOWER Testosterone levels and HIGHER cortisol levels (both bad).
So out of all the natural testosterone boosting supplements out there I only really recommend tongkat ali extract, d-aspartic acid, and ashwagandha. There are a many others out there, but none that meet the standard that these do. And most of the other ones are actually in Testofuel. But remember, use at your own discretion. Even natural supplements can have side effects, so talk to your doctor first, and start slow.
“This study establishes testosterone levels at which various physiological functions start to become impaired, which may help provide a rationale for determining which men should be treated with testosterone supplements,” Finkelstein says. “But the biggest surprise was that some of the symptoms routinely attributed to testosterone deficiency are actually partially or almost exclusively caused by the decline in estrogens that is an inseparable result of lower testosterone levels.”
If in a 46 XY individual testosterone is either not produced in adequate concentrations as in gonadal dysgenesis (MacLaughlin and Donahue 2004), or in the absence of the enzyme 17 alpha-hydroxylase so that testosterone is not produced (Ergun-Longmire et al 2006), or testosterone androgen receptors are absent as in the androgen insensitivity syndrome (Hughes and Deeb 2006), phenotypic females will result.
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.
If you remember Popeye the Sailor Man, then your childhood was probably awesome. You might remember that Popeye takes spinach and he becomes miraculously powerful within seconds. Although it's not an accurate depiction of spinach's abilities, it is safe to say that it shouldn't be avoided in a man's diet. Spinach may not be excessively rich in zinc yet it holds many other vitamins and minerals.
Keep in mind that you can use virtually any type of equipment you want for this – an elliptical machine, a treadmill, swimming, even sprinting outdoors (although you will need to do this very carefully to avoid injury) -- as long as you're pushing yourself as hard as you can for 30 seconds. But do be sure to stretch properly and start slowly to avoid injury. Start with two or three repetitions and work your way up, don't expect to do all eight repetitions the first time you try this, especially if you are out of shape.
In accordance with sperm competition theory, testosterone levels are shown to increase as a response to previously neutral stimuli when conditioned to become sexual in male rats.[40] This reaction engages penile reflexes (such as erection and ejaculation) that aid in sperm competition when more than one male is present in mating encounters, allowing for more production of successful sperm and a higher chance of reproduction.
The use of anabolic steroids (manufactured androgenic hormones) shuts down the release of luteinising hormone and follicle stimulating hormone secretion from the pituitary gland, which in turn decreases the amount of testosterone and sperm produced within the testes. In men, prolonged exposure to anabolic steroids results in infertility, a decreased sex drive, shrinking of the testes and breast development. Liver damage may result from its prolonged attempts to detoxify the anabolic steroids. Behavioural changes (such as increased irritability) may also be observed. Undesirable reactions also occur in women who take anabolic steroids regularly, as a high concentration of testosterone, either natural or manufactured, can cause masculinisation (virilisation) of women.
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