“About 2 weeks after starting Andro400, I noticed my belly fat disappearing. Now, after only one month, I've lost about ten pounds all in my mid section. What a miracle! I have more energy and don't have to hold my gut in any longer. I'm more relaxed and my libido has increased 5 fold! I'm 58 years old and beginning to feel like a teenager again! Your product has delivered exactly as advertised. I'm elated!” 

In summary, low testosterone levels are linked to the presence of numerous cardiovascular risk factors. Testosterone treatment acts to improve some of these factors, but effects may vary according to pre- and post-treatment testosterone levels, as well as other factors. There is little data from trials specific to aging males. Appropriately-powered randomized controlled trials, with cardiovascular disease primary endpoints, are needed to clarify the situation, but in the meantime the balance of evidence is that testosterone has either neutral or beneficial effects on the risk of cardiovascular disease in men. It is particularly important to define the effect of testosterone treatment on cardiovascular disease in view of its potential use as an anti-anginal agent.
Here’s a scary thought: You may be less of a man than your father was—at least hormonally. A study in the Journal of Clinical Endocrinology and Metabolism found that, on average, testosterone levels were higher in men of the same age in the ’80s than they were in the 2000s (due, researchers speculate, to higher rates of obesity and the wider use of medication these days).  
Everlasting T is the most extreme and most affordable testosterone supplement we've ever come across. By utilizing revolutionary, scientifically-proven all-natural testosterone boosting ingredients, Everlasting T naturally and safely ignites testosterone levels to give you every benefit of healthy testosterone levels. Everlasting T is the perfect testosterone booster to help you add lean muscle mass, increase strength, reduce body fat, enhance sexual performance and increase energy.
I’m afraid I have no super cool “secrets” to share and there are no easy shortcuts to increasing your T. If you were expecting some magical potion or supplement or weird body hack that will instantly and naturally increase your T levels, what follows is bound to disappoint. Despite what some companies or websites might tell you, there’s no single thing that will boost your testosterone naturally for the long term.
Studies also show a consistent negative correlation of testosterone with blood pressure (Barrett-Connor and Khaw 1988; Khaw and Barrett-Connor 1988; Svartberg, von Muhlen, Schirmer et al 2004). Data specific to the ageing male population suggests that this relationship is particularly powerful for systolic hypertension (Fogari et al 2005). Interventional trials have not found a significant effect of testosterone replacement on blood pressure (Kapoor et al 2006).
There is also solid research indicating that if you take astaxanthin in combination with saw palmetto, you may experience significant synergistic benefits. A 2009 study published in the Journal of the International Society of Sports Nutrition found that an optimal dose of saw palmetto and astaxanthin decreased both DHT and estrogen while simultaneously increasing testosterone.6 Also, in order to block the synthesis of excess estrogen (estradiol) from testosterone there are excellent foods and plant extracts that may help to block the enzyme known as aromatase which is responsible producing estrogen. Some of these include white button mushrooms, grape seed extract and nettles.7
Testogenix is quickly becoming one of the best-selling testosterone supplements on the market! Its 12 clinically-proven ingredients have helped men everywhere dramatically raise their testosterone levels and do it safely with a 100% All-Natural Ingredients. Priced under $40, it is no wonder why Testogenix has become our User’s Favorite Testosterone Supplement. When surveyed, Testogenix was chosen as their top choice for its affordable, safe & effective formulation all for UNDER $40!

Millions of American men use a prescription testosterone gel or injection to restore normal levels of the manly hormone. The ongoing pharmaceutical marketing blitz promises that treating "low T" this way can make men feel more alert, energetic, mentally sharp, and sexually functional. However, legitimate safety concerns linger. For example, some older men on testosterone could face higher cardiac risks.
There are a lot of test booster blends out there. A lot of them are junk. I have tried to cover the most effective herbs above. As always, I recommend doing your own research and experiment to see if you notice an effect. If you would like one easy herbal solution I recommend starting with Mike Mahlers Aggressive Strength product purely because I have solid anecdotal evidence of its effectiveness. But again, supplements should be seen purely as that - a supplement to a healthy diet, plenty of sleep, hard training with adequate rest.
A study out of the University of Mary Hardin-Baylor in Belton, Texas, examined the effects of fenugreek supplementation on strength and body composition in resistance-trained men. Researchers found that while both the placebo and fenugreek groups significantly increased their strength during the first four weeks, only the fenugreek group saw significant increases in strength after eight weeks of training and supplementation.[5]
Since then there have been many publications documenting suppressed testosterone and gonadotropins (Daniell 2006) in men using opioid medications whether these agents were administrated orally (Daniell 2002) or intrathecally (Finch et al 2000). Not only do opioids act centrally by suppressing GnRH, they also act directly on the testes inhibiting the release of testosterone by Leydig cells during stimulation with human chorionic gonadotropin (Purohit et al 1978). Although the large majority of men (and women) receiving opioids do develop hypogonadism, about 15 percent also develop central hypocorticism and 15 percent develop growth hormone deficiency (Abs et al 2000).
A: Testosterone production declines naturally with age. Low testosterone, or testosterone deficiency (TD), may result from disease or damage to the hypothalamus, pituitary gland, or testicles that inhibits hormone secretion and testosterone production. Treatment involves hormone replacement therapy. The method of delivery is determined by age and duration of deficiency. Oral testosterone, Testred (methyltestosterone), is associated with liver toxicity and liver tumors and so is prescribed sparingly. Transdermal delivery with a testosterone patch is becoming the most common method of treatment for testosterone deficiency in adults. A patch is worn, either on the scrotum or elsewhere on the body, and testosterone is released through the skin at controlled intervals. Patches are typically worn for 12 or 24 hours and can be worn during exercise, bathing, and strenuous activity. Two transdermal patches that are available are Androderm (nonscrotal) and Testoderm (scrotal). The Androderm patch is applied to the abdomen, lower back, thigh, or upper arm and should be applied at the same time every evening between 8 p.m. and midnight. If the patch falls off before noon, replace it with a fresh patch until it is time to reapply a new patch that evening. If the patch falls off after noon, do not replace it until you reapply a new patch that evening. The most common side effects associated with transdermal patch therapy include itching, discomfort, and irritation at the site of application. Some men may experience fluid retention, acne, and temporary abnormal breast development (gynecosmastia). AndroGel and Testim are transdermal gels that are applied once daily to the clean dry skin of the upper arms or abdomen. When used properly, these gels deliver testosterone for 24 hours. The gel must be allowed to dry on the skin before dressing and must be applied at least 6 hours before showering or swimming. Gels cannot be applied to the genitals. AndroGel is available in a metered-dose pump, which allows physicians to adjust the dosage of the medication. Side effects of transdermal gels include adverse reactions at the site of application, acne, headache, and hair loss (alopecia). For more specific information on treatments for low testosterone, consult with your doctor or pharmacist for guidance based on current health condition. Kimberly Hotz, PharmD

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“I'm 55 years old and hitting the ball further than I've ever hit, and I'm not getting tired going 18 holes! And when I play softball I'm hitting the ball further. I work for the DWP in LA and it's a very physically demanding job. Andro400 really helps because we work 16 hour days a lot. I was turning down a lot of overtime, but when I started taking Andro400, it got me through the day. I really notice a difference – even my wife did. It really works!”
Testosterone supplements are typically used by men who want to increase the level of the male hormone testosterone that controls functions such as sexual desire and muscle gain. There are several types of over-the-counter testosterone supplements available in nutritional supply stores. You should speak to your doctor before using any type of testosterone supplement since none of the effects advertised have been approved by the Food and Drug Administration. Additionally, there are prescription-based testosterone therapies that produce better results.

Boron, a mineral, keeps the cell walls of plants strong. Eating dried fruits and nuts gives you abundant amounts of boron. You can also take boron supplements. It's important to keep your daily boron intake at less than 20 mg, however, according to a current factsheet available from the U.S. National Library of Medicine. High doses of boron can cause serious side effects such as skin inflammation and peeling, irritability, tremors or depression.
Acne and Allergic Reactions: The testosterone is universally regarded as one of the triggering factors for acne. It stimulates the activity of oil glands making the skin more oily and vulnerable to acne. This body hormone might also cause allergic reactions, such as hives, rash, difficulty breathing, itching, chest tightness, and big swelling of the facial parts.
^ David KG, Dingemanse E, Freud JL (May 1935). "Über krystallinisches mannliches Hormon aus Hoden (Testosteron) wirksamer als aus harn oder aus Cholesterin bereitetes Androsteron" [On crystalline male hormone from testicles (testosterone) effective as from urine or from cholesterol]. Hoppe-Seyler's Z Physiol Chem (in German). 233 (5–6): 281–83. doi:10.1515/bchm2.1935.233.5-6.281.
There are no studies showing its effects on healthy males, but it has been shown to drastically improve testosterone in infertile males (ref 77). It's also packed full of minerals, so is a great superfood nevertheless. I use the Sunfoods brand. Make sure you buy from a quality brand, as there are a lot of poor shilajit products out there, also some have been shown to be high in heavy metals. 

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.
Take 250 mg of Forskolin, standardized to 10 percent, twice a day. Take one serving before training and the other with a meal. According to "Natural Anabolics," Forskolin decreased body fat and increased free testosterone levels in training individuals as compared to a placebo. Forskolin comes from the herb coleus forskohlii and is also known as Forslean.
While researchers in Brisbane, Australia, found that while Testofen (“a standardized [fenugreek] extract and mineral formulation”) significantly improved the sexual arousal, orgasm, and the general quality of life of participants, it did not remarkably increase testosterone above normal levels. Participants who took Testofen were more satisfied with their energy, well-being, and muscle strength than those who took the placebo.
DHEA (dehydroepiandrosterone) extract - this is a chemical that used in your body which a ‘hormone precursor’. This means it’s the chemical used by the body to create hormones like oestrogen or testosterone. When taken as supplement it is believed to boost testosterone levels, but DHEA has not been shown to increase testosterone in men. DHEA comes in two form:
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.
Grape seed extract is another ingredient with not enough research to suggest a dosage. Grape seed extract can interact with drugs like “blood thinners, NSAID painkillers (like aspirin, Advil, and Aleve), certain heart medicines, cancer treatments, and others.” If this sounds like you (or if you ever pop an Advil to clear off a headache), you’ll need to speak with a doctor to make sure this supplement is safe to take.
The effects of testosterone in humans and other vertebrates occur by way of multiple mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.[109][110] Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors.[111][112][113]
The effects of testosterone in humans and other vertebrates occur by way of two main mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors. Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. DHT binds to the same androgen receptor even more strongly than T, so that its androgenic potency is about 2.5 times that of T. The T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.
Once your elevate testosterone levels, you will also sharpen your focus, enhance sports performance, and enjoy enormous competitive spirit. You will also soon notice that the lack of motivation is no longer your problem. Being highly motivated and aggressive due to the action of testosterone boosters, you will experience better muscle gain. Whether you are a novice or a professional sportsman, you will quickly reach your sports goals.
While it would be nice to buy a testosterone pill from the local supplement store and have your testosterone levels go up, such a magic pill does not exist. As you can see from the above rundown, while a few supplements may be somewhat effective if your T levels are already low, none will significantly raise your testosterone above a baseline level. Thus, the basics of keeping your T levels high remain pretty simple:
And remember, saturated fats work best (along with monounsaturated fats – olive oil, almonds, avocados etc.). In fact higher intakes of polyunsaturated fats (canola oil, sunflower oil, soybean oil, safflower oil, margarine etc.) are linked to LOWER testosterone levels (14 & 15). I explore the dangers of PUFA's in a lot more detail in this article - PUFA's: The Worst Thing For Your Health That You Eat Everyday.
I have been using HerbalT for almost two months. I noticed improvement in my sleep, energy and mood within 3-4 days. Prior to use, I had a sleeping disorder and would wake up tired in the morning. My energy level was low and the sexual desire needed a trigger. After using this product, my energy level has improved. I wake up in the mornings and feel that my system is default. My mood has also improved. I don’t think to feel/think negative and hardly stress over anything.
Heavy metal, fluoride, chlorine, pesticides, dioxins and other dangerous chemicals that are in our food, products and even the air we breath are wreaking absolute havoc on our endocrine systems (responsible for testosterone production). It’s hard to avoid these (especially if you’re a smoker) but they are major contributors to man’s decline in testosterone.
Epidemiological studies suggest that many significant clinical findings and important disease states are linked to low testosterone levels. These include osteoporosis (Campion and Maricic 2003), Alzheimer’s disease (Moffat et al 2004), frailty, obesity (Svartberg, von Muhlen, Sundsfjord et al 2004), diabetes (Barrett-Connor 1992), hypercholesterolemia (Haffner et al 1993; Van Pottelbergh et al 2003), hypertension (Phillips et al 1993), cardiac failure (Tappler and Katz 1979; Kontoleon et al 2003) and ischemic heart disease (Barrett-Connor and Khaw 1988). The extent to which testosterone deficiency is involved in the pathogenesis of these conditions, or to which testosterone supplementation could be useful in their treatment is an area of great interest with many unanswered questions.

Magnesium comes with a strict upper cap. Excess magnesium is hard on your kidneys, and can lead to kidney failure. The NIH recommends that men consume 400-420 mg of magnesium daily, but that they should not exceed 350 mg of supplemental magnesium per day. Because while it’s rare for people to chronically overdose on magnesium through diet (you’d have to eat a lot of almonds and spinach, for example), overdose by supplement is far more common.


The prevalence of biochemical testosterone deficiency increases with age. This is partly due to decreasing testosterone levels associated with illness or debility but there is also convincing epidemiological data to show that serum free and total testosterone levels also fall with normal aging (Harman et al 2001; Feldman et al 2002). The symptoms of aging include tiredness, lack of energy, reduced strength, frailty, loss of libido, decreased sexual performance depression and mood change. Men with hypogonadism experience similar symptoms. This raises the question of whether some symptoms of aging could be due to relative androgen deficiency. On the other hand, similarities between normal aging and the symptoms of mild androgen deficiency make the clinical diagnosis of hypogonadism in aging men more challenging.
Growth of spermatogenic tissue in testicles, male fertility, penis or clitoris enlargement, increased libido and frequency of erection or clitoral engorgement occurs. Growth of jaw, brow, chin, and nose and remodeling of facial bone contours, in conjunction with human growth hormone occurs.[21] Completion of bone maturation and termination of growth. This occurs indirectly via estradiol metabolites and hence more gradually in men than women. Increased muscle strength and mass, shoulders become broader and rib cage expands, deepening of voice, growth of the Adam's apple. Enlargement of sebaceous glands. This might cause acne, subcutaneous fat in face decreases. Pubic hair extends to thighs and up toward umbilicus, development of facial hair (sideburns, beard, moustache), loss of scalp hair (androgenetic alopecia), increase in chest hair, periareolar hair, perianal hair, leg hair, armpit hair.
Longitudinal studies in male aging studies have shown that serum testosterone levels decline with age (Harman et al 2001; Feldman et al 2002). Total testosterone levels fall at an average of 1.6% per year whilst free and bioavailable levels fall by 2%–3% per year. The reduction in free and bioavailable testosterone levels is larger because aging is also associated with increases in SHBG levels (Feldman et al 2002). Cross-sectional data supports these trends but has usually shown smaller reductions in testosterone levels with aging (Feldman et al 2002). This is likely to reflect strict entry criteria to cross-sectional studies so that young healthy men are compared to older healthy men. During the course of longitudinal studies some men may develop pathologies which accentuate decreases in testosterone levels.
It sounds like a creature from Jurassic World, but this plant is worth learning to pronounce, especially if you haven’t had great sex since dinosaurs roamed the earth. A 2012 study showed that consuming six grams of tribulus root for 60 days improved erections and frequency of sex in men with low sperm counts. It also reduced sexual fatigue. Furthermore, their testosterone jumped by a whopping 16%. “Trib,” as it’s called, is thorny and bitter, so look to a supplement for consuming it. Epiq’s Quad Test includes Tribulus terrestris. (epiqresults.com)
Like other steroid hormones, testosterone is derived from cholesterol (see figure).[124] The first step in the biosynthesis involves the oxidative cleavage of the side-chain of cholesterol by cholesterol side-chain cleavage enzyme (P450scc, CYP11A1), a mitochondrial cytochrome P450 oxidase with the loss of six carbon atoms to give pregnenolone. In the next step, two additional carbon atoms are removed by the CYP17A1 (17α-hydroxylase/17,20-lyase) enzyme in the endoplasmic reticulum to yield a variety of C19 steroids.[125] In addition, the 3β-hydroxyl group is oxidized by 3β-hydroxysteroid dehydrogenase to produce androstenedione. In the final and rate limiting step, the C17 keto group androstenedione is reduced by 17β-hydroxysteroid dehydrogenase to yield testosterone.
A testicular action was linked to circulating blood fractions – now understood to be a family of androgenic hormones – in the early work on castration and testicular transplantation in fowl by Arnold Adolph Berthold (1803–1861).[177] Research on the action of testosterone received a brief boost in 1889, when the Harvard professor Charles-Édouard Brown-Séquard (1817–1894), then in Paris, self-injected subcutaneously a "rejuvenating elixir" consisting of an extract of dog and guinea pig testicle. He reported in The Lancet that his vigor and feeling of well-being were markedly restored but the effects were transient,[178] and Brown-Séquard's hopes for the compound were dashed. Suffering the ridicule of his colleagues, he abandoned his work on the mechanisms and effects of androgens in human beings.
Studies also show a consistent negative correlation of testosterone with blood pressure (Barrett-Connor and Khaw 1988; Khaw and Barrett-Connor 1988; Svartberg, von Muhlen, Schirmer et al 2004). Data specific to the ageing male population suggests that this relationship is particularly powerful for systolic hypertension (Fogari et al 2005). Interventional trials have not found a significant effect of testosterone replacement on blood pressure (Kapoor et al 2006).

Testosterone is the main hormone associated with muscle mass, strength gains, and libido. But that's far from the only thing it does in the body. As Chris Lockwood, Ph.D., explains in the article "All About Testosterone," it impacts everything from mood and memory to bone health—but yes, to be clear, it also makes muscles bigger and stronger, and helps increase endurance and athletic performance.
When we face stress, our adrenal glands secrete cortisol to prepare our bodies and minds to handle the stressful situation — the primal fight-or-flight response. In small dosages, cortisol is fine and even useful, but elevated cortisol levels for prolonged periods can do some serious damage to our bodies and minds. One area that seems to take a hit when cortisol is high is our testosterone levels. Several studies have shown a link between cortisol and testosterone. When cortisol levels are high, testosterone levels are low; and when testosterone levels are high, cortisol levels are low.
The testicles produce an enzyme called 11ßHSD-1 which protects your testosterone molecules from the effects cortisol.  During times of prolonged stress and chronically elevated cortisol, there simply is too much cortisol for 11ßHSD-1 to handle.  This results in testosterone molecules being destroyed inside the gonads before they even enter the bloodstream (8, 9).
The biggest change I made to my diet was increasing my fat and cholesterol intake. There’s a reason why old school strong men would drink raw eggs — studies have suggested that higher fat and cholesterol consumption results in increased levels of total T; men eating low-fat diets typically have decreased testosterone levels. The emphasis on increasing fat and cholesterol consumption meant I got to eat like Ron Swanson for three months — bacon and eggs and steak was pretty much the staple of my diet.
Infertility in men and women Infertility or a couple being unable to conceive a child can cause significant stress and unhappiness. There are numerous reasons for both male and female infertility but many ways in which medical assistance can overcome problems that people may face. Everything concerning infertility is discussed and explained here. Read now
Osteoporosis refers to pathological loss of bone density and strength. It is an important condition due to its prevalence and association with bone fractures; most commonly of the hip, vertebra and forearm. Men are relatively protected from the development of osteoporosis by a higher peak bone mass compared with women (Campion and Maricic 2003). Furthermore, women lose bone at an accelerated rate immediately following the menopause. Nevertheless, men start to lose bone mass during early adult life and experience an increase in the rate of bone loss with age (Scopacasa et al 2002). Women of a given age have a higher prevalence of osteoporosis in comparison to men but the prevalence increases with age in both sexes. As a result, men have a lower incidence of osteoporotic fractures than women of a given age but the gap between the sexes narrows with advancing age (Chang et al 2004) and there is evidence that hip fractures in men are associated with greater mortality than in women (Campion and Maricic 2003).
Insulin causes lower Testosterone levels, so go easy on the carbs and eat more protein right? Well you need to be careful with protein consumption – Excess protein without fat can also cause insulin spikes. So go easy on that chicken breast with a side of egg white omelets washed down with a protein shake. From an insulin point of view you may as well drink a can of soda with some aminos acid! So what should you do? Eat more fat.
Testosterone is a male hormone. Hormones are chemical messengers that are secreted by the brain directly into the blood, which carries them to organs and tissues of the body to perform their functions. Testosterone is produced by the testicles, two oval organs that produce sperm in men. Dietary supplements help with increasing the levels of hormones if we have low levels in the body. In men, testosterone plays a key role in the development of male reproductive organs. In addition, it helps with increasing muscle mass, bone mass, and the growth of body hair. It is also good for general health and well-being. It also prevents loss of bone mass and density. Testosterone also helps maintain the sex drive and energy levels. Moreover, it helps with production of sperm and red blood cells. Testosterone levels start to fall with age. As a result, some men who have low testosterone levels may benefit from testosterone prescribed by their doctor. Testosterone booster supplements may also help.

Nearly 1 out of every 4 men over age 50 experience the pain of losing the ability to perform sexually as a result of erectile dysfunction (ED). Common causes of ED are atherosclerosis, diabetes, prescription drug use (namely high blood pressure, depression, and allergy drugs), and—you guessed it—low testosterone. Supplements that may help include the following:
Miscellaneous: Sleep: (REM sleep) increases nocturnal testosterone levels.[142] Behavior: Dominance challenges can, in some cases, stimulate increased testosterone release in men.[143] Drugs: Natural or man-made antiandrogens including spearmint tea reduce testosterone levels.[144][145][146] Licorice can decrease the production of testosterone and this effect is greater in females.[147]
ZMA (unnecessary). So when I researched how to increase testosterone, a supplement called ZMA kept popping up. It’s a blend of zinc, magnesium, and vitamin B6. The purported benefits of ZMA include better and deeper sleep which indirectly is supposed to increase testosterone. Zinc and magnesium are necessary minerals in testosterone production, so a mega-dose should be useful, right? Well, no. I bought some and took it during the duration of experiment. I should have done some more research before I made the purchase. While one study in 1998 showed increased strength among athletes taking ZMA, two recent studies (study 1, study 2) have shown that it has absolutely no effect on total or free testosterone levels. Crap. My advice, unless you have a zinc and magnesium deficiency, no need to waste your money on this.
The partial synthesis in the 1930s of abundant, potent testosterone esters permitted the characterization of the hormone's effects, so that Kochakian and Murlin (1936) were able to show that testosterone raised nitrogen retention (a mechanism central to anabolism) in the dog, after which Allan Kenyon's group[186] was able to demonstrate both anabolic and androgenic effects of testosterone propionate in eunuchoidal men, boys, and women. The period of the early 1930s to the 1950s has been called "The Golden Age of Steroid Chemistry",[187] and work during this period progressed quickly. Research in this golden age proved that this newly synthesized compound—testosterone—or rather family of compounds (for many derivatives were developed from 1940 to 1960), was a potent multiplier of muscle, strength, and well-being.[188]
The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".[78][79] Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.[78] The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.[80] Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.[81][82][83][84][85]

Cross-sectional studies have not shown raised testosterone levels at the time of diagnosis of prostate cancer, and in fact, low testosterone at the time of diagnosis has been linked with more locally aggressive and malignant tumors (Massengill et al 2003; Imamoto et al 2005; Isom-Batz et al 2005). This may reflect loss of hormone related control of the tumor or the effect of a more aggressive tumor in decreasing testosterone levels. One study found that 14% of hypogonadal men, with normal digital rectal examination and PSA levels, had histological prostate cancer on biopsy. It is possible that low androgen levels masked the usual evidence of prostate cancer in this population (Morgentaler et al 1996). Most longitudinal studies have not shown a correlation between testosterone levels and the future development of prostate cancer (Carter et al 1995; Heikkila et al 1999; Stattin et al 2004) but a recent study did find a positive association (Parsons et al 2005). Interpretation of such data requires care, as the presentation of prostate cancer could be altered or delayed in patients with lower testosterone levels.
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.
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