That there is an association between depression and testosterone concentration seems possible because of the observation that depression may be associated with reduced testosterone concentrations, hypogonadal men may have their symptoms of depression relieved by TRT and that testosterone itself may have anti-depressant properties (Pope et al 2003). The evidence, however, is inconsistent. Seidman and colleagues (2002), for example, found that there was no relationship between testosterone and depression but there was an association of testosterone with dysthymia. McIntyre and colleagues (2006), on the other hand, found that middle-aged men with depression did have a reduction in bio-available testosterone.
Disclaimer: While we work to ensure that product information is correct, on occasion manufacturers may alter their ingredient lists. Actual product packaging and materials may contain more and/or different information than that shown on our Web site. We recommend that you do not solely rely on the information presented and that you always read labels, warnings, and directions before using or consuming a product. For additional information about a product, please contact the manufacturer. Content on this site is for reference purposes and is not intended to substitute for advice given by a physician, pharmacist, or other licensed health-care professional. You should not use this information as self-diagnosis or for treating a health problem or disease. Contact your health-care provider immediately if you suspect that you have a medical problem. Information and statements regarding dietary supplements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease or health condition. assumes no liability for inaccuracies or misstatements about products.

Ten healthy men aged around 24 years old spent 1 week sleeping for 8 hours per night at home, they then spent the next 11 nights in a lab. They slept for 10 hours per night for 3 nights, followed by 8 nights of restricted sleep, when they slept for only 5 hours. Doctors checked their blood every 15 to 30 minutes during the last night that they slept 10 hours, as well as on the sleep-restricted session.
5. Beef.  Is there a manlier food than steak? Release your inner carnivore if you want to boost your testosterone level. Lean beef is rich with zinc, saturated fat, iron, protein and magnesium. We’ve already mentioned earlier on how zinc can enhance the production of testosterone. Lean beef can be an excellent food choice, since you can increase your testosterone level and muscle mass at the same.
A previous meta-analysis has confirmed that treatment of hypogonadal patients with testosterone improves erections compared to placebo (Jain et al 2000). A number of studies have investigated the effect of testosterone levels on erectile dysfunction in normal young men by inducing a hypogonadal state, for example by using a GnRH analogue, and then replacing testosterone at varying doses to produce levels ranging from low-normal to high (Buena et al 1993; Hirshkowitz et al 1997). These studies have shown no significant effects of testosterone on erectile function. These findings contrast with a similar study conducted in healthy men aged 60–75, showing that free testosterone levels achieved with treatment during the study correlate with overall sexual function, including morning erections, spontaneous erections and libido (Gray et al 2005). This suggests that the men in this older age group are particularly likely to suffer sexual symptoms if their testosterone is low. Furthermore, the severity of erectile dysfunction positively correlates with lower testosterone levels in men with type 2 diabetes (Kapoor, Clarke et al 2007).
Inaccurate or misinterpreted test results can either falsely diagnose or miss a case of testosterone deficiency. Your testosterone level should be measured between 7 am and 10 am, when it's at its peak. Confirm a low reading with a second test on a different day. It may require multiple measurements and careful interpretation to establish bioavailable testosterone, or the amount of the hormone that is able to have effects on the body. Consider getting a second opinion from an endocrinologist.
To find the best testosterone booster, we collected every supplement available on, and cross-checked our list against the top results on best of lists like MensFitness, BroScience, and BodyNutrition. We only looked at pills since some of the ingredients in testosterone boosters have a reputation for tasting bad, and powders just prolong the experience. There are a lot — 133 of them to be precise — and they all claim to boost testosterone levels. Testosterone (for men) is “thought to regulate sex drive (libido), bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm.” If a supplement can increase your natural testosterone levels, the rest should follow. As we mentioned above, it’s not that simple, and at best, you’ll experience only a short-lived boost.
I highly recommend using a great essential amino acid mix post-exercise in order to boost testosterone.  These essential amino acids and especially the concentrated branched chain amino acids leucine, isoleucine and valine stimulate muscle protein synthesis.  Getting these amino acids in the post-workout window dramatically boosts testosterone production (14).  I like using our Amino Strong and will often recommend a scoop pre-workout and post-workout for the best muscle building, testosterone boosting benefits.
There is an increased incidence of hypogonadism in men with rheumatoid arthritis. Tengstrand et al (2002) studied hormonal levels in 104 men with rheumatoid arthritis and 99 age-matched healthy men. They divided their subjects into 3 age groups: 30–49, 40–59, 60–69. Mean non-sex hormone binding globulin-bound testosterone (bioavailable testosterone) was lower in men with rheumatoid arthritis for each of the three groups. LH was also found to be lower in the patients with rheumatoid arthritis suggesting a hypothalamic-pituitary cause of the reduced bioavailable testosterone. Of the 104 men with rheumatoid arthritis, 33 had hypogonadism compared to 7 of the 99 healthy controls.
Testosyn has been the #1 Testosterone Supplement for the 3rd straight year! This testosterone-boosting formula surpasses any product we have reviewed including prescription strength products! Formulated with a powerful set of clinically-proven ingredients, Testosyn can help men everywhere dramatically raise their testosterone levels safely. Testosyn is engineered with the most advanced ingredients and is often considered the most powerful testosterone supplement on the market to help you develop increased athletic performance, improved muscle tone and mass, increased recovery, and enhanced sexual performance.
Elevated testosterone levels have been demonstrated to increase the growth of body muscles and contribute to better activation of the nervous system, resulting in more power and strength, a better mood, enhanced libido, and many other benefits.[3] Previous researches done on the anabolic role of testosterone and its impact on muscular strength in training-induced adaptations has provided rather conflicting findings, and a positive correlation between testosterone-mediated responses and both functional performance and body composition was found.[4,5] There are a number of naturally occurring substances that can boost testosterone levels in the body. Foods containing such substances are known as testosterone-foods; and they tend to be rich in vitamins, antioxidants, and minerals like zinc, which plays a key role in testosterone production.[2,6-8]
The unsexy truth is that increasing T naturally simply comes down to making some long-term changes in your diet and lifestyle. As you’ll see, what I did to increase T largely boils down to eating better, exercising smarter, and getting more sleep. That’s pretty much it. But as with most things in life, the devil is in the details, so I’ll share with you exactly what I did and provide research that explains why the things I did helped boost my testosterone.
I bought most of the ingredients for my Testosterone Salad at Whole Foods. For those curious, I added up all the ingredients and divided by six (I typically ate six of these salads in a week). The cost per salad was roughly $5. That’s about the price many folks pay every day for a crappy fast food meal. If you’re on a budget, I’m sure you could get the ingredients at Walmart and bring the cost per salad down even more.
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. (

All the active substances available in TestoGen are fully natural. And their efficacy and safety is science-backed. So, if you don’t have individual sensitivity to the supplement ingredients and purchase the product directly from the manufacturer instead of purchasing from unknown suppliers, the likelihood of side effects during the supplementation is minimal. And the customer feedback proves this.

Dr. Anthony’s Notes: Here's a funny little effect – fenugreek can make you sweet and your urine smell sweet like Maple Syrup. Hell, this could be a good thing for you! This supplement is commonly used for good reasons – it's quite effective for enhancing libido when stacked with the other herbs on this list. Medical Note: Fenugreek may interact with blood thinning medications (Warfarin, Coumadin, Xarleto). Check with your doctor before taking any of these supplements. How To Take Fenugreek: Take 400-600mg (capsule) with food; it's best to take a product standardized for fenuside.
Dr. Anthony's Notes: Creatine is damn effective. Period. It's research proven to benefit testosterone, energy levels, muscle preservation, and your brain function. Although creatine can be found naturally in a good high-protein diet, taking 5g daily is a great idea for most guys – especially those over 35. Remember to take your creatine AWAY from caffeine – the two substances inhibit each other's absorption. Verdict: this is one of the natural testosterone supplements that work. Best Food Sources: wild game (including venison, elk, buffalo, and bison), grass-fed beef, organic chicken, organic turkey, and wild-caught fish. How To Take Creatine Monohydrate: 5g daily away from caffeine.
Bottom line: testosterone boosters aren’t right for a lot of people. We dive deep into ingredient research below, but typically, testosterone boosters contain at least one (and often three or more) different ingredients that each impact your circulatory system — both the heart and blood. If you’re taking any kind of blood-thinner medication, or you have a history of heart disease, these supplements can get really dangerous, really quickly. The simple fact of the matter is that hormones are tricky things to mess with, and a doctor should be your first port of call to help you safely achieve your goals — whether they’re related to fitness, weight, or libido.
Disclaimer: While we work to ensure that product information is correct, on occasion manufacturers may alter their ingredient lists. Actual product packaging and materials may contain more and/or different information than that shown on our Web site. We recommend that you do not solely rely on the information presented and that you always read labels, warnings, and directions before using or consuming a product. For additional information about a product, please contact the manufacturer. Content on this site is for reference purposes and is not intended to substitute for advice given by a physician, pharmacist, or other licensed health-care professional. You should not use this information as self-diagnosis or for treating a health problem or disease. Contact your health-care provider immediately if you suspect that you have a medical problem. Information and statements regarding dietary supplements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease or health condition. assumes no liability for inaccuracies or misstatements about products.
1) Eat a good diet daily consisting of 10 servings of fresh vegetables (recommend juicing, and go heavy on the carrots & broccoli), lots of cholesterol in the form of eggs, butter, bacon, avocados, good fat, and take in moderate levels of protein. Avoid all trans fat and limit sugars, carbohydrates and any grains. Lastly, snack on nuts throughout the day between meals to keep your metabolism going.

There have been case reports of development of prostate cancer in patients during treatment with testosterone, including one case series of twenty patients (Gaylis et al 2005). It is not known whether this reflects an increase in incidence, as prostate cancer is very common and because the monitoring for cancer in patients treated with testosterone is greater. Randomized controlled trials of testosterone treatment have found a low incidence of prostate cancer and they do not provide evidence of a link between testosterone treatment and the development of prostate cancer (Rhoden and Morgentaler 2004). More large scale clinical trials of longer durations of testosterone replacement are required to confirm that testosterone treatment does not cause prostate cancer. Overall, it is not known whether testosterone treatment of aging males with hypogonadism increases the risk of prostate cancer, but monitoring for the condition is clearly vital. This should take the form of PSA blood test and rectal examination every three months for the first year of treatment and yearly thereafter (Nieschlag et al 2005). Age adjusted PSA reference ranges should be used to identify men who require further assessment. The concept of PSA velocity is also important and refers to the rate of increase in PSA per year. Patients with abnormal rectal examination suggestive of prostate cancer, PSA above the age specific reference range or a PSA velocity greater than 0.75 ng/ml/yr should be referred to a urologist for consideration of prostate biopsy.

Vitamin D is a fat-soluble vitamin and is obtained from sunlight. In the active form, it acts as a steroid hormone in the body. These days many people suffer from vitamin D deficiency because lacking exposure to sunlight, but taking vitamin D supplements to improve the weakness. Low vitamin D levels also lower the testosterone levels, but with intake of vitamin D, the testosterone levels boost. In typical cases, vitamin D doesn’t show the significant result in testosterone levels but people who are vitamin D deficient shows an increase in testosterone levels.
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.
Testosterone is an androgenic sex hormone produced by the testicles (and in smaller amounts in women’s ovaries), and is often associated with “manhood.” Primarily, this hormone plays a great role in men’s sexual and reproductive function. It also contributes to their muscle mass, hair growth, maintaining bone density, red blood cell production, and emotional health.
Xenoestrogen is a chemical that imitates estrogen in the human body. When men are exposed to too much of this estrogen-imitating chemical, T levels drop significantly. The problem is xenoestrogen is freaking everywhere — plastics, shampoos, gasoline, cows, toothpaste. You name it and chances are there are xenoestrogen in it. The ubiquitous nature of this chemical in our modern world is one reason some endocrinologists believe that testosterone levels are lower in men today than in decades past. It’s also a reason doctors say the number of boys born with hypospadias — a birth defect in which the opening of the urethra is on the underside of the penis and not at the tip — has doubled.  Note to expecting parents: make sure mom stays away from xenoestrogens during the pregnancy.

The science backs up the soldier’s self discovery, in fact, exposure to radiation (whether it’s from an army radar or the cell phone in your pocket, or the wifi router in your house) has been shown to lower sperm quality, fertility and testosterone. This is true not only for military personnel (88, 89,90) but all males living in a modern world (91).
Testosterone is an androgenic sex hormone produced by the testicles (and in smaller amounts in women’s ovaries), and is often associated with “manhood.” Primarily, this hormone plays a great role in men’s sexual and reproductive function. It also contributes to their muscle mass, hair growth, maintaining bone density, red blood cell production, and emotional health.
Among my favorite stress management tools is the Emotional Freedom Technique (EFT), a method similar to acupuncture but without the use of needles. EFT is known to eliminate negative behavior and instill a positive mentality. Always bear in mind that your emotional health is strongly linked to your physical health, and you have to pay attention to your negative feelings as much as you do to the foods you eat.
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).
Epidemiological studies have also assessed links between serum testosterone and non-coronary atherosclerosis. A study of over 1000 people aged 55 years and over found an inverse correlation between serum total and bioavailable testosterone and the amount of aortic atherosclerosis in men, as assessed by radiological methods (Hak et al 2002). Increased intima-media thickness (IMT) is an early sign of atherosclerosis and has also been shown to predict cardiovascular mortality (Murakami et al 2005). Cross-sectional studies have found that testosterone levels are negatively correlated with carotid IMT in independently living men aged 74–93 years (van den Beld et al 2003), diabetic men (Fukui et al 2003) and young obese men (De Pergola et al 2003). A 4-year follow up study of the latter population showed that free testosterone was also inversely correlated with the rate of increase of IMT (Muller et al 2004).
"The Journal of Clinical Endocrinology and Metabolism" published that males who switched from a high-fat diet to a low-fat diet also saw a decrease in their testosterone levels. If you want to put some fat back into your diet without fearing cardiac implications, plant-based saturated fat like coconut is just the ticket. Meat-based fat is also acceptable if kept to less than 10% of your dietary fat intake.
^ 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.
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.
This herb, used for centuries in foods, even poultices, was reported in the International Journal of Sport Nutrition and Exercise Metabolism to have reduced body fat and improved total testosterone levels versus a placebo in a double-blind trial. Fenugreek may also be helpful if you feel your sex drive is on the wane, as other research has found it can boost libido. You can get it in curries (it’s used to flavor them) and teas, or as a supplement in TestroVax, by Novex Biotech, which promises to boost testosterone levels 42% in 12 days. (

The final two studies looked directly at soy vs testosterone levels. The first looked at introducing consumption of soya flour on testosterone levels. They found that those who ate the Soy flour lowered their T levels during the study (43). And the second study looked at the consumption of soy protein isolates (powder) in healthy men. They found that testosterone levels decreased upon consumption of soy powder (45).
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.
The maximum hormone concentration in the blood is reported immediately after the workout. And the effect lasts throughout the day. However, it’s important to ensure that your physical activity is moderate. The matter is that too much high-intensity exercise can give an undesirable result. But even if for any reason you can’t attend a gym, it’s not a problem. Just move as much as possible during the day. Even simple walking will be of great benefit.
If you do take DAA I recommend cycling it (i.e. 5 days on, 2 off, over 4 weeks then 4 weeks off). And taking it with an aromatase inhibitor (which ensures the aspartic acid doesn’t get converted to estrogen). Especially as more studies are coming out showing the increase in testosterone is limited to a week or two before it drops back to normal levels.
The sexual hormone can encourage fair behavior. For the study, subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. Two later studies have empirically confirmed these results.[71][72][73] However men with high testosterone were significantly 27% less generous in an ultimatum game.[74] The Annual NY Academy of Sciences has also found anabolic steroid use which increase testosterone to be higher in teenagers, and this was associated with increased violence.[75] Studies have also found administered testosterone to increase verbal aggression and anger in some participants.[76]

6. Foods rich in vitamin D. If you’ve been thinking of increasing your testosterone levels, you better stock up on those mushrooms, salmon and milk. Clinical Endocrinology’s August 2010 issue published a study that was conducted by Austria’s Medical University Graz. According to the researchers, mushroom, salmon and dairy products are examples of food that are rich in Vitamin D. These researchers also found a relationship between Vitamin D and testosterone. Their study has shown that individuals with high levels of Vitamin D also had high testosterone levels. The obvious inverse relationship was true as well.  Click here for a convincing study on HUMAN BEINGS to back this up.

Finally, we looked at the proprietary blends of our remaining boosters, and dug into their ingredient lists. Supplements frequently include ingredients known for their “folk-lore” value; they’re believed to work, even when there isn’t any scientific background to prove it. Though we didn’t ding points if an ingredient wasn’t proven to be good (just so long as it wasn’t proven to be bad), we didn’t want to include any ingredient with evidence of causing harm.
Dr. Darryn Willoughby, a professor of health, human performance and recreation and the director of the Exercise and Biochemical Nutrition Laboratory at Baylor University, told us that even in studies where there was an increase in testosterone, it was only around 15–20 percent. “In men with clinically normal testosterone levels, this modest increase will most likely not be anabolic enough to improve exercise performance,” he says. So if you have normal testosterone levels, and are simply trying to get an extra edge in gaining muscle, losing weight, or some extra time in the bedroom — you might see some results from taking a testosterone booster. But really, these will be most useful for men with low testosterone trying to get back to a healthy testosterone range.
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.
This is because your body is really good at self-regulating your hormone levels. So if you have normal testosterone levels, boosting above your natural base level may at best give you a few hours while your body makes, and then immediately processes out, the excess testosterone. This means you might experience higher than your average testosterone levels, but not by much, and only for a little while.

Intracoronary artery infusion of testosterone causes significant coronary artery dilatation and not constriction as previously thought (Webb et al 1999). When degree of coronary obstruction is assessed by angiography, there is a direct relationship between degree of coronary artery narrowing and reduced testosterone levels (Phillips et al 1994). Men with low testosterone levels have been observed to have: premature atherosclerosis, increased visceral adipose tissue, hyperinsulinemia, and other risk factors for myocardial infarction (Phillips 2005). Insulin resistance has been shown to be associated with a decrease in Leydig cell secretion of testosterone (Pitteloud et al 2005). Muller and colleagues suggest that low endogenous total testosterone and SHBG levels increase the risk of metabolic syndrome in aging and aged men. They demonstrated that low levels of testosterone are related to lower insulin sensitivity and higher fasting insulin levels (Muller et al 2005). These authors speculate that testosterone might play a protective role in the development of metabolic syndrome, insulin resistance, diabetes mellitus and cardiovascular disease in aging men.
Changes in body composition are seen with aging. In general terms, aging males are prone to loss of muscle mass and a gain in fat mass, especially in the form of visceral or central fat. An epidemiological study of community dwelling men aged between 24 and 85 years has confirmed that total and free testosterone levels are inversely correlated with waist circumference and that testosterone levels are specifically related to this measure of central obesity rather than general obesity (Svartberg, von Muhlen, Sundsfjord et al 2004). Prospective studies show that testosterone levels predict future development of central obesity (Khaw and Barrett-Connor 1992; Tsai et al 2000). Reductions in free testosterone also correlate with age related declines in fat free mass (muscle mass) and muscle strength (Baumgartner et al 1999; Roy et al 2002). Studies in hypogonadal men confirm an increase in fat mass and decrease in fat free mass versus comparable eugonadal men (Katznelson et al 1998). Taken together, the epidemiological data suggest that a hypogonadal state promotes loss of muscle mass and a gain in fat mass, particularly visceral fat and therefore mimics the changes of ‘normal’ aging.
Testosterone is an essential hormone for men, and a decline in the levels can occur due to many reasons, but these natural supplements are great. They are safe to use and don’t have any side effects, that’s why you can take these supplements without doctor consultations. But if you have any other health issues, then consult a doctor before taking them.
Directions — SUGGESTED USE: As a dietary supplement take 3 capsules daily, preferably with a meal, or as directed by a healthcare professional. — Take two capsules with a meal twice a day. On days that you are not training, take two capsules in the morning and two capsules at night. On days that you train, take two capsules about an hour before workouts and take two capsules in the morning or at night depending on when you train.
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
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]
The regulation of testosterone production is tightly controlled to maintain normal levels in blood, although levels are usually highest in the morning and fall after that. The hypothalamus and the pituitary gland are important in controlling the amount of testosterone produced by the testes. In response to gonadotrophin-releasing hormone from the hypothalamus, the pituitary gland produces luteinising hormone which travels in the bloodstream to the gonads and stimulates the production and release of testosterone.