^ Southren AL, Gordon GG, Tochimoto S, Pinzon G, Lane DR, Stypulkowski W (May 1967). "Mean plasma concentration, metabolic clearance and basal plasma production rates of testosterone in normal young men and women using a constant infusion procedure: effect of time of day and plasma concentration on the metabolic clearance rate of testosterone". The Journal of Clinical Endocrinology and Metabolism. 27 (5): 686–94. doi:10.1210/jcem-27-5-686. PMID 6025472.
In addition to its role as a natural hormone, testosterone is used as a medication, for instance in the treatment of low testosterone levels in men and breast cancer in women. Since testosterone levels decrease as men age, testosterone is sometimes used in older men to counteract this deficiency. It is also used illicitly to enhance physique and performance, for instance in athletes.
Looking for ingredients that work in the realm of supplements can be like finding a needle in a haystack. Testosterone boosters, like all dietary supplements, are not approved by the Food and Drug Administration prior to marketing. This lack of oversight dates back to the 1994 Dietary Supplement Health and Education Act (DSHEA), which stipulated that purveyors of supplements weren’t required to prove the safety of their products or the veracity of what’s on the labels to the FDA before listing them for sale. Often, there isn’t a lot of scientific backing behind an ingredient, or research has been done solely on animals, not humans.
I am also suspect of the fact that men 100 years ago had testosterone levels of 800-2000 ng/dL. The truth is that there are men today that are stronger and more muscular than the men from 100 years ago. Sure the “average man” of today is less than the “average man” of prior generations, but this is because we sit around in offices all day, and then come home to sit on the couch and watch tv…little to no activity.
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).
Testosterone treatment is unequivocally needed in classical hypogonadism for reasons discussed in subsequent subsections. In classical hypogonadism, testosterone production is usually clearly below the lower limit of normal and patients are highly symptomatic; the various symptoms are easily related to the deficiencies in various bodily systems where testosterone action is important. Symptoms of testosterone deficiency are listed in Table 2. A few prominent causes of classical hypogonadism are listed in Table 3.
Most Americans today are sleep deprived, which may be a contributing factor to declining testosterone levels in men. See, our body makes nearly all the testosterone it needs for the day while we’re sleeping. That increased level of T that we experience at night is one of the reasons we wake up with “Morning Wood.” (If you don’t have Morning Wood on a consistent basis, you might have low T).
A blood test may not be enough to determine your levels, because testosterone levels can fluctuate during the day. Once you determine that you do have low levels, there are a number of options to take. There are synthetic and bioidentical testosterone products out on the market, but I advise using bioidentical hormones like DHEA. DHEA is a hormone secreted by your adrenal glands. This substance is the most abundant precursor hormone in the human body. It is crucial for the creation of vital hormones, including testosterone and other sex hormones.
During the second trimester, androgen level is associated with sex formation. This period affects the femininization or masculinization of the fetus and can be a better predictor of feminine or masculine behaviours such as sex typed behaviour than an adult's own levels. A mother's testosterone level during pregnancy is correlated with her daughter's sex-typical behavior as an adult, and the correlation is even stronger than with the daughter's own adult testosterone level.
Overall, few patients have a compelling contraindication to testosterone treatment. The majority of men with late onset hypogonadism can be safely treated with testosterone but all will require monitoring of prostate parameters HDL cholesterol, hematocrit and psychological state. It is also wise to monitor symptoms of sleep apnea. Other specific concerns may be raised by the mode of delivery such as local side effects from transdermal testosterone.
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. However men with high testosterone were significantly 27% less generous in an ultimatum game. 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. Studies have also found administered testosterone to increase verbal aggression and anger in some participants.
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.