Testosterone is the male sex hormone; it is found in both genders and throughout many different species. Testosterone serves a variety of functions in the body such as sexual and bodily development, metabolic and behavioral influence, and much more. It is important to know what increases and decreases this hormone, as well as when levels are too high or low in your body.
- Introduction to Testosterone
- The Good
- The Bad (Associated Diseases)
- Testosterone Increases Competitiveness, Aggression, and Protectiveness
- Testosterone Increases Risk-Taking
- What Decreases Testosterone?
- What Increases Testosterone?
- Other Herbs That Increase Testosterone
- Testing For Testosterone
Introduction to Testosterone
Testosterone (T) is the male sex hormone. It is produced primarily in the testicles in males and the ovaries in females. This steroid hormone has extensive effects on sexual development, body composition, and behavior. Excess or deficiency of this hormone can cause a variety of diseases, and both dietary and behavioral factors affect T levels.
Testosterone Advances Puberty and Other Aspects of Aging
While testosterone grows throughout age before puberty, a significant jump occurs at approximately age 10 (both chronological and bone age) (R).
Testosterone concentrations appear to be highest during Tanner stage 3 and 4 of puberty (R).
External exposure to testosterone (in creams and gels, for example) can cause early puberty (R).
The 5α-reductase enzyme is more present in papilla (part of the hair follicle) cells in certain parts of the body. Hair follicles with a high amount of these androgen-sensitive cells, such as those in the beard, respond more to testosterone and grow hair more consistently (R).
A strong connection between testosterone and growth hormone has been established, especially during puberty. While the combination of GH and T have positive effects on body composition (detailed below), there appears to be a minimum level of GH needed for the T effects to happen (R).
Nocturnal testosterone levels are correlated with the release of GH throughout puberty (R).
Testosterone treatment of 4 months can help determine if boys with constitutional delayed puberty (CDP) have growth-hormone deficiency. Linear growth in responses to testosterone is usually restricted by growth hormone (R).
In one study involving boys with CDP, testosterone administration increased the amount of GH secreted in each burst of the pituitary gland (R).
Low-dose depot testosterone is a safe method for combatting CDP (R).
Low-dose T administration can increase height growth rate in boys with CDP (R).
Craniofacial growth increases with T levels, and low-doses of testosterone can accelerate this growth in boys with delayed puberty (R).
Experimental research in non-human mammals suggests that testosterone is necessary for proper neurobehavioral development, especially prenatally, and in early infancy (R).
Furthermore, a study on Chinese boys found a correlation between T levels and fluid intelligence (problem-solving skills) during certain stages of puberty (R).
Testosterone Improves Metabolism and Body Composition
Testosterone is associated with fat loss, and testosterone treatment can decrease fat percentage (R).
T metabolism itself is not affected by a habit of resistance training (R).
In hyperprolactinemic and hypogonadal men, testosterone replacement improves the metabolic profile (R).
In men with lowered bioavailable T levels and Type 2 diabetes, testosterone replacement therapy improved body composition (R).
Those with Type 2 diabetes tend have decreased testosterone levels prior to and during the development of the disease. Sertoli cells (cells that help create sperm) tend to accumulate glycogen in type 2 diabetes conditions, instead of fully completing their original function (R).
T levels and cholesterol levels have always been shown to be inversely proportional. In pigs fed high fat and cholesterol diets, those that were castrated for T deficiency developed much higher levels of LDL, as well as the PCSK9 enzyme (an enzyme that binds to an LDL receptor). This presents a possible mechanism for the reason behind this inverse relationship (R).
The hormone also might prevent atheroma formations (plaque -induced degeneration of arteries) and progression to acute coronary syndrome (R).
Testosterone Bolsters Structural Anatomy
Testosterone increases bone mineral density in the lumbar spine (R).
T treatment is shown to prevent bone loss and hip bone mineral density (R).
Testosterone can increase muscle strength (R).
Skeletal muscle produces 5α-reductase enzyme and can turn testosterone and dehydroepiandrosterone (DHEA) into DHT. This androgen can be used to activate the GLUT4 regulation pathway, which is used to decide when glucose is stored and when it is used (R, R1).
Testosterone can reduce temporomandibular joint (connecting cheekbone to jaw bone) pain (R).
Minimum T Level Allows Proper Sexual Function
Hormone replacement therapy with testosterone is used to treat hypogonadism (in people with normal liver function). However, patients with end-stage renal disease (ESRD) tend to experience hypogonadism, and it is untested whether testosterone treatment works equally well for them (R).
Data suggests that there are two thresholds for testosterone’s effect on erections in males. The higher one impairs sexual behavior but allows regular night-sleep erections, while the lower impairs both (R).
“Testosterone therapy improves well-being, mood, and sexual function in premenopausal women with low libido and low testosterone,” (R).
In hysterectomized women (uterus removed), testosterone treatment yielded better sexual function, leaner body mass, and increased strength (R).
Men with sexual dysfunction/ED associated with Type 2 diabetes reported improved sexual function and mood when treated with testosterone replacement (R).
Testosterone has been shown to increase expression of dopamine transport (DAT) and vesicular monoamine transporter (VMAT), both of which allow dopamine to promote sexual desire. This neurotransmitter is a possible mechanism for testosterone’s effects (R).
Testosterone Can Fight Autoimmune Disease
Androgens such as testosterone could have an influence on T cell differentiation (R).
Autoimmune diseases may be associated with low blood testosterone concentrations (R).
The Bad (Associated Diseases)
- Obesity, Metabolic Syndrome, and Type 2 Diabetes (R)
- Insulin resistance (R)
- Hypogonadism (R)
- Osteoporosis (R, R1)
- Depression (R)
- Prostate Cancer (R)
High Testosterone or Excessive T Therapy/Anabolic Steroids
- Adverse Effects on Cardiovascular System, such as High Blood Pressure (R, R1, R2, R3)
- Polycystic Ovary Syndrome in Women (R, R1)
- Social/Behavioral Changes in Men (R)
- Testicular Shrinking/Atrophy (R, R1)
- Gynecomastia (Breast Development) in males (R, R1)
- Borderline Personality Disorder (BPD) (R)
- Non-gender specific cancer aggressiveness (R)
- Anxiety disorders in children of mothers exposed to excess androgens (R)
Via the 5α-reductase enzyme, testosterone becomes dihydrotestosterone. This hormone increases red blood cell creation and maintains proper blood iron levels. Testosterone completes these functions as well (R).
Testosterone inhibits the binding of Substance P to its receptor. Substance P is associated with inflammation and pain (R).
Testosterone can reverse apoptotic damage caused by the STZ chemical in rats (R).
Testosterone Increases Competitiveness, Aggression, and Protectiveness
Male rats without proper androgen levels show less rough/competitive play behaviors than those who do (R).
The number of CAG codon repeats in the androgen receptor gene (see Mechanism) has been shown to be associated with androgenic (manly) traits. Shorter repeat lengths correlate with increased androgenic effects, such as intrasexual competitiveness in males (R).
Women with high testosterone have shown a strong sense of intrasexual competitiveness (R).
While testosterone is known to be linked to aggressive behavior, one possible mechanism is reduced activity in the orbitofrontal cortex of the brain, which handles impulse control (R).
Beyond inherent testosterone levels, it is difficult to predict the effects of external testosterone on qualities such as aggression (R).
Mice studies suggest that the timing of peak plasma testosterone during pregnancy and first few days of birth can predict possible aggressive behavior in adulthood (R).
Testosterone Increases Risk-Taking
Changes in salivary testosterone can predict future risk-taking behavior better than only wins and losses (R).
More specifically, some studies suggest that risk-taking increases in certain situations, and not others – namely, in those of known possibilities and strategic decision making (R).
Similar to aggression, it is believed that the orbitofrontal cortex (impulse control) could be responsible for the relationship between testosterone and risk-taking (R).
The orbitofrontal cortex’s growth is delayed during puberty while testosterone is produced at a higher rate, giving rise to the behavioral traits (R).
Other explanations add that T affects not just risk-taking, but the related abstract reasoning ability (R).
What Decreases Testosterone?
- Tesosterone decreases with age (R)
- Stress (R)
- Heavy acute alcohol drinking (R)
- Sleep disorders (R)
- Obesity (R)
- Injury to the testes
- Prostaglandins (fats that act like hormones in the body) A1 and A2 (R)
- Severe traumatic brain injury (sTBI) affecting the pituitary gland (R)
- Diabetes, hemochromatosis, HIV/AIDS, mumps, meningitis, syphilis, and other infections are all known to have a negative effect on T levels (R)
- Methadone (opioid-dependence medication) (R)
- Grade B and C nonalcoholic liver disease (R)
- Soy-phytoestrogens (molecules that imitate estrogens), decreased T levels in rats (R)
What Increases Testosterone?
- Dietary Fat: one of the side effects of a low-fat diet is significantly reduced testosterone levels; one study showed a reduction of 12% after 8 weeks on a low-fat diet (R, R1)
- DHEA (R) – DHEA appears to boost testosterone most of the time in people older than 40 years of age, but not often not in younger men.
- Lactate (R)
- Zinc – In human studies of zinc deficiency supplementation of zinc is able to increase circulating testosterone concentrations (R), but some studies don’t show a testosterone increase when there’s an adequate amount (R).
- Vitamin D3 – increases free and total testosterone in clinical trials when 3000iu is takem if it’s under 50nmol/l (R, R)
- Porn (R, R, R) – The increase when sexually aroused is minor and transient.
- Social interaction with attractive females – After a 5 minute conversation with an attractive woman, male testosterone levels can increase up to 30% from baseline (relative to an increase of 13% for conversing with males) (R, R).
- Calcium supplementation in athletes (R)
- Magnesium (R)
- Resveratrol (R)
- D Asparitic acid – however, in one study it decreased testosterone (R)
- EGCG (R)
- Boron supplements in diet increases both testosterone and 17β-estradiol (R)
- Aerobic exercise (R)
- Low-dose amount of alcohol (short term) (R)
- Getting enough sleep (R)
- Ginger (R)
- Fenugreek extract increases Testosterone and Estradiol (R, R1). However, fenugreek can also decrease DHT, which on balance will dampen the classical testerone effects.
- Garlic (R)
- Oleuropein (R)
- Caffeine (acute) (R)
Other Herbs That Increase Testosterone
- Ginseng (R)
- Cinnamon: (R, R1, R2)
- Pomegranate (R)
- Boron (R)
- Tribulus (deficiency state of castration, may not be relevant to healthy rats) (R)
- Shilajit in healthy volunteers (R)
- Cordyceps (R)
- Astragalus in vitro (concentrations relevant to oral dosing) (R)
- Yacon (R)
- Royal jelly (R)
- Curcumin (R)
- Rose oil (preserves levels in oxidative state) (R)
- Chrysin (R)
- Ashwagandha (R)
- Mucuna pruriens (R)
- Garlic (R)
- King oyster (R)
- Olive leaf extract (R)
- Green tea (in vivo) (R)
- Holy basil (decreases pituitary hormones) (R)
- Black seed oil (R, R1, R2)
- Onion juice (R)
- Andrographis (R)
- Red wine phenolics (R)
- Epimedium (R)
- Forskolin (free test) (mild increases in total) (R)
- Morinda officinalis (R)
- Aloe vera (R)
- Eurycoma longifolia (R)
- Chlorophytum borivilianum (human study) (R)
- Salvia officinalis (R)
- Walnut oil (R)
- Extruded kidney bean (R)
- Guajava (R)
- Clomiphene in hypogonadal men and men with ED (R, R1)
- Sildenafil (R)
- Varicocelectomy (R)
- Pathways: inhibiting aromatase, prolactin, increasing 17beta-HSD, CYP17A1