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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.

Best Testosterone Booster

A high protein diet and supplementing Oleuropein together increases testosterone by 300% in rats while halving rat cortisol [R]. 40% casein protein and around 100 mg/kg of body weight per day of Oleuropein. Although, that’s a lot of Oleuropein.

Doing 4 hours of exercise per day increases testosterone by 250% compared to doing 2 hours of exercise. This was found while studying 90 obese men at a moderate intensity (55-70% of maximum heart rate) [R]. Administering pure lactate (a by-product of exercise) has a similar effect [R].

Supplementing with DHEA increases testosterone by 200% in middle-aged men and by about 180% in young men [R]. There were 16 people in the study doing high-intensity interval training and only 50 mg was needed to increase testosterone within 24 hrs (DB-RCT).

Vitamin D increases testosterone by 25% in overweight men that are deficient in Vitamin D [R]. 3000 IU per day over a year worked for 165 young-to-middle-aged men.

Too much testosterone is said to shrink testicles, but when this happens the testicles return to normal size after testosterone lowers again [R].

Androgens Such As Testosterone Are Produced By The Gonads

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. This hormone in excess or deficiency can cause a variety of diseases, and both dietary and behavioral factors affect T levels.

Interesting Facts About Testosterone

Testosterone Increases Monogamy in Men

In male mice who are in relationships, testosterone decreases their desire for other females (R).

Testosterone Increases Attraction to Femininity in Women

Changes in salivary testosterone levels in men contribute to the strength of men’s reported attraction to femininity in women’s faces (R).

The Good

Testosterone Advances Puberty and Other Aspects of Aging

While testosterone grows throughout age before puberty, a significant jump occurs at around age 10 (both chronological and bone age) (R).

Inhibin B and testosterone are positively correlated in early childhood as well as early stages of puberty (R, R1).

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).

T treatment also led to increases in insulin-like growth factor 1 (IGF-1), which is pivotal in childhood growth (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). Growth from testosterone occurs mostly in the 4 months after treatment.

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).

Too much testosterone in females before birth induces excess insulin (hyperinsulinemia), early puberty, and reproductive problems similar to polycystic ovary syndrome (PCOS) (R).

Testosterone Improves Metabolism and Body Composition

Testosterone is associated with fat loss, and testosterone treatment can decrease fat percentage (R).

The hormone reduces total cholesterol as well (R).

T metabolism itself is not affected by a habit of resistance training (R).

T treatment does not significantly lower the levels of triglycerides in men, but it decreases total fat mass while increasing fat-free mass (R).

No causative relationships have been found between testosterone and sugar metabolism. Treatment does not necessarily improve glucose metabolism (R).

While people sometimes turn to testosterone treatment to aid in weight loss and help with metabolic disorders, healthy dietary/lifestyle choices are the only proven methods (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).

Independent of aromatase enzymes (which change testosterone into estradiol), testosterone can still accomplish its positive functions on bones and musculoskeletal tissue (R).

Testosterone can reduce temporomandibular joint (connecting cheekbone to jaw bone) pain (R).

Minimum T Level Allows Proper Sexual Function

A baseline T level (~12 nmol/L (R)) allows for healthy intercourse, sexual drive, and induced and nocturnal erections in men (R).

Adding testosterone beyond the apparent baseline does not continue to increase these characteristics; in fact, the effects are unclear (R, R1).

However, treating hypogonadal men with testosterone helps to repair these functions, and promoting other functions such as bone mineral density and body composition (see above) (R, R1, R2).

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).

Vaginally applied testosterone, estrogen, and polyacrylic acid has been shown to improve sexual function in postmenopausal women (R).

Orally, testosterone was shown to improve sexual function in tandem with estrogen for postmenopausal women (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).

High volume, moderate-intensity aerobic exercise for at least 200 minutes a week showed great improvements in sexual function and T levels (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)

Low Testosterone

High Testosterone or Excessive T Therapy/Anabolic Steroids

  • Adverse Effects on the Cardiovascular System, such as High Blood Pressure  (R, R1, R2R3)
  • 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)

Other Effects

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).

Sex hormones have an effect on semantic retrieval (memory of facts and knowledge). Testosterone is shown to be correlated with activation of the left prefrontal lobe of the brain (R, R1).

Sex hormones such as testosterone, DHT, and estradiol are limited by sex-hormone binding globulin (SHBG) (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 Cycle

Testosterone is higher in the morning than at night according to a study of 66 men [R]. It’s about 32% higher in the morning for 30-year-olds, but the cycle becomes more constant as men age, getting to only 8% higher in the morning at 70 years old.

Thus, Testosterone levels should be tested in the morning [R].

This Testosterone cycle is also found in women, and young girls (even as young as 5) and boys increase in testosterone on their way to puberty [R, R].

Daily rhythms of testosterone are associated with parenting [R]. 341 parents with two children (per couple) were tested and higher evening Testosterone in mothers was associated with more sensitivity to the oldest and youngest child.

Also for mothers, more daily changes in Testosterone was associated with less sensitivity to both children and less respect for the youngest child.

For fathers, more daily changes in Testosterone was associated with more sensitivity and respect for their youngest children.

Testosterone Increases Competitiveness, Aggression, and Protectiveness

Male rats without proper androgen levels show less rough/competitive play behaviors than those who do (R).

Studies show a strong association between plasma testosterone levels and physical and verbal aggression/dominance (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

Various measures of risk-taking propensity have shown that high testosterone and low cortisol led to risk-taking in financial markets and otherwise for both sexes (R, R1R2, R3, R4).

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).

Another study finds no relation in adolescent females between testosterone and risk-taking, but a strong association between estradiol (E2) and risk-taking (E2 is aromatized from testosterone) (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?

  • Testosterone 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 and E2 (R, R)
  • Dibutyryl cAMP (increases aromatase) [R]
  • Severe traumatic brain injury 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)
  • IL-6 (increases aromatase) [R]
  • Broad beans [R]
  • Anything containing Quercetin, Genistein, and Flavone (but we don’t know how much needs to be taken before they start lowering Testosterone) [R]
  • Statins (HMG-CoA reductase inhibitors) lower cholesterol which is a precursor to testosterone, so taking statins has a side effect of lowering testosterone [R].

What Increases Testosterone?

  • Foods that increase 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 taken 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) (RR).
  • Calcium supplementation in athletes (R)
  • Magnesium (R)
  • Resveratrol (R)
  • D Aspartic 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 testosterone effects.
  • Garlic (R)
  • Oleuropein (R)
  • Caffeine (acute) (R)

Other Herbs That Increase Testosterone

  • Ginseng (R)
  • Cinnamon: (RR1R2)
  • 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 an 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 (RR1R2)
  • 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

Boost Bioavailable Testosterone

Testosterone is converted into estrogen by aromatase [R]. This can be stopped with aromatase inhibitors. Here are 5 of the best foods that boost bioavailable Testosterone by inhibiting aromatase (20-90% inhibition) [R]:

Others include:

  • Chaparral (greasewood),
  • Damiana,
  • Fermented Pomegranate (non-fermented skin is half as good),
  • Feverfew,
  • Willowherb (Epilobium),
  • Willow bark,
  • Cat’s Claw (Uncaria tomentosa),
  • Mistletoe (Viscum album),
  • Propolis

Then there are ones that inhibit it, but were measured differently:

  • Mushrooms (button, lion’s mane, portobello, almond, shiitake, oyster)
  • Peppers (bell – particularly the leaves)
  • Coffee
  • Asparagus
  • Mustard (greens)
  • Collards
  • Kale
  • Lemons
  • Grapefruit
  • Strawberry
  • Mangosteen
  • Chicory
  • Tomato (leaves)
  • Parsley
  • Eggplant (‘fruit’ and leaves)
  • Spinach
  • Cocoa
  • Beer and Wine
  • Chamomile (contains apigenin)
  • Myosmine and Nicotine (both found in tobacco and others)

These were all taken from one super study taking extractions and testing against aromatase in a test tube [R].

Irregular Testosterone Levels?

If you have not yet tested your testosterone levels, I recommend that you ask your doctor to do it. If you already have your blood test results and you’re not sure what to make of them, you need to check out Lab Test Analyzer. It does all the heavy lifting for you. No need to do thousands of hours of research on what to make of your various blood tests.


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