Testosterone is an androgenic anabolic steroid hormone that is derived from cholesterol and secreted by the testes and, in small amounts, by the adrenal cortex (located on top of the kidneys) in males. A normal healthy young man produces about 7 mg per day, of which less than 5% is derived from adrenal secretions. In healthy aging, the amount of testosterone produced progressively decreases to about 50%; however, many factors can prematurely lower the amount of free-testosterone, leading to hypogonadism, even in young men.
Hypogonadism is a clinical condition caused by disturbances in testosterone bioavailabilty and/or its actions. Hypogonadism may be due to abnormalities of the hypothalamus, pituitary gland, testes or target tissues, environmental factors, as well as increases in the amount of testosterone converted to estrogen by aromatase enzyme. Common symptoms of low testosterone are loss of vitality, fatigue, loss of libido, erectile dysfunction, sleepiness, depression and poor concentration. Overall, hypogonadal men tend to gain fat mass and lose muscle mass, bone mass, and strength.
Perusal of published meta-data quickly highlights how several common North American behaviors and traits exacerbate the decline in testosterone levels among young and older men. Although aging seems to contribute naturally to this decline, it is made worse by increasing cases of obesity, work stress, alcohol use, inactivity, and lack of adequate quality sleep.
A large scaled population level study published in The Journal of Clinical Endocrinology and Metabolism tell us that testosterone levels have declined among American men by ~17% overall in less than 20 years! This is alarming considering the study controlled for health and lifestyle characteristics, like smoking and obesity, known to decrease testosterone levels. This means that, although you may be a young and fit non-smoker, you are still susceptible to several factors that lower testosterone. Testosterone’s profound effects on strength, protein synthesis, recovery, appetite stimulation, energy, and aggression highlight the importance to optimize blood testosterone in athletes of all types and at all levels.
Testosterone: total, bound, and free?
Optimizing serum testosterone levels goes beyond simply increasing total testosterone, as blood testosterone comes in 3 ‘flavors’— total, bound, and free. Total testosterone refers to all testosterone (i.e., free + bound) found in the blood. Bound testosterone is all of the testosterone in the blood that is bound to sex hormone-binding globulin (SHBG), and to albumin. The largest fraction of blood testosterone is bound to SHBG and, since it cannot interact with testosterone receptors in the body, SHBG-bound testosterone is considered non-bioavailable. Free testosterone and albumin-bound testosterone are the most bioavailable fractions of testosterone in the blood, with albumin-bound testosterone being slightly less bioactive. However, since albumin binds testosterone weakly, it dissociates from albumin and becomes free testosterone in the capillaries (the smallest blood vessels and the site of molecular exchange in all of our organs and muscles).
3 key supplements to maximize your testosterone levels.
Supplement: Tongkat Ali (a.k.a., Eurycoma Longfolia or Longjack)
What is it? A small flowering evergreen tree that is native to Indonesia and Malaysia. Tongkat Ali extract contains high levels of bioactive compounds called quassinoids. Eurycomanone, the major quassinoid found in Tongkat Ali, has been reported to increase bioavailable testosterone levels.
How does it work? According to the research there seems to be more than one mechanism of action whereby supplementation of Tongkat Ali increases testosterone levels. A recent study illustrated that 1 month of Tongkat Ali supplementation raised testosterone to normal levels in men with a low testosterone condition called hypogonadism. Another study reported that Tongkat Ali supplementation increased fat free mass, reduced body fat, and increased muscle strength and size in healthy resistance trained men— due to its effects on testosterone bioavailability.
How to take: Products may vary in potency, so take as directed on label. For best results, look for Tongkat Ali extracts that contain patented LJ100 for highest potency.
Supplement: Ashwagandha (a.k.a., Indian ginseng or Withania somnifera Dunal).
What is it? A perennial flowering shrub that is commonly used in Ayurveda, the traditional system of medicine in India. In Sanskrit, Ashwagandha means “the smell of a horse”, as it is believed to produce vigor and strength in those who take it. In scientific terms, Ashwagandha is a potent antioxidant and is known as an adaptogen, which means it increases the body’s ability to handle stress and fatigue, such as from exercise, by maintaining hormonal balance.
How does it work: Ashwagandha contains many active compounds, the most studied are called withanolides. Research has shown that, Aswagandha supplementation with high concentrations of withanolides, increases blood testosterone levels, promotes a healthy response to every day stress, supports normal levels of mental clarity and focus, and enhances exercise and sports performance. A recent study investigated the effects of Aswagandha supplementation on testosterone levels, muscle mass, and strength in healthy young men undergoing an 8-week weight-training program. It was reported that those who took Aswagandha root extract had an over 400% increase in testosterone levels, which equated to greater increases in upper and lower body strength, upper body muscle size, and fat loss compared to placebo. Another study showed that taking Ashwagandha led to a 33% reduction in perceived stress during weight loss, a 22% decrease in the stress hormone cortisol, and a significant reduction in uncontrolled and emotional eating behavior compared to the placebo group.
How to take: As with most herbal supplements, choose products that have been standardized for the active ingredient and take as directed. In the case of Ashwagandha, look for products that have been standardized to withanolides (at least 1.5%). Products with patented KSM-66 Ashwagandha have the highest potency (with at least 5% withanolides), while retaining therapeutic properties of Ashwagandha’s many other active compounds.
Supplement: Zinc Methionine
What is it? Zinc-Methionine is zinc organically bound to methionine, which significantly boosts blood zinc levels without affecting blood copper levels. This is important because high blood levels of zinc can deplete blood copper levels. Zinc is a nutritionally essential trace element, meaning that you must get it from the diet. It is important in many cellular signaling events including those associated with proper liver function, cellular repair, and hormonal maintenance.
What does it do? One of zinc’s fundamental roles is to initiate protein synthesis through activating mTOR, a necessary cell-signaling event for muscle growth. Studies show that stress, regular heavy weight training, cycling exercise, and even just sweating can lead to zinc deficiency. Studies in humans illustrate that even mild dietary zinc deficiency leads to decreased serum testosterone levels, low sperm count, decreased immunity, and loss of lean body mass. Fortunately, zinc supplementation in reverses problems associated with zinc deficiency. In a study where elite strength athletes completed 4 weeks of exhaustive training with and without supplemental zinc, those who did not receive zinc supplements had significant declines in testosterone and thyroid hormone levels; whereas, those who received daily zinc had augmented testosterone and thyroid hormone levels.
How to take: Take 30mg of Zinc-Methionine, up to twice per day on an empty stomach. Make sure 1 dose is taken before bed.
Travison, TG, AB Araujo, AB O’Donnell, V Kupelian, JB McKinlay. A population-level decline in serum testosterone levels in American men. Journal of Clinical Endocrinology and Metabolism. 2007 92:196–202.
Khera M, Broderick GA, Carson CC 3rd, Dobs AS, Faraday MM, Goldstein I, Hakim LS, Hellstrom WJ, Kacker R, Köhler TS, Mills JN, Miner M, Sadeghi-Nejad H, Seftel AD, Sharlip ID, Winters SJ, Burnett AL. Adult-Onset Hypogonadism. Mayo Clin Proc. 2016 Jul;91(7):908-26.
Ahern T, Wu FC. New horizons in testosterone and the ageing male. Age Ageing. 2015 Mar;44(2):188-95.
Oliver JM, Kreutzer A, Jenke S, Phillips MD, Mitchell JB, Jones MT. Acute response to cluster sets in trained and untrained men. Eur J Appl Physiol. 2015 Jul 17. [Epub ahead of print]
Crewther B, Cronin J, Keogh J, Cook C. The salivary testosterone and cortisol response to three loading schemes. J Strength Cond Res. 2008 Jan;22(1):250-5.
Cardarelli R, Singh M, Meyer J, Balyakina E, Perez O, King M. The Association of Free Testosterone Levels in Men and Lifestyle Factors and Chronic Disease Status: A North Texas Healthy Heart Study. J Prim Care Community Health. 2014 Jan 26;5(3):173-179.
Fui MN, Dupuis P, Grossmann M. Lowered testosterone in male obesity: mechanisms, morbidity and management. Asian J Androl. 2014 Mar-Apr;16(2):223-31.
Reed MJ, Cheng RW, Simmonds M, Richmond W, James VH. Dietary lipids: an additional regulator of plasma levels of sex hormone binding globulin. J Clin Endocrinol Metab. 1987 May;64(5):1083-5.
George A, Henkel R. Phytoandrogenic properties of Eurycoma longifolia as natural alternative to testosterone replacement therapy. Andrologia. 2014 Sep;46(7):708-21.
Kuo PC, Shi LS, Damu AG, Su CR, Huang CH, Ke CH, Wu JB, Lin AJ, Bastow KF, Lee KH, Wu TS (2003) Cytotoxic and antimalarial beta-carboline alkaloids from the roots of Eurycoma longifolia. J Nat Prod 66:1324–1327.
Bhat R, Karim AA (2010) Tongkat Ali (Eurycoma longifolia Jack): a review on its ethnobotany and pharmacological importance. Fitoterapia 81:669–679.
- Hamzah, A. Yusof. THE ERGOGENIC EFFECTS OF EURYCOMA LONGIFOLIA JACK: A PILOT STUDY. Br J Sports Med 2003;37:464-470
Hunt CD, et al. Effects of dietary zinc depletion on seminal volume and zinc loss, serum testosterone concentrations, and sperm morphology in young men. AM J Clin Nutr 1992:56:148-57.
Kilic M, et al. The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc. Neuro Endocrinol Lett. 2006 Feb-Apr;27(1-2):247-52.
Wong WY, et al. Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial. Fertil Steril. 2002 Mar;77(3):491-8.
Takihara H, et al. Zinc sulfate therapy for infertile male with or without varicocelectomy. Urology. 1987 Jun;29(6):638-41.
Mahajan SK, et al. Effect of oral zinc therapy on gonadal function in hemodialysis patients. A double-blind study. Ann Intern Med. 1982 Sep;97(3):357-61.