Free Testosterone

Understanding Free T:

• Free Testosterone = Total T minus SHBG-bound and albumin-bound fractions
• Only ~2-3% of total T circulates free; this is the biologically active portion
• Free T can be low even with normal total T if SHBG is high
• Free T can be disproportionately high if SHBG is suppressed (oral AAS, insulin resistance)

If elevated (on cycle / TRT):

• High free T is the goal on cycle — no intervention needed unless side effects present
• If SHBG is suppressed (common with oral AAS): expect disproportionately high free T; this normalises after discontinuation
• Monitor androgenic side effects: acne, hair thinning, prostate symptoms (PSA if >40 years old)
• If experiencing androgenic sides despite moderate total T, check SHBG — very low SHBG means more free androgen exposure

Supplements (to support natural free T):

• Boron -- 10mg/day (shown to lower SHBG by ~10% and raise free T within 1 week)
• Zinc -- 30mg/day (picolinate or citrate, before bed on empty stomach)
• Magnesium -- 400-500mg/day (glycinate, before bed)
• Vitamin D3 -- 5000 IU/day (with fat-containing meal; deficiency lowers T)
• Ashwagandha -- 600mg/day (KSM-66 extract; studies show 15-17% increase in free T)
• Stinging Nettle Root -- 300-600mg/day (may reduce SHBG binding)

SHBG Management (when SHBG is too high, lowering free T):

• Boron -- most evidence-supported supplement for lowering SHBG
• Address insulin resistance (high insulin lowers SHBG, but metabolic health matters more)
• Avoid excessive alcohol (raises SHBG)
• Adequate caloric intake -- chronic caloric deficit raises SHBG

SHBG Management (when SHBG is too low, elevating free T):

• Very low SHBG (<10 nmol/L) is common on oral AAS (Anavar, Winstrol, Proviron, Dianabol)
• Implications: rapid testosterone clearance, unstable levels between injections, increased androgenic side effects (acne, hair loss, prostate stimulation)
• Discontinuing oral AAS is the primary intervention — SHBG typically recovers in 4-8 weeks
• Tamoxifen — 10-20mg/day (SERMs raise SHBG via estrogenic hepatic action)
• Increase dietary fibre and reduce refined carbohydrates (insulin resistance lowers SHBG)
• Thyroid optimisation — hypothyroidism lowers SHBG; ensure TSH and Free T4 are optimal

Lifestyle:

• Optimise sleep (7-9h) -- poor sleep directly reduces T production
• Resistance training -- compound lifts acutely boost T
• Maintain healthy body fat (12-18%) -- excess fat increases aromatisation, very low fat impairs T production
• Minimise chronic stress -- elevated cortisol directly suppresses GnRH and T production
• Avoid excessive endurance training (>60 min intense cardio suppresses T)

When to investigate further:

• If free T is persistently low with normal total T, check SHBG and albumin
• If both total and free T are low off-cycle, assess full HPTA (LH, FSH, prolactin, E2)

References:

• Naghii, M. R., Mofid, M., Asgari, A. R., Hedayati, M., & Daneshpour, M.-S. (2011). Comparative effects of daily and weekly boron supplementation on plasma steroid hormones. Journal of Trace Elements in Medicine and Biology, 25(1), 54-58. DOI: 10.1016/j.jtemb.2010.10.001
• Prasad, A. S., Mantzoros, C. S., Beck, F. W. J., Hess, J. W., & Brewer, G. J. (1996). Zinc status and serum testosterone levels of healthy adults. Nutrition, 12(5), 344-348. DOI: 10.1016/S0899-9007(96)80058-X
• Cinar, V., Polat, Y., Baltaci, A. K., & Mogulkoc, R. (2011). Effects of magnesium supplementation on testosterone levels. Biological Trace Element Research, 140(1), 18-23. DOI: 10.1007/s12011-010-8676-3
• Wankhede, S., Langade, D., Joshi, K., Sinha, S. R., & Bhattacharyya, S. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery. Journal of the International Society of Sports Nutrition, 12, 43. DOI: 10.1186/s12970-015-0104-9
• Lopresti, A. L., Drummond, P. D., & Smith, S. J. (2019). A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha in aging, overweight males. American Journal of Men's Health, 13(2), 1557988319835985. DOI: 10.1177/1557988319835985