15. Men's health Flashcards
What is testosterone - androgens?
Testosterone = a steroid sex hormone under hypothalamic and pituitary gland control.
where is testosterone produced?
- Produced: In men >95% from the testes by Leydig cells, with the remainder mostly from the adrenals.
what is the function of testosterone ?
- Functions: Male sexual characteristics — facial hair, deepening of voice, development of penis and testes, libido and sperm production. Skeletal muscle growth and increases bone density.
how does testosterone circulate?
- Circulation: ~60% is weakly bound to albumin and ~40% tightly bound to SHBG. ‘Free testosterone’ accounts for ~1-2%. ‘Bioavailable testosterone’ = free + albumin-bound testosterone.
what is low testosterone?
Low testosterone = the most common type of male sex hormone imbalance (often combined with high oestrogen).
signs and symptoms of low testosterone?
- Signs / symptoms: Central weight gain, low energy, low libido, erectile dysfunction, infertility / low sperm count / motility, osteoporosis, hair loss, fatigue, loss of muscle bulk and strength, mood changes.
causes and risk factors of low testosterone? x9
1* – Ageing — declines with age after 40 years by ~1% each year.
Associated with symptoms referred to as the ‘andropause’.
2* – Chronic stress — cortisol and epinephrine have inhibitory effects on testosterone release.
3* Elevated SHBG ― binding too much testosterone, e.g., medications (metformin, tamoxifen); liver disease and dysfunction ― impaired SHBG detoxification; anorexic states and overtraining.
4* Thyroid dysfunction ― likely through its effects on SHBG.
5* Zinc deficiency ― it supports testosterone production.
6* Increased aromatase activity (e.g., obesity, insulin resistance, excess alcohol; inflammation and ↑ PGE2).
7* Environmental toxins ― e.g., BPA can bind to androgen receptors.
8* Sleep deprivation ― testosterone is made mostly during sleep.
9* Medications ― e.g., opioids (inhibit GnRH).
Low testosterone is also associated with IR and ↑CVD risk
natural approach to low testosterone? x6
1* Address the cause, e.g., stress support (see stress lecture), weight loss, thyroid support (see endocrine lecture) etc.
2* CNM Naturopathic Diet with low GI foods, healthy dietary fats (pregnenolone synthesis), zinc-rich foods (testosterone synthesis).
3* Exercise ― resistance training (e.g., weights) and HIIT ↑ testosterone.
4* Sleep hygiene; avoid xenoestrogens (see women’s health).
5* Support liver detox and balance gut microbiome (oestrobolome) ― to ↓ SHBG and oestrogens (see Detoxification + Women’s Health).
6* Mitochondrial support (e.g., B vitamins, CoQ10, alpha-lipoic acid, Se, glutathione, etc.,) ― pregnenolone is formed in mitochondria.
Nutrients for low testosterone x5
- Zinc 15‒30 mg / day * Supports testosterone production, and promotes spermatogenesis.
- Vitamin D Optimise levels * Increases Leydig cell testosterone production and supports a health testosterone / oestradiol ratio.
- Magnesium 200‒400 mg / day * In combination with zinc and B6 shown to improve testosterone levels in athletes.
- B complex 50‒150 mg / day * Mitochondrial support (for pregnenolone synthesis). Methylation support (↓ homocysteine and CVD risk).
- D-chiro-inositol 600 mcg x 2 / day * Modulates aromatase — ↓ conversion to oestrogens. Also supports cell insulin sensitivity.
Herbs for low testosterone x4
Ashwagandha (Withania somnifera) 2‒5 g powder/ day * Increases testosterone (and DHEA) by stimulating GnRH production. Might also inhibit aromatase activity.
Mucuna pruriens Up to 100 mg / day * ↑ Leydig cell production of testosterone, likely through ↑ dopamine↑ GnRHFSH + LH.
Tribulus terrestris 500–650 mg / day * ↑ free testosterone by ↑ LH release. It also ↑ libido, NO synthesis and sperm motility.
Shatavari (Asparagus racemosus) Up to 3 g powder / day * Its steroidal glycosides exert
testosterone-like effects. Considered an aphrodisiac.
Nettle root, fenugreek and maca root also support testosterone levels
What is DHT?
Dihydrotestosterone (DHT):
* Produced: From testosterone by 5a-reductase.
* Activity: The more potent androgen (approx. 2–5 x stronger than testosterone). It binds more strongly to androgen receptors and does not aromatise into oestrogen
What are the consequences of increased DHT?
Increased DHT levels: Associated with acne, male pattern baldness, mood (anger), prostate disorders.
Causes for increased 5 alpha reductase activity? where is it located?
Causes of ↑ 5a-reductase activity: Inflammation (i.e., poor diet gut health etc.,) ↑ insulin, obesity, low zinc status, pesticides, steroid 5-alpha reductase type 2 (SRD5A2) SNP.
5a-reductase is located in the gonads, skin, hair and NS
How to lower DHT via a reduction of 5 alpha reductase?
Address inflammation (see immune lecture), stabilise blood glucose levels and support insulin sensitivity (see endocrine lecture), reduce adiposity, eat organic.
Herbs/nutrients to reduce 5 alpha reductase x3
- Zinc 15–30 mg / day * ↓ 5α-reductase activity, stabilising DHT levels.
- Saw palmetto (Serenoa serrulata)
500–1000 mg (berry) * Its high levels of beta-sitosterol inhibit 5α-reductase and DHT binding to androgen receptors. - Stinging nettles (Urtica dioica)
300–600 mg (root) * Inhibits 5α-reductase and aromatase (reducing DHT and oestrogen); binds to SHBG, increases testosterone.