When we think of men that are known for their physical strength, masculinity or “manliness”, certain famous names might come to mind: Bruce Willis, Dwayne “The Rock” Johnson, Vin Diesel etc. One thing these men all have in common, other than their muscularity and deep voices, is their lack of head hair. Yes, these men all had a full head of hair earlier in their adult lives, but they are now all heavily balding if not entirely bald, a transition that seems to have perhaps occurred earlier for them than the average man. A popular assumption is that these men have lost their head hair quicker because of their high levels of testosterone, indicated in part by their muscle mass, deep voices and other high testosterone secondary male characteristics. However, the relationship between testosterone and hair loss is more complex than it may first appear, a relationship we’ll explore in greater depth in this Health Centre article.
Testosterone is the primary sex hormone in males, and plays an important role in the development of male reproductive tissues, as well as contributing to secondary sexual characteristics like increased muscle mass and body hair growth. 43% – 45% of testosterone in the blood is bound to a protein called sex hormone binding globulin (SHBG). Bound so tightly, this testosterone isn’t available for other cells to use. 53-55% of testosterone is bound to the albumin protein, and although it can be made available for use in the body, it is not as available as free testosterone, which accounts for 0.5% – 3% of total testosterone. If you have low levels of SHBG, you may have higher levels of free testosterone. An individual’s levels of the bioavailable testosterone (albumin-binding and free testosterone) is what ultimately causes responses in bodily tissues. Therefore, it is not necessarily a greater total amount of testosterone in the body that may cause secondary male characteristics, but more so the amount of bioavailable testosterone (which is something lab tests have been known to struggle observing separately).
What is DHT and what does it do?
Around 10% of testosterone in adults is converted to dihydrotestosterone (DHT), a hormone important for the sexual differentiation of the male genitalia during embryogenesis, development through puberty, and maintenance of the prostate gland. DHT has similar effects to testosterone in terms of contributing to some sexual functions and physiological processes, but is between 3 and 6 times more powerful. Abnormally high levels of DHT have been linked to prostate cancer, coronary heart disease, and slow healing of the skin following an injury, as well as affecting hair growth.
The link between DHT and balding
Hair on the body grows from follicles in the skin, which follow a growth cycle of hair growth to resting to eventually shedding the hair strand, before repeating the cycle. High levels of DHT can shrink the hair follicles and shorten the growth cycle, causing the individual hairs to be thinner and more brittle, and shed at a faster rate. Additionally, DHT can cause a delay in hair regrowth following the shedding phase.
This may seem like a straightforward relationship between total DHT levels (affected by bioavailable testosterone) and hair loss, but another variable adds complications: DHT sensitivity. Variations in the androgen receptor gene can increase the susceptibility of the scalp follicles to DHT, resulting in increased male pattern hair loss. This sensitivity is in part hereditary, which is why you’re much more likely to experience pattern hair loss if there’s a history of hair loss in your family.
With this in mind, hair loss is therefore not entirely dictated by testosterone levels, but rather DHT sensitivity. High levels of testosterone may cause greater DHT levels overall, which may prompt more hair follicle shrinkage, but it’s equally possible for an individual with average to low testosterone levels to have a hereditary DHT sensitivity, resulting in early hair loss.
Reducing DHT and treating hair loss
Thankfully, there are several methods to combat hair loss, either by altering the uptake of DHT or by hair follicle stimulation.
This is a popular prescription medication taken orally in tablet form. 5-alpha reductase is the enzyme that converts testosterone to DHT, and Finasteride contains a 5-AR inhibitor that blocks this process . DHT is prevented from binding to the receptors in the hair follicles, and therefore hair loss is halted. The treatment has been found to be successful at preventing future hair loss or even prompting new hair growth in 87% of men. As this treatment interacts with the male sex hormone testosterone, Finasteride is not effective at reducing hair loss in females.
Minoxidil is another very popular treatment that aids blood flow to the scalp, increasing the follicle size and therefore hair shaft diameter. Regaine Extra Strength Solution and Regaine Foam for Men are topical treatments that contain minoxidil; they are massaged into the scalp twice a day. They have been shown to stabilise hair loss in 80%-90% of men, and actively encourage hair regrowth in 60% of men. Unlike Finasteride, women can also benefit from Minoxidil treatment using either Regaine for Women Solution or Regaine for Women Extra Strength Foam.
Although this area of research is in its infancy, some studies have suggested that caffeine may contribute to the prevention of hair loss. One 2014 study found caffeine may make the hair grow longer, extend their growth phase, and promote keratin production (a protein present in the hair). Treatments containing the active ingredient caffeine, such as Alpecin Shampoo or Alpecin Liquid stimulate the hair follicles and work to promote hair growth.
Having a deficiency in vitamin B, particularly B-6, can cause symptoms including hair loss, so it’s important to get this nutrient either through supplementation, or by eating vitamin B-6-rich foods such as pork, poultry, peanuts, soya beans, oats or bananas.
Whilst having high levels of total testosterone is not a risk factor for early hair loss, having high DHT levels, or more importantly high DHT sensitivity, will increase chances of hair loss. Treatments like Finasteride block DHT from binding to 5-AR receptors in the hair follicles, and Minoxidil and caffeine can improve blood flow to the follicles, all of which can prevent hair loss and promote hair regrowth. The beauty of these treatment options is that there is no risk associated with taking more than one approach simultaneously, since each treatment targets a different element of the hair loss process, so for best results you should adopt a combined strategy.
Visit our Health Centre for more information on hair loss prevention and treatment.