The first signs that testosterone is linked to male pattern baldness were the eunuchs, who unlike their uncut male friends, never lost any hair. Fifteenth century castrati in the Italian opera always had a full head of hair. So did all soldiers whose battlefield injury happened to include any harm to the testosterone and DHT manufacturing center – the testes. But the hormonal link in balding is complex. Eunuchs, who produce no testosterone, never go bald even if they have a baldness gene. However, if castrated men with a family history of baldness are given testosterone, they lose hair in the classic horseshoe-shaped pattern. So how does the testosterone affect the male pattern baldness?

Normally the scalp loses roughly 100 hairs a day and sprouts 100 new ones. But the sex hormone testosterone can upset this break-even dynamic. Testosterone, in the form of DHT, or dihydrotestosterone stimulates hair growth on the face and the body. But in men who carry a certain common gene, the same hormone gradually defoliates the scalp, causing their aging heads to grow shiny even as their ears, noses and shoulders sprout more hair. Scalp hair loss is influenced by the transformation of testosterone into dihydrotestosterone (DHT). If there is already a hereditary tendency for hair loss, chances are, the scalp hair will thin and lead to male pattern baldness.

How does testosterone, the very same hormone that in your mother’s womb made you a male instead of a female, actually promote hair loss on your head? Studies show that while balding men don’t have higher than average circulating testosterone levels, they do possess above-average amounts of DHT in the scalp follicles. So it isn’t the testosterone itself that promotes your shiny noggin. Testosterone transforms into dihydrotestosterone (DHT) by an enzyme called 5-alpha reductase, which is produced in the prostate, various adrenal glands, and the scalp. Over time, the action of DHT causes the hair follicle to degrade and shortens the active growth phase in the hair follicles. Although the follicle is technically still alive and connected to a good blood supply (it can successfully nurture a transplanted follicle which is immune to the effects of DHT) it will grow smaller and smaller as the male pattern baldness progresses. However, the sebaceous gland attached to it remains the same size. As the hair shafts become smaller, the gland continues to pump out about the same amount of oil. So as your hair thins, you will notice that your hair becomes flatter and oilier.

Some follicles will gradually die, but most will simply shrink to the size they were when you were born. Meaning the hair that grows in these “baby” follicles is weaker, thinner, just as it was when you were a couple of days old. With a steadily shorter active growing cycle in the follicles, more hairs are shed, the hairs becoming thinner and thinner until they are too fine to survive daily wear and tear. Balding hair gradually changes from long, thick, coarse, pigmented hair into fine, un-pigmented “peach fuzz” hair, just like those fine little hairs on your forehead or on women’s cheeks.

But excess DHT doesn’t cause male pattern baldness on its own. Most men who lose their hair have a hereditary condition called androgenic alopecia. If such men indeed have increased levels of a hormone known as 5-alpha reductase and this transforms testosterone into dihydrotestosterone (DHT), then they may suffer from hair loss. The rate of hair shedding in androgenic alopecia is speeded up by three forces: advancing age, an inherited tendency to bald early, and our already most familiar friend, excess DHT in the hair follicle.

So who’s at most risk for hair loss? Genetically, light-haired and skinned men are more likely to lose their hair than dark-haired and skinned men. Furthermore, Caucasian males are much more likely to lose their hair than non-Caucasians. So, if you are a blond, light skinned Caucasian, with a family history of male pattern baldness, you are several times more likely to lose your hair than a Japanese man, for example, or an African-American man.

Of course, genetics and over-production of DHT in the hair follicle are not the only causes for hair loss. Hair loss is aggravated by your diet, which in turn can affect the way your body produces hormones. In a recent study in Japan, it was found that more and more men are suffering from baldness and hair loss the more westernized their diet becomes. It is known that fatty foods and red meat, two staples of a westernized diet, contribute to hair loss. And of course stress, which activates production of adrenaline (the same family of testosterone), encourages hair loss as well.

So what can you do aside from pray to wake up tomorrow as a big strapping black basketball player? Keep calm. Eat balanced and healthily, even adopt a more eastern diet with more vegetables and soy products. But as far as male pattern baldness, remember this. There is nothing to be ashamed of. Your bald head and hair loss is just nature’s way of indicating that you’re a guy pumped to the gills with all the good stuff that makes you a sexual male – testosterone and DHT.

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