According to scientists, there are three causes of alopecia in either men or women.

Too much DHT
Pseudo-oestrogen chemicals
Lack of vital nutrients

DHT
Free testosterone is broken down into DHT (a more potent form of testosterone). This chemical binds to the hair follicle receptors blocking vital nutrients from accessing the hair. The hair becomes miniaturized and thin and eventually dies. It is what's called the "peach fuzz ? look on young men with hair loss.

This is why eunuchs never had any hair loss which got Plato wondering. It is also why only men get male pattern baldness and women don't. Hair loss in women is more evenly distributed with a thinning over the whole scalp. Also, effective DHT inhibiting treatment was only effective on young men with hair loss and not older men or women. Excessive DHT is therefore not the only reason for losing your hair.

PSEUDO-OESTROGEN CHEMICALS
It is normally unheard of for women in China to get hair loss at any age. Over the last 20 years increasing number of Chinese women in the industrialized areas of China are experiencing hair loss. This has been put down to chemicals form the industrial process which mimic the chemical effects of oestrogen. These pseudo-oestrogen chemicals bind tighter to the hair follicle receptors than normal oestrogen does, starving the hair follicle of vital nutrients, similar to the way DHT does.

Also, this seems to the reason for hair loss in obese men. Fat cells in obese and balding men contain more of the enzyme aromatase (responsible for converting testosterone into oestrogen). Also bacteria in fat cells produce oestrogen-like chemicals.

LACK OF VITAL NUTRIENTS
The hair needs a variety of nutrients to sustain itself. The theory is that both DHT and estrogen-like chemicals block the hair follicle by binding to it too tightly. Even without these chemicals, a person lacking in these nutrients will experience hair loss.

There have been experiments on mice which show the effect of a deficiency of certain vitamins or minerals. Scientists knocked out the genes in mice responsible for the regulation of the hair and scalp. These genes are in turn normally regulated by vitamin D. The result was rickets and hair loss with dermal cysts appearing quite early on. When scientists injected naturally "nude ? mice with vitamin D, they started sprouting hair at an alarming rate.

It has been shown that copper and zinc, if lacking together, increase a loss of hair. In fact, a copper peptide was shown to induce hair growth in the skin around the wound of a person. The copper peptide was first used as healing accelerant.

For women, a lack of iron and the essential amino acid L-lysine has been associated with losing one's hair. This therapy has proven to be very beneficial for women who are losing their hair.