It is interesting to note that countries that traditionally have little male pattern baldness (referred to hereafter by the initials M.P.B) like Japan, China, India and Africa, do see their males develop M.P.B once they settle in the western world. As their genes do not change on such a relocation it would be logical to
conclu- de that other factors interplay with a genetic predisposition. The incidence of MPB appears to increase in each successive generation that remains in the western world.
One problem with MPB is that it is not considered strictly a medical problem and as such no reliable statistics are to hand. Fortunately there is another model we can switch to that is well documented, that gives us a clue as to the impact of environmental factors: Dihydrotestosterone (DHT), is the main
hor- mone believed to be implicated in hair loss and is also implicated in prostatic enlargement and prostate cancer. By studying the figures on prostate cancer, more light is shed on the subject of DHT and hence hair loss: Native Japanese men have an incidence rate of prostate cancer of 4 per 100,000. The rate amongst Japanese living on the U.S. mainland increases to between 12 to 20 per 100,000 and a staggering 36 per 100,000 for those living in Hawaii.
Clearly environmental factors must affect DHT production or its cellular
uptake. (Ref W. Martin, 'My Prostrate & Me' ISBN 1-56877-88-8).
Summary
There appears to be a genetic predisposition involved in hair loss which would seem to be affected by environmental factors. Scientists believe they have
iso- lated the "bad guy" in hair loss which is an enzyme known as five alpha
reduc- tase (5AR). Studies of the inhibition of 5AR look promising in providing a
solu- tion to hair loss and appear to have limited risk of side effects.
5AR inhibitors have now been developed and are available in either drug form or as nutritional supplements. DHT is metabolised from testosterone, which is
ma- de by the testes. Castrates produce less DHT and do not suffer hair loss, it has often been suggested that higher levels of testosterone are the cause. No study has established a direct correlation between Testosterone, DHT and hair loss. In fact one study demonstrated that bald men have in fact lower testosterone levels than other men. Other studies show that the levels of testosterone are within normal ranges or are at the upper end of normal range.
What must also be understood is that total testosterone alone is not that
impor- tant, as it is transported through the blood on a carrier molecule known as sex hormone binding globulin (SHBG). The free portion that is not bound in this
man- ner is available to be converted through to DHT. There is a commonly held view that the genetic predisposition is the conversion rate from testosterone to DHT in the area of hair loss.
Little work has been done into what lowers sex hormone binding globulin but it is known that there is an inverse correlation between SHBG and insulin level. Insulin is touched upon in the dietary section but it is worth noting that its levels are raised by our dietary habits, stress and being over
weight.
