Since the notification system isn't working, and I don't believe
you'll find a more comprehensive source of the information you're
seeking than the one I've provided, I'm going to go ahead and
post a formal answer. You can post a Request for Clarification
if you have any questions.
'The World of Hair', an on-line reference by Dr. John Gray, provided
by the Procter and Gamble Hair Care Research Center, makers of the
Pantene, Herbal Essences, Clairol, Head & Shoulders, Vidal Sassoon,
and Physique lines of hair care products, tells you literally all
you could want to know about hair and proper hair care:
As you will see, the major factor in the nature of your hair is
your genetic heritage, about which you can do nothing. Assuming
you eat a normally nutritious diet, there is no supplement which
will change the nature of your hair.
The amount of sebum your scalp produces is also genetically
determined. About all you can do is use a shampoo that is
designed for the type of hair you have, and shampoo according
to the guidelines discussed in the section of the book that
addresses that. This index page may prove helpful in finding
topics of interest to you, though I recommend you read the
entire book, which is very informative, and dispels many myths:
As for eyebrow hair, it sits below the brow and is fed by
oils which drop onto it from the forehead, while the hair
on top of the head is exposed to the air, heat, and sun,
and the oils on the head are not able to soften the head
hair as easily unless regular brushing occurs to distribute
it (hence the 100 brush stokes per day tradition). Otherwise,
gravity keeps the oils on the surface of the scalp, and not
on the hair.
I knew of the Procter & Gamble site, and had it bookmarked.