If all it did was anchor that head-turning head of hair you intend to keep for the next 67 years, your scalp would still rank as a VIBP (Very Important Body Part). But the skin on top of your noggin can determine more than whether you're going to have a good hair decade. The cells found at the roots of hair are the most rapidly developing and the most sensitive to changes in nutrition and body functions. So if your scalp is healthy, chances are the rest of your body is too.

Scalp cells are produced at the lowest level of the skin and migrate toward the outer surface; once there, they flatten out and are invisibly shed. When things are working properly, the entire process takes about a month. But a sick scalp can shed cells in as little as a week, leaving large, ugly snowdrifts politely known as dandruff.

Those nasty flakes on your shoulders are probably the result of something simple, such as too frequent shampooing, which can strip the scalp of natural oils. On the other hand, too infrequent shampooing can result in clogged follicles and lead to more severe forms of seborrheic dermatitis, e.g., an itchy red rash. While treatable with nonprescription shampoos, seborrheic dermatitis can sometimes indicate an immune-system disorder, so any recurrent case is worth reporting to your physician. (For more simple solutions, see "Simple Solutions," page 69.)

Improvements can also be made from the inside out. For a healthy head, cut out excess amounts of fats, sugar and salt--and avoid stress, says Albert Kligman, M.D., professor of dermatology at the University of Pennsylvania School of Medicine. When you're tense, your body produces an excess of cortisol, which can suppress the immune system and increase the growth of yeast organisms on the scalp, which leads to inflammation and dandruff.

Because physical exercise also relieves stress, your daily workout can help keep you healthy toe to head. Giving your pate its own quick workout won't hurt either: A daily two-minute scalp massage not only feels great, it improves blood flow to the head, bringing vital nutrients to follicles. While you're at it, occasionally treating your scalp to a little jojoba oil can break up encrusted oil and remove dead cells.

Aveda spokeswoman Sarah Quincy recommends shampooing once a day, or half as often if you're a swimmer. If you're showering at home and at the gym, Quincy says, it's best to just rinse your hair when you hit the stall a second time. Unless you're drenched with sweat, not washing your hair immediately after a workout isn't a bad thing. The scalp contains oil-producing sebaceous glands, and perspiring distributes this oil, which prevents dryness and flaking.

The weekly use of a special shampoo (labeled "clarifying" or "detoxifying") will help keep pores clear of gunk, strip away buildup from waxy hair products, and reduce chlorine damage for pool users. Shampoos containing aloe vera may stabilize a dry scalp, while those with balsam balance oilier heads. Sage, thyme, rosemary and lavender are also traditional herbal treatments. Echinacea, everyone's favorite cold remedy, moisturizes and soothes sick scalps, and a good dose of chamomile tea, dumped right on your head every couple of weeks, can cleanse away built-up toxins.

If chamomile cures aren't your cup of tea, you can nurture your scalp with daily supplements. Any multivitamin that contains antioxidants and unsaturated fatty acids will clean up clogged pores and promote scalp-oil production. Vitamins A, C and E facilitate the normal shedding of dead cells, and most B vitamins feed follicles and hair roots.

"The top of your head is like every other part of your body," says Kligman. "If you keep it clean and well-cared for, it'll be fine. The first sign of trouble will show up on your shoulders, and your girlfriend will let you know right after the first flake has fallen."

ITCHY, OILY, FLAKY: CARTOON CHARACTERS OR SCALP AILMENTS?

Condition: Dry scalp

Symptoms: Itching, swelling, redness

Cause: Abrasive shampoo and other hair-care products; shampooing more than once a day.

Cure: Switch to a plant-based, pH-balanced product. In extreme cases, massaging a few drops of an essential oil (such as jojoba) into your scalp once a week before shampooing will help.

Condition: Oily scalp

Symptoms: Flaky dandruff

Cause: Heredity, mostly. Stress, as well as hot and humid weather, can activate an oily scalp.

Cure: Shampoos that contain jojoba oil or tea tree oil help eliminate oily deposits and reduce shedding.

Condition: Painful scalp

Symptoms: Dandruff with buildup and soreness

Cause: Overuse of styling products

Cure: Topical oils or hair products containing eucalyptus and sage will help heal a head that's been damaged by overprocessing.

SIMPLE SOLUTIONS

If your head has turned on you, check your hair habits.

Cast away chemicals. Whenever possible, keep harsh soaps, styling products, and dyes away from your scalp, and minimize use or steer clear of alcohol-based gels and sprays.

Rinse. To repeat: Rinse. Product residues do no scalp good.

Cool down. "When you rinse your hair, turn down the water temperature," says Dale Abadir, M.D., a New York City dermatologist. "Hot water might feel good, but it can aggravate a dry scalp. If the water's too hot, you're not hydrating your scalp, you're dehydrating it."

Blow low. Using the lower settings on your blow-dryer with a snap-on diffuser is a good idea; towel-drying your hair is a better one.

Brush yourself off. Brushing loosens dead skin, which may be clogging pores. (Bonus: If you're a finger-comber, your scalp's natural oils will help keep cuticles flat and lubricated.)

Shave, don't scrape. Men with curly hair who shave their heads too closely can end up with ingrown hairs and razor bumps that end up trapping bacteria.

Keep it shady. Fair-skinned or chrome-domed fellows should don a cap or rub sunscreen (minimum SPF 6) into their heads about 30 minutes before going outdoors.