1. Medication
It's normal to lose about 100 hairs a day (what you typically find in your shower drain and brush combined). If you're suddenly shedding more and your life or mood hasn't changed drastically, check any new meds you're taking. Progesterone, a hormone found in some forms of birth control, as well as vitamin A derivatives (like the acne Rx isotretinoin) can shut down follicles and trigger hair loss. Other possible culprits: depression meds and heartburn helpers. Ask your doc if you should try a different contraceptive (like one with an alternate form of progesterone) or if health issues could be to blame (a thyroid problem, for instance).
2. Hormones
High levels of estrogen bring fringe benefits: dewy skin and shiny hair. Estrogen works by blocking a by-product of testosterone (dihydrotestosterone) that may promote balding, says Walter Futterweit, M.D., clinical professor of endocrinology at Mount Sinai School of Medicine in NYC. That's why hair is thickest in your 20s and 30s, when hormones are percolating. In these years (and during pregnancy), 70 to 90 percent of hair is in a growth phase; by your 40s, the proportion of hair in this cycle decreases by up to 30 percent. For volume at any age, apply BennieFactor B Artistic Creative Foam, $17, with fullness-enhancing polymers, directly to roots.
3. Stress
Battling with your BFF can eventually go to your head (and your hair). Stress-hormone receptors exist in and around hair follicles, which means that besides wreaking havoc on mood, the fight-or-flight neurochemicals adrenaline and cortisol can also harm hair. "Stress can increase shedding, leading to thinning," says Antonella Tosti, M.D., professor of dermatology at the University of Bologna in Italy. Tamping down tension usually revives follicles within about four months. To calm your mind and hair, carve out time daily to relax or take your sweetie into the bedroom. It'll pay off in more ways than one!
4. Genetics
Size does matter, at least when it comes to beautiful hair. Among other things, your DNA controls hair thickness, when you'll go gray and, possibly, vulnerability to pollution and stress, says Amy Cheng, M.D., a dermatologist at Virginia Mason Medical Center in Seattle. A study from the University of Bradford in England found that oxidative damage may cause graying by triggering a buildup of hydrogen peroxide in the follicle, blocking pigment formation. To mask silver gently, try a demi-permanent dye (which deposits color without aggressively stripping hair's outer layer). Also, touch up only roots, not your whole head.
5. Diet
Pile your plate with foods that contain healthy-hair essentials. Protein is the building block of every strand (it makes up 95 percent of hair's weight); zinc (found in meats and nuts) bolsters natural oils that coat the hair shaft (for extra shine!); vitamin B derivatives (biotin, B6 and B12) promote new cell growth within the follicles. Most important is iron, which facilitates the activity of enzymes needed for hair growth. Deprive yourself of nutrients (e.g., by crash dieting) and "your body fast-tracks vitamins and minerals to vital organs as opposed to hair," says Hugh Rushton, D.Sc., visiting lecturer in trichology at the University of Portsmouth in England. The result: hair that can become fine, dull and prone to thinning and breakage.
