Inside out: your internal flora promote healthy skin. (innerbeauty).

In last month's column, we looked at healthier, gentler alternatives to conventional skin-care products to help cleanse your skin and restore its original glow. But beauty is much more than skin deep. For really healthy skin, we have to go below the surface and address the delicate balance of our inner body ecology.

According to Oz Garcia, New York-based nutritionist and author of Look and Feel Fabulous Forever, many stubborn skin problems are driven by hormonal and immune-related issues governed by the tiny, unseen bacteria in our intestines. Fungal and inflammatory skin conditions such as dandruff, acne, Candida, eczema, nail infections and even athlete's foot can arise when pathogenic bacteria and fungi gain power in our gastrointestinal (GI) tracts and on our skin.

in balance

At any given time, the average healthy person is host to countless beneficial and potentially harmful microbes. For example, the H. pylori bacteria, infamous for causing ulcers, is present in one out of every two adults, but causes no problems in most. The yeasts Candida albicans and Pityrosporum ovale--also known as Malassezia ovalis, a common cause of dandruff and skin rashes--are also common in healthy humans, and can cause their head-to-toe symptoms when your immune resistance is low or your army of defending beneficial bacteria has been depleted.

Immune problems, stress, high blood sugar, steroid drugs, oral contraceptives and chlorinated water can deplete the protective intestinal-and skin-dwelling "good" bacteria that normally keep pathogenic microbes in check. Anti-bacterial soaps, as well as antibiotics, have also been shown to both wipe out protective bacteria and indirectly give rise to more powerful pathogenic strains.

The most obvious and immediate signs of such imbalance--which may show up when you're taking an antibiotic--are digestive symptoms such as diarrhea and bloating. What may follow is the proliferation of unopposed pathogenic bacteria or fungi. Malassezia yeasts, for example, can cause not only dandruff, but red, flaky patches near the eyebrows and eyelids, in nasal folds and even in fingernails. Candida infections can proliferate in your mouth, feet, nails and genital area.

What is less obvious, though perhaps more serious, is the cascade of inflammatory reactions that may result from this internal imbalance-sometimes long after you've finished your antibiotic regimen.