Maintaining a balance between good and bad bacteria in the body has benefits beyond the digestive tract, it may also affect the health and appearance of the skin, researchers have found.

Consuming probiotics, or the “good bacteria,” similar to the trillions of microorganisms that already live in the body, in foods or as dietary supplements, might help to prevent or treat certain skin conditions, some early studies suggest.

The benefit of probiotics is that they introduce healthy bacteria to the gut and create a barrier to reduce inflammation, which can trigger certain skin conditions, said Dr. Whitney Bowe, a clinical assistant professor of dermatology at Mount Sinai Medical Center in New York City, who has researched the effect of probiotics on acne. She said there is compelling evidence that probiotics hold promise for treating acne and rosacea.

Another exciting area of research is the development of topical probiotics, which can be applied directly to the skin, Bowe said. Several manufacturers are currently experimenting with adding strains or extracts of probiotics to their skin care products, including moisturizers, cleansers, peels and lotions, and some products are already on the market.

Still, further study is needed to determine which strains may work best and how many of the bacteria survive once the probiotics are spread onto the skin’s surface.

Bowe said probiotics — whether they are eaten as foods, taken as supplements or spread topically — are not a stand-alone treatment for skin problems, but could be used by patients in combination with their current treatment.

She said she typically recommends probiotics to her patients with acne or rosacea who are taking antibiotics, which can wipe out both good and bad gut bacteria. She suggests getting probiotics daily from foods, such as yogurt with live active cultures or kefir (a fermented milk drink), or by using supplements.

A few of her patients have been experimenting with probiotics by applying Greek yogurt directly to their skin once a week for 10 minutes. Bowe says they have been pleased with the results from this do-it-yourself facial mask. Although the home remedy has never been scientifically tested, some patients have reported having fewer acne lesions, while others who have tried it to achieve younger-looking skin said their skin developed better texture and seemed brighter.

As more research emerges, here are four skin conditions that seem the most promising for probiotics, according to Bowe.

Acne. Small studies from Italy, Russia and Korea have found that probiotics from food or supplements used in conjunction with standard acne treatments may increase the rate of acne clearance, and also helps patients better tolerate acne treatment with antibiotics, Bowe told Live Science. Some probiotic strains found to be effective in studies of acne include Lactobacillus, L. acidophilus, and B. bifudum.

Preliminary studies of topical probiotics for acne have shown they may help reduce the number of active skin lesions, Bowe said. Probiotics applied to the skin might help acne by forming a protective shield that prevents harmful pimple-causing bacteria from reaching the skin, aggravating the immune system and triggering inflammation, she said.

Eczema. Finnish researchers looked at pregnant women who took probiotic supplements (containing Lactobacillus rhamnosus GG) for two to four weeks before giving birth, and also after delivery if they were breast-feeding, or added the bacteria to infant formula for at least six months. They found the probiotics reduced the odds of eczema in babies who had strong family histories of the itchy skin condition until at least age 2, and possibly longer.

Another recent study showed that infants who developed eczema before they turned 1 had a less diverse collection of gut bacteria when they were 7 days old than infants without eczema, suggesting a link between gut bacteria early in life and the development of the skin condition.

Rosacea. This inflammatory skin condition causes facial redness on the cheeks, nose, chin or forehead, as well as small red bumps or pimples. Probiotics may help control rosacea flare-ups and symptoms, studies suggest.

“Probiotic extracts in conjunction with medication can reduce the redness seen in rosacea, and also improve and strengthen the skin barrier to reduce its stinging, burning and dryness,” Bowe said.

Anti-aging. The use of probiotics to protect skin from the effects of aging is an exciting new area that shows early promise, but needs more research, Bowe said. She said there’s some evidence that probiotics may help to build collagen, the main protein in skin that affects its texture and tone.

Increased numbers of good bacteria may also help to hydrate aging skin, reduce sun damage and improve the appearance of fine lines and wrinkles, Bowe suggests.

Originally published on Live Science