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By now, most of us have heard about the benefits of maintaining the good bacteria in our gut through probiotics. Eating yogurt and fermented foods, drinking kombucha and kefir, or taking supplements, are all ways of keeping our digestive systems (and as a result, the rest of our bodies) very happy. Next up in microbiome maintenance: our skin. When applied topically, probiotics may actually solve a number of skin conditions as well.

The human skin microbiome—which includes all layers of the skin—contains about 1,000 different species of bacteria, according to some estimates. When the tiny ecosystem of these bacteria is balanced (meaning the right ratio of good bacteria to bad bacteria are living in harmony on the skin) the skin microbiome protects against invading bacteria, which is essential for healthy, clear skin.

Unfortunately, there are a number of ways the skin microbiota get imbalanced. Harsh soaps kill off the good bacteria or make an inhospitable environment, for example. Infections and allergic reactions might also cause the immune system to attack the microbiome. An unhealthy gut might also cause a chain reaction that harms the skin. Whatever the cause, we know that an unhealthy microbiome leads to skin conditions such as acne, rosacea, eczema, and dry skin. 

How probiotics affect skin health

The basic concept of probiotics is all in the name: They're good bacteria that you apply to the skin or ingest to repopulate your microbiome. Once you apply probiotic skincare products, the bacteria ideally settle in and reproduce there.

Probiotics for the skin can prevent bad bacteria from growing more, by taking up more of the share of resources in your skin's ecosystem. Studies have also shown that certain species of good bacteria actually create antimicrobial substances that kill off the bad bacteria. 

From itchy skin to breakouts: Probiotics and the skin immune system

The immune system knows when bad bacteria are present, and inflammation is its reaction to try to heal from the invading species. Inflammation happens when blood vessels widen in order to make it easier for white blood vessels to kill off microbes and heal any damage. That sounds like a good thing, but in the skin, inflammation often shows up in the form of acne and redness. In some cases of sensitive skin, this results in bad cases of eczema or dermatitis—dry, itchy, flaky skin. When probiotics restore the balance, they put a stop to this inflammatory response

How probiotics help all skin types heal and stay hydrated

Scientists are now discovering how healthy bacteria affect the body in other ways. In the gut, bacteria break down nutrients into molecules that do things like stimulate cell growth in the intestines and send signals to the nervous system. Similarly, in the skin, bacteria break down and trigger a number of processes. 

Studies have found that certain species of bacteria increase the amount of ceramides in the skin, which in turn make up the cells in the natural barrier of the skin. That barrier prevents water from evaporating from the skin and causing dryness. Another species may also stimulate the growth of skin cells in a way that can help heal from damage caused by injury or UV rays from the sun. All this is to say that probiotics enhance the effectiveness of moisturizers by restoring the skin's own natural defense mechanisms. Because fine lines and wrinkles are less visible in well-hydrated skin, probiotics help diminish signs of aging. 

What are the best probiotics for skin?

There is still plenty of research to be done to identify the many species of bacteria in our skin and what roles they play in keeping skin healthy. But some helpful probiotics have already been identified, particularly Lactobacillus and Bifidobacterium species. 

As for potential probiotic side effects in skin, they are rare but may occur in anyone with an immune deficiency. A more common problem is the risk of a sticky mess if you choose the DIY route and make yogurt masks for your face. You might also risk wasting money if you buy an expensive lotion that's improperly packaged or stored in such a way that the probiotics are no longer effective—it's worth seeking out high-quality moisturizers that utilize probiotics properly

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