Why Probiotics Are Good For Your Skin
Why do my patients keep asking about apple cider vinegar? Why do so many young people drink kombucha?
One reason is probiotics.
It seems as though we're hearing a lot more about probiotics these days. In the refrigerated aisle, I've seen multiple products--yogurt, juice, miso, sauerkraut, kimchi--that loudly announce that they contain probiotics. Products I'd never heard about before-like kefir, a fermented milk beverage, and kombucha, a fermented tea beverage-suddenly seem to be very popular.
One of the reasons they're increasing in popularity is due to research. Multiple research studies have now demonstrated that some probiotics have health benefits. They even appear to promote skin health.
Dermatology researchers have become very interested in probiotic supplements and probiotic foods. That's because a number of clinical trials have suggested that they may help in the treatment of inflammatory skin diseases. The most evidence comes from studies of patients with atopic dermatitis (also known as eczema). In one summary study, researchers combined the results of multiple trials to see if there was any benefit to using probiotics as a part of eczema treatments. In this study, researchers looked specifically at synbiotics. (Chang) Synbiotics are a combination of probiotics and prebiotics. In this summary study, researchers found that synbiotics were helpful in the treatment of atopic dermatitis in adults and children (over the age of 1 year), when used for at least 8 weeks, and when the probiotics combined multiple strains of bacteria.
What are probiotics? And why are they believed to be good for the health of our skin?
Probiotics are defined as live microorganisms (such as bacteria) which, when consumed, provide a health benefit. You may have heard them referred to as "good bacteria". When you buy a carton of yogurt that advertises the presence of "live, active cultures", you're buying probiotics.
Yogurt containing "live, active cultures" is one type of probiotic food
Probiotic foods have been prized in many cultures for centuries. I met a colleague from Czechoslovakia who told me how her grandparents were adamant about eating a daily dose of sauerkraut every day in the winter. Friends from India tell me that when they were growing up, they were told to eat their yogurt every single day because it was good for their them.
Research has now shown that probiotics are indeed important for our health, and studies have started to unravel why that is.
To begin with, studies have shown that having a healthy gut microbiome is important for our overall health. This means that having "good" bacteria and other "good" microbes in our gut is important for our health.
How do you ensure that you have plenty of these good microbes?
The most important factor is that you feed them the right food. This helps you grow and maintain plenty of good microbes in your gut. Prebiotics are defined as foods or substances that promote the growth of good microbes. [Gibson] One of the most common type of prebiotic food category is foods rich in plant fibers. That means plenty of fiber-rich vegetables. [Holscher]
You can also consume these "good" microbes, also known as probiotics. Probiotics are defined as live microorganisms which, when consumed in adequate amounts, provide a health benefit.
Probiotics may come in the form of foods or supplements. For foods, this includes a wide variety of fermented foods in which "live, active cultures" of microbial communities are a key component. This includes fermented dairy products (such as yogurt and kefir), fermented cabbage (such as sauerkraut and kimchi) and others (such as miso, tempeh, vinegar, other pickled vegetables, and other foods).
Probiotic foods include a number of fermented foods in which "live, active cultures" are present
There are a number of commercially available food products also, in which live microbes are added to food products, such as juices and snack bars. There haven't been enough studies on these to know how effective they are, but studies have suggested that they contain a much lower number and diversity of microbes. [scourboutakos]
In terms of probiotic supplements, there's been a lot of research but no definitive answer as to which are best. In the summary study looking at atopic dermatitis, the individual studies used a number of different probiotic supplements. These vary quite a bit in terms of variety and type of microbes, as well as a huge variation in dosage of microbes.
There are still many unanswered questions about probiotic foods and supplements. Can the ingested microbes survive in our gut? (For some, research indicates that they can survive, at least temporarily.) What is the best type and dose? These are areas in which we definitely need more research. While I can't recommend one optimal probiotic supplement, I can definitely recommend ingesting more probiotic foods.
How do probiotics act to help the skin? Research has suggested several ways.
1. First, probiotics help to counter the "bad" bacteria in our guts. [also known as "pathogenic" bacteria] These pathogenic bacteria have been linked to several chronic diseases.
2. Probiotics also are likely to help because they have anti-inflammatory effects. In a study in mice, taking an oral probiotic bacteria helped to calm down T-cell mediated skin inflammation. [Hacini-Rachinel]
3. Probiotic bacteria also produce certain substances, called metabolites, that have effects of their own. In a laboratory study, these metabolites were able to combat the formation of reactive oxygen species. (ROS) [Benson] I've talked about ROS before, because they're a type of free radical, and free radicals have been linked to skin damage.
4. Finally, we know that probiotics help protect the lining of our gut, known as the intestinal epithelium. They've also been shown to help our skin barrier. In one trial, the use of an oral probiotic in human subjects helped improve the function of the skin barrier, and helped reduce skin sensitivity. [Gueniche]
Because of these key features of probiotics, I've included them in my dietary recommendations for healthy skin. One of my main recommendations for healthy skin is to "eat power", meaning focus on eating foods that provide powerful nutrients. That includes a dose of probiotic foods, and it includes a healthy dose of plant fibers (prebiotic foods) to help those good microbes grow and thrive.
Benson, K. F., Redman, K. A., Carter, S. G., Keller, D., Farmer, S., Endres, J. R., & Jensen, G. S. (2012). Probiotic metabolites from Bacillus coagulans GanedenBC30TM support maturation of antigen-presenting cells in vitro. World Journal of Gastroenterology, 18(16), 1875–1883.
Chang YS, Trivedi MK, Jha A, Lin YF, Dimaano L, Garcia-Romero MT. Synbiotics for prevention and treatment of atopic dermatitis: a meta-analysis of randomized clinical trials. JAMA Pediatr. 2016;170(3):236–42
Gibson GR, Scott KP, Rastall RA, Tuohy KM, Hotchkiss A, Dubert-Ferrandon A, Gareau M, Murphy EF, Saulnier D, Loh G. Dietary prebiotics: current status and new definition. Food Sci Technol Bull Funct Foods 2010; 7:1-19
Gueniche, A., Benyacoub, J., Philippe, D., Bastien, P., Kusy, N., Breton, L., … Castiel-Higounenc, I. (2010). Lactobacillus paracasei CNCM I-2116 (ST11) inhibits substance P-induced skin inflammation and accelerates skin barrier function recovery in vitro. European Journal of Dermatology, 20(6), 731–737
Hacini-Rachinel, F., Gheit, H., Le Luduec, J. B., Dif, F., Nancey, S., & Kaiserlian, D. (2009). Oral probiotic control skin inflammation by acting on both effector and regulatory T cells. PLoS ONE, 4(3).
Holscher HD. Dietary fiber and prebiotics and the gastrointestinal microbiota Gut Microbes. 2017; 8(2): 172–184
Scourboutakos MJ, Franco-Arellano B, Murphy SA, Norsen S, Comelli EM, L’Abbe MR. Mismatch between Probiotic Benefits in Trials versus Food Products. Nutrients 2017 Apr; 9(4): 400.
Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.