A lot of you may have read about probiotics before or are at least likely familiar with them when it comes to eating yogurt. Most of us know that they can help improve our gut, but did you know that they may also help with our skin?
Just briefly, there is evidence that probiotics can help prevent eczema from developing in newborns, may help treat eczema in adults, may help reduce acne, and may help with wound healing. Today, we’re going to look more at how probiotics can also help with another common rash called psoriasis.
Psoriasis is a common rash that presents as pink, scaly thickened areas often on the elbows, knees, and scalp, though it can affect most areas of the body, including the genital area, under the breasts and armpits and even the palms and soles. It’s associated with increased risk of joint involvement, called psoriatic arthritis, but also other conditions including inflammatory bowel disease (where you can get bloody diarrhea), diabetes, high cholesterol and even heart disease. There are a number of factors that are thought to play into why we get psoriasis, including genetics, infections, and immune factors. The question with probiotics is, does our gut bacteria play a role too? Or if we improved our gut bacteria, does it help treat psoriasis?
The answer is that it might!
There are at least three randomized controlled studies that looked at whether probiotics can help with psoriasis. One study out of Spain looked at 90 adults with psoriasis; half were given a probiotic pill once daily that contained 3 probiotics called Bifidobacterium longum, B lactis, and Lactobacillus rhamnosus, and the other half were given a sugar pill. They selected these probiotics because two of them may have antioxidant properties (B lactis and L rhamnosus) while the third, B longum, has been shown to be anti-inflammatory. Both groups could use topical steroids and vitamin D creams too. After 12 weeks, the individuals that got the probiotics had a better response and showed more improvement in their skin; 67% of them were able to get their skin at least 75% clear as compared to only 42% of people that got the sugar pill. Further, those who took the probiotics also had lower need to continue the topical prescriptions. Even more interesting, 6 months after taking the probiotics, those that took them were found to have a lower risk of relapsing with their psoriasis. The probiotics were well tolerated; no one stopped the study early.
Was the improvement from an actual change in the gut flora? It seems that this is likely, because the authors then looked at composition of gut flora and found that it had in fact changed with probiotic use.
A second randomized controlled trial from China looked at 50 adults taking a probiotic supplement 2-3 times/day in combination with a prescription pill called Acitretin for 12 weeks vs a sugar pill together with Acitretin. Once again, more improvement was seen in those that were taking the probiotics than those that were not. Of note, though there was some overlap with which specific probiotics were used in this study as compared to the first study, they were not the exact same combination, thus making it hard to conclude which would be the best to take. Those used here included Bifidobactetrium, lactobacillus, Enterococcus and Bacillus.
The third randomized controlled trial was a study done in Ireland, and this study showed that with a probiotic, called Bifidobacterium infantis, used for 8 weeks in adults allowed for reduced inflammation that otherwise contributes to psoriasis, particularly when looking at levels of a molecule called TNFa.
Similar improvement has also been seen in animal studies. There are at least three studies done in mice that showed that levels of inflammatory markers that typically cause psoriasis (called the TH17 and TH22 pathways) were reduced after using probiotics for 6 weeks. Further, skin lesions and their thickness in these mice studies also improved. Unfortunately, just like in the human studies, there was some variability in which probiotics were used, thus making it hard to conclude which one is best.
Though these were small studies, it does seem that probiotics may benefit patients with psoriasis, even if they’re otherwise being treated with medical therapies. Why would this be?
Well, studies show that humans with psoriasis have lower gut diversity in terms of their bacteria (as do patients with inflammatory bowel disease, which is sometimes increased in psoriasis patients). This can become a problem, because normally the good bacteria in our gut can actually help lower inflammation by increasing what are called Treg cells and reducing inflammatory pathways, like TH1 and TH2 pathways. The good bacteria ferment fiber, producing short chain fatty acids, and these also maintain our normal intestinal barrier and are anti-inflammatory. Psoriasis patients have less short chain fatty acids in their stools, or poop, which reflects that they have less anti-inflammatory activity and ability to modulate their immune system because of their altered gut bacteria.
In addition to this, the altered ratio of bacteria leads to more inflammation at baseline, which damages the intestinal barrier allowing bacteria and their metabolites to go into the blood stream, leading to more systemic inflammation which could in turn aggravate psoriasis.
Thus, if we restore the good bacteria with probiotics, we are potentially increasing the body’s ability to modulate your immune system, decrease inflammation that normally contributes to psoriasis, and maintain a healthy gut, preventing bacteria from being able to cause a widespread systemic inflammatory response.
Though the studies are early, you can see that starting a probiotic may help you if you have psoriasis, even if you’re on prescription treatments for your psoriasis. More studies are currently in process, including one looking at Lactobacillus in patients with moderate plaque psoriasis (phase 2 study); hopefully these studies will define which probiotics are best. For now, you could consider starting a probiotic supplement or even just adding a serving or two of yogurt, which contains a variety probiotics, to your diet each day, or alternatively, trying Kefir or even kombucha. If you’re choosing yogurt route, I would choose plain yogurt rather than flavored, as yogurts otherwise tend to have a lot of hidden sugar. Or, if you’re going to choose kefir or kombucha, make sure to choose one low in sugar. After all, we want to avoid a lot of sugar to lower our risk of being overweight or getting diabetes (or for that matter, acne! As studies show that sugar worsens acne too).
References
Soung J. Making the Case For Probiotics in psoriasis care. Practical Dermatology 2022: 51-52.
Zeng L et al. The Effectiveness and Safety of probiotic supplements for psoriasis: a systematic review and meta-analysis of randomized controlled trials and preclinical trials. Journal of Immunology research 2021.