Eczema is a general term for rash-like skin conditions with atopic dermatitis being the most common form. Atopic dermatitis is a chronic inflammatory skin disease characterised by itching and recurrent eczema patches. Up to 20 percent of children can be affected by atopic dermatitis, but even in adults, it is far from uncommon with prevalence rates of between 1 and 3 percent. One growing area of study in the cause and treatment of atopic dermatitis is the role of the gut and skin microbiome through its effects on our immune system. One area of interest is the role of probiotics in treating eczema. And while much of the research here has been on infants and children, there has been a growing evidence base for adults as well. And that’s what I’ll be exploring in today’s podcast.
Eczema is a general term for rash-like skin conditions. There are many different types of eczema, but the most common type is called atopic dermatitis. The word ‘atopic’ here refers to an allergy. Atopic dermatitis presents as dry, itchy and inflamed skin which often begins before age 5 and can continue into the teen and adult years.
The symptoms of eczema are explained by a person’s inability to repair damage to the skin barrier. Once the skin barrier is compromised, moisture leaves the skin, leaving the skin dry and scaly. Environmental allergens can also enter the skin and activate the immune system, producing inflammation that makes the skin red and itchy.
The prevalence of atopic dermatitis has shown a recent 2–3- fold increase in developed countries with the prevalence of 10–20 percent in children and 1 to 3 percent in adults over the last 30 years. Studies point to environmental factors including irritants and allergens that trigger the immune system as contributing to the rise in the number of people with eczema.
A lot is going on with the immune system here as people with atopic dermatitis are at higher risk of developing food allergies, hay fever and asthma.
There is also some evidence that the gut microbiome, through its effects on the immune system, may be involved in the development of atopic dermatitis. Adding to this connection, you also see imbalances in both the skin and intestinal microflora in people with atopic dermatitis. For instance, on the skin in people with atopic dermatitis, there is increased colonisation of Staphylococcus aureus and a reduced microbiome diversity. While in the gut there is a decline of short-chain fatty acid-producing bacteria, such as Bifidobacterium.
That all points to the gut microbiome as one of the mediators of the immune response seen in atopic dermatitis. This opens the door to exploring how regulating the gut microbiome through supplementation with probiotics could be useful treatment in atopic dermatitis.
Previous studies have shown the utility of probiotics for the treatment and prevention of atopic dermatitis and they appear to do this through inhibition of allergen-specific T helper 2 cells. Although when the research has been grouped together, the story is one of divergent results in diverse population groups with different probiotic strains used - making it difficult to draw definite conclusions. And a lot of that work has focused on the efficacy of probiotic supplementation on atopic dermatitis in children which of course is the largest group to study. But there hasn’t been as much work done in adults.
Children and adults are different groups and their microbiomes can differ between them because of the development stage in life they are in. So, how does the evidence stack up for an effect of probiotic supplementation in adults with atopic dermatitis? That was the topic of a recently published systematic review and meta-analysis.
The review included 9 randomised controlled trials that examined the effect of supplementation with probiotics, compared with placebo, on atopic dermatitis severity and quality of life in a total of 402 men and women aged between 16 and 60 with atopic dermatitis. A range of different preparations of probiotics was used with most based on the Lactobacillus and Bifidobacterium genera. The duration of the interventions ranged from 4 to 24 weeks. And I’ll link to the study in the show notes. https://pubmed.ncbi.nlm.nih.gov/35670101
So, what were the results? Things looked pretty good with probiotic supplementation reducing the severity of atopic dermatitis in the short term of 4 weeks and longer term of 8 weeks or more. Probiotic supplementation also improved the quality of life in the long term to a moderate degree although there were not a lot of studies that assessed the quality of life so the results here were quite variable.
A mixture of the strains of Lactobacillus salivarius LS01 and Bifidobacterium breve BR03 had the highest probability of being the best probiotic formulation for atopic dermatitis in both the short and the long term. Probiotics are commonly used to restore gut microbial function with those of the Lactobacillus and Bifidobacterium genera being frequently administered. So, it was positive to see a good therapeutic effect on adult atopic dermatitis from a mixture of these two bacteria from the present study. And it was also good to see that most of the studies were rated as high quality.
As to how probiotics could be working here, that may be attributed to the regulation of the immune system, competitive suppression of pathogenic microbes, modification of pathogenic toxins or host products, and enhancement of skin barrier function. Further, probiotics are known to reduce the pro-inflammatory response which would assist with the condition.
So, let’s wrap all this up. Despite the positive results from this review, everyone’s mileage who uses probiotics varies so anyone considering trialling the types of probiotic strains used in this study for atopic dermatitis should keep this in mind. For example, the effect of probiotic supplementation can be closely associated with the condition of a person’s baseline gut microbiota which might contribute to the final effect of the probiotic. So, while this podcast was about probiotics, longer-term when it comes to good gut health, it is all about having plenty of prebiotic fibre from a variety of plant foods to help feed and promote the growth of the beneficial bacteria in the first place.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.