The Microbiome in Psoriasis: Role of Foods and Herbs

What is the Gut Microbiome?

The “gut microbiome” refers to the thousands of different species composed of trillions of organisms and their byproducts that live in our intestines. Ideally, these organisms live in homeostasis (in healthy balance) with the host (us) to aid in digestion, produce vitamins, strengthen our immune system, and help prevent harmful bacteria from causing disease. However, disruption in these peaceful communities of “gut bugs” can potentially lead to inflammation, disease, GI distress, and even manifest adverse skin effects. The gut microbiome of every individual not only varies widely but can also change with travel and aging. An important research niche investigation shows dietary patterns play a prominent role in significantly altering the types of species that live in our gut.^[1]

The Link Between the Gut and Skin

How exactly the gut microbiome plays a role in skin health is a rapidly growing area of dermatological research. Researchers often refer to this association as the skin-gut axis: the relationship between skin diseases and the complex communication network of the gut, nervous system, hormones, and the immune system.^[2] Links have already been established between irritable bowel disease and characteristic rashes, celiac disease and dermatitis herpetiformis,^[3] as well as certain dietary patterns in acne patients.^[4]

How does the Gut Microbiome Change in Psoriasis?

Although research is still scarce, investigators are researching whether people who suffer from psoriasis and/or psoriatic arthritis have altered gut microbiomes as compared to those without psoriasis. For instance, researchers have shown that people with psoriasis and psoriatic arthritis have a significantly “less diverse” microbiome than healthy controls. This means healthy people have a greater number of different species of gut bacteria than people with psoriasis.^[5] In another study, psoriasis patients exhibited a significantly lower count of certain groups of gut bacteria, including Coprococcus, Ruminoccocus, and Akkermansia, which have also been shown to be reduced in patients with Crohn’s disease._^[6] Researchers hypothesize that a disrupted gut microbiome may lead to an exaggerated immune response and increased disease severity in susceptible individuals.^[7] While these early findings are intriguing, further research is needed to determine how these changes may or may not influence psoriasis. 

The Role of Foods in Psoriasis

Although many patients with psoriasis turn to lifestyle and diet changes to alleviate symptoms in psoriasis, official dietary guidelines for psoriasis patients don’t exist. However, several clinical studies have shown that certain foods and dietary factors appear to worsen psoriasis symptoms. Certain studies have demonstrated a link between alcohol consumption and an increased risk for psoriasis, with some studies linking alcohol to a decrease in treatment efficacy.^[8-11] In people with celiac-specific antibodies, it is believed that a gluten-free diet may improve symptoms of psoriasis.^[12,13] One study showed those patients who followed a diet rich in fresh fruits and vegetables and who avoided meat and refined carbohydrates had a significant reduction in psoriasis severity.^[14] These associations between certain foods and psoriasis symptoms suggest a possible link between diet and disease pathogenesis and further supports the importance of gut health.

Foods and Herbs that May Alter the Gut Microbiome

If psoriasis is associated with a reduction in the diversity of the gut microbiome, then perhaps an increase in diversity would be associated with improvement in symptoms. Unfortunately, this hypothesis has never been tested in a clinical trial in patients with psoriasis. However, certain dietary factors have been shown to increase the diversity of the gut microbiome and potentially improve overall health.

Scientists have shown how the bacterial species in our gut can change after just 2 days of switching from an animal-based diet to a plant-based diet and vice-versa.^[15] More detailed discussions of helpful foods for the microbiome can be found here, and harmful foods can be found here.

Fermented foods containing probiotics, such as Kefir, Kombucha, Sauerkraut, and yogurt, as well as probiotic supplements, can help diversify the microbiome and promote a healthier gut.^[16-18] High fiber foods, such as vegetables, berries, seeds, and whole grains, contain an abundance of prebiotics, which have been shown to promote gut microbiome diversity and reduce gut inflammation.^[19] 

Beans, unripe bananas, yams, cooled potatoes, and rice contain “resistant starch,” which is a type of fiber that cannot be absorbed by the intestines. These resistant starches are metabolized by our gut microbiota to produce beneficial fatty acids promoting gut homeostasis.^[20] 

Although research is limited regarding the role of certain herbs on the microbiome, curcumin (a component found in the spice turmeric) has been shown to alter the diversity of the microbiome.^[21] A clinical study demonstrated that oral curcumin supplementation for 12 weeks significantly decreased the severity of symptoms and inflammatory blood markers of people with psoriasis.^[22]

Food and Gut Health in Psoriasis

Psoriasis is a chronic, relapsing disease notoriously difficult to treat. The gut-skin connection is a significant area of research that exemplifies the importance of dietary patterns in people with psoriasis.

Understanding how the gut microbiome may influence symptoms in psoriasis is important because it may provide new avenues for treatment. At this time, the dermatological community doesn’t possess adequate research that provides definitive answers about the links between diet, the gut microbiome, and psoriasis pathogenesis. However, early research is promising and may jump start a commitment to healthier eating.

Psoriasis is caused by a range of contributing factors, and is often accompanied by frustration, mental illness in the form of depression, and physical discomfort. It is important to consider gut health and the possible contribution of dietary patterns to symptoms.