Psoriasis and the Gut-Skin Axis
What is Psoriasis?
Red, inflamed patches of skin topped with silvery scales are characteristic of psoriasis. The chronically inflamed lesions commonly appear on the elbows, knees and scalp and less commonly on fingernails, ears and belly (around the tummy button). However, they can occur on any part of the body. Symptoms can include mild itching, but can be severe in some people . Irritation, burning and stinging are also common. 
Psoriasis can occur at any age but it tends to appear more between the ages of 15-25 and 50-60 years. Approximately 3% of people are affected  and it is generally considered to be an incurable, lifelong condition .
People with psoriasis are also more likely to suffer several other conditions including inflammatory bowel disease (IBD), Coeliac disease, obesity, metabolic syndrome, heart disease, gout, liver disease, Type 2 diabetes, eye inflammation (uveitis), and depression. [1,11]
What causes Psoriasis?
Psoriasis is considered a systemic autoimmune inflammatory condition [4,11], yet no associated antibody has ever been identified. The presence of chemical messengers called cytokines leads to inflammation, causing overgrowth of the skin cells. Normally, skin cells travel rapidly from the lower layers of the skin to the surface, die and are shed within about 6 weeks. When these cells cannot be shed quickly enough, they build up, forming the recognisable silvery scaly plaques of the condition. Psoriasis commonly appears in related people – about one third of sufferers have a family member with it. 
Are there Different Forms of Psoriasis?
There are four different types, including:
- Chronic plaque: This is the most common, and is about 90% of cases 
- Guttate: This is commonly triggered by a viral or bacterial infection (most commonly Streptococcus),
- Flexural: (sometimes called inverse psoriasis) tends to appear where skin meets skin, such as under breasts and in the genital region .
- Pustular: Less common and has several different subtypes.
- Erythrodermic: This type accounts for about 2-3% of all cases, and is accompanied by fever, chills, and headache.
Psoriatic arthritis is joint inflammation, which affects about 15% of those with the skin form .
Psoriasis sometimes also affects the nails (of fingers and /or toes), causing them to have a pitted appearance, such as shown in the image here.
Nail involvement may affect 40-45% of those with any skin form of the disease, and is more common (up to 90%) in those with the arthritic form. Other nail changes include it bleeding under the nail, whitening, thickening under the nail, crumbling and loosening or separation of it.
Image by Seenms -CC BY-SA 3.0, https://commons.wikimedia.org
How is the Gut Involved?
The gut is home to a microbial population of about the same number of cells as the human body. The gut microbiome has many functions, including protection against pathogens, breaking down food components, influencing the immune system, maintaining the health of the intestinal barrier, and producing short chain fatty acids that provide fuel for the cells lining the intestines [5,12]. The gut microbiome is also involved in the development of immune cells that have been implicated in psoriasis.
Several studies have investigated the gut microbiome in people with psoriasis and found that it is significantly altered, although results varied in the kinds of alterations found [2,4,12,14]. Case reports of improvement of psoriasis following faecal microbial transplant (FMT) increase the strength of the role of gut bacteria .
High diversity of the gut microbiota is generally accepted as desirable. Psoriasis appears to be associated with decreased diversity, and – interestingly -lower diversity is seen in those with moderate to severe compared to those with mild symptoms .
Dysbiosis or imbalance of the gut microbiome may lead to “leaky gut” (intestinal hyperpermeability). This increases the risk of the movement of bacteria (and their by-products) into the systemic circulation. This may be involved in triggering psoriasis by promoting chronic systemic inflammation [4,12] and exacerbating the condition. The presence of these components in the blood may activate the immune response and skin cells, starting the inflammatory cascade .
Additionally, microscopic lesions and inflammatory changes have been seen on the protective mucous membrane lining the bowel in people with active psoriasis and psoriatic arthritis – even without any noticeable bowel symptoms. 
Interestingly, microbial dysbiosis (a shift away from healthy balance) is also implicated in many of the other conditions associated with psoriasis, including digestive diseases, diabetes, obesity, metabolic syndrome, Coeliac disease, and mental illness.  You can do a stool microbiome test – order here.
The Liver in Psoriasis.
Psoriasis sufferers are more likely to have concurrent liver disease than the general population. Up to 50% of psoriasis sufferers have non-alcoholic fatty liver disease (NAFLD) and the more severe the psoriasis, the more likely the individual is to have NAFLD. Fat storage in the liver leads to an increased risk of cirrhosis, where scar tissue forms. Cirrhosis of the liver has been reported in 13% of psoriasis patients. As well as NAFLD, psoriasis may also be associated with inflammation and damage to the bile ducts.
7 Tips to Support Gut Health in Psoriasis
- Living microorganisms that confer a health benefit when consumed (WHO). Preliminary trials have been carried out using probiotics for psoriasis with encouraging results. However, researchers state that more studies are needed to confirm the results [2,10].
- Reduce or eliminate alcohol.
- Alcohol can play a role in the development of the problem, and in aggravating the symptoms. This may be related to the impact of alcohol on the gut including unfavourable changes in the microbiome, inflammatory effects, and its role in increasing intestinal permeability (leaky gut).
- Eating a high fibre, varied diet to help improve microbiome diversity.
- Avoiding hot spices such as chili and black pepper.
- These can contribute to leaky gut
- Bile acid supplementation.
- Supplemental bile acids were given to 500 participants in one study, and 78% of them reported improvements. The study author’s theory is that the bile acids break up bacterial toxins in the gut, reducing their absorption
- This is a natural compound, found in high amounts in onions, apples, citrus fruit, and buckwheat. Quercetin has antioxidant and anti-inflammatory effects and may improve intestinal barrier function to reduce absorption of bacterial toxins.
- St Mary’s thistle
- A fabulous herb that may help to improve liver function 
Get to Know Your Gut
Knowing your microbial profile may be helpful to identify pathogens (or potential pathogens) and patterns of dysbiosis. Armed with this information, your practitioner can support you with diet and nutritional (and perhaps herbal) interventions to help correct imbalances at the level of the gut.
To determine the role of intestinal hyperpermeability, we recommend conducting the lactulose-mannitol test.
To get started on restoring your skin and saying goodbye to psoriasis, book an appointment with Janine. She will take a comprehensive health history and support you on a healing journey.
- BPAC NZ. Chronic plaque psoriasis: An overview of treatment in primary care. 2017, https://bpac.org.nz/2017/docs/psoriasis-1.pdf
- Chen, G., et al. Gut–Brain–Skin Axis in Psoriasis: A Review. Dermatology and Therapy, 2021, 11(1), 25–38. https://doi.org/10.1007/s13555-020-00466-9
- Chiricozzi, A. Psoriasis [Podcast]. BMJ Best Practice. 2020 https://soundcloud.com/bmjpodcasts/nephrolithiasis?in=bmjpodcasts/sets/bmj-
- Codoñer, F. M., et al. Gut microbial composition in patients with psoriasis. Scientific Reports, 2018, 8(1), 1–7. https://doi.org/10.1038/s41598-018-22125-y
- De Pessemier, B., et al. Gut – skin axis : Current knowledge of the interrelationship between microbial dysbiosis and skin conditions. Microorganisms, 2021 9(2), 1–34. https://doi.org/10.3390/microorganisms9020353
- Dei-Cas, I., et al. Metagenomic analysis of gut microbiota in non-treated plaque psoriasis patients stratified by disease severity: development of a new Psoriasis-Microbiome Index. Scientific Reports, 2020, 10(1), 1–11. https://doi.org/10.1038/s41598-020-69537-3
- Eddy, L. Liver problems and psoriasis. 2020. DermNet. https://dermnetnz.org/topics/liver-problems-and-psoriasis
- Ely, P. H. Is psoriasis a bowel disease? Successful treatment with bile acids and bioflavonoids suggests it is. Clinics in Dermatology, 2018. 36(3), 376–389. https://doi.org/10.1016/j.clindermatol.2018.03.011
- Losurdo, G., et al. The influence of small intestinal bacterial overgrowth in digestive and extra-intestinal disorders. Int J Mol Sci 2020, 21(10), 1–16. https://doi.org/10.3390/ijms21103531
- Navarro‐lópez, V.,et al. Probiotics in the therapeutic arsenal of dermatologists. Microorganisms, 2021, 9(7). https://doi.org/10.3390/microorganisms9071513
- Oakley, A., Jones, C., & Gupta, M. . Psoriasis. 2020 https://dermnetnz.org/topics/psoriasis
- Polak, K., et al. Psoriasis and Gut Microbiome — Current State of Art. Int J Mol Sci, 2021, https://doi.org/https://doi.org/10.3390/ijms22094529
- Scarpa, R., et al., Microscopic inflammatory changes in colon of patients with both active psoriasis and psoriatic arthritis without bowel symptoms. J Rheum, 2020, 27(5), 1241–1246. https://pubmed.ncbi.nlm.nih.gov/10813294/
- Xiao, S., et al. Deciphering gut microbiota dysbiosis and corresponding genetic and metabolic dysregulation in psoriasis patients using metagenomics sequencing. Front Cell Infect Microbio, 2021, 11(April), 1–12. https://doi.org/10.3389/fcimb.2021.605825
- Jiadong Yu, et. al., Pathogenesis, multi-omics research, and clinical treatment of psoriasis, Journal of Autoimmunity,2022, https://doi.org/10.1016/j.jaut.2022.102916.