Home General Health Psoriasis link to gut bacteria

Psoriasis link to gut bacteria

Injections and Syringe. Psoriasis Diagnosis, Medical Concept. Composition of Medicaments

Dysbiosis, a disruption of the gut microbiome with loss of good bacteria and increases in pathogens has now been clearly established as causal in skin psoriasis.

Psoriasis is an increasingly common and chronic dermatological disease.  It was traditionally viewed a systemic inflammatory disorder with anti-inflammatory steroids routinely prescribed. And immunological and genetic studies confirmed IL-17 and IL-23 as key drivers in inflammation and its development (1).

It is not simply one disease – there are five classifications of psoriasis:

  • Plaque-dominated psoriasis vulgaris,
  • Punctate (droplet) or hemorrhagic psoriasis,
  • Pustular psoriasis (represented by sterile pustules),
  • Arthritic psoriasis (with arthritis as the main manifestation), and
  • Erythrodermic psoriasis with systemic involvement, (psoriasis vulgaris is 90% of cases)

However, it has become increasingly clear that there is a gut-skin axis, with changes to the microbiome of the skin reflective of changes to the gut microbiome. Gut bacterial changes can lead to metabolites and even pathogens ‘leaking’ through the gut wall and causing disturbances and inflammation in the skin. However, a meta-analysis in 2020 of eight studies (2) showed that there is still much to learn.

Butyrate, a short chain fatty acid, is known to heal the gut wall and reduce inflammation. This may be an important first step in controlling the disease.

One of the first studies we covered – a 2015 study from researchers at New York Hospital (3) – showed that low levels of beneficial bacteria such as Coprococcus species, and Akkermansia, Ruminococcus and Pseudobutyrivibrio were found in patients with Psoriatic Arthritis, (PsA) and skin psoriasis, when compared with people without the disease. The researchers likened the changes in the gut microbiome to those seen in IBS. When we published these results, two separate dermatologists in New York each wrote telling us that we were wrong!

“Supernatants of fecal samples from patients revealed an increase in sIgA levels and decrease in RANKL levels. Analysis of fatty acids revealed low fecal quantities of hexanoate and heptanoate in both patients with Psoriasis arthritis and patients with psoriasis,” states the abstract. NB: sIgA levels increase when more pathogens are present; hexanoate and heptanoate are anti-inflammatory fatty acids.

Of course, a healthy gut microbiome and the gut bacteria present are particularly susceptible to drugs, antibiotics, stress, smoking, infection, poor diet, alcohol, food poisoning and chemical toxins. All of these will disrupt the microbiome. For example, many people find their psoriasis becomes worse in stressful situations.

Other studies showed environmental toxins and particularly Dioxins might be causal.

Go to: Common chemicals link to psoriasis

Chris Woollams, former Oxford University Biochemist said, “We are seeing this situation time and time again. Where doctors didn’t understand a disease fully they called it an inflammatory autoimmune disease. But there’s no such thing really. For example, consuming certain foods (such as EV olive oil, fish oils, walnuts, avocado, berries) produces higher numbers of bacteria in the gut that make anti-inflammatory compounds; whereas consuming trans fat, refined foods and processed, high salt, foods increases the numbers of bacteria producing inflammatory molecules. Having high levels of yeasts in the gut can cause damage to the gut wall and so on.  If good bacteria are missing and/or there are pathogens around, you can produce an inflammatory immune response. That’s what is happening here.”

About 5 per cent of the population are thought to suffer from Psoriasis, which at one point was even, wrongly, thought to be largely genetic. According to Dr Jose Scher of New York Hospital, if a person has skin psoriasis, there is a 20-30% chance they will develop psoriatic arthritis.

One issue with psoriasis is that it recurs. This is a classic occurrence with a damaged microbiome – loss of good bacteria fails to keep certain pathogens under control. A review of psoriasis and the microbiome (4) referenced a link between psoriasis and Chrohn’s disease and ulcerative colitis. Another study showed women (but not men) were more likely to develop colorectal cancer if they had psoriasis.

In a 2021 review on infection-provoked psoriasis (5), the researchers listed pathogens, such as streptococci and staphylococci as causal factors; fungal pathogens, such as Candida and Malassezia; viruses such as human immunodeficiency virus (HIV), hepatitis C virus infection and human papillomavirus (HPV).  Even recently, other pathogens, such as Helicobacter pylori, Zika virus and scabies, have been shown to have the potential to trigger psoriasis.

If you have psoriasis and/or eczema, start your healing programme by fixing your gut.

Go to: Heal your Gut; Heal your Body



  1. Therapeutics targeting the IL-23 and IL-17 pathway in psoriasis. Ghoreschi, K. et al.Lancet 2021; 397, 754–766. 
  2. Gut Microbiome in Psoriasis: An Updated Review; Mariusz Sikora et al; Pathogens. 2020 Jun; 9(6): 463.
  3. Decreased bacterial diversity characterizes the altered gut microbiota in patients with psoriatic arthritis, resembling dysbiosis in inflammatory bowel disease; Jose U Scher et al; is Rheumatol, 2015 Jan;67(1):128-39.
  4. Advances in psoriasis and gut microorganisms with co-metabolites; Qiushuang Zhu et al; Front. Microbiol., 16 November 2023 
  5. Infection-provoked psoriasis: Induced or aggravated (Review); Yan Teng et al; Exp Ther Med. 2021 Jun; 21(6): 567.