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What is psoriasis?


Learn all about psoriasis, a chronic inflammatory disease, including common symptoms, treatments, and which dietary and lifestyle factors play a part.

Affecting approximately 2% of the UK population, psoriasis is a chronic inflammatory disease, the exact cause of which remains unclear. Nutritionist Kerry Torrens explores what we know about this complex condition.


What is psoriasis?

Psoriasis is an inflammatory immune condition that affects the skin and sometimes the joints. The name is derived from the Greek work psora, to itch. Those with psoriasis experience a rapid skin turnover, with cells taking just a few days to renew rather than the normal 21-28 days. This causes cells to accumulate on the surface of the skin which as a result become scaly, itchy and red.

Psoriasis occurs on any part of the body including the scalp, hands and feet. There are a number of different types of the disease with the amount of skin affected varying dependent on severity. Psoriasis may be associated with other inflammatory diseases, including inflammatory bowel disease.

Occurring at any age, psoriasis is more likely to appear at two life stages – these are the late teens to early thirties and between 50 and 60.

How is it diagnosed?

Your GP may diagnose the condition based on the appearance of your skin, although in some cases a skin sample may be taken and sent away for analysis. This allows the exact type of psoriasis to be diagnosed and ensures other conditions are ruled out.

What causes psoriasis?

Studies suggest the changes that cause psoriasis trigger immune cells called T cells, which respond as if they were fighting an infection or healing a wound. This sets off an inflammatory process.

Like other auto-immune conditions, flare ups are often triggered by stress, anxiety and hormonal fluctuations, as well as other life time events. There may also be a genetic predisposition, but this is not relevant for all. Environmental triggers play a key part and include alcohol, medication, stress, smoking, being overweight as well as strep-related throat infections. Managing the triggers relevant for you through lifestyle changes may prove helpful.

What else may play a part?

Low levels of the sunshine vitamin vitamin D is thought to weaken the body’s ability to keep the skin healthy. Although some vitamin D is obtained via our diets, from foods such as egg yolks, oily fish, fortified spreads, the majority is made by the action of sunlight on our skin. Those with psoriasis have an accumulation of dead cells on the surface of the skin and are more likely to cover up, potentially reducing the amount of UVB light the skin absorbs. This reduces the amount of vitamin D the skin produces and in turn impairs how the skin regulates new cell production. Vitamin D has been found to regulate the immune system, with low levels increasing the susceptibility to auto-immune disease.

Recent research also supports the role our gut, and the many microbes that live there (the gut microbiota), plays in our immune function. Gut dysbiosis involves an imbalance in the microbiota which, over time, may have a negative effect on the skin and how it functions. Interestingly, those with psoriasis appear to have a less diverse mix of gut microbes. Studies which have looked at the use of probiotic supplementation to modify the gut microbiota are limited in number, but look promising.

What are the treatments for psoriasis?

There is no cure for psoriasis, but the good news is that the condition may be managed, although finding the right treatment may take trial and error. The first treatment you are likely to be offered is a topical one such as a gel, cream or ointment which is applied to the skin. The product chosen will have an active ingredient. One example is a vitamin D based gel or ointment, which works by promoting normal cell growth and skin turnover.

If topical treatments are insufficient or your psoriasis is more severe, then phototherapy, which involves exposing the skin to a specific type of UV light, may be helpful. Other treatments include systemic therapies such as retinoids.

Can diet help psoriasis?

Salmon, walnuts, avocado and olive oil

Anecdotal reports suggest eliminating some foods may be helpful, however, to date there is limited quality data to support this. If you think this may be relevant to you keeping a detailed food diary and working with a registered dietitian may help you identify possible problem foods.

Changes to your diet alone are unlikely to be the answer to your psoriasis, but may help support first line treatments. For example, adopting a Mediterranean diet has been shown to help reduce inflammatory processes. A Mediterranean diet is characteristically rich in fish, including the omega-3 oily variety, nuts, seeds, wholegrains and vegetables.

There are a number of nutrients which are beneficial for the health of the skin. These include vitamins A, C and D, omega-3 fatty acids and minerals such as zinc and selenium. Studies examining diets rich in these nutrients, or supplemented with them, suggest they may be supportive to other first line treatments.

What can I do to help myself?

If you have psoriasis keeping fit, maintaining a healthy weight and adopting a positive mental outlook as well as eating a balanced diet will help support your management of the condition. 

Maintaining regular contact with your health-care team, such as GP or dermatologist, and taking your treatment as prescribed is important for controlling flare-ups.

Now read

Am I getting enough vitamin D?
What is an anti-inflammatory diet?
Eat your way to fabulous skin
How to eat for great skin – dietary fats
How to eat for great skin – digestion

This page was published on 6th July 2020.

Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.


All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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