Psoriasis diet: what to eat, according to the evidence

What is psoriasis, and what can nutrition do?

Psoriasis is a chronic inflammatory skin disease involving the immune system. It appears as red, scaly patches on the elbows, knees, hands, feet, scalp and torso, and often itches or hurts.

A predisposition to psoriasis is inherited. Factors that trigger or worsen it can act on this predisposition, including smoking, alcohol, emotional stress, infections, some medicines, dry cold weather and excess weight. In 2022, around 1.9% of the Spanish population had psoriasis, according to primary care records [3].

It flares up, with better and worse periods, and currently no treatment or diet makes it disappear completely. Dermatology teams treat it with creams, phototherapy, and systemic or biologic medicines. Nutrition can help in two specific areas: weight management when needed, and heart health.

Obesity, high blood pressure, diabetes and high cholesterol are more common among people with psoriasis than in the general population. That is why cardiovascular risk assessment from diagnosis and support with lifestyle habits are recommended [4].

Some people with psoriasis also develop psoriatic arthritis, which inflames the joints and requires rheumatology care. It is often confused with rheumatoid arthritis, which has its own diet guide for rheumatoid arthritis.

Is there a diet for psoriasis?

There is no specific diet, and it is worth saying this up front because many diets circulate. The medical board of the National Psoriasis Foundation reviewed 55 studies and concluded that the evidence on specific foods and nutrients is low quality [1]. According to that review, dietary changes can complement standard medical treatment [1].

One dietary pattern has more support than the others: the Mediterranean diet, the same one described in the anti-inflammatory eating guide. It includes vegetables, fruit, pulses, fish, nuts, wholegrains and extra virgin olive oil.

In a trial in Madrid involving people with mild or moderate psoriasis treated with creams, sixteen weeks of a Mediterranean diet guided by a dietitian-nutritionist reduced disease severity compared with usual dietary advice [2]. It was a small trial at a single hospital. Even so, its findings point in the same direction as the broader evidence.

Can losing weight improve psoriasis?

Yes, if you have excess weight. Of all the ways nutrition can help here, this has the strongest support. The National Psoriasis Foundation review recommends strongly weight loss through a lower-calorie diet for people with overweight or obesity [1].

A later analysis of thirteen trials found that weight-loss interventions reduce plaque severity and improve quality of life [5]. The average weight loss was 6.7 kilos more than in the comparison group [5].

The approach is the usual one: a moderate calorie deficit, protein spread throughout the day, strength training two or more days a week, and changes you can maintain. No crash diets. At Alimmenta, we do not recommend diets below 1,200 kcal a day. Going below that amount requires medical supervision and can lead to nutrient deficiencies. A reasonable pace is half a kilo of fat per week. The full approach is in the guide to losing fat without regaining it.

One important nuance: in the Madrid Mediterranean diet trial, improvement occurred without weight loss [2]. If you do not have excess weight, changing your eating pattern can still make sense.

Example of a day’s menu for people with psoriasis

You do not need a special menu. It is enough to spread meals across the day in a way that follows the guidance above without making things complicated. For example:

• Breakfast: wholemeal bread with tomato and extra virgin olive oil, plus an egg or plain yoghurt with fruit. Coffee or an herbal tea.
• Mid-morning: a piece of fruit and a handful of nuts.
• Lunch: a salad or vegetables to start, lentils with vegetables, and fruit.
• Afternoon snack: plain yoghurt, or a slice of toast with cheese.
• Dinner: pumpkin purée, and mackerel or sardines with potato.

What matters is being able to keep it up. Plan the week, shop with a list, and have two or three ten-minute dinners ready to go, because it can be harder to stick to the plan at dinner. These nine quick dinner ideas work just as well here.

Should you cut out gluten? What about dairy or tomatoes?

This is what we are asked most often in consultations. The National Psoriasis Foundation recommends a gluten-free diet only for people who test positive for gluten sensitivity, and the recommendation is weak [1].

Outside that situation, removing gluten is not indicated. If you suspect coeliac disease, ask your doctor for the blood test before stopping gluten, because removing it distorts the result.

There is not even that level of evidence for removing dairy, tomatoes or other nightshades in psoriasis. The same applies to eggs. AESAN recommends up to four eggs a week for the general population. Up to one a day can also fit into a healthy eating pattern. If you have high cholesterol, at Alimmenta we recommend two or three a week. The cost of removing foods, however, is clear: each food group you cut out makes your diet poorer, more expensive and harder to maintain.

Some people end up with a growing list of foods they have cut out, and social meals become a problem. If that sounds familiar, or eating has become a source of anxiety, talk about it. This is something that can be addressed through nutrition psychology.

Do omega-3, vitamin D or antioxidants help?

For supplements, the evidence is low quality, as it is for other specific nutrients [1]. The only supplement that review recommends, and only weakly, is vitamin D for psoriatic arthritis [1].

A supplement is a short-term support, never the foundation, and should be recommended by your doctor or dietitian-nutritionist after reviewing blood test results. It makes more sense to get omega-3 from fish at least three times a week, prioritising oily fish, than from capsules. Colourful vegetables and fruit provide antioxidants and cost less. If your vitamin D is low, it is treated because it is low.

Do alcohol and smoking make psoriasis worse?

Yes. Both are associated with a worse course of the disease, and they are among the few factors you can act on directly. In consultations, we also see a knock-on effect with alcohol: people who drink often tend to eat less well, with more saturated fat and fewer vegetables and less fruit.

Because cardiovascular risk is already higher with psoriasis, recommendations for dermatologists, rheumatologists and family doctors call for advice on diet, exercise and smoking for everyone with the condition [4].

If you also have COPD, a condition closely linked to smoking, the COPD diet guide explains how to eat.

What mistakes do we see most often in consultations?

Starting with a list of foods to cut out. Many people eventually give up on this approach. Start by adding vegetables, pulses, oily fish, fruit and extra virgin olive oil. Once those habits are in place, consider whether anything needs to be reduced, if anything does.

Expecting food to do what treatment does. No eating plan replaces the treatment prescribed by your dermatology team. Stopping treatment because “you are eating well now” is the costliest mistake of all.

Judging results after a few days. Studies that find improvement last for months: sixteen weeks in the Madrid trial [2] and several months in the weight-loss interventions [5]. If you change your plan every fifteen days, you will not see any change. As our own criterion, try dietary changes for three months before assessing whether they are helping.