Psoriasis: What diet should be adopted to reduce symptoms?

The psoriasis is a systemic and chronic inflammatory skin eruption. It presents itself as red and thick plaques that flake off. Psoriasis is characterized by an excessive renewal and accumulation of epidermal cells, leading to a local inflammation. This disease primarily affects adults, with a peak onset generally between the ages of 20 and 40.

Histological analyses show an increase in the thickness of the epidermis (acanthosis) and incomplete differentiation of keratinocytes (parakeratosis).Its manifestation is triggered by the combination of several risk factors. These include the immune system, genetic predisposition, and environmental factors. The skin symptoms of psoriasis can affect any area of the body, from the ears to the tongue, including the genital areas. However, the scaly plaques are generally located on the scalp, elbows, and knees. They are sometimes accompanied by a rheumatism.

Adopting a healthy and appropriate diet helps individuals with psoriasis to alleviate symptoms. To do this, each food contributes its specific effect:

• Foods rich in fiber (brown rice, whole grain bread, whole wheat, oats) optimize the composition of the gut flora while reducing intestinal permeability. They reduce inflammation by down-regulating plasma inflammatory markers such as C-reactive protein (CRP), IL-6, or TNF-α. This is explained by the fact that these dietary fibers, once fermented, produce short-chain fatty acids that promote the activity of T lymphocytes;

• Foods rich in Vitamin B12 (fish/crustaceans): This vitamin suppresses the activation of NF-κB induced by ROS and the NF-κB-dependent production of inflammatory cytokines by inactivating NADPH oxidase;

• Foods containing Vitamin A : Retinoic acid, the most acidic form of Vitamin A, has a beneficial effect in soothing psoriasis. It inhibits the development of Th17 lymphocytes by suppressing IL-6Rα and IL-23R.

The development of psoriasis can be attributed to stress and anxiety. If this is your situation, foods rich in and containing magnesium are particularly recommended for you. They help to overcome fatigue and combat stress. For instance, whole grains, dried fruits, and chocolate are beneficial to the body.

While some foods can help slow down the development of psoriasis, others can exacerbate the symptoms. Here is a list of foods to avoid if you are prone to this chronic skin disease:

• Gluten

Celiac disease is an inflammatory enteropathy caused by an immune response to the protein gliadin, found in gluten-containing foods such as wheat. Several studies have reported an association between psoriasis and celiac disease, including a threefold increased risk of celiac disease in patients with psoriasis in a 2017 meta-analysis. This correlation may be explained by the fact that Th1 cytokines are involved in the pathogenesis of both conditions. These cytokines tend to produce pro-inflammatory responses.

• Alcohol

Alcohol should be avoided in individuals with psoriasis as it releases pro-inflammatory compounds, known as cytokines. Alcohol also triggers the proliferation of keratinocytes by increasing the levels of integrin α5, KGFR, and cyclin D1, which are characteristic transcripts of keratinocytes.

• Sugar

Excessive sugar consumption promotes the differentiation of Th17 lymphocytes by activating TGF-β. This will enhance the production of IL-17 cytokines, one of the main causes of psoriasis.

• Caffeine

Experiments in rats have demonstrated that caffeine has pro-inflammatory effects when administered during an inflammatory process. It exacerbates tissue damage by amplifying the mRNA levels of TNF-alpha, TNF-β, lymphotoxin-β, IL-6, and IFN-gamma in the spleen, and by increasing IFN-gamma in the blood. Notably, cytokines like IFN gamma act as mitogens for keratinocytes in psoriasis, promoting their proliferation.

• Saturated Fatty Acids

Saturated fatty acids induce the NLRP3 inflammasome and IL-23/IL-17. These innate immunity complexes and interleukins trigger a cascade of inflammatory reactions. Red meat, which contains saturated fatty acids, when consumed excessively, could exacerbate psoriasis.

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CHOUDHARY S. & al. Psoriasis: Role of dietary management in diminution of its symptoms. Bioscience Biotechnology Research Communications (2016).

WU A. G. & al. The Impact of Diet on Psoriasis. Cutis (2019).

KANDA N. & al. Nutrition and Psoriasis. International Journal of Molecular Sciences (2020).