Our skin forms a barrier to protect us from infection and cells are replenished constantly, taking about 21-28 days to replace themselves. With psoriasis this process is greatly accelerated and cells are replaced every 2-6 days, resulting in an accumulation on the surface of the skin, forming a psoriatic plaque. This plaque is comprised of silvery white scales – the build up of cells waiting to be shed – under which there is often redness, due to an increase in blood vessels required to support the increase in cell production.
Approximately 80% of suffers have common plaque psoriasis (also referred to as psoriasis vulgaris), in which the plaques are mainly confined to the elbows, knees, lower back and scalp, although the condition can affect any part of the body. Psoriasis affects between 2-3% of the population with men and women equally susceptible.
Psoriasis is technically classed as an autoimmune disease – a condition in which an overactive immune response causes the body to attack its own cells. Understanding the role of the immune system can help us understand how to treat psoriasis. T cells are involved in protecting the body against bacteria and viruses, and this type of immunity is known as cell-mediated immunity. T-cells produce inflammatory chemicals which act as signals for other cells to come and help deal with the infection.
In psoriasis these T-cells are over stimulated, constantly acting as if they were fighting an infection or healing a wound – this ongoing process leads to the rapid growth of skin cells, resulting in plaques. The reason why these cells become overactive is not known, but around 30% of people with psoriasis have a family history of the condition, and certain genes have been identified as being linked to psoriasis. Despite genetic predisposition, a trigger is required for psoriasis to develop, including infection, injury, certain drugs and physical or emotional stress.
Research suggests that diet plays a vital role in treating psoriasis, with omega-3 fatty acids being of particular importance because of their anti-inflammatory and healing properties. The overproduction of eicosanoids from the omega-6 fatty acid arachidonic acid (AA) has been implicated in many inflammatory and autoimmune disorders and also in psoriatic skin lesions, which are often inflamed, being itchy and painful.
Elevated concentrations of both AA and its derivative leukotriene B4 (LTB4), have been measured in the skin and red blood cell membranes of patients with psoriasis. Diets rich in omega-3 fatty acids result in the substitution of AA by omega-3 polyunsaturated fatty acids in membrane phospholipids. As EPA acts as a competitive inhibitor of AA conversion to inflammatory eicosanoids, diets rich in EPA exhibit anti-inflammatory effects, which can significantly reduce psoriasis symptoms.
In addition to supplementation, suggested foods to limit in the diet include:
• hydrogenated fats and margarines which can encourage inflammation
• refined carbohydrates
• sugary or salty foods
Drinking lots of water to hydrate the skin and eliminate toxins, as well as ensuring you get enough sleep (to avoid stress) is also crucial for healthy, glowing skin.