Psoriasis is a long-term (chronic) skin problem that causes skin cells to grow too quickly, resulting in thick, white, silvery, or red patches of skin.
Normally, skin cells grow gradually and flake off about every 4 weeks. New skin cells grow to replace the outer payers of the skin as they shed.
But in psoriasis, new skin cells move rapidly to the surface of the skin in days rather than weeks. They build up and form thick patches called plaques. The patches range in size from small to large. They most often appear on the knees, elbows, scalp, hands, feet, or lower back. Psoriasis is most common in adults, but children and teens can get it too.
Having psoriasis can be embarrassing, and many people, especially teens, avoid swimming and other situations where patches can show. But there are many types of treatment that can help keep psoriasis under control.
Experts believe that psoriasis occurs when the immune system overreacts, causing inflammation and flaking of skin. In some cases, psoriasis runs in families.
People with psoriasis often notice times when their skin gets worse. Things that can cause these flare-ups include a cold and dry climate, infections, stress, dry skin, and taking certain medicines.
Psoriasis isn’t contagious. It can’t be spread by touch from person to person.
Symptoms of psoriasis appear in different ways. Psoriasis can be mild, with small areas of rash. When psoriasis is moderate or severe, the skin gets inflamed with raised red areas topped with loose, silvery, scaling skin. If psoriasis is severe, the skin becomes itchy and tender. And sometimes large patches form and may be uncomfortable. The patches can join together and cover large areas of skin, such as the entire back.
Psoriasis can also affect the fingernails and toenails, causing the nails to pit, change color, and separate from the nail bed.
In some people, psoriasis causes joints to become swollen, tender, and painful. This is calledpsoriatic arthritis.
Symptoms often disappear (go into remission), even without treatment, and then return (flare up).
Researchers reviewed studies testing the benefits of fournutritional supplements: vitamin D, vitamin B12, selenium and omega-3 fatty acids. Of these, omega-3 fatty acids, taken in fish oil supplements, were found to offer the most benefit to people with psoriasis.
Omega-3 fatty acids can decrease overall inflammation, the authors note. Several studies found that people taking fish oil supplements, either alone or with other treatments, experienced a decrease in psoriasis severity.
Vitamin D was also shown to improve psoriasis and psoriatic arthritis. However, vitamin D can also cause serious side effects by raising the calcium level in the blood. “Sometimes that can lead to things like kidney stones and maybe even gout,” Liao said.
Researchers did not find significant evidence that selenium or vitamin B12 improved psoriasis.
What to avoid
- Multiple studies have shown that increased alcohol use increases the risk of developing psoriasis—and may influence disease severity.
- Patients in some studies had fewer psoriasis symptoms when theyeliminated gluten (a protein found in wheat and other grains) from their diets. However there are no large-scale studies confirming this connection.