Psoriasis is a common, chronic autoimmune inflammatory disease that causes raised, scaly patches, known as plaques, to appear on the skin.
These scaly patches appear most often on the knees, scalp, and the outside of the elbows, and are the result of skin cells growing abnormally quickly. People with psoriasis often experience itchiness, and burning and stinging sensations in these areas.
People can develop psoriasis at any age, but they are most frequently diagnosed with the illness between the ages of 15 and 35. It is estimated that as many as 7.5 million Americans have the condition.
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What is vitamin D?
Alongside sunshine, fatty fish, cheese, egg yolks and mushrooms contain vitamin D.
Vitamin D, also known as the sunshine vitamin, is a very important vitamin. It helps the muscles, heart, lungs, and brain to work well. It also helps to maintain strong, healthy bones.
Vitamin D is unique among vitamins for two reasons. Firstly, when the skin is exposed to sunlight, the body can make its own stores of this vitamin. Other vitamins must be consumed in food.
Secondly, unlike other vitamins, the body turns vitamin D into a hormone. This hormone is called "activated vitamin D" or calcitriol.
Vitamin D helps maintain the health of bones and teeth and supports the health of the immune system, brain, and nervous system. It plays a role in controlling insulin levels and helps lung function and cardiovascular health.
This vitamin also has some links to the development of cancer.
How might vitamin D help with psoriasis?
There is a complex relationship between vitamin D and psoriasis. Research suggests that if the body does not process vitamin D normally, psoriasis symptoms may become worse.
Because of this, vitamin D features in some oral and topical psoriasis treatments. Some studies have found that, when used alone, these treatments produce similar results to corticosteroid-based treatments.
These treatments may be even more effective when used in combination with a high-quality topical steroid. In fact, a recent study found that the combination of a topical vitamin D treatment and a topical steroid was more effective at treating scalp psoriasis than steroids alone.
However, when used alone, the vitamin D treatment resulted in a significantly higher risk of adverse side effects, compared with using the steroid treatment alone.
These adverse side effects included:
- Yeast infection
- Red, inflamed, dry skin
When the two therapies were used in combination, there was less risk of side effects.
Vitamin D and UVB
Ultraviolet B (UVB) light therapy is also sometimes used to treat psoriasis. The treatment mimics the spectrum of the sun's UVB rays that are known to trigger the production of vitamin D in the skin. UVB is effective at reducing psoriasis symptoms in 70 percent of patients.
In a 2010 study, participants were given UVB treatment. By the end of the test period, all had achieved increased levels of vitamin D. In fact, the levels more than doubled, by average. Most of these people reported that their psoriasis symptoms had improved.
However, the researchers were unable to plot a significant link between improvement in psoriasis symptoms and levels of vitamin D.
How to get more vitamin D
UVB light therapy, which mimics the sun's rays, may be used to treat psoriasis.
Vitamin D deficiency is common, especially among the following groups of people:
- People with dark skin
- People who live at higher latitudes
- People who do not get much exposure to the sun
Everybody needs a certain amount of vitamin D per day. A person can take a simple blood test to find out their vitamin D levels. If the levels are too low, they can take oral supplements to replenish them.
Although vitamin D supplements are widely available, there is little evidence to suggest that these supplements are helpful in improving psoriasis symptoms. Doctors also advise against sunbathing or using commercial tanning beds in an attempt to increase vitamin D levels.
Vitamin D deficiency and psoriasis
Low vitamin D levels are common among people with long-term plaque psoriasis. Experts believe that having a vitamin D deficiency does not cause psoriasis, but it might limit the body's ability to keep skin healthy.
Studies have found that in the winter, when there is less available sunlight, vitamin D deficiencies and psoriasis symptoms often get worse.
Other vitamins and supplements that might help with psoriasis
There is not much evidence to suggest that vitamins or dietary supplements help reduce symptoms of psoriasis. However, some people with psoriasis believe that omega-3 fatty acid supplements help ease their psoriasis. Omega-3 fatty acids have been shown to reduce inflammation.
Psoriasis is an inflammatory disease, which is why some people believe the supplements help. But more long-term clinical trials are needed to show whether these supplements are effective for treating psoriasis.
The National Psoriasis Foundation warn that people with psoriasis should check with their doctor before taking these supplements. Any supplements could interfere with other medications the person is taking.