Psoriasis is a lifelong disease where the normal cycle of skin cell development and shedding is sped up by signals from the immune system. According to womenshealth.gov, it is considered an autoimmune disease, which shows itself by "attacking" regular body systems. These diseases produce symptoms that cause the body to change typical patterns of function, and can sometimes destroy itself, such as Type1 diabetes, lupus and rheumatoid arthritis. Certain vitamins can worsen psoriasis and cause symptoms to flare up.
Vitamin A
Vitamin A is a fat-soluble vitamin and is one of the few that is stored in your body -- in your liver and fatty tissues. Also known as retinol, vitamin A has a tolerable, upper intake level of 3,000 mcg per day. If you ingest more than this limit, you could experience toxicity. This would worsen psoriasis by causing an increase in dry, rough skin that would cause the cell turnover to occur even faster. You are not likely to get this toxic level by your diet alone, but it can occur in supplements and even some multivitamins. When you choose a multivitamin, make sure the vitamin A is in the form of beta-carotene. Signs and symptoms of vitamin A toxicity include dry, itchy skin, headache, nausea and vomiting and a loss of appetite.
Vitamin C
Vitamin C foods, such as citrus and tomatoes, as well as unbuffered supplements, can cause a flareup of psoriasis. Vitamin C can also cause a unique type of arthritis that can occur with psoriasis and shows up as inflammation and pain in your joints. Vitamin C foods and supplements can be high in acidity, and this is what triggers the flareups. Other acids that can worsen psoriasis are from coffee, red meat and dairy products. Choose a buffered form of high-quality vitamin C in a supplement that is in a powder form.
Vitamin B3
Vitamin B3 is also known as niacin, and this vitamin may aggravate psoriasis by causing what is known as "niacin skin rash." This would be quite troublesome who already has psoriasis. If you have an allergy to B3, which is fairly common, hives or a red rash will show itself quickly. These are accompanied by itchy, swollen skin. With a mild case, itchy or not, you may experience flushing -- turning red and feeling warm -- especially in the face and neck. B3 can even cause jaundice in some people. Toxicity occurs with misuse of supplements and dry, itchy skin, and hyperpigmentation, or skin darkening, may occur. Niacin may also cause light sensitivity and if you have psoriasis and are exposed to UV rays from sun exposure or in psoriasis treatments, you can experience a painful rash, flushing, scaly and darkened skin, mouth sores and swelling and redness of the tongue. Vitamin B3 is also known as niacinamide, nicotinamide and nicotinic acid. (Reference 4)
