Pilot Study to Evaluate the Effect of Nicotinamide Riboside on Immune Activation in Psoriasis

Background: Psoriasis causes chronic inflammation in the body. Researchers want to see if a kind of vitamin B3 dietary supplement can help. This might lead to more treatment options. Objective: To test if the dietary supplement nicotinamide riboside can improve immune system function in the blood and skin of people with mild to moderate psoriasis. Eligibility: People ages 18-80 with mild to moderate active psoriasis not currently treated with biological therapy Design: Participations will be screened with: * Medical and medication history * Physical exam * Measure of body mass index * Skin exam * Blood and urine tests Participants will have visit 1. They will have repeats of the screening tests. They may also have 2 skin biopsies, which are optional. These will be from both lesions and unaffected areas. The areas will be injected with a numbing medicine. A round cutting device will remove small pieces of skin from each area. Participants will take the study supplement or a placebo starting at the first visit. Neither participants nor the study team will know which they receive. Participants will take capsules twice daily for a total of 4 weeks. Participants will then have visit 2. This will include the tests performed at visit 1. Participants may by contacted by phone or email between visits to see how they are doing. If participants develop any side effects in the 7 days after they stop taking the capsules, they may have another visit.