13. Vitamin D
Vitamin D plays a crucial role in bone health, immune system function, and inflammation regulation. People with psoriatic arthritis often have low levels of vitamin D, which may worsen both joint and skin symptoms. Supplementation can help correct deficiencies and improve immune balance.
Vitamin D modulates the activity of immune cells, including T-cells, which are involved in autoimmune reactions. Adequate vitamin D levels may help reduce the frequency and severity of flare-ups by lowering inflammatory cytokine production. This is especially relevant in autoimmune conditions where the immune system mistakenly attacks healthy tissues.
Natural sources of vitamin D include sunlight, fatty fish, egg yolks, and fortified foods such as milk and cereal. However, many people do not get enough sunlight exposure or dietary intake to meet their needs. Blood tests can determine current vitamin D levels and guide appropriate supplementation.
A common daily dose for adults with low vitamin D is between 1000 and 2000 international units (IU), although some individuals may require higher doses under medical supervision. Taking vitamin D with a meal that contains fat improves absorption.
In addition to its immune-modulating effects, vitamin D also supports calcium absorption and bone health. This is important for psoriatic arthritis patients who may be at increased risk of osteoporosis due to inflammation, inactivity, or corticosteroid use.
Because vitamin D is fat-soluble, excessive intake can lead to toxicity. Symptoms of overdose include nausea, weakness, and kidney problems. For this reason, supplementation should always be based on lab testing and professional advice.