Psoriasis

Psoriasis

Keratinocyte turnover that normally takes about 28 days compresses to 3 or 4 days in psoriasis, and the thick silvery-scaled plaques are the visible residue of that acceleration. The driver is immunological rather than dermatological in origin: the Th17 and interleukin-23 axis sustains a self-reinforcing inflammatory loop, with genetic susceptibility at HLA-Cw6 setting the predisposition. The condition affects 2 to 3 percent of the global population, and plaque psoriasis accounts for 80 to 90 percent of cases. Three ingredients carry an evidence grade here, one at Grade B and two below it, across 28 studies and roughly 2,950 participants.

Vitamin D holds Grade B on 16 studies and 2,200 participants, the strongest entry by a clear margin. Its relevance to psoriasis is unusually well grounded, since calcipotriol and related vitamin D analogues are established topical agents and the receptor pathway they act on regulates keratinocyte proliferation and differentiation directly. A systematic review of off-label topical vitamin D use in dermatology documents the breadth of that application ^[1], and reviews of vitamin D in skin describe the same receptor biology from the cutaneous side ^[2]. The oral evidence is the weaker half of that picture, and conflating the two is the most common error in reading this literature.

Curcumin sits at Grade C on 6 studies and 350 participants, acting on the inflammatory limb through nuclear factor kappa B signalling, with bioavailability the persistent methodological complaint. Omega-3 fatty acids hold Grade D on 6 studies and 400 participants despite a long-standing mechanistic rationale involving the displacement of arachidonic acid from membrane phospholipids and a consequent shift in eicosanoid profile, a relationship documented across inflammatory and autoimmune disease ^[3].

The most informative recent datum concerns the incidence of new autoimmune disease rather than the course of established plaques. In the VITAL randomized controlled trial, vitamin D and marine omega-3 supplementation were assessed against incident autoimmune disease over five years in a large cohort ^[4]. A dedicated review of nutritional supplements in psoriasis reaches a more restrained conclusion for established disease, finding the supplement literature substantially thinner than the systemic and biologic therapy literature it sits alongside ^[5].

Several modifiers act independently of any supplement. Obesity, smoking, alcohol, streptococcal infection and psychological stress are each associated with severity, and beta-blockers, lithium and antimalarials can provoke flares. The Koebner phenomenon means new plaques arise at sites of trauma, which is why skin injury is itself a trigger.

Psoriasis is systemic rather than confined to skin. Psoriatic arthritis develops in roughly 30 percent of patients, and joint damage that accrues before diagnosis is not recoverable, which places joint symptoms firmly in rheumatologic territory. The graded ingredients above are studied as adjuncts to that care.