Does Vitamin B12 have effects on psoriasis?

The psoriasis is a skin condition affecting approximately 2% of the French population. It is characterised by the appearance of thick red patches covered with scales, primarily on the scalp, face, lower back, elbows, knees and feet. The psoriasis is caused by an abnormal renewal of skin cells, triggered by several risk factors that include the immune system, genetics and environmental factors. Progressing through unpredictable flare-ups, this disease is not contagious but can be very difficult to live with, causing irritations and itching. Several studies have looked into the effectiveness of vitamin B12 in topical application to alleviate symptoms. Two clinical trials can be particularly mentioned in this regard.

• Conducted in 2001, the first study involved 13 individuals with chronic psoriasis plaques. Over a period of 12 weeks, the volunteers applied a cream based on avocado oil and containing 0.07% of vitamin B12 twice a day. At the end of the treatment, the PASI (Psoriasis Severity Index) decreased by 91%. This score, which assesses the severity of psoriasis, takes into account the area of the epidermis affected as well as the degree of scaling and redness.

• A more recent, yet quite similar study, was conducted with 24 adults suffering from psoriasis. The cream tested was also formulated with 0.07% of vitamin B12 in an avocado oil base. This was applied for 12 weeks to half of the patients' psoriasis plaques, while a placebo cream was used on the other half. A mean improvement of 86% in the PASI was noted for the side treated with the cream containing vitamin B12, compared to 15.7% for the side where the placebo cream was used.

These two clinical trials seem to suggest that vitamin B12 could act against psoriasis. However, one might question whether the apparent effectiveness of the tested creams is entirely due to vitamin B12, or if it results from the synergy between this molecule and the avocado oil, known for its nourishing properties. Regardless, even if the studies hint at the potential benefits of vitamin B12 in combating psoriasis, it is important to remember that it cannot replace a dermatological treatment prescribed by a doctor.

What mechanisms allow Vitamin B12 to act against psoriasis?

If vitamin B12 appears to be so effective in the case of psoriasis, it is due to its anti-inflammatory properties. Indeed, it has been shown that this molecule can limit the synthesis of nitric oxide (NO), a compound playing a role in the pathogenesis of psoriasis. By stimulating the proliferation of keratinocytes, NO is partly responsible for the hyperkeratinisation characteristic of this dermatosis and the resulting inflammation. Furthermore, nitric oxide is a vasodilator: it increases the diameter of blood vessels, which promotes the occurrence of redness and oedema. It should also be noted that vitamin B12 is capable of inhibiting the production of pro-inflammatory cytokines by T lymphocytes, molecules affecting a wide range of cells and involved in the induction and persistence of pain.