Why is psoriasis uncommon in Africans? The influence of dietary factors on the expression of psoriasis.

Psoriasis is uncommonly seen in Africans, probably partly due to genetic factors. However, the dietary habits of Africans may provide another explanation, which is explored in this paper. Maize, the staple diet in most parts of Africa, is high in linoleic acid but low in other polyunstaturated fatty acids and riboflavin. Linoleic acid is a precursor of prostaglandin E2 (PGE2) and its high intake, especially in the absence of other polyunsaturated fatty acids (PUFAs) and riboflavin, results in high tissue production of PGE2. PGE2 is known to suppress cellular immunity, resulting in decreased expression of psoriasis.