Dietary factors and the risk of psoriasis. Results of an Italian case-control study

We have conducted a case-control study to explore the relation between the consumption of selected foods and psoriasis. The out-patient services of nine teaching hospitals and five general hospitals in northern and southern Italy took part. Cases were newly diagnosed psoriatics with a history of skin problems of no more than 2 years. As controls, we selected subjects with newly diagnosed skin conditions, other than psoriasis, who were seen in the same out-patient clinics. Inclusion of cases and controls was limited to the age group 16-65 years. A total of 316 psoriatics and 366 controls were recruited. Anthropometric measures, including height and weight, were obtained. Diet was assessed by a semiquantitative food frequency questionnaire. Psoriasis appeared to be positively associated with body mass index (chi 2(1) trend 4.3, P < 0.05). Significant inverse relations with psoriasis were also observed for the intake of carrots (chi 2(1) trend 4.8, P < 0.05), tomatoes (chi 2(1) trend 26.3, P < 0.01), fresh fruit (chi 2(1) trend 11.7, P < 0.01) and index of beta-carotene intake (chi 2(1) trend 9.1, P < 0.01). Although largely explorative, these results provide some evidence for a potential role of diet in psoriasis.