High prevalence of nickel allergy in an overweight female population: a pilot observational analysis

CONTEXT: In our Allergy Unit, we incidentally observed that a low Nickel diet, prescribed for delayed allergy to Nickel sulfate, reduced body mass index (BMI) and waist circumference in overweight patients. OBJECTIVES: This pilot cross-sectional analysis was undertaken to compare the prevalence of Nickel allergy of overweight individuals versus the general population. We also had the chance to report the efficacy of a low Nickel diet on BMI and waist circumference in Nickel-sensitive overweight subjects. METHODS: Eighty-seven overweight subjects, with a BMI > 26 Kg/m2, were consecutively enrolled in a health prevention program, and screened for the presence of Nickel allergy. The enrolled population was mostly females (72/87) (82.8%). Forty-three overweight women and two men showed a Nickel allergy and started a low Nickel diet. After 6-months of dieting, 24 overweight allergic women could be traced and changes in BMI and waist circumference were calculated. MAIN OUTCOME MEASUREMENTS: Prevalence of Nickel allergy in overweight. RESULTS: Prevalence of Nickel allergy in overweight female was 59.7%, compared with a prevalence rate of 12.5% in the general population. A significant reduction in BMI was observed in 24 out of 43 overweight females with Nickel allergy after 24 weeks of a low Nickel diet. Relative to baseline, mean BMI decrease was 4.2 ± 0.5 (P < 0.001) and the mean decline in waist circumference was 11.7 ± 0.6 cm (P < 0.001). CONCLUSIONS: This pilot observational analysis showed a substantially higher prevalence of Nickel allergy among overweight females, especially those with metabolic syndrome and fatty liver disease. A normocaloric low Nickel diet was effective in reducing BMI in this population. Further research is strongly needed to confirm these preliminary findings.