Dietary Intervention for Control of Clinical Symptom in Patients with Systemic Metal Allergy: A Single Center Randomized Controlled Clinical Study

Abstract

Patients with eczema with a systemic metal allergy, such as nickel (Ni), cobalt (Co), chromium (Cr), and tin (Sn), should pay attention to symptomatic exacerbation by excessive metal intake in food. However, dietary intervention for systemic metal allergy can be difficult. In this study, we evaluated the effect of dietary intervention by a registered dietitian on clinical symptoms in patients with a systemic metal allergy. Forty-four patients with cutaneous symptoms who were diagnosed with a metal allergy were randomly assigned to the dietary intervention group (DI group, n = 29) by a registered dietitian or the control group (C group, n = 15). The DI group was individually instructed by a registered dietitian how to implement a metal-restricted diet and then evaluated 1 month later. Dermatologists treated skin lesions of patients in both groups. Skin symptoms assessed by the Severity Scoring of Atopic Dermatitis (SCORAD) index, blood tests, and urinary metal excretion were evaluated. The DI group showed decreased Ni, Co, Cr, and Sn intake (all P ≤ 0.05), and an improved total SCORAD score, eczema area, erythema, edema/papulation, oozing/crust, excoriation, lichenization and dryness after 1 month of intervention compared with before the intervention (all P ≤ 0.05). However, the C group showed decreased Ni and Sn intake and an improved oozing/crust score (all P < 0.05). It showed the effective reduction of dietary metal intake controls dermatitis due to a metal allergy. In conclusion, dietary intervention by a registered dietitian is effective in improving skin symptoms with a reduction in metal intake.

Keywords: Chromium; Cobalt; Dietary intervention; Nickel; Systemic metal allergy; Tin.

Educational materials for the dietary intake provided to patients used in Kobe University Hospital. Registered dietitians instructed patients to eat a nutritionally balanced diet. They recommended eating grain dishes such as rice, bread, and noodles, main dishes such as meat, fish, eggs, and soybean products, and side dishes such as vegetables.

Copyright © 2012 Karger Publishers, Basel, Switzerland (24).

Figure 1. Flow diagram of the progress through the phases of a parallel randomized trial of 2 groups (that is, enrollment, intervention allocation, follow-up, and data analysis)

*The patient stopped coming to see the doctor after the day of the allocation.

Figure 2. Study design

The study was a two-arm, randomized, controlled, clinical trial. The solid line indicates the process by a dietitian in the DI group and the dotted line indicates the process by a dermatologist. DI, dietary intervention; C, control; RCT, randomized, controlled trial.

Figure 3. Skin symptoms and the SCORAD index

A: Distribution of eczema, ranging from 0% to 100% of the body’s surface involved. B: Severity of symptoms. Grades of 0–3 include erythema, edema/papulation, oozing/crust, excoriation, lichenization, and dryness. C: Subjective scale of daily itching and somnolence, ranging from 0 to 10, with a maximum total score of 20. D: Total SCORAD score, which was calculated as follows: SCORAD = A/5 + 7B/2 + C. (26). Data are expressed as the mean ± standard deviation. ^$p < 0.05, ^$$p < 0.01 vs. the DI group before the dietary intervention; ^#p < 0.05 vs. the C group before the intervention. Data were analyzed by the paired t-test (total SCORAD [B] score, total SCORAD score) or the Wilcoxon signed-rank test (others). SCORAD, Severity Scoring of Atopic Dermatitis; DI, dietary intervention; C, control.