Low-antigen-content diet in the treatment of patients with IgA nephropathy

Since dietary macromolecular antigens can be involved in thepathogenesis of IgA nephropathy (IgAN), the effect of a low-antigen-contentdiet was evaluated in 21 patients (10 women, 11 men, mean age27.7±10 years) with immunohistochemical findings of activeIgAN. The diet was followed for a 14–24-week period (mean18.8±6); in all cases the effects of the treatment wereevaluated by clinical and serological parameters, and in 11patients also by repeat renal biopsy. After dietetic therapy a significant reduction of urinary proteinswas recorded (P< 0.001); in particular, heavy proteinuria(>1 g/day), present in 12 cases during the 6 months precedingthe treatment, was markedly reduced or disappeared in 11. Atposttreatment control biopsy mesangial and parietal depositsof immunoglobulins, complement C₅, fraction and fibrinogen weresignificantly reduced. The improvement of the objective parameterssuch as heavy proteinuria, a strong predictor of a poor prognosis,and of immunohistochemical alterations indicate that a low-antigendiet can positively affect patients with IgAN. These resultscould be ascribed to a reduction of nephritogenic food antigeninput and to a putative functional restoration of the mononuclearphagocytic system.