The relevance of using the C3d/immunoglobulin G test in clinical intervention.

Context: A large subset of the population is afflicted with a wide range of food-related inflammatory conditions, with at least 100 million people affected worldwide. The C3d/immunoglobulin G (IgG) test measures both the innate and adaptive responses of the immune system.

Objective: The study intended to validate the C3d/IgG test for food sensitivity for its ability to manage the symptoms of patients with intestinal and extraintestinal symptoms.

Design: The research team designed a retrospective study based on a cohort of patients treated at a medical center.

Setting: The patients were seen at Progressive Medical Center of Atlanta, an integrative medicine clinic, and patients' samples were analyzed at Dunwoody Laboratory.

Participants: The study included 30 individuals, 9 males and 21 females, ranging in age from 7-71 y who presented with symptoms associated with food sensitivity.

Intervention: The study reviewed the treatment and results of patients who were placed on an exclusion dietary regimen for treatment of possible food sensitivity. From an initial C3d/IgG test, foods causing elevated anti-C3d/IgG, with the exception of ones causing mild reactions, were identified and eliminated from each patient's diet.

Outcome Measures: At baseline and at an average of 10.7 mo on the dietary regimen, 2 C3d/IgG tests were performed on each patient's serum by the method of indirect enzyme-linked immunosorbent assay (ELISA). Both food sensitivities and chief complaints were reassessed in that second test to determine if participants' symptoms improved with food elimination. Outcomes were based on the status of the patients' primary complaints.

Results: Patients who complied with the avoidance of anti-C3d/IgG dietary antigens demonstrated a statistically significant reduction in C3d/IgG-testing sensitivity and a marked reduction in symptoms that they had reported before beginning the diet. The P values were .000002, .007, and .001 for changes in the severe, high, and moderate test results, respectively, between the initial and second test.

Conclusion: Overall, patients' well-being improved when C3d/IgG food sensitivity decreased as a result of an exclusion diet, demonstrating that food removal based on the C3d/IgG test could be an effective approach to patients' care.