Evaluating the clinical relevance of food sensitivity tests: a single subject experiment

A number of tests are available to identify food sensitivities. This article presents an analysis of the diagnostic value of nine different food sensitivity tests run concurrently on a healthy 33-year-old female with a previous diagnosis of environmental allergies. This case study evaluated conventional allergy tests (skin prick and serum IgE), tests of other immune-mediated reactions (serum IgG and salivary IgA), and tests that claim to measure the energetic reaction of the whole person to particular foods (kinesiology, Vega, and Carroll testing). The results of an elimination/challenge test were used as indicators of true food reactions in order to calculate the sensitivity, specificity, and positive predictive value (PPV) of each test. In a separate evaluation, the variability of results across the four tests measuring IgG was determined. Results show several tests (one of the two serum tests of IgG alone, both serum tests of IgE and IgG, skin prick testing, and Carroll testing) may have very high (100 percent) specificity and PPV when test results are compared to the results of an elimination/challenge test. Sensitivity, however, is low across tests (50-60 percent), likely because different tests measure different mechanisms of food reactions and because food sensitivities can be the result of a number of different mechanisms. Very little consistency was found among the results of the four tests measuring IgG - 79-83 percent disagreement. This study shows a number of tests may be useful in identifying foods to which a patient is reactive; however, no one test is likely to identify all reactive foods.