It can take as long as 6 months after eliminating a food from the diet for the IgG response to that specific food antigen to return to normal levels. If a person is not consuming the food, or has not done so in over 6 months, it is unlikely to trigger a significant immune response and will not appear as elevated on the test. A low reactivity to a particular food does not imply that the person can now tolerate it or that the food can be reintroduced safely. It only indicates that the person has been diligent in avoiding it. Conversely, if a person has avoided consuming a specific food and the test result shows positive, cross-contamination with structurally similar proteins in the diet is likely responsible.