Many of the patients who come to the Center have three symptoms in common: headache, fatigue, and joint/muscle pain. If one or more of these symptoms are found during the history and physical examination, allergy or sensitivity to food is suspected. Other symptoms or complaints may include gas, bloating, diarrhea, irritable bowel syndrome, etc. As part of the biochemical examination, the cytotoxic food sensitivity test is ordered.

In 1956, Black introduced the cytotoxic food test. It was later refined and modified by Bryant and Bryant in 1960 Although the original Bryant test measured the reactivity of WBCs to food allergens, in 1971 they modified the test to also include the reactions of RBCs and platelets. In the test, the response between sensitized cells and specific food allergens is thought to be a combination of a type IV cell mediated, delayed-type immune reaction with involvement of a type I immediate hypersensitivity response. If a food "allergy", symptoms appear very quickly, if a food "sensitivity", symptoms appear later. It is postulated that food allergens remain in the G.I. tract and cause a set of symptoms from there, or that they leave the gut, enter the circulation, and eventually arrive at the target cell where they may combine with specific antibody receptors of RBCs, WBCs and platelets.