FIT 22 (Food Inflammation Test)


The FIT 22 measures of both IgG and Immune Complex containing C3d (IC-C3d) simultaneously, which is the key to assessing food sensitivities. Measuring both IgG and IC-C3d simultaneously generates twice the signal which improves the sensitivity over other tests.

Detailed Description

Link Between Complement (C3d) and Inflammation

Any food antigen entering the bloodstream can produce symptoms associated with food sensitivities. Most food antigens enter the bloodstream through the intestinal epithelium (gut wall) and stimulate the production of IgG immune antibodies. IgG antibodies bind to food antigens that are free in the blood or that have deposited in tissues and form immune complexes (IC).

These immune complexes activate complement C3 which becomes linked to the IgG forming IC-C3b. Ultimately, the C3b on the IC is cleaved forming IC-C3d. During this process, C3a (anaphylatoxin) is released which causes smooth muscle contraction and has a potent vascular effect. Under normal circumstances, circulating IC-C3b bind to the CR1 receptors on red blood cells and are cleared from the circulation in the liver and spleen. Continued production of antibody and formation of IC may result in deposition of IC in tissues which results in activation of the terminal complement pathway C5-9 on the surface of the tissue causing celllysis and increased inflammation.

The Relevance of IgG + C3d

An IgG antibody reaction to a food is a delayed reaction (anywhere from several hours to days). Research has indicated that IgG antibodies produced in the blood against particular foods may promote certain inflammatory reactions within the body.

Testing for Complement (C3d) is a direct measurement of inflammation in the body – and is therefore a very important inclusion for any food inflammation test. Activation of Complement alongside high production of IgG antibodies makes it very clear as to what foods will need to be eliminated from your patient’s diet.

Commonly, we see patient results that show high IgG antibodies to many foods. Understanding which of these foods are actually causing your patient inflammation is crucial in avoiding an excessive elimination program, resulting in a more positive patient experience.

The Food Inflammation Test (FIT) by KBMO measures both IgG(1-4) and Complement (C3d) – combining them into one easy-to-understand bar reading.


For more information email Dr. Neil Wootten at [email protected]