Intestinal Barrier Function Screening
The Intestinal Barrier Function Screen uses a single saliva sample toassessthe level of secretory immunoglobulin A (sIgA) and the levels of free IgA and IgM to combined dietary proteins (wheat/gliadin, corn, soy, cow’s milk, egg); aerobic bacteria (Escherichia coli and E. enterococcus);anaerobic bacteria (Bacteroides fragilis and Clostridium perfringens); Candida albicans yeast.
The lining of the gastrointestinal tract, from the mouth to the anus, is covered by a mucosal barrier, which provides our first line immune defense against pathogens and a mechanism for proper processing of food antigens. The mucosal barrier contains specific immune defenses including mucosal antibodies. A healthy mucosal barrier defense contains sufficient antibodies and responds to normally encountered antigens and deals with them appropriately. All of the dietary proteins, yeasts, and bacteria used in this test are normally found in the human body or diet. IgA is the predominant antibody quantitatively in the mucosal immune system.
This test measures total sIgA production which helps determine whether there is an appropriate mucosal immune response.
Secretory IgA Level
- This is an important indicator of the strength of mucosal immunity and can help to establish the validity of other Ig values.
- If total sIgA is elevated an infection exists and further testing is recommended to determine its type.
- If total sIgA is low it can indicate compromised mucosal immunity, however, it is a measurement at a point in time; it needs to be looked at over time and correlated with cortisol rhythm and lifestyle.
IgA and IgM to antigens in the Dietary Protein, Yeast, Aerobic & Anaerobic Bacteria Compartments
- The immune system should have “normal” recognition of these antigens and process them appropriately.
- If all reported results are < ref range , then the mucosal barrier is totally shut down, regardless of the level of sIgA. This means that there is effectively no mucosal immune response to antigens that present and also indicates severe intestinal permeability “leaky gut”.
- Assessing the levels of antibodies to foods is important in determining the cause of possible chronic gastrointestinal inflammation. Such inflammation can be accompanied by symptoms, or it can be subclinical. If immune markers to dietary proteins are elevated, it is important to do further testing to determine which food the mucosal immune system is reacting to.
- If IgA is elevated in the yeast compartment it means that Candida is attempting to invade the intestinal mucosa.
- Determining the levels and ratio of bacterial groups to each other helps assess digestive and absorptive function. The ratios of the levels of the same specific immune marker for aerobic and anaerobic bacteria (i.e. IgA aerobic/IgA anaerobic) should be about one to one. If these ratios are >2 or <0.5, then a dysbiotic condition exists. Specific infections should be ruled in or ruled out. However, dysbiosis can result from a course of antibiotic therapy without proper efforts to recolonize the gut.
- If one or more of the antibodies in each compartment (dietary proteins, yeast, aerobic bacteria and anaerobic bacteria) is elevated then the gut is leaky and proteins (antigens) are entering the general circulation.
The evaluation of the intestinal mucosa as a selective filter can be regarded as an essential tool in assessing overall health status. The Intestinal Barrier Function Screen (BHD #304) can be used as an immunological indicator of intestinal mucosal integrity and an index of gastrointestinal physiology. This test is especially effective for differential diagnosis in complex and refractory cases. It can assist in both directing further testing and tailoring therapeutic protocols more precisely. It also is sufficiently comprehensive to be used either in initial screening or as follow-up.
Conditions that may be assessed include an abnormal ratio of aerobic-to-anaerobic bacteria, pathogen or yeast overgrowth, intestinal mucosal immune dysfunction, systemic immune deficiency, autoimmunity, food allergy, gluten enteropathy, malabsorption, and “leaky gut.”