Reduced sIgA levels are commonly seen in individuals with low immune system, food allergies, bacterial overgrowth of the small intestine and other digestive disturbances, chronic Candida and parasitic infections. Many people with sIgA-deficiency are asymptomatic. It is not understood why some individuals with sIgA deficiency have almost no complains while others are quite sick.
Those who do have symptoms typically have recurring ear, sinus, or lung infections that may not respond to regular treatment, even with antibiotics. Other problems include multiple food allergies, asthma, chronic diarrhoea, and autoimmune diseases such as lupus and rheumatoid arthritis.
Since sIgA serves to protect the gut, lower levels can also lead to an increased risk of ‘leaky gut’ or dysbiosis (microbial overgrowth in the small intestine). When sIgA is decreased and is unable to adequately fight invaders attacking the intestinal wall, the gut becomes inflamed and irritated resulting in the integrity of the gut wall becoming weakened allowing toxins or undigested food particles to enter the body via the blood stream. These food particles cause the body to react by creating other classes of immunoglobulins, primarily IgG, to protect the blood and tissues. A person with leaky gut may therefore have IgG reactions to many foods which are detected in blood tests.
For more detailed information on IgA and its importance for our overall health please see my article on 'Importance of secretory Immunoglobulin A (sIgA) for digestive and overall health'.