Food Allery, Food Sensitivity, and Celiac Disease

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Food allergies start early in childhood but most adults build immunity over time and can eat almost all type of foods as they grow up. However, in certain cases abnormal reactions to food may persist into adult life. These may be life threatening food allergies or mild food sensitivities, or even genetic proclivity to certain foods as in the case of celiac disease.

Food allergies are often serious conditions. The typical response from an allergy inducing food is immediate—almost within minutes. Symptoms include red skin, rashes, swelling, difficulty breathing, and often require a visit to emergency room in the rare life-threatening cases of anaphylaxis. In US, peanut allergy is notoriously common, especially among kids. Certain nuts and shellfish are also well-known for causing serious allergic reactions. In a 2003 study almost 3 million Americans were reported to be at the risk of peanut and tree nuts, raising serious health concerns.

Such allergic responses involve an overreaction by immune system that produce antibodies called immunoglobulin E (IgE). There are several different kinds of antibodies—two other well-known are called IgA and IgG—produced in the body over a longer period.

In case of food sensitivity, the allergen from certain foods might not cause an immediate response, but the body still develops an immune response. This slow response causes mild, non-life-threatening symptoms that include bloating, stomach discomfort, flatulence, itching, irritable bowl, hives, headache, migraine, fatigue, mouth ulcers, constipation, sinus congestion, irritability and mood swings.

Such food intolerance produces immunoglobulin A (IgA) in the mucous and intestinal lining. However, the more abundant form produced by the immune system is the immunoglobulin G (IgG), which circulates in the blood. Another antibody that has gotten attention during the COVID-19 pandemic is immunoglobulin M (IgM). It is produced during the initial encounter with a new source of allergy and lasts for few weeks before the IgG antibodies can take over the immune response and immunity is developed against the allergen.

Because intolerance to foods is not clearly understood, it can be hard to diagnose. A food sensitivity test can help understand what foods might be causing these symptoms. A diet rotation plan can help confirm the results once the suspect foods are identified. Such a test looks for IgG and sometime IgA antibodies in a blood sample.

Some allergies have known genetic causes. One of the most common examples is celiac disease which is caused by allergy to gluten in wheat, barley, and rye grains. The disease, also called gluten-sensitive enteropathy involves formation of a dimer by certain genes that react with gluten and severe damage to the intestinal lining prevents food absorption. Common symptoms include diarrhea, bloating, stomach cramps, constipation, fatigue resulting in long term impact on the body through malnutrition, anemia, and osteoporosis.

However, the symptoms are completely reversed when gluten is removed from the diet. Therefore, a gluten-free diet can help live a normal life. But very small amount of gluten from contamination in regular food can bring back the symptoms of celiac disease.