- Celiac disease
- Gluten sensitivity
- Lactose intolerance
- Other food sensitivities
- The role of IgG and IgA testing
Celiac disease is systemic disorder that occurs when the body is unable to tolerate gluten, the protein found in wheat, barley, and rye, and is estimated to affect close to 1% of the U.S. population. Symptoms of celiac disease can often be confused with many other intestinal disorders, including lactose intolerance and irritable bowel syndrome.
The signs & symptoms of celiac disease include:
- Abdominal cramping
- Excess gas
- Unintentional weight loss
- Canker sores
- Itchy blisters on elbows & knees
- Balance & gait problems
- Iron deficiency with anemia
Celiac disease is triggered by an immune reaction to gluten – this reaction causes inflammation in the lining of the small intestine that in turn damages the structures (villi and microvilli) that are part of the normal digestive process. The damage to these structures results in the inability to properly absorb nutrients during digestion, which can lead to malnourishment over time. Those with celiac disease are also more likely to have other autoimmune diseases, including thyroid disease and type I diabetes.
Testing for celiac disease involves a blood test to look for specific antibodies. It is important to note that the accuracy of the blood testing is greatly improved if there is gluten in your system – for this reason, you should not limit gluten in your diet prior to testing. If the blood antibodies are positive, a biopsy can be done to confirm the diagnosis.
The only treatment for celiac disease is a gluten-free diet.
Gluten sensitivity is different from celiac disease as it is not an immune-mediated process. While those with celiac disease are not able to tolerate any amount of gluten in their diet, those with gluten sensitivity may be able to tolerate small amounts of gluten and do not risk damaging the intestinal lining.
The symptoms of gluten sensitivity include:
- Abdominal cramping
- Balance problems
It appears that the inflammatory response plays a role in gluten sensitivity, however at this time there is no diagnostic testing available for this condition. Research is on-going in this arena.
Lactose intolerance stems from a deficiency of lactase, an enzyme that breaks down lactose into two smaller molecules that can be absorbed through the small intestine. When there is not enough lactase present in the small intestine, lactose is able to pass wholly into the colon where it is then broken down by intestinal bacteria, leading to excess gas and bloating.
The symptoms of lactose intolerance include:
- Abdominal cramping
Lactase deficiency can be diagnosed with a hydrogen breath test, a test that measures the concentration of hydrogen in the breath. Hydrogen is a by-product of lactose being broken down in the colon and some of that hydrogen passes into the bloodstream where is transported to the lungs and then exhaled.
The best approach to lactose intolerance is avoidance of all dairy products. Lactase supplements (such as Lactaid) can be taken to aid in the digestion and breakdown of lactose if dairy products are consumed.
Other food sensitivities& conditions:
- Histamine intolerance
- Impaired complex carbohydrate digestion
- Sulfite sensitivity
- Food dyes
- Other conditions that may be worsened by foods
Histamine intolerance – Histamine is released by mast cells that line the airways and digestive tract. Histamine causes a variety of allergy symptoms and can also dilate blood vessels and trigger the release of some stomach acids. Certain foods, including tomatoes, spinach, beans, some cheeses, and alcohol, contain a chemical called histidine that gets broken down into histamine. Typically these histamines are deactivated during digestion by an enzyme called diamine oxidase (DAO). In people who have low DAO levels, ingestion of histamine/histidine-rich foods can lead to headaches, flushing, runny nose, rash, itching or swelling of lips and tongue, and diarrhea. Symptoms can be treated with antihistamines or avoidance of offending foods.
Impaired complex carbohydrate digestion – Symptoms of impaired complex carbohydrate digestion are similar to those of lactose intolerance. If large quantities of foods containing fermentable carbohydrates (beans, bran, fruits, some vegetables, fructose, or sugar alcohols) are consumed, the body’s enzymes are unable to keep up with the volume of carbohydrates in the digestive system. This causes the intestinal bacteria to break down some of these carbohydrates, leading to excess gas and bloating. Probiotics and tablets of an enzyme called alpha-galactosidase (Beano) can be helpful in reducing symptoms.
Sulfites – Sulfites are used as an additive in many foods to prevent browning and discoloration. Sulfite sensitivity most commonly occurs in patients with asthma. People with sulfite sensitive asthma typically experience asthma symptoms when they consume foods or beverages containing sulfites.
MSG (monosodium glutamate) – MSG is a common food additive. There have been many reports over the years of adverse reactions to MSG, including headache, flushing, numbness and tingling, chest pain, nausea, and weakness. These symptoms are generally mild and resolve without treatment. No definitive link has been found to implicate MSG as a cause of the above symptoms.
Food dyes–Food dyes are currently under study for a link to attention deficit hyperactivity disorder (ADHD). To date, no biological mechanism has been identified to link the two, but some studies have shown that certain colorings and additives may increase hyperactivity in some children. The most common additives under study are sodium benzoate, FD&C Yellow No. 6, D&C Yellow No.10, FD&C Yellow No. 5, and FD&C Red No. 40.
Other conditions that may be worsened by foods – Other medical conditions may be triggered or worsened by certain foods. These conditions include migraine headaches, rosacea, acid reflux, and gout. Keeping a food diary is helpful to identify particular triggers.
The role of IgG and IgA testing
The European Academy of Allergology and Clinical Immunology (EAACI) has issued a position paper against the utility of IgG testing for the diagnosis of food allergy. Positive IgG results can be seen after exposure/ingestion to the foods being tested – for example, a person who drinks and tolerates cow’s milk everyday could have a positive IgG level to cow’s milk – and have no risk for an adverse or anaphylactic reaction to cow’s milk. Therefore, after careful consideration of available data, the EAACI concluded that IgG testing for specific foods is not related to food intolerance or allergy. The American Academy of Allergy, Asthma, & Immunology supports of the position of the EAACI.
Similarly, IgA testing has not been proven to have a scientific role in the diagnosis of food allergy. Currently, the gold standard for the diagnosis of food allergy remains accurate patient history and skin prick testing for immediate hypersensitivity. IgE blood testing, in combination with history and skin testing, is the only proven laboratory diagnostic tool for food allergy.