Sorting out Food Allergies, Intolerances and Sensitivities

Sorting out Food Allergies, Intolerances and Sensitivities

Food allergies, intolerances and sensitivities seem to be more and more prevalent or at least we’re hearing more about them with our 24/7 news via traditional, Internet and social media channels. But what’s the difference and how can you truly know if you have one? Keep reading for the lowdown.

A food allergy is an adverse reaction that results from an abnormal immune response to a food protein. The body produces IgE antibodies against the food. When the food is eaten, the immune system thinks the food is harmful and releases histamine and other chemicals. Symptoms can include swelling, itching, hives, wheezing, coughing, runny nose, itchy and watery eyes, nausea, vomiting, diarrhea, lightheadedness or a drop in blood pressure. About 4% of Americans have food allergies. The most common food allergies are milk, eggs, peanuts, tree nuts, wheat, soy, fish and shellfish. To test for a food allergy, either a skin prick or blood test is done to determine if there is an IgE reaction to a food. The most reliable way to verify a food allergy is with an oral food challenge.

In contrast, food intolerances involve an adverse reaction to a food that does not produce IgE antibodies. An example is lactose intolerance in people who produce little or no lactase enzyme that breaks down lactose, the sugar in milk. Celiac disease, characterized by intolerance to gluten – a protein in wheat, rye and barley – is another non-IgE condition that affects less than one percent of the U.S. population. Up to six percent more may have a non-celiac gluten intolerance yet 20 – 30% of U.S. consumers say they’re avoiding gluten. Fructose intolerance is the inability to properly absorb fructose, a sugar in fruit, vegetables, honey, sugar, molasses, agave nectar and high fructose corn syrup. All of these conditions can cause problems like nausea, vomiting and diarrhea, which are relieved by eliminating or moderating intake of the offending food.

On the other hand, food sensitivities that don’t fall into these two categories are less easy to diagnose. While many claim to have them and cite an array of symptoms, tests purported to diagnose them like MRT (mediator release test) or ALCAT are not universally accepted or used by allergists. But based on the results of these tests, individuals are often given a long list of foods to eliminate. And this can lead to a nutritionally inadequate diet says registered dietitian nutritionist, Maria-Paula Carrillo, who works with a board-certified allergist to provide nutrition counseling to food allergy patients at Lemond Nutrition in Plano, Texas. “I support avoiding problem foods when medically necessary whether it’s an allergy, intolerance or sensitivity but when the restrictions are based on unreliable testing, it’s a different story. It’s ideal to have counseling with a registered dietitian nutritionist who works with a board-certified allergist. The RDN can develop a nutritionally adequate eating plan in the face of limited food choices. At the same time the allergist can retest to determine if offending foods can be reintroduced so those without a reaction can be eaten again.”

Interestingly, research with people who believe they have food intolerances sometimes finds they actually do not. In one study (1), 37 self-identified gluten-sensitive individuals consumed one of three diets for one week each: high-gluten, low-gluten, and no-gluten without knowing which diet plan they were on. In the end, all 3 diets caused pain, bloating, nausea, and gas to a similar degree. It didn’t matter if the diet contained gluten. In another study (2), 48 people who self-reported a sensitivity to the low calorie sweetener aspartame and 48 who did not were all given snack bars with or without aspartame at least on week apart. None of the participants knew which bars they were eating. Results found there were no differences in symptoms between those eating aspartame and non-aspartame bars, or between aspartame sensitive and non-sensitive participants. However, aspartame sensitive participants reported more symptoms, particularly in the first test session no matter which bar they had eaten.

So what’s the best course of action if you suspect you are allergic, intolerant or sensitive to a food or ingredient? Maria-Paula recommends seeing a board certified allergist who can perform the appropriate testing to pinpoint foods that need to be excluded. “If an allergic reaction is ruled-out, intolerances like lactose or fructose can be tested for, usually by a gastroenterologist. For other adverse reactions, foods will need to be eliminated and reintroduced in a systematic way, at least until reliable testing is available.”

  1. “No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates” Gastroenterology. 2013 Aug; 145(2): 320-8
  1. “Aspartame sensitivity? A double blind randomised crossover study” PLoS One. 2015 Mar 18; 10(3): e0116212


Neva CochranNeva Cochran, MS, RDN, LD is a registered dietitian nutritionist based in Dallas. She was a freelancer with Woman’s World magazine for 20 years and currently serves as a nutrition communications consultant to a variety of food and nutrition organizations, including the Calorie Control Council. She is passionate about promoting fact-based food and nutrition information to help people enjoy nutritious eating. Follow her on Twitter @NevaRDLD and check out her blog at

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May 13, 2015 Lifestyle Advice