People often confuse food intolerance with food allergy, says Lisa Frazier, clinical dietitian with Skaggs Regional Medical Center.
“I have patients who say they are allergic to milk and they are intolerant to the lactose in milk. A true allergy to milk, which is usually in children, can produce anaphylactic shock,” Frazier.
While medical professionals report seeing an increase in both problems, there are distinct differences between food allergies and intolerance and it’s important to know the difference.
“People use the term allergies very loosely to refer to anything they have a reaction to. Allergy refers to a special type of response,” says Dr. Laura Esswein, allergist with Mercy Medical Group in St. Louis.
Adults are more likely to have a food intolerance, whereas children are more likely to have a food allergy, says Esswein.
More than 12 million Americans — about 4 percent of the population — have food allergies. The incidence is highest in children under age 3, according to the Food Allergy & Anaphylaxis Network.
Differences
A food intolerance is an inability to process a certain food and it tends to be a digestive response.
People who are lactose intolerant lack the enzyme to digest lactose, a milk sugar. This causes gas, bloating and diarrhea, says Frazier.
Common food intolerance are wheat, dairy, and additives like MSG and sulphites, says Frazier.
Some people get a migraine when they eat MSG, but that is an intolerance, not an allergy, says Esswein. It’s not known what causes the migraine.
Lactose intolerance, the most common food intolerance, affects about 10 percent of Americans, according to WebMD.
Sometimes people mistake Irritable Bowel Syndrome (IBS), food poisoning or even pollen on food not the actual food itself with an allergy/intolerance, says Adam Pruett, RD, St. John’s Nutrition Center Coordinator.
A food allergy is an immune response to a protein in the food, says Dr. Michael Borts, allergist in St. Louis and faculty member at St. Louis University Division of Allergy and Immunology.
An allergic reaction can include abdominal distress, but often involves the release of histamine, which can cause itching, hives, sneezing, or wheezing, Borts says.
A severe allergic reaction can be life threatening and can cause blood pressure to drop and airways to become restricted.
Another difference between the two is food allergies are not dose-related, a trace amount can trigger a reaction. A food intolerance can be dose-related, Esswein says.
There’s also a condition called oral allergy syndrome where people with seasonal allergies have a sensitivity to certain foods with similar proteins, but it rarely develops past a scratchy throat.
People allergic to “birch pollen may have sensitivity to apples, carrots or peaches,” says Frazier. “People allergic to ragweed may be sensitive to melon, zucchini or cucumbers. Latex (may be sensitive) to bananas or kiwi.”
That is a heat-sensitive protein so when the food is cooked, people don’t have symptoms, says Esswein.
Eight foods — eggs, tree nuts, peanuts, dairy, soy, shellfish, fish, wheat — account for 90 percent of all food allergies, according the Food Allergy & Anaphylaxis Network.
Food allergies, which are considered atopic disorders, are increasing, says Borts. People with food allergies are more likely to have other atopic disorders such as asthma, dermatitis, or seasonal allergies, says Borts.
No one knows why they are on the rise, although theories abound, echoed these experts.
Diagnosis
A food allergy is diagnosed with a skin test or an IgE factor blood test, says Pruett.
Those are not 100 percent accurate so patient history is taken into account, says Borts.
If a food intolerance is suspected, the patient will be put on an elimination diet, says Pruett.
A health care professional will have the patient eliminate anything they suspect may be causing problems and then slowly, reintroduce foods to see if there is a reaction, says Pruett.
Someone who has not been diagnosed should not take it upon themselves to cut a food from their diet, because they could unnecessarily miss out on important nutrients, Pruett says.