Expert Q&A: Eating With Food Allergies
An interview with Stanley Cohen, MD.
How are allergies diagnosed?
There are several ways to confirm an allergy. First is the old-fashioned prick test, where the skin is scratched with the allergen and observed for reactions. The second is the patch test, which is similar to the prick test, and the last are specific food allergy blood tests. In all of these tests, there is a possibility for false positives and negatives, so physicians usually try an elimination diet, in which the suspected food is avoided. This is followed by a food challenge in which the suspected food is reintroduced under careful observation on three separate occasions to confirm the allergy.
How do you treat allergies?
At this time, there are no medications that cure food allergies. The most important treatment is the elimination of the allergy-causing food. Careful reading of ingredient labels is essential to avoiding all foods with the allergy-causing ingredient. For example, milk may be listed by its components casein or whey, and eggs can be labeled as albumin. If you have an allergy to a certain food, you must become familiar with all related ingredients that could potentially cause a reaction. A good rule of thumb is, when in doubt, don't eat it.
Evolving research suggests that certain probiotics ("friendly" bacteria) may help to prevent or moderate the effects of some allergies. Consult your physician to determine if you might benefit from including probiotics in your diet.
What is the difference between an intolerance and an allergy?
Most people think the terms "food allergy" and "food intolerance" mean the same thing. Yet a food intolerance or reaction does not involve the immune system and can involve components of the food other than proteins. Milk or dairy is a good example in which many people confuse an allergy with intolerance. A milk allergy can only occur if the individual is allergic to the milk proteins (casein, whey, or lactalbumin). Intolerance to milk is caused by an inability or reduced ability to digest the milk carbohydrate (lactose), and results in diarrhea, bloating, gas, pain but no vomiting or rash.
Other common food intolerances are to wheat and corn products. Approximately 33% of adults and 6%-8% of children have had some kind of intolerance or adverse food reaction.
Can intolerances be diagnosed with a medical laboratory test?
If you suspect you are lactose-intolerant, your doctor can give you a hydrogen breath test to verify the condition. Blood tests can confirm a gluten intolerance. Eliminating suspected foods, then reintroducing them in a planned way, helps confirm a diagnosis of food intolerance.
Is it true that people with lactose intolerance can tolerate some dairy products?
Yes, but they need to proceed cautiously to determine that it is an intolerance, and not an allergy. If you have some degree of tolerance to dairy, test your limits by consuming small portions at meals and watch for symptoms. Good choices for this kind of testing are aged cheeses and yogurts with active cultures, which have less lactose. Other options are to drink milk that contains predigested lactose, or take an enzyme that aids in lactose digestion. Keep in mind that dairy is sometimes not well-tolerated immediately following a bout of gastroenteritis, but this is only temporary.