Food Allergies Can Develop at Any Age

DEAR DR. BLONZ: A series of reactions had my family physician order allergy testing. The results were a bit surprising because they identified items I had never reacted to before. Why might I have developed an allergic reaction to a food when there was no problem for so many years?

W.S., Tulsa, Oklahoma

DEAR W.S: Food allergies are a more common experience in our early years, but they can develop at any age — even to foods you once tolerated and enjoyed. It begins when a food part, usually a protein fragment, slips through the intestinal wall into the digestive system before it’s been completely digested.

Once absorbed, the fragment is flagged by the immune system, which attacks the intruder and primes the body for future encounters.

Eating the same food again can trigger immune responses like GI upset, sneezing, asthma, rashes, swelling, headaches, or even a life-threatening drop in blood pressure—common culprits include nuts, eggs, shellfish, wheat, milk, and soy.

Why these? During digestion, they may form segments uniquely able to slip through the intestinal wall. Some childhood allergies fade over time, while others persist into adulthood.

Events that impact the immune system—like hormonal changes, medications, stress, infections, or illnesses, especially those affecting digestion—can influence the likelihood of developing food allergies.

Drugs and alcohol can also have an impact. Our genetics are also involved. All these variables can make you susceptible to a food allergy reaction that might not normally occur. In addition, changes in geographical location can raise the level of allergens above your particular sensitivity threshold.

A good place to start is with physicians certified through the American College of Allergy and Immunology. Get more information at foodallergy.org.

(Ed Blonz, Ph.D., is a nutrition scientist and an assistant clinical professor at the University of California, San Francisco.)

— Asia Features