Every morning, Susan pours milk on cereal, adds cream to coffee and butters a piece of toast. By lunchtime, she's nibbling a slice of cheese or eating a cup of yogurt. And after dinner, she's dishing up scoops of ice cream. She's cultivated these habits for years — but lately, some troubling symptoms have forced her to reconsider.
Stricken by abdominal cramps, bloating and diarrhea, Susan is reeling from a new reality. At age 40, she's become one of the 30 to 50 million people in the United States who is unable to fully digest the sugars in dairy products [source: Johns Hopkins Medicine]. Susan is in shock over her new lactose intolerant lifestyle, and she's even more confused when she's diagnosed with a full-blown milk allergy. How could she become allergic to something she'd consumed so regularly? Did she somehow cause her milk allergy?
It's a myth that allergies are predetermined at birth. The truth is, many allergies don't develop until later in life. Allergies arise when a person's immune system goes haywire. Nearly any substance can begin to over-stimulate the immune system at any time, including pet dander, mold, pollen and, yes, certain foods. When this happens, the immune system releases mass amounts of histamine, which triggers common allergy symptoms like swollen nasal passages, itchy and watery eyes, hives and digestive issues.
Most people with adult-onset allergies probably aren't experiencing those symptoms for the first time, even if they think they are. It's likely they had an allergic reaction before but may have been too young to remember it. Or it could have been such a mild reaction that they ignored it or attributed it to another cause. In Susan's case, she'd unknowingly dealt with a mild milk allergy for years, and changing her diet caused a heightened response in her immune system [source: Stewart].
Although food is a common culprit for adults diagnosed with first-time allergies, it isn't the only one. Half of all newly diagnosed allergies occur in adulthood, and many of these allergies are common, everyday substances. Perhaps in adulthood your allergy has evolved into a more serious one, or you're exposed to the allergen more frequently than you were before. For example, if you've never spent much time around dogs, and you've recently adopted one, it's possible to develop an allergy to pet dander because of your increased exposure [source: Peri].
When combating allergies, awareness is half the battle. Once you've gotten professional help to determine what you're allergic to, you can develop strategies to avoid those allergens. You'll be on the road to recovery — or in Susan's case, on the road to acquiring a taste for soy yogurt!