The prevalence of food allergy has dramatically increased over the past two to three decades, and not just among children.
Preliminary results from a national study, led by Dr. Ruchi Gupta, a researcher at Ann and Robert H. Lurie Children’s Hospital, reveal nearly 52 percent of Americans with food allergies experienced the onset after age 18.
The study, a survey of over 40,000 adults, was sparked by accounts from worldwide medical conferences that a growing number of adults were reporting food allergies.
Besides confirming a greater incidence of adult onset food allergy, the Gupta study showed that shellfish is the most common adult food allergy, followed by peanuts, and then tree nuts. Though many children outgrow their food allergies, those that develop in adulthood tend to be lifelong.
Why The Increase?
Why more adults are developing food allergies is a question of interest for Dr. Gupta and colleagues, so they asked the study participants what they believed triggered their allergies. The answers included moving to a different part of the country, hormone changes, and the effects of viral illnesses.
Researchers generally think there may be several factors contributing to adult onset food allergy, for instance:
- Vitamin D. Three-fourths of the U.S. population lacks sufficient vitamin D, and scientists have found an association between vitamin D deficiency and food allergy development.
- Chemicals. Potential allergens in our food supply - pesticides, herbicides, additives, and other chemicals - have increased greatly over the past couple decades.
- Further, many pesticides used today have an antibiotic action that can decimate gut microbes, including a common bacterium called Clostridia. Research suggests that Clostridia protects against the development of food allergies.
- Genetic Modification. Genetically modifying food may be increasing the level of protein allergens in our plants, and could be creating new, difficult to detect allergens as well.
- Soy, a common allergen, is used as a filler in many of our processed and packaged foods. Unlike the fermented soy consumed in Asian cultures, the soy filler used in Western food is not fermented, and may be genetically modified.
- One study found genetically modified (GM) soy contained an unexpected protein likely to trigger allergies. Other test results showed that cooked GM soy contains up to seven times more trypsin inhibitor - a known soy allergen - than cooked non-GM soy.
It’s difficult to know whether, or how much GM foods are responsible for allergy increases since long-term studies to determine their safety are not required.
The Gupta study is not the only one tracking the age of allergy onset. Research conducted by Food, Allergy, Research and Education (FARE) showed that of people with food allergies, at least 15 percent will develop them after turning 18. However, not all upsetting food reactions are caused by allergens.
Adults experiencing disturbing symptoms after eating certain foods are recommended to see a doctor who can determine if the symptoms are owed to food allergy, or a food intolerance. Food intolerance occurs in the digestive tract. Food allergies are a systemic immune response.
Though both intolerance and food allergy symptoms are distressing, allergies can cause immediate life threatening reactions that sufferers - and their family and friends - need to recognize, and be prepared to treat.