In another article in the same journal, Dr. Scott Sicherer of the Mount Sinai School of Medicine wrote about the difficulty in estimating the prevalence of food allergies in a population. The difficulty arises both because some tests don’t diagnose true allergies, he wrote, and because allergies may show up or go away at certain times in life and people living in different places may be exposed to certain allergy-triggering foods but not others.

While the current study and previous research don’t agree on the actual prevalence of peanut allergies, there is a general consensus that the rate of recorded allergies is increasing.

According to Sheikh, that trend may be due to better diagnosis of peanut allergies and better recording by doctors.

Gupta, however, said that the increasing prevalence could reflect an upswing in actual allergies - and not just the fact that peanut allergies are more likely to be recognized now than in the past. However, the reason is unclear, she said.

“There’s a ton of theories,” Gupta said, “from the hygiene hypothesis to how we process our foods in today’s world.” Under the hygiene hypothesis, she said, kids who grow up in an environment that has less dirt and fewer germs than in the past are more likely to have allergies because of “the body not having anything else to fight.”

It’s also unknown whether peanut allergy rates are increasing only in industrialized countries, she said, or if they are increasing everywhere but only being recorded in places like the U.S., Canada, and Europe.

SOURCE:  The Journal of Allergy and Clinical Immunology, online January 14, 2011.