NEW YORK (Reuters Health) - People in Portland are more likely than those in Iceland to be sensitive to certain foods, but reactions to fish, eggs and cow’s milk appear rare in both places, new research suggests.
The study, of more than 4,500 adults from 13 Western countries, found that nations varied in the rate of people who were sensitive to at least one food — ranging from about 25 percent of those in Portland, Oregon, to just under 8 percent of those in Reykjavik, Iceland.
However, countries tended to be similar in the specific culprit foods.
What’s more, certain foods that people commonly view as potential allergy triggers — namely, milk, eggs and fish — were among the least common causes of food sensitivity across countries.
For the study, published in the journal Allergy, the researchers tested participants’ blood for antibodies against a range of foods. This gauges food sensitivity, which refers to an immune system response to a food’s proteins. Not everyone who is sensitive to a food has a clinical allergy, which means that a person has specific symptoms, like wheezing, hives, swelling or digestive problems, after eating the food.
Along with the U.S., Germany, Italy and Norway had the highest prevalence of food sensitivity — with about 22 percent of people from each country showing antibodies against some type of food.
The lowest rates were seen in Iceland (11 percent), Spain (11 percent), France and the UK (each around 14 percent).
When it came to the types of foods behind people’s sensitivities, hazelnuts, peaches, shrimp, wheat and apples emerged as the most common. At the other end of the spectrum, fish, eggs and cow’s milk were the least common causes of sensitivity.
Those patterns were fairly consistent across countries — more consistent than would be expected by chance, according to the researchers, led by Dr. Peter Burney of Imperial College London in the UK.
Across countries, less than 1 percent of people had sensitivities to fish, eggs or milk. In several countries, including the U.S., Italy, France, Australia and Iceland, no one had fish sensitivity; egg sensitivity was also absent in a few nations.
Seven percent of people across the nations had sensitivity to hazelnuts, with some countries — including the U.S., Germany, Norway and Sweden — showing a prevalence of 12 percent to 15 percent. The next most common causes of sensitivity were peaches, shrimp and wheat, which each affected about 5 percent of people across countries.
Exactly why countries were similar in the patterns of food sensitivity is not clear. There are differences, Burney and his colleagues note, in the typical diets of the various nations studied — suggesting that a nation’s overall consumption of a food does not determine the prevalence of allergies to it.
Nor was there a clear relationship between a nation’s prevalence of sensitivity to airborne allergens — like pollen and dust — and its prevalence of food sensitivity. That finding is unexpected, according to Burney’s team, and it suggests that the two types of allergies arise from at least partly separate causes.
SOURCE: Allergy, online February 22, 2010.