Salmon meat is among the healthiest in the world.

Rich in vitamins A and D and an excellent source of fish oil and polyunsaturated fats — the good kind of fat — salmon is recommended by a wide variety of public health agencies as a healthy protein source.

Unfortunately, salmon is also a food that prompts 8-year-old Duncan Cook of North Mankato to suffer severe allergic reactions the moment it hits his tongue.

“I grew up in Florida,” said his mother, Amy Edelstein. “I love fish. But we can’t eat it at home.”

Duncan was just a little younger than 2 when his mother fed him his first bite of salmon. Expecting her child to lick his lips in delight, Edelstein was terrified when Duncan immediately vomited and broke out in hives.

Weeks later, before Edelstein could get her son in to see a specialist, Duncan had the same reaction when he accidentally ate a bite of steak that had merely shared a plate with a grilled salmon fillet.

“It was scary,” Edelstein said. “Very scary. But when those kinds of things happen, you just have to educate yourself.”

And millions of other parents are having to educate themselves as well.

According to a 2006 survey by the International Study of Asthma and Allergies in Childhood that looked at more than 700,000 children in 56 countries since 1991, allergies are on the rise all over the world. A 2003 Mount Sinai School of Medicine study reported peanut allergies in kids younger than 5 have doubled. And the Food Allergy and Anaphylaxis Network says one out of every 17 kids younger than 3 years old has a food allergy.

At home, those numbers had much to do with the Mankato Clinic’s recent hire of its first full-time allergist, Dr. Srinivasan Ramanuja. The clinic’s allergy department is the first of its kind in the area and, Ramanuja said, will supply a growing demand.

“It’s important to have a service like this, especially in a growing community,” Ramanuja said. “The incidence of allergies has definitely been increasing over the last decade.”

But even though Ramanuja and much of the medical community seem in agreement that allergies are becoming more prevalent, the causes of such an increase are obscure.

Some posit the “hygiene hypothesis” that says children in developed countries — where clean water, antibiotics and vaccines are the norm — have immune systems that don’t encounter toxins often enough to build immunities. A 2003 study published by the Journal of Allergy and Clinical Immunology reported the nation’s increase in Caesarean section births is correlated to the increase in food allergies because those babies are not exposed to the healthy bacteria found inside the birth canal.

“Allergies are being diagnosed more,” Ramanuja said. “I really think people are just becoming more aware of them.”

After Duncan’s second allergic reaction, he underwent allergy skin tests. The results showed Duncan was also allergic to nuts and that he would react most severely to fish — especially cod and salmon. And while Duncan’s allergy diagnosis was not exactly life threatening, that’s not the case with all allergies.