Food allergies are on the rise. Children are more likely than ever before to suffer from them. This increase has been most evident in industrialized countries. Currently, they affect over 10% of children in the United States, as well as some 7% of children in the United Kingdom, 9% in Australia, and (strangely) about 2% in Europe. 

What is an allergic reaction? Allergens, which are normally harmless substances in the environment, trigger the immune system. Allergic reactions include skin rashes, hives, swelling, vomiting, diarrhea, and most seriously, difficulty breathing and anaphylactic shock. 

The most common allergy causing foods in children include milk, eggs, peanuts, tree nuts (walnuts, almonds, pine nuts, brazil nuts, and pecans), sesame, fish, and shellfish.

Could the increases in those with allergies, and differences among countries, actually be due to disparities in reporting and increasing awareness? Scientists think this is not the case, and that the current level of increased sensitivity to foods is likely some combination of the effects of our Western lifestyle with various environmental factors. The rates of allergies are much lower in developing countries, and occur in urban rather than rural areas. Theories abound to explain this. They include:

• The impact of pollution.

• The effects of dietary changes. 

• When exposure to microbes is reduced, our immune systems actually respond more strongly to exposure. Ironically, most of the world’s populations now have less exposure to microbes due to cleanliness and improved hygiene. 

• Vitamin D helps our immune system to develop healthy responses, and makes us less susceptible to allergies. However, most people don’t get enough vitamin D. There are several reasons for this, including avoiding dairy products due to lactose intolerance, and staying out of the direct sun. The rate of vitamin D deficiency in the United States is thought to have doubled in just over a decade. 

• When babies consume trigger foods during weaning, it can lead to a healthy immune response and prevent an allergy from developing. Newer practices include introducing new foods slowly, which can actually encourage the formation of allergies. (A major study in the U.K. showed about an 80% reduction in peanut allergy in five-year old children who regularly ate peanuts from the year they were born. This study led to changes in U.S. guidelines regarding peanut consumption during infancy.) 

Families with an allergic child must constantly be on alert. Food allergies can be deadly; consuming minute amounts, or even breathing the fumes of certain foods, such as peanuts, can trigger a life-threatening reaction. Managing the condition relies on avoiding the dangerous foods, and on having an emergency plan in case of exposure. An emergency plan includes always having an EpiPen nearby, and always knowing the location of the closest hospital. 

The diagnosis of a food allergy is made when the same reaction occurs each time a food is consumed. Blood tests can identify most common food allergens, but aren’t conclusive. A supervised oral food challenge is still the most definitive test to confirm a diagnosis. 

There is no cure, but some find improvement through allergen immunotherapy. This involves introducing small amounts of the offending allergen, which gradually reduces sensitivity.  

Are childhood food allergies permanent? Allergies to milk, eggs, wheat and soy sometimes disappear over time, while allergies to peanuts, tree nuts, fish and shellfish tend to be lifelong. Those with food allergies learn to be extra careful when dining in restaurants, as waiters may not always know the ingredients of every dish on the menu. Depending on the level of sensitivity, simply walking into a kitchen or a restaurant can trigger an allergic reaction. 

It is unfortunate that food allergies remain a source of worry and concern for children and their families. However, the future of preventing or minimizing food allergies in children looks promising. Researchers are investigating the use of probiotics to change the microbiota (bacteria in the intestines), and a host of oral immunologic therapies are being investigated to help desensitize children. Stay tuned.

Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 8301 E. Florence Ave., Suite 100, Downey, CA 90240.