What you don’t know about food allergies



Reaction to foods with pollen, the appearance of symptoms in adults, and cross-reactivity are just some of the surprising ways our body responds to food.  (Grace Lam / The New York Times)


© Distributed by The New York Times Licensing Group
Reaction to foods with pollen, the appearance of symptoms in adults, and cross-reactivity are just some of the surprising ways our body responds to food. (Grace Lam / The New York Times)

(Science Times) ; (Personal Health)

My grandson Tomas first noticed a worrying reaction to hazelnuts when he was 8 years old. Every time she ate Nutella, her mouth and throat felt swollen and tingly, so this spread was eliminated from her diet and from the house.

A few years later, Tomas had the same reaction when he ate raw carrots. In my research to write this column, I learned that hazelnuts and carrots, despite not having any botanical relationship, have a protein with birch pollen, to which Tomas is allergic. However, you have no problem eating cooked carrots as cooking denatures that allergenic protein.

Now 21, he still hasn’t had any reactions to other foods that also contain birch pollen protein, namely celery, potato, apple and peach, although at some point he could become sensitive to one or more of these foods. His father said that as an adult he has developed similar symptoms in his mouth and throat when he eats apples and peaches, especially in the pollen season.

I also learned that there is another common link between pollen and food sensitivity. People who are allergic to ragweed also have reactions to bananas and melons. Again, the culprit is a protein they have in common. This type of allergy is believed to begin with sensitization to inhalation of the irritant pollen, which then produces an allergic reaction when protein in food is consumed.

Fortunately, pollen food allergy syndromes, while unpleasant, are usually mild and not life threatening.

Unfortunately, an increasing number of people can have serious and potentially fatal reactions to certain foods, most of which are present everywhere in the American diet. The main culprits, called “the big 9 allergenic foods” (milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, soybeans and sesame, which were recently added to the list), constitute about 90 percent of the allergic reactions to food.

Although food packaged for marketing must now have labels alerting you to the possible or true presence of major allergenic foods that can cause fatal reactions, other food allergens are not required to be listed. They also don’t have to list sesame, which affects more than a million children and adults in the United States, until 2023.

Changing habits is contributing to this problem. Today, our increasing dependence on food prepared in restaurants, shops, and factories makes it more difficult to avoid food allergens. People with life-threatening anaphylactic reactions should be extremely careful, even when they have no reason to be suspicious about the presence of a life-threatening allergen. A few years ago, a college student who knew she was allergic to peanuts passed away after consuming a sauce that had been thickened with peanut butter.

A family I know with a son who is very allergic to peanuts, tree nuts, sesame seeds and their oil, only dines at Italian restaurants and coffee shops that are least likely to use these ingredients. However, they always alert the local to the child’s allergies and he brings an EpiPen with him, which can be used to prevent a fatal reaction should a mistake arise.

The prevalence of severe food allergies ranges from 10 percent in 2-year-old children and 7.1 percent in boys between the ages of 14 and 17 to 10.8 percent in adults over 18 years of age. Although babies and young children almost always outgrow allergies to milk, eggs, wheat, and soy, other allergies to the Big 9 Foods last almost a lifetime. And allergies can also develop in some people who did not have any allergies when they were young. New food allergies can appear at any age.

According to Scott H. Sicherer, an allergist at the Icahn School of Medicine at Mount Sinai in New York, and his co-authors, “It is surprising that about half of American food-allergic adults report that at least one of their allergies appeared during adulthood and that the allergy to shellfish is responsible for the largest number of these cases ”.

Sicherer explained that the only true food allergies are adverse immune responses. The body reacts to potentially harmless food as if it were a life-threatening infection and then launches a major offensive. Symptoms may include hives, shortness of breath, vomiting and anaphylaxis, which is a strong shock reaction that can be fatal and occurs within a few seconds or minutes of exposure to an allergen, which sometimes has only been consumed in very small quantities. That’s why airlines no longer offer peanuts to their passengers, as a single sprinkle of peanut powder can prove fatal to some people who are allergic to peanuts.

Sometimes stopping a food for a long time can cause an allergic reaction when that food is eaten again. This can happen to children who have skin allergies and who avoid milk; they may later have an allergic reaction when at some point they consume it. Exposure at work, the use of skin care products, even tick bites can sometimes result in food allergies that arise in adulthood when there is cross-reactivity to an allergenic substance present in both situations.

Also, while families with a history of allergies were advised in the past not to give their children peanuts until they were 3 years old (a recommendation that may have contributed to the current tremendous increase in peanut allergies in children) ), it now appears to actually be more protective of them by giving them a highly allergenic food at a young age – at six months – which reduces the risk that they will have a reaction later in life, Sicherer noted.

One fact that further complicates the food allergy landscape is that people can react differently to the same foods under different conditions. Thus, some people may have an allergic reaction only when they consume that food in large amounts or in combination with alcohol or vigorous exercise, which allergists call “escalation factors.”

Some recent desensitization studies, which aim to decrease sensitivity to allergenic foods by gradually exposing people to trace amounts of allergens over several months, and others that are underway can make life less scary for many people who suffer from severe food allergies. Meanwhile, avoiding the foods that cause harm offers the best protection against any serious allergic response.

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