My grandson Tomas first noticed a distressing reaction to
hazelnuts at age 8. Whenever he ate
Nutella, his mouth and throat felt tingly
and swollen, and so this sweet spread was then banned from his diet and the
household.
اضافة اعلان
A few years later, Tomas had the same reaction when he ate raw
carrots. In researching this column, I learned that hazelnuts and carrots,
although botanically unrelated foods, share a protein with birch pollen, to
which Tomas is allergic. However, he can eat cooked carrots safely because cooking
denatures the allergenic protein.
Now 21, he has not yet reacted to other foods that also contain
the birch pollen protein, namely celery, potato, apple and peach, although he
could eventually become sensitive to one or more of them. His father said that
as an adult he has developed similar mouth and throat symptoms when he eats
apples and peaches, especially during pollen season.
I also learned of another common link between pollen and food
sensitivities. People allergic to ragweed may also react to bananas and melons.
Again, a shared protein is responsible. This type of allergy is believed to
start with sensitization to inhalation of the offending pollen that later
results in an allergic reaction when the food protein is consumed.
Fortunately, pollen-food allergy syndromes, although not
pleasant, are nearly always mild and not life-threatening.
Unfortunately, a growing number of people can experience severe,
potentially fatal reactions to certain foods, most of which are omnipresent in
the American diet. The main culprits, the so-called “Big 9” — milk, eggs,
peanuts, tree nuts, fish,
crustacean shellfish, wheat, soy and sesame, which
was recently added to the list — account for about 90 percent of food allergy
reactions.
Although commercially packaged foods now must label the actual
or possible presence of major allergenic foods that can cause fatal reactions,
other food allergens are not required to be listed. And sesame, which affects
more than 1 million children and adults in the United States, is not required
to be listed on foods until 2023.
Changing eating habits are adding to the problem. Today’s
growing dependence on foods prepared outside the home by restaurants, stores
and factories makes avoiding food allergens more challenging. People with
potentially fatal anaphylactic reactions can’t be too careful, even when they
have no reason to suspect the presence of a life-threatening allergen. Years
ago a college student who knew she was deathly allergic to peanuts died after
eating chili that had been thickened with peanut butter.
A family I know with a child who is severely allergic to
peanuts, tree nuts, sesame seeds and their oils, dines only in Italian
restaurants and diners that are least likely to use these ingredients. Still,
the venue is always told about the boy’s allergies, and he carries an EpiPen
that can be used to avert a fatal reaction in case a slip-up occurs.
The prevalence of serious food allergies ranges from 10 percent
in 2-year-olds and 7.1 percent in children 14 to 17 to 10.8 percent in adults
18 and older. Although allergies to milk, eggs, wheat and soy in infants and
young children are frequently outgrown, others in the Big 9 are nearly always
lifelong. And people who were allergy-free as youngsters do not necessarily
remain so. New food allergies can develop at any age.
According to Dr. Scott H. Sicherer, allergist at the Icahn
School of Medicine at Mount Sinai in New York, and co-authors, “Remarkably,
approximately half of US food-allergic adults report developing at least one of
their food allergies during adulthood, with shellfish allergy responsible for
the largest number of such cases.”
The only real food allergies are adverse immunological
responses, Sicherer explained. The body reacts to an otherwise innocent food as
if it were a life-threatening infection and launches a full-scale offensive.
Symptoms may include hives, trouble breathing, vomiting or anaphylaxis — a
severe, potentially fatal shock reaction that occurs within seconds or minutes
of exposure to an allergen, sometimes in only tiny amounts. That is why most
airlines no longer offer peanuts to flyers — a mere sprinkling of peanut dust
can prove fatal to some people with peanut allergies.
Sometimes, long-term avoidance of a food can result in an
allergic reaction when that food is eventually consumed. This can happen to
children with skin allergies who avoid milk; they may later experience an
allergic reaction when they finally consume it. Occupational
exposures, the use of skin care products, even tick bites can sometimes result
in adult-onset food allergies if there is cross-reactivity to an allergenic
substance in both.
And while in years past allergy-prone families were advised to
avoid exposing their children to peanuts until age 3 (advice that is likely to
have contributed to the current explosion of peanut allergies in children), it
now appears that early introduction — at 6 months — of a highly allergenic food
is actually protective, diminishing the risk of a later-in-life reaction,
Sicherer said.
Further confusing the food-allergy picture is the fact that
under different conditions people may respond differently to the same food.
Thus, for some, an allergic reaction may occur only when the food is consumed
in large amounts or in conjunction with alcohol or intense
exercise, which
allergists call “augmentation factors.”
Recent desensitization studies, which aim to reduce sensitivity
to allergic foods by gradually exposing people to minute amounts of allergens
over several months, and others underway may make life less terrifying for many
people with severe food allergies. Meanwhile, avoiding offending foods offers
the best protection against a severe allergic response.
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