Food allergies are most common in children, but some food allergies last into adulthood---or develop in adulthood. Both childhood and adult food allergies are on the rise, though. Learn the similarities and differences between food allergies in children and adults.
Food allergies develop in childhood more often than they do in adulthood, and food allergies are more common in children than in adults.
Some childhood food allergies last into adulthood, though, and some food allergies only begin in adulthood.
Surprisingly, the amount of food allergies that start in adulthood (adult-onset food allergies) are increasing. While we understand why childhood food allergies are on the rise, the reasons for the increase of adult-onset food allergies are less clear.
Today, we'll break down the similarities and differences between food allergies in children and adults.
Food Allergic Reactions: Same Potential Symptoms In All Ages
In the United States, food allergies affect as many as 32 million people. Approximately 1 in 10 U.S. adults in the United States, and 1 in 12 children, has a food allergy.
When someone has a food allergy, their immune system treats the proteins in a certain food as foreign invaders, much like it treats viruses and certain bacteria.
If someone eats a food that they're allergic to, their immune system will over-defend their body against the food's proteins. Their immune system will prompt the body to develop an allergic reaction every time the person eats a food that they're allergic to.
In people of all ages, allergic reactions can range from mild to severe, and can sometimes be life-threatening.
Food allergies cause largely the same symptoms in children and adults, and can affect the skin, eyes, mouth, respiratory system, gastrointestinal system, or cardiovascular system.
See our chart below to learn all the possible symptoms of a food allergy reaction.
In people of all ages, food allergies also have the potential to cause anaphylaxis, a severe reaction that requires immediate medical attention and an epinephrine injection to treat. When the symptoms of a food allergic reaction are severe, and involve more than one organ system, this is known as anaphylaxis, and this could be life-threatening.
Food Allergy: A Breakdown Of, Or Delay In, Food Tolerance
Regardless of when it develops, a food allergy results from a breakdown in tolerance, or a delayed development in tolerance, of the proteins in a certain food. And although some food allergies are outgrown, once a food allergy develops, there is no cure.
A child may develop a food allergy because their body hasn't yet developed a tolerance to a food protein, but then may "outgrow" the allergy and build up a tolerance to that food.
Conversely, a child or adult may tolerate a food at first (sometimes for years), but then develop an allergy to that food because their tolerance of that food breaks down. For example, someone may eat shellfish without any issues for years, but then develop a shellfish allergy in their 30s because their tolerance to shellfish breaks down.
Someone's body may also never build up tolerance to a food after it breaks down or is delayed. If this happens, they'll have a food allergy for the rest of their life.
The top 8 food groups that become food allergies
Among the general population (both children and adults), 8 food groups account for around 90% of all food allergies. These 8 most common food groups are:
- Cow's milk
- Tree nuts
- Finned fish
But which of these food allergies are most common in children, and which usually develop in adults? Which tend to be outgrown, and which tend to be lifelong? Thanks to several studies, we have a clearer picture.
Common Food Allergies In Children
Overall, food allergies are more common in children than in adults.
The most common food allergies in children include milk, peanut, egg, and tree nut allergies.
Milk, egg, and peanut allergies are the most common food allergies in young children by far. According to one study by Dr. Ruchi Gupta, these three foods account for around 80% of food allergies in children age 5 and under.
In addition to milk, egg, and peanut allergies, tree nut allergies are also very common in children age 14 and under.
While many children tend to outgrow milk and egg allergies later in life, peanut and tree nut allergies are more likely to be lifelong.
According to the study, shellfish allergies are also among the top 5 food allergies in children age 14 and under. However, other studies have shown that shellfish allergies are much more common in adults than babies and young children. In addition, severe reactions to shellfish in children are rare.
Common Food Allergies In Adults
Another study by Dr. Ruchi Gupta examined rates of different food allergies in over 40,000 adults.
According to this study, shellfish allergies are clearly the most common food allergy in adults, with an estimated 7.2 million adults affected.
The other top allergies in adults, in order, are milk, peanut, tree nuts, finned fish, and egg.
For more on this study of food allergies in adults, watch this news report from CBC:
Shellfish and finned fish allergies both tend to develop in adulthood, and both tend to be lifelong. This means that many people are able to eat shellfish or finned fish for years without issues, but then suddenly develop an allergy as an adult, and never gain back their tolerance to the food(s) they become allergic to.
Meanwhile, peanut, egg, and milk allergies in adults tend to start in childhood, then persist through adulthood, without the person ever outgrowing them.
Why are childhood food allergies on the rise?
Childhood food allergies develop through a combination of genetic and environmental factors. The main risk factors are eczema, family history of food allergy, and delayed introduction of common allergy-causing foods (such as peanut, egg, and milk).
While the first two main risk factors cannot be changed, we have control over when we feed a child common allergy-causing foods. This greatly influences the prevalence of childhood food allergies.
Starting approximately 20-30 years ago, doctors inadvertently gave advice that increased children's food allergy risk. Back then, the advice was to avoid introducing common allergy-causing foods to a child for their first 1-3 years of life.
But thanks to recent landmark clinical studies (LEAP, EAT and PETIT), we now know that between 1997 and 2008, the amount of peanut allergies in children more than tripled, and that it is important to introduce allergens early.
In contrast, the results of these landmark studies show that introducing peanut, egg, and milk in a baby's first year of life (starting as early as 4 months of age), and continuing to sustain exposure over several months, is important. Hopefully, the early introduction of foods like peanut, egg, and milk will become more commonplace.
Why are adult food allergies on the rise?
Like childhood food allergies, adulthood food allergies are becoming increasingly prevalent.
According to the 2015-2016 study led by Dr. Ruchi Gupta, which involved over 40,000 American adults:
- 1 in 10 adults has a food allergy.
- 51% of the adults with food allergies have had a severe allergic reaction, and over 38% needed emergency care for at least one allergic reaction.
Part of the rise in adult food allergies can be attributed to children growing up, but not outgrowing food allergies. Since childhood food allergies have become more prevalent due to delayed food introduction, more adults now have lasting food allergies.
But more people are also developing food allergies as adults.
Dr. Gupta's 2015-2016 study reports that:
- 48% of adults with food allergies developed at least one food allergy as an adult.
- Around 25% of the adults with food allergies developed their first allergy in adulthood.
The reasons for the rise in adult-onset food allergies aren't very clear, though. We do know, however, that if someone develops a food allergy in adulthood, it's more likely to be lifelong. While many children outgrow their food allergies as they get older, if an adult has a food allergy, they likely won't outgrow it. Now that we know that rates of adult-onset food allergies are rising, more research is needed to discover why these allergies are becoming more common.
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