Can Adults Develop Food Allergies?

Most of the processed and packaged foods you find on your grocery store shelves are laden with additives, preservatives, colorings, flavorings and a number of other chemicals designed to make the product look and taste good. However, each of these additional chemicals increases your risk you'll have an adverse reaction.

Food allergies are the fifth leading cause of chronic illness in the U.S.,1 and the number of people who suffer from them is on the rise. In the decade between 1997 and 2007, the incidence of food allergies rose by nearly 18 percent in children under 18.2 Today, nearly 1 in every 13 children has some type of food allergy.3

Some of the more common foods that spark an allergic reaction in children are nuts, soy, wheat, shellfish and milk. Why those particular foods are the leading triggers is still not fully understood. Dr. Kari Nadeau, director for the Stanford Alliance for Food Allergy Research, points out there is no one protein similar between the foods, and that 30 percent of people who do have food allergies often are allergic to more than one food in that group.4

Scientists have found that allergies may run in families, meaning there may be a genetic factor, as well as environmental factors in the development of food allergies. However, at this point, there is no complete answer as to why some people develop a highly sensitive reaction to some foods and others don't. In the past, many of the cases of food allergies began in childhood, but today, it is not uncommon for those over 18 to develop an allergic reaction to foods, even those they have been eating their whole life.

Adult Onset Food Allergies Are Not Uncommon

Preliminary data from a national study shows that nearly 52 percent of Americans who have food allergies developed them after the age of 18.5 These same results showed that shellfish is the most common food allergy, followed by peanuts and then tree nuts, such as walnuts, pecans and cashews. Interestingly, when children are allergic to eggs, milk or wheat products, they may grow out of the reaction as they age. However, adults who develop a food allergy usually continue to suffer for the remainder of their life.

Dr. Ruchi Gupta, a food allergy researcher at Ann and Robert H. Lurie Children's Hospital, led this national study. She had found that in medical meetings around the world there appeared to be a higher number of adults reporting food allergies. However, as this was anecdotal evidence, Gupta and her team set out to quantify the information.6 The researchers surveyed over 40,000 adults from a national sample and found the foods that triggered allergic reactions in adults were the same as those affecting children.

Once the data was compiled, Gupta expressed interest in "why" adults develop food allergies. While gathering data from the sample, researchers asked the participants why they thought they had developed food allergies as an adult. The answers ranged from changing hormonal levels, moving to another area of the country or a viral illness.7 Gupta hopes to answer questions about why children maintain allergies through adulthood, and how adults are developing new ones, as these answers may have a significant public health impact.

The results of this study confirmed results of another study by FAIR Health that found a 377 percent jump in severe food reactions in the past decade.8 FAIR Health9 is a nonprofit, national repository of insurance claims data. The group looked through 24 billion insurance claims filed by 150 million people for diagnoses where anaphylaxis was caused by food reactions.

They discovered that not only had the number of individuals who experienced a severe food allergy jumped nearly fivefold from a decade ago, but nearly 25 percent of the claims were made in 2016.10 Another study by Food, Allergy, Research and Education (FARE), found that at least 15 percent of people who suffer from food allergies will develop them after age 18.11 Medical records of over 1,100 people diagnosed with food allergies were reviewed. The researchers found:12

  • The age of the first reaction peaked in the individual's 30s
  • The older the person at the time of the first reaction, the more severe the reaction
  • A higher percentage were female
  • Approximately 16 percent were allergic to more than one food

Do You Have a Food Allergy or Food Intolerance?

There is a difference between allergic food reactions and food intolerances. Although some of the symptoms may be similar, the differences are very important. If you are intolerant to a food, you may be miserable for hours to days after eating.13 However, if you are allergic, it could lead to a life-threatening situation. A food intolerance occurs in the digestive tract, while a food allergy triggers a systemic immune response.

The job of your immune system is to identify foreign invaders, separate them and destroy them. When your immune system overreacts to food or other allergens, it can result in a systemic allergic reaction. During an allergic reaction, your immune system mistakenly identifies specific a molecule as dangerous and produces immunoglobulin E (IgE) in an effort to neutralize the threat.14 Researchers suggest that childhood food allergies might be prevented with prenatal or early postnatal strategies toward desensitization.

Symptoms of a food allergy include hives, swelling, nausea and vomiting.15 If it progresses to cause life-threatening symptoms such as difficulty breathing or a drop in your blood pressure, it is called anaphylaxis. Some allergic reactions are less obvious, especially in children. Colic, reflux, eczema and chronic diarrhea may be signs of a food allergy in young children. One study found that up to 50 percent of cases of eczema in young children are the result of a food allergy.16

Symptoms of a food intolerance may be the result of an inability to digest the food from an enzyme deficiency or sensitivity to any of the food additives or chemicals. Sometimes, if you are intolerant, you may be able to eat small amounts of the food without experiencing a reaction. However, if you have a food allergy, you aren't able to eat any of the food without experiencing a reaction.17

A food intolerance does not involve the immune system and may be immediate or be triggered up to 20 hours after you've eaten the food. Symptoms of a food intolerance may be vague, such as bloating, passing gas, diarrhea or indigestion.  Another type of intolerance is called oral-allergy syndrome, during which you may get tingling or swelling around your mouth after eating some fruits and vegetables.18

This reaction is common in 50 to 75 percent of people who are allergic to birch tree pollen as the proteins in some fruits and vegetables are the same as those in the birch tree. Oral-allergy syndrome is a type of contact allergic reaction that usually appears immediately after eating the offending fruit or vegetable, does not usually lead to swelling of the throat and neck, and often disappears within hours.

Symptoms of Food Allergies May Not Be Obvious

In some instances, symptoms of a food allergy may not be as obvious as hives or swelling. For instance, an exercise-induced food allergy19 occurs when specific foods are eaten just before exercise, which may increase your potential for experiencing an allergic reaction, including serious or life-threatening reactions. Carefully track the foods you ate before the reaction and avoid them in the future. Not eating for two hours or more before exercise can help prevent this problem.

In many cases, gastrointestinal (GI) symptoms, such as bloating or gas, are related to a food intolerance. During a systemic immune response, histamine is released in your body. If the histamine is released to your skin, you develop hives that may progress to an anaphylactic response. However, if the histamine is released into your GI tract, it can cause nausea, diarrhea, vomiting and abdominal pain,20 in much the same way a food intolerance may present.

A rare food allergy to a protein in red meat may lead to GI symptoms, hives or anaphylactic shock.21 Many times, the allergic reaction is delayed by four to six hours, but not always. You may develop an allergic reaction to a protein molecule in red meat after being bitten by a Lone Star tick.22

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