When I was a kid, I used to tell people that I was allergic to beets so I wouldn’t have to eat them. Fortunately, I’ve learned to love beets over the years, therefore fibbing about that delicious veggie is no longer necessary. Yet, for a multitude of reasons, countless Americans may be guilty of their own allergy fibs. Allow me to keep you honest and informed.

As hard as it is to believe, many people restrict their diets unnecessarily based off erroneous self-diagnosed food allergies. While we’ve all encountered the occasional drama queen intent on making others accommodate imaginary dietary restrictions, I believe most people are justifiably baffled over allergies and are just trying to make the best decisions they can from the information they’ve encountered. With that in mind, let me add the synopses of some legitimate scientific research to your knowledge base. Over the next four posts, I will share some specifics I’ve learned about allergies through my years of being a food scientist. My studies have extended to literature written by some of the world’s leading experts on the subject, hundreds of pages of sensitivity sense. To restate, below you will find facts not propaganda, and more importantly, I hope you will find some answers.

How common are allergies?

Due mostly to confusion but perhaps sometimes delusion, 20% of the population believes they are allergic to at least one food. How close is that belief to reality? Only about one or two of every 100 adults and one in 10 children have a food allergy. What does this mean? Most kids outgrow their allergies and most adults are mistaken.

What causes allergies?

Allergies involve an immunological mechanism, usually a type I hypersensitivity reaction. This exaggerated response is mediated by IgE antibodies and can involve the skin, gastrointestinal tract, respiratory system, and cardiovascular system. It usually develops rapidly and doesn’t last long.

IgE antibodies are thought to have once been involved in defending our bodies against parasites. Our ancient ancestors may have had much need of their assistance, but modern living has largely eliminated the usefulness of their function. Since the only parasite currently in your life is that uncle that keeps borrowing money, your IgE are left bored and purposeless. Idle antibodies are the root of mischief in this case. In an attempt to stay relevant, these immunoglobulins have become the drama queens of the immune system. “Shellfish? Oh no you dit-ten!”

What are the most common food allergens?

The most widespread food allergies are milk, egg, peanut, tree nuts, fish, shellfish, soy, wheat, fruits, and legumes.

Is a food intolerance an allergy?

While intolerances are frequently mistaken for allergies, they are not allergies. Food allergies have an underlying immunological mechanism; food intolerances do not. Intolerances can be caused by deficiencies of certain digestive enzymes amongst other things. While intolerance can cause a great deal of discomfort, not to mention diarrhea, they do not pose a serious health threat.

Although there are a lot of reasons for adverse food reactions beyond the immune system, people tend to erroneously blame allergies. This leads to the overestimating of food allergies. If you and a certain food don’t get along, an allergy is just one of many possible explanations.

What specifically in foods causes allergies?

Proteins are generally the culprit though other substances like nickel can also cause responses. Proteins that resist digestion and are stable through cooking are more likely to cause allergic reactions as they are not broken down easily into their amino acid components.

Do you have to eat a food to have an allergic reaction to it?

No, allergic reactions to food ingredients can be caused by ingestion, skin contact, or inhalation. Yes, just touching a food or breathing its vapors can induce an allergic response in those susceptible.

What are the common skin symptoms of a food allergy?

Hives and swelling are typical demonstrations of a food allergy. Skin symptoms are the most common manifestations of a food allergy.

Skin reactions can occur from either consumption or direct skin contact. The foods usually associated with contact reactions are raw fish, shellfish, vegetables, and fruit.

What are the common gastrointestinal symptoms of a food allergy?

Anything from nausea, vomiting, abdominal pain, or diarrhea can mean a GI tract is dealing poorly with an allergen. These symptoms can be accompanied by issues in other organs or be the only indicators.

What are the common respiratory symptoms of a food allergy?

Respiratory reactions to a food allergen can occur due to inhalation or ingestion. Symptoms include stuffy nose, itchy eyes, bronchial swelling, bronchospasms, and bronchial hypersensitivity.

Some people allergic to fish, shellfish, or legumes may experience stuffy nose or sneezing when inhaling steam as these foods are cooking. Baker’s asthma, which is caused by the inhalation of flour, is one of the most pervasive occupational respiratory disorders. It impacts 15-30% of all millers, bakers, farmers, and pastry plant workers.

On a side note, the process of sensitization through the lungs is much more direct than sensitization through the gut. This is because inhaled proteins are in their native form not altered by digestion and cooking.

What is anaphylaxis?

Anaphylaxis is a potentially life-threatening expression of a food allergy that can simultaneously impact many body systems. It usually occurs within minutes of exposure and can cause itching, hives, swelling of the skin, swelling of the throat, difficulty breathing, abdominal cramps, vomiting, diarrhea, cardiac arrhythmias, hypotension, and shock. A third of all ER cases involving systemic anaphylaxis are a result of food allergies making those the most common cause. The foods most frequently implicated in ER visits are peanuts, tree nuts, fresh fruits, celery, seeds, legumes, seafood, eggs, and milk. Fatal anaphylaxis is more frequently observed in adults and adolescents; it seldom transpires with children. Acute asthma attacks associated with food-induced anaphylaxis can be particularly serious and are the most common reason for death in these instances.

How do the allergies of children vary from those of adults?

Allergies are most widespread during the first few years of life. Allergies that develop in infants are usually the result of proteins resisting digestion in the GI tract. Baby guts lack sophistication.

For children, the most common allergens are eggs and milk. These are usually outgrown, meaning a tolerance develops. However, kids allergic to peanuts, tree nuts, and shellfish typically remain allergic their entire lives.

In contrast, most food allergies that develop in adulthood are connected to pollens and other inhalant allergens and are a result of cross-reactivity. Cross-reactivity will be covered in my next post.

Are allergies region specific?

Peanut allergy is common in America whereas fish allergy is widespread in Japan. In Europe, many people are allergic to mustard seed. This demonstrates that the development of allergies is related to the degree of exposure.

Is there an association between atopic dermatitis, asthma, and food allergies?

The occurrence of allergies is greater in children with conditions like atopic dermatitis. Roughly 40% of children with mild-to-moderate dermatitis also have a food allergy. Further, childhood food allergies increase the likelihood of asthma and nasal allergies in adulthood.

What type of allergic response is most frequently experienced by adults?

Oral allergy syndrome is the most common way a food allergy presents itself in adults and seems to have become more ubiquitous in the last few decades. It involves contact hives, itching, and swelling restricted to the mouth and lips. It typically exhibits five to 15 minutes after consumption. This reaction is limited to the mouth because the proteins causing the allergy are broken down during the digestive process.

Oral allergy syndrome is regularly seen in adults and adolescents that are allergic to pollens of birch, ragweed, mugwort, or grasses. The triggering food is usually a fresh fruit or vegetable. Among those with pollen allergies, 40% have an associated plant food allergy. This is known as cross-reactivity. Cross-reactivity will be the subject of my next post in this four-part series. Tune in again soon for more overexcitement.

Reference: Mills and Shewry. (2004). Plant Food Allergens. Blackwell Publishing.