There are different kinds of adverse reactions to food - some are considered allergic and others are non-allergic. Those that are considered allergic are called food allergies. Those that are non-allergic are called food intolerance. When someone is having an allergic reaction, it is important to determine what is allergy and what is food intolerance.
Food allergies occur when your immune system reacts adversely to a particular food or food additive. Chemically, it is believed that your body is responding to the proteins in the food. This is what is causing an allergic reaction. Unfortunately, even a very small amount of the protein can trigger a reaction. Also, most proteins can cause reactions even after being cooked, though cooking or canning these foods may reduce or eliminate your allergy symptoms.
It is estimated that in the US, up to 8% of children and 2% of adults are affected by food allergies.
A small number of foods are believed to cause the majority of food allergies. The top eight food allergens are:
- Fish (including cod, salmon, and tilapia)
- Shellfish (including crab, shrimp, and lobster)
- Tree nuts (including walnuts, almonds, and cashews)
- Cow's milk
Some interesting information:
- Sometimes, ingestion of the offending food must be tied to something else (such as exercise) to induce a reaction.
- An allergy to one food sometimes results in an allergy to all foods of the same family. For example, allergy to one type of shellfish (let’s say crab meat) puts you at higher risk of being allergic to others (shrimp and lobster). This is called cross-reactivity.
- It is possible for people allergic to beef to be able to safely drink cow’s milk, and for patients allergic to chicken to eat eggs. It is also possible to have an allergic reaction to egg yolks but not egg whites (because they contain different proteins).
In any of these instances, however, it is always important to exercise caution and consider avoiding the food entirely. Consult your NY allergist for further information regarding your particular situation. Some patients have what is called Food-Pollen Allergy Syndrome. In this condition, individuals with strong reactions to certain pollens will experience cross-reactivity with certain fruits and vegetables. These allergic reactions may not show up on typical allergy testing. Our allergy clinics will help determine which of these fruits and vegetables are causing your reactions.
In small children, temporary, non-allergic food reactions are common, especially fruits, egg white, cow’s milk, and wheat. For example, your child may have a temporary rash near the mouth that is simply caused by the natural acids in foods like oranges and tomatoes. Another example is diarrhea caused by the high sugar content in fruit juice or other beverages.
- Hives (itchy, red, swollen areas of skin; also called urticaria)
- Swelling and itching in the throat and mouth
- Diarrhea, abdominal cramps, vomiting, or gas
In extreme cases, eating or drinking a food that you are allergic to cause anaphylaxis - a life-threatening, whole-body, allergic reaction.
The signs of anaphylaxis include:
- Flushing, tingling, or warmth in the mouth
- An itchy, red rash
- Shortness of breath
- Severe sneezing
- A feeling of unease or doom
- Cramping in the abdomen and/or uterus
- Vomiting and/or diarrhea
Anaphylaxis symptoms are treated with injectable epinephrine and antihistamines. If there is any possibility that you are experiencing the signs of anaphylaxis, you should seek emergency medical treatment.
We mentioned above that food allergies are allergic reactions to the proteins found in foods. On the other hand, food intolerance is a non-allergic reaction to components in a food other than its proteins. One common example is lactose intolerance, which is a reaction to lactose, a type of sugar that is found specifically in milk. It occurs in individuals who lack the enzymes that are needed to properly digest lactose, and causes uncomfortable abdominal symptoms.
Different food intolerance reactions may be triggered by the chemicals found in a specific food. For example, a person may experience nervousness after drinking caffeine in soft drinks or coffee, headaches caused by chemicals in chocolate or cheese, or a variety of adverse reactions to food additives, whether they are artificial colors, preservatives, etc.
These food additives are known to cause reactions:
- BHT and BHA
- FD&C artificial dyes (specifically Red No. 3 and Yellow No. 5)
- MSG (monosodium glutamate)
- Nitrates and nitrites
The most effective way to prevent food intolerance reactions is to avoid the food or food additive that causes your symptoms. You can start by reading the "Treatment" section below. We also recommend that you contact the allergy specialists and NY allergists at the NY Allergy & Sinus Centers, who can help you determine the difference between food intolerance and food allergy, and help you in establishing a management plan.
An allergist is specially trained to diagnose food allergies and will begin your visit by taking a medical history and performing a physical exam. This will likely involve the following questions:
- Which specific symptoms do you experience?
- How often?
- How severe?
- Immediately after eating? Or with some delay?
Your doctor will also likely perform allergy skin tests to determine which foods, if any, are causing your allergic symptoms. This testing will answer your question: "What am I allergic to?"
If the diagnosis of food allergy remains in doubt, the NY allergy doctor may recommend a test called a "food challenge". This test involves the patient eating small amounts of a suspected allergen under the close supervision of a NYC specialist that is prepared to treat the patient in case of a severe reaction. When properly performed, a food challenge is very effective at confirming that a specific food is truly causing your symptoms.
The first step of treating food allergies is to avoid the food that triggers your allergies. To this end, you should always read food labels when you are at the store, and you should always ask what ingredients are in the food you are selecting at a restaurant. To go further, it is a great idea to let the restaurant know of your food allergies so that they can recommend safe foods and ensure that your meal does not come into contact with your triggers.
The process of avoiding your food triggers is complicated by the fact that many foods have alternate names. For example, when you are checking the ingredients on a food label, you may not find "milk", but you may find "casein". If you know that casein is a protein found in milk, you will know to avoid that product. The allergists at NYASC can provide you with helpful handouts that will list ingredients, scientific names, and even other foods that you should avoid.
For our patients who have experienced an anaphylactic reaction to a food, we recommend:
- Carrying an injectable epinephrine with you at all times. Your NYC allergy dr can prescribe this medication for you and train you on how to administer it.
- Wear a MedicAlert® ID at all times.