A true food allergy is a heightened response of the immune system to a food or food component. When someone with a true food allergy ingests a food or food component to which they are allergic, the body’s immune system labels it as a foreign invader. To defend against the perceived threat, the immune system commands the body to produce large amounts of proteins called immunoglobulin antibodies. The antibodies attach themselves to specific cells called mast cells, which triggers the release of histamine and other chemicals into the bloodstream. It’s these chemicals that cause a variety of symptoms in several parts of the body.
People at risk for food allergies include those whose parents had any kind of allergies, including hay fever and asthma, and those whose mothers smoked during pregnancy. But people without a family history of allergies can develop them, too.
Food allergies often become apparent during early childhood, but they can also emerge in later childhood and even in adulthood.
Allergy symptoms appear anywhere from a few minutes to two hours after being exposed to a food allergen. Response times differ from person to person and can vary even in individuals exposed to the same allergen on different occasions. Symptoms can be milk or severe and can include the following.
• Flushed skin or skin irritations such as hives, rashes, or eczema
• Tingling or itchiness in the mouth
• Swelling in the face, tongue, lips, throat, or vocal chords
• Gastrointestinal symptoms such as stomach cramps, diarrhea, or vomiting
• Wheezing or breathing problems
• Coughing, sneezing, or a runny nose
• Dizziness or lightheadedness
People who have both food allergies and asthma are especially vulnerable to developing a severe reaction when exposed to a food allergen. Anaphylaxis, a life-threatening condition, can occur very quickly after exposure to a food allergen. It can affect several body parts at the same time, causing blocked airways in the lungs, extremely low blood pressure and anaphylactic shock, or a swelled throat that can lead to suffocation. Of all food allergens, peanuts and tree nuts typically cause the most severe symptoms.
If you or one of your children experiences symptoms after eating a particular food, be sure to speak with a physician or a board-certified allergist (if possible, while experiencing symptoms), as subsequent exposures might produce a more severe reaction.
Your doctor can recommend any combination of an elimination diet, skin tests, blood tests, or a double-blind placebo-controlled food challenge (to verify the diagnosis).
Common Food Allergens
Although more than 160 foods can trigger food allergies, the following are the most common food allergens in the United States:
• Tree nuts (including almonds, walnuts, pecans, cashews, Brazil nuts, pistachios, hazelnuts, pine nuts, macadamia nuts, chestnuts, and hickory nuts)
• Crustacean (including shrimp, crab, lobster, and crayfish)
• Fish (including all species of finfish such as bass, flounder, and cod)
Less common but still notable:
• Certain fruits
• Vegetables (such as celery)
• Seeds (such as sesame, poppy, or sunflower)
• Mollusks (such as clams and oysters)
Some people can have a cross-reactivity food allergy in which one food or plant allergy causes them to be allergic to other similar foods. For example, people allergic to cashews or to natural rubber latex may develop a cross-reactivity allergy to mangoes, because of similar antigens in the plants. Most individuals who have a food allergy are also allergic to dust or have other allergies unrelated to food.
Prevention and Treatment
Although exclusive breastfeeding can delay or prevent the onset of food allergies in infants, there is currently no known cure for established way to prevent food allergies from developing altogether. Although allergies to peanuts, tree nuts, and fish often persist throughout life, many children allergic to milk, soybeans, wheat, or eggs eventually outgrow these allergies.
According to American college of Allergy, Asthma, and Immunology (ACAAI) recommendations, parents of infants who have a family history of allergies of any kind should wait until their infants are at least 6 months old before introducing solid foods. The following food introduction timeline is also recommended:
• Dairy products – 12 months of age
• Hen’s eggs – 24 months of age
• Peanuts (including peanut butter), tree nuts, fish, and seafood – 36 months of age (or later)
Because soybeans and wheat are also common allergens, the ACAAI recommends speaking with a pediatrician to determine when those foods can be introduced. A registered dietitian can help parents create appropriate meal plans for their children to ensure they’re getting all they key nutrients needed to support optimal growth and development.
The ACAAI also advises that infants and children who don’t appear to be at risk for allergies not be given solid foods until at least 6 months of age and to offer potential food allergens (including eggs, peanuts/peanut butter, tree nuts, fish, and seafood) one at a time and with caution to help parents better identify an allergic reaction if it does occur.
For those who have food allergies, avoiding allergenic foods (and foods processed or prepared with them) is critical because even tiny amounts of an offending food can trigger a severe or fatal reaction. Fortunately, since 2006, the Food Allergen Labeling and Consumer Protection Act (FALCPA) has required food manufacturers to state simply and clearly on food and beverage packages the food source of the eight “major food allergens” (milk, tree nuts, peanuts, soybeans, wheat, egg, crustacean shellfish, and fish). These are responsible for 90 percent of all food allergies that occur in the United States.
Ingredients (including flavorings, colorings, or any other food additives) that contain proteins derived from any of these foods must also be clearly labeled on food and beverage packages.
If the food source of a “major food allergen” is not part of an ingredient’s common or usual name or is not already listed on the ingredients list, it can appear in the ingredients list in parentheses after the name of the ingredient. For example:
• Whey (milk)
• Lecithin (soy)
• Flour (wheat)
• Enriched flour (wheat flour) and so on
Another option is to put a “contains’ statement immediately after or next to the ingredients list. For example – Contains Wheat, Milk, Eggs, and Soy
Because the statements “can contain” and “free” are not defined by the FDA for use on food packages, it’s better to err on the side of caution and avoid such foods unless you’ve been assured by the manufacturer that the product does not contain any ingredients to which you’re allergic.
It’s very important that individuals with food allergies, including those allergic to foods that don’t need to be declared on food packages (such as sesame seeds), carefully read a product’s ingredient list before consuming the food. Because food labels are not available when eating away from home, at outings, at events, or in restaurants and labels (and allergen labeling) are not required for fresh produce, meat, and some highly refined oils, it’s critical to be careful when choosing any foods that are not labeled and make sure they’re prepared in a way that protects them from contamination with allergens.
It’s also important to keep checking the labels of foods and beverages you regularly consume because manufacturers often change their packaging or ingredients; if you’re unsure whether a particular packaged food is safe to eat, contact the manufacturer.
Those with food allergies should always have an epinephrine autoinjector (such as an EpiPen or Twinject) on hand with instructions for others should they experience a severe reaction and require help with a lifesaving injection. Wearing a medical alert bracelet or carrying a card in your wallet or purse that indicates you have a food allergy can also be helpful.
Histamine is a powerful chemical found in some of the body’s cells and produced by the breakdown of histidine, an amino acid. It is responsible for many of the symptoms experienced by those with allergies to foods, dust, or other substances and can cause a variety of symptoms that affect the eyes, nose, throat, lungs, skin, or gastrointestinal tract. Histamine can be found in improperly stored fish, and in some cheeses, fermented soy products, sauerkraut, alcoholic beverages, and vinegars.
Food Allergy and Anaphylaxis Network (FAAN) is a nonprofit organization of more than 30,000 consumers, health professionals, government representatives, and others worldwide. It raises awareness of, provides resources for, and enhances the understanding of food allergies and anaphylaxis.
Anaphylaxis is a severe systemic reaction (involving many body systems) caused by the immune system after consumption of an allergenic food or food component. It can cause you to stop breathing.
An elimination diet is a diet that is used to identify a food or food component that prompts an allergic response in an individual. Foods that appear to cause problems are removed from the diet one by one until the one that causes the symptoms is identified.
The immune system is the most complex system in the human body. A diverse mix of tissues, proteins, cells and organs work together to support total body defense. Without proper nutrition, the immune system can become weak and ineffective.