Food allergies occur when the immune system mistakenly believes that something you eat is harmful to your body. In an attempt to “protect” the body, the immune system makes IgE antibodies against the food. These antibodies cause cells called mast cells (a type of allergic cell) to release certain chemicals into the bloodstream.
One such chemical is histamine, which acts on the eyes, nose, skin and/or digestive tract, causing the symptoms of allergic reactions.
As soon as the body makes antibodies against a certain food, these antibodies recognize it instantly. And every time a person ingests that type of food again, his or her body releases his or her own into the bloodstream, the allergic symptoms reappear. In severe food allergies, an allergic reaction can occur even when the affected person touches or inhales particles of the allergenic food.
Are food allergies hereditary?
Whether or not a person develops an allergy is partly influenced by heredity. For example, if both parents have conditions of allergic origin (such as eczema), the child will have a 40-60% chance of developing an allergy, but not necessarily a food allergy.
About the reactions
Some allergic reactions are very mild and only affect one system of the body, such as the appearance of hives on the skin, while more severe reactions affect more than one system. Most reactions last less than a day and can affect any of the following four systems:
Skin reactions are the most common type of allergic reaction to a food. They may take the form of red spots or hives associated with itching (hives), eczema, redness, and swelling on the face and/or around the mouth.
Symptoms may take the form of cramping, nausea, vomiting, or diarrhea.
Symptoms can range from runny or stuffy nose, sneezing, itchy eyes and watery eyes to asthma attacks associated with episodes of coughing, wheezing (“whistling” when breathing).
Those affected may experience dizziness and/or fainting.
Most reactions occur shortly after eating the allergenic food. However, everyone is different, so even though two people have peanut allergies, their allergic reactions may differ considerably. And even the same person may have different allergic reactions to the same food, depending on factors such as the amount of food they have been exposed to.
Food allergy or food intolerance?
People often confuse food allergies with food intolerance (such as lactose intolerance). But food intolerance does not involve the immune system. In fact, it occurs because of a problem digesting or breaking down certain substances. The symptoms of food intolerance are not as dangerous as those of food allergies.
When a person has a severe allergic reaction that affects more than one system, this condition is called anaphylaxis. These are sudden, life-threatening allergic reactions. In addition to the symptoms mentioned above, anaphylaxis can cause inflammation of the airways, severe breathing difficulties, drop in blood pressure, loss of consciousness, and, in some cases, even death.
Because food allergies can be severe, people who think they might be allergic to a certain food should see their doctor. It may be tempting to think that it is enough not to eat the food in question, but the allergens may be hidden in unexpected places and, without a doctor’s diagnosis, a person may not know exactly what to avoid.
What do doctors do?
Your doctor will study the possibility that you may have some other condition that could be causing your symptoms. For example, if you have diarrhea after drinking milk, your pediatrician will test to see if lactose intolerance may be the cause of your symptoms rather than a food allergy. Another condition whose symptoms may resemble those of food allergies is celiac disease. People affected by this disease do not tolerate gluten (a protein found in wheat and other cereals).
If your doctor thinks you have a food allergy, he or she will most likely refer you to an allergist (an allergy specialist). The allergist will ask you questions and do a physical exam (where, for example, he or she will listen to your lungs). He or she may also give you some tests to help diagnose your problem.
The most commonly used allergy test is a skin test. A doctor or nurse will superficially scrape your skin (usually the skin on your forearm or back) after placing a small amount of extract and then wait a few minutes to see if any reactions appear. Allergologists may also perform other tests, such as blood tests. This test can detect the presence of antibodies in the blood to a certain food, which is indicative of immune system sensitivity to that food.
If you have a food allergy, you will need to work with your allergist to develop a treatment plan tailored to your particular needs. You should also work with your child to develop an allergy action plan to use in an emergency; you should keep a copy of your action plan in your study centre to avoid severe allergic reactions and to guide you if you do develop them.
Food allergies cannot be cured (although they may remit on their own over time) and the only real way to treat them is to avoid the food in question. Fortunately, doctors can prescribe medication to help alleviate allergic symptoms if they do occur and even to save a person’s life if they develop a severe reaction.
Medications to treat food allergies
Antihistamines can treat isolated symptoms, such as hives, runny nose or abdominal pain, typical of mild allergic reactions.
Are food allergies dangerous?
Food allergies are dangerous, as in some cases they can lead to death after anaphylactic reactions.
Symptoms related to the severity of the allergic reaction are:
Choking sensation, hoarseness, tightness in the throat, difficulty swallowing
Inspiratory beeping or wheezing, shortness of breath, tightness in the chest
Itching, general tingling sensation in hands, feet, neck and throat
These symptoms can occur immediately and their evolution can be very rapid from minutes of ingestion to 1 hour, constituting a medical emergency and requiring immediate treatment with adrenaline.
What are the most common allergies?
The most common allergies are those that appear in early childhood when solid foods are first incorporated into the diet after breastfeeding.
Before one year of age, cow’s milk and egg allergies can often be seen.
Between 1 and 2 years of age, allergies to soybeans, cereals and fish can occur.
Allergies to fruits, vegetables, cereals, nuts and dried fruit, among others, are more frequent in people over 2 years of age.
In general, food allergies are lifelong, in some cases such as allergies to eggs or cow’s milk may disappear between the ages of 2 to 4 years.
What are the foods that can cause allergy?
The proteins in cow’s milk
Casein, rennet casein, caseinates, lacto albumin, lactulose. They normally appear in the first year of life.
Ovalbumin is frequently used in the food and bakery industry as an additive, preservative, stabilizer, food coloring, artificial flavors, in baking, pasta, ice cream, meringues, marzipan, chocolates, nougat, etc.
They are usually part of excipients or diluents in preparations such as medicines.
Vaccines (measles, mumps, rubella) can also be prepared by growing the viruses in chicken embryo cultures.
Egg allergy is often associated with cow’s milk protein allergy.
Nuts and dried fruit
Peanuts, nuts, almonds, oils or derivatives such as butter or peanut flours. African Indian, Chinese, Indonesian, Thai, Vietnamese, North American and Mexican cuisine uses peanut derivatives such as nuts, oils, flours, butter and seasonings.
Allergies are common in children and adults. Allergy to white fish (hake, sole, sea bream, trout, etc.) is more frequent than blue fish (sea bream, salmon, sardine, anchovy, etc.). Vapors from cooking or frying fish may cause allergies by inhalation.
Crustacean shellfish such as lobster, prawn, Norway lobster, barnacles, and molluscs such as mussels, clams, oysters, squid, cuttlefish, octopus, and snails can cause severe allergic reactions. Products that are released from cooking may also cause allergy by inhalation.
Soya allergy is relatively common
Fruits such as peach and rosaceae (apricot, nectarine, cherry, plum, strawberry, pear, apple), Elkiwi, banana or pineapple may also be responsible for allergies.
Legumes such as lentils or chickpeas can cause allergies. Allergies to fruits, nuts and vegetables often coexist.
Additives such as sulphites, nitrites, glutamate, etc., which function as preservatives, sweeteners, flavourings, dyes, emulsifiers and stabilisers, are present on food labels under the letter E, may be responsible for food allergies or may cause the release of inflammatory substances causing abdominal cramps, skin rashes, bronchial obstruction of non-allergic origin, but indistinguishable from allergic reactions.
What steps can I take to avoid food allergies?