Food allergies

Food allergies occur when a person is allergic to a food and he or she ingests it, keeping in mind that he or she has been previously exposed to the same food.

The prevalence of this type of allergy is 5% in the general population. In any case, a large percentage of people present intolerance to some type of food; this is not the same as a food allergy.

What are the symptoms?

When a person ingests a food they are allergic to, the following may occur:

  • Rash, reddening and generalised itching of the skin.
  • Nasal congestion, itching, sensation of obstruction, sneezing and watering of the eyes.
  • Nausea, vomiting, abdominal cramps and diarrhoea.

Are food allergies dangerous?

Food allergies are dangerous, as in some cases they may cause death after anaphylactic reactions.

The symptoms related to the severity of the allergic reaction are:

  • Sensation of suffocation, hoarseness, throat tightness, difficulty swallowing.
  • Wheezes or whistles on inhaling, difficulty breathing, sensation of chest tightness.
  • Itching, sensation of generalised tingling in the hands, feet, neck and throat.

These symptoms may occur immediately and they may evolve rapidly from minutes after the ingestion up to one hour afterwards, constituting a medical emergency and requiring immediate treatment with adrenaline.

What are the most frequent allergies?

The most frequent allergies are those that occur as an infant when solid foods are added to the diet after breastfeeding.

Allergy to cow's milk and eggs can frequently occur before one year of age.

Between the age of 1 and 2, allergies to soy, cereals and fish may manifest.

Over the age of 2, allergies to fruit, legumes, cereals and nuts are most frequent, among others.

It is important to keep in mind that food intolerance to lactose may revert with time as enzymes are developed for intestinal absorption, thereby improving intolerance to cow's milk protein which causes chronic diarrhoea, vomiting, atopic dermatitis, etc.

In general, food allergies are for life; in some cases, such as allergy to eggs and cow's milk, they may disappear between the ages of 2 and 4 years of age.

What are the foods that can cause allergy?

The proteins in cow's milk:
Casein, rennet casein, caseinates, albumin lactalbumin, lactulose. This allergy tends of appear during the first year of life.

Egg protein:
Ovoalbumin, used frequently in the food industry and confectionery industry as an additive, preservative, stabilising agent, artificial colours, artificial flavour, in bread-baking, pasta, ice cream, meringue, marzipan, chocolates, nougats, etc.
It tends to be part of excipients or diluents in preparations such as medicinal products.
Vaccines may also be prepared (measles, mumps, rubella), cultivating viruses in chicken embryo cultures.
Egg allergy is often associated to allergy to cow's milk protein.

Peanuts, walnuts, almonds, oils or derivatives such as peanut flours or butters. Peanut derivatives, such as nuts, oils, flours, butters and condiments, are common in African, Indian, Chinese, Indonesian, Thai, Vietnamese, North American and Mexican food.

Fish proteins:
These allergies are frequent in children and adults. Allergy to white fish (hake, sole, gilthead sea bream, sea bass, trout, etc.) is more frequent than blue fish (red bream, salmon, sardines, anchovies, etc.). Allergies may be caused by inhaling the steam that comes from cooking or frying fish.

Both crustacean shellfish (lobster, prawns, crawfish and barnacles) and molluscs (mussels, clams, oysters, squid, cuttlefish, octopus and snails) may cause severe allergic reactions. Allergies may also be caused by inhaling the products emitted from cooking these foods.

Soy allergy is relatively frequent.

Cereals such as wheat, oats, barley and rye. The allergy occurs because of a common compound called gluten and this allergic disease is called celiac disease.

Fruit such as peaches and the Rosaceae family (apricots, nectarines, cherries, plums, strawberries, pears, apples). Kiwi, banana and pineapple may also be responsible for allergies.

Legumes such as lentils or chickpeas may cause allergies. Allergies to fruit, nuts and legumes often occur together.

Additives such as sulphites, nitrites, glutamates, etc., that serve as preservatives, sweeteners, flavouring agents, artificial colours, emulsifying agents and stabilising agents are listed on food labels under the letter "E", and may be responsible for food allergies or cause the release of inflammatory substances thereby leading to abdominal cramps, skin rashes and bronchial obstruction of non-allergic origin, but undistinguishable from allergic reactions.

What measures can I take to avoid food allergies?

  • Read all the labels of tinned food and preserves before consuming them.
  • Read the package leaflets of medicines and vaccines in the excipients sections.
  • Breastfeeding is recommended until the age of 6 months; solid foods should be avoided until recommended.
  • Introducing other dairy products, cheese or yoghurt is not recommended until one year of age.
  • Eggs should be introduced after the age of 2.
  • Small children should not ingest nuts, peanuts, walnuts or fish until the age of 3.

What should I do if I have some type of food allergy?

The main thing is to identify the food you are allergic to, as treatment is mainly based on avoiding this type of food.

How can I find out if I am allergic to some type of food?

If you suspect you are allergic to some type of food, you should visit your allergist for studies and follow-up.