It’s critical for people who have food allergies to identify them and to avoid foods that cause allergic reactions. The word ‘allergy’ means that the immune system has responded to a harmless substance as if it were toxic. Allergies are an over-reaction of the body’s immune system to a specific component, usually a protein. These proteins may be from foods, pollens, house dust, animal hair or mounds and are known as allergens.

What is Food Allergy

A food allergy is an abnormal response to a food triggered by the immune system. Food normally doesn’t provoke a response from the human immune system, the body’s defense against microbes and other threats to health. In food allergies, two parts of the immune response are involved,one is the production of an antibody called immunoglobulin E (IgE) that circulates in the blood. The other part is a type of cell called a mast cell. Mast cells occur in all body tissues but especially in areas that are typical sites of allergic reactions, including the nose, throat, lungs, skin, and gastrointestinal tract.

Our bodies are protected from infections by our immune system. We produce molecules, called antibodies, which recognise the germs causing an infection. There are a number of different sorts of antibody, and the one which causes an allergic reaction is called immunoglobulin E (IgE).

The IgE acts like a tag, sticking to molecules in food or pollen called allergens. When someone who has an allergy eats a problem food the IgE attaches to the allergens, setting off an allergic reaction. One of the common effects that IgE triggers is the release of histamine, which causes the changes we see in our bodies as symptoms, like nettle rash or wheezing.

Allergens are usually proteins, and there are generally several kinds of allergen in each food. We do not know what makes some proteins, and not others, food allergens

Risk of Food Allergy May increase if:

• You have a family history of allergy. Food allergies are most common in people who are atopic, meaning they have an inherited tendency to develop allergic conditions such as asthma, various allergies, and atopic dermatitis. If both of your parents have allergies, you have an increased chance of developing allergies.

• You have another allergic condition such as atopic dermatitis or asthma.

• You are young, Infants and children have more food allergies than adults.

• You have a medical condition that makes it easier for allergens to pass through the walls of the stomach and intestines and enter the bloodstream. These conditions include gastrointestinal disease, malnutrition, prematurity, and diseases that impair the immune system.

Symptoms of food allergy

The onset of symptoms from food allergy tend to be more immediate and can be life-threatening. Common symptoms include:

• Itching and burning and swelling around the mouth

• Runny nose

• Skin rash and hives, eczema, urticaria (skin becomes red and raised)

• Diarrhoea, abdominal cramps

• Breathing difficulties, including wheezing and asthma

• Vomiting, nausea

• Life-threatening anaphylaxis.

Allergenic Foods Includes:

Cow’s Milk: Two out of a hundred infants under one year old suffer from cow’s milk allergy, making it the most common food allergy of childhood. In general children lose this sensitivity as they grow up with nine out of ten losing it by the age of three; it is unusual for adults to suffer from this allergy. Symptoms are frequently vomiting and diarrhoea in children, with 30-50% also having skin rashes of some type. A small number of children have an anaphylactic reaction to milk which tends to be lifelong. The major allergens in milk are the caseins and the whey protein b -lactoglobulin. People are usually allergic to more than one kind of milk protein. The proteins from cow’s milk are very similar to those from goats and sheep, and can cause the same sorts of reaction in cow’s milk-allergic subjects. Thus goat’s or sheep’s milk cannot be used as a cow’s milk substitute in allergic individuals.

Eggs: Allergy to eggs is usually observed in young children rather than adults, and like cow’s milk allergy, fades with time. Occasionally children suffer from a severe form of allergy which is not outgrown. The main allergens are the egg white proteins ovomucoid, ovalbumin, and ovotransferrin. The eggs of other poultry, such as ducks, are very similar to those of hens and can cause reactions in egg-allergic individuals.

Fish and shellfish: Allergies to shellfish are unusual in children, mostly being experienced by adults. Reactions to fish are found in children and adults. The incidence of seafood allergy is higher in those countries with a high consumption of fish and shellfish. Severe reactions are more frequently found with these foods, including anaphylaxis. Cooking does not destroy the allergens in fish and shellfish, and some individuals maybe allergic to the cooked, but not raw, fish. The major allergens in fish are flesh proteins called parvalbumins which are very similar in all kinds of fish. This is why people allergic to cod tend to be allergic to fish such as hake, carp, pike, and whiting as well. Shellfish allergens are usually found in the flesh and are part of the muscle protein system, whilst in foods such as shrimps, allergens have also been found in the shells.

Fruits: In general allergic reactions to fruits and vegetables are mild, and are often limited to the mouth, and are called the oral-allergy syndrome (OAS). Around four out of ten people having OAS are also allergic to tree and weed pollens. Thus people who are allergic to birch pollen are much more likely to be allergic to apples.There allergens in fruits and vegetables are not as complicated as other foods. Many of them are very like the allergens in pollens, which is why people with pollen allergies are also allergic to certain fruits.

Many fruit allergens are destroyed by cooking, and thus cooked fruits are often safe for fruit allergic people to eat. Allergies to latex gloves, especially amongst health professionals, are increasing. As many of the latex allergens are like those found in certain tropical fruits, such as bananas, these people can get an allergic reaction to handling or eating these foods .