FOOD ALLERGY: AN OVERVIEW

MEENAKSHI BHARKATIYA*, KAMAL SINGH RATHORE, ANKUR MAHESHWARI, SUNITA PANCHAWAT, R. K. NEMA

B. N. GIRLS? COLLEGE OF PHARMACY, UDAIPUR-RAJ. 31002

INTRODUCTION

Food allergy is recognized as a common worldwide problem, and, like other atopic disorders, its incidence seems to increase. In the past years, investigations of allergic food proteins and related immunological responses have moved to the molecular level, and the newly-found knowledge might provide novel experimental strategies for the laboratory diagnosis and the immuno-modulatory control of food-induced allergic reactions (1, 2).

Approximately 20% of the population alters their diet for a perceived adverse reaction to food, but the application of double-blind placebo-controlled oral food challenge, the ?gold standard? for diagnosis of food allergy, shows that questionnaire-based studies overestimate the prevalence of food allergies. The clinical disorders determined by adverse reactions to food can be classified on the basis of immunologic or no immunologic mechanisms and the organ system or systems affected (3, 4, 5).

The true prevalence of food allergy is lower and seems to range from 1% to 4% of the general population and about 6% of the general population and about 6% of the paediatric population, but does occur in as much as 25% of children with eczema6. Allergic hypersensitivity simply put, is an adverse immune reaction to a protein (or allergen) in our environment, which is normally harmless to the non-allergic person. It may present as mild itching of the skin, tissue swelling and wheezing or even progress to full-blown anaphylaxis and death. 18 million allergy sufferers live in the UK where 4% of the populations also have a food allergy.

Allergy develops after repeated exposure to the causative allergen. Sensitization takes place on initial exposure (a process that may take up to six weeks to develop) and no adverse reaction appears to occur during initial sensitization (6).

(A) DEFINITION

A food allergy is an immunologic response to a food protein and caused by allergens in the food that are a kind of protein in the food. These proteins resist the cooking process, the acid in the stomach and the enzymes in the stomach and intestines and enter the blood stream and they cause the allergy reaction after they enter the blood stream.

(B) SIGNS AND SYMPTOMS

Symptoms of food allergies are: –

1. Anaphylaxis: – a severe, whole-body allergic reaction that can result in death. Leads to vasodilation and, if severe, symptoms of life-threatening shock.

2. Angioedema: – rapid swelling (edema) of the skin, mucosa and submucosal tissues, especially of the eyelids, face, lips, and tongue.

3. Eczema is a form of dermatitis, or inflammation of the upper layers of the skin.

(a). Atopic eczema (aka infantile e. , flexural e. , atopic dermatitis) is believed to have a hereditary component, and often runs in families whose members also have hay fever and asthma. Itchy rash is particularly noticeable on face and scalp, neck, inside of elbows, behind knees, and buttocks.

(b). Contact dermatitis is of two types: allergic (resulting from a delayed reaction to some allergen, such as poison ivy or nickel), and irritant (resulting from direct reaction to a solvent, for example). Some substances act both as allergen and irritant (e. g. wet cement). Other substances cause a problem after sunlight exposure, bringing on phototoxic dermatitis.

(c). Xerotic eczema (aka asteatotic e. , e. craquele or craquelatum, winter itch, pruritus hiemalis) is dry skin that becomes so serious it turns into eczema. It worsens in dry winter weather, and limbs and trunk are most often affected. The itchy, tender skin resembles a dry, cracked, river bed. This disorder is very common among the older population.

(d). Seborrhoeic dermatitis (aka cradle cap in infants, dandruff) causes dry or greasy scaling of the scalp and eyebrows. Scaly pimples and red patches sometimes appear in various adjacent places. In newborns it causes a thick, yellow crusty scalp rash called cradle cap which seems related to lack of biotin, and is often curable.

4. Skin rashes, such as nettle rash (also called urticaria or hives). Some of these longer lasting rashes are called atopic dermatitis.