Sensitivities to Food

Food can cause individualistic adverse health effects. In other words, everyone has different reaction to the same food.

This entry will give a snapshot on the adverse effects of food which are generally classified into two types i.e. food allergy and food intolerance.

Food allergy involves abnormal immunology reactions. There are two types of food allergy. The first type is known as immediate reaction, which occurs within 60 minutes of exposures. This is characterized by skin rash and itchy, abdominal discomfort, and may lead to shock. Examples of foods involved are fish, shellfish, shrimp, nuts, legumes, eggs, milk and berries. The second type is delayed reaction which occurs within one to two days of exposures. The sign and symptoms are almost the same, but the severity depends on the amount of the food consumption. The symptoms usually decrease in severity with prolonged avoidance. Examples of foods involved are milk, wheat, chocolate, cola, corn, eggs, beef, pork, chicken, legumes, tomatoes, oranges, cucumbers, and garlic.

Food intolerance occurs through different mechanism without involving immunological reactions. The effects depend on type of enzyme released due to food consumed. The signs and symptoms are headache, migraine, tremor, sweating and palpitations. Other symptoms are diarrhoea and concentration disorders. Examples of foods for this mechanism are coffee, tea, chocolate, cheese, bananas, yeast extracts and food rich in monosodium glutamate (MSG).

Diagnosis of food allergy and intolerance is quiet difficult. This requires careful interpretation of the patient’s history, clinical observations, dietary background and some supporting examination. The most common methods are challenge tests, in which patients are challenged by the suspected foods or food components. Another method is by performing elimination diets by excluding the suspected foods. Laboratory test such as RAST (radioallergosorbent test) and skin tests are often unreliable, giving false positive and negative results. Thus, the best approach to diagnosis of food allergy combines dietary history, clinical observations and laboratory tests.

When the suspected foods or food components have been known, the patients need to avoid consumption of the substance. Food labelling and nutrition education are therefore important in the prevention of adverse reactions to food by susceptible individuals.

Source:

Briggs DR, Lennard LB. Food Sensitivities. In Wahlqvist ML. Ed. Food and Nutrition – Australia, Asia and the Pacific. Sydney: Allen&Unwin Pty Ltd, 1997; 425-433.