FOOD ALLERGIES

…a number of conditions can cause adverse food reactions. Most are caused by food intolerance rather than a true food allergy: writes, Kepha Nyanumba-Nutritionist AAR Sarit

An allergy is an adverse immunological reaction to a substance that is harmless in similar amounts to the majority of people. Allergies occur when the immune system mistakenly identifies a harmless substance as a dangerous invader. When you eat the food you're allergic to, the immune system releases symptom-causing substances such as histamine. Food allergy signs and symptoms can include:

·                     Constriction and tightening of airways

·                     A swollen throat or a lump in your throat that makes it difficult to breathe

·                     Shock, with a severe drop in blood pressure

·                     Rapid pulse

·                     Dizziness, lightheadedness or loss of consciousness

A number of conditions can cause adverse food reactions. Most are caused by food intolerance rather than a true food allergy. Unlike a true food allergy, food intolerance doesn't involve the immune system and may not be as severe. With food intolerance, you may be able to eat small amounts of the offending food without trouble. But if you have a true food allergy, even a tiny amount of the allergy-causing food can cause symptoms. In any case, diagnosis is important because either condition may require treatment and avoidance of a certain food or foods.

Food intolerance could result from enzyme deficiency, digestion problem or reactions to chemicals in foods. Food allergy is much more common in children, but fortunately some children outgrow their food allergies. 

 The typical symptoms of food allergy are varied, and usually develop within 15 to 30 minutes after eating the particular food.  Therefore, if your symptoms develop more than 1-2 hours after eating the food, it is less likely that you may have food allergies, and it may be food intolerance instead. 

Almost 75% of adverse reactions are caused by milk, walnuts, peanuts, soyabeans, shellfish, and finned fish (i.e., tuna, salmon).  Children tend to be more allergic to foods including eggs and milk, and fortunately usually outgrow these food allergies by ages 2-3 years.  However, if a child develops allergies to the foods mentioned above for adults (nuts, peanuts, shellfish and finned fish), it is less likely that he or she will outgrow these allergies and will have them as an adult.  It is also not unusual for an adult to develop food allergy, and no one really knows why this happens. 

If you think that you may have a food allergy, the most important thing to first do is to seek diagnosis. Even eating a small amount of the food may cause a life threatening reaction, especially with peanuts.  It is also critical at this point, that you read food labels, as many foods may contain trace amounts of the food to which you are allergic.  Fortunately, food labels have been made easier to read for the general public to let people know about food ingredients.  Also, if you are allergic to a food, you need to be careful when going to restaurants and visiting friends’ houses to eat. It is also important to seek advice about eating foods that may “cross-react” with the food to which you are allergic.  For example, if you are allergic to one of the tree nuts, you may also be allergic to another type, or if you are allergic to lobster, you may also be allergic to another shellfish. 

Food allergy or food intolerance can be properly diagnosed with scientifically sound methods of testing. If someone thinks that they may be suffering from an allergic response to certain food substances, the first step is to go to a doctor to ensure that the symptoms are not due to another condition and who can refer the patient to a dietician or a specialist on allergy.

The first step to a reliable diagnosis is reached by getting a detailed history of the patient's and family's medical background. Special attention will be given to the type and frequency of the symptoms, along with when the symptoms occur in relation to eating particular foods. A complete physical examination of the patient will also be undertaken. Then, the following main detection methods are used:

§     Skin tests

On the basis of past diet history, foods suspected to cause allergic reactions are included in the panel used for skin tests. The tests involve placing on the skin extracts of a particular food, which are then pricked or scratched into the skin to look for a reaction of itching or swelling.

§     Food elimination diets

The principle of the elimination diet is that a single or combination of suspect foods may be removed from the diet for around 2 weeks prior to a food challenge. If the symptoms disappear during this period, suspect foods are added back to the diet, one at a time, in small but gradually increasing amounts until a normal consumption pattern is achieved. Once all the suspect foods have been checked out, those foods causing problems can be avoided.

§     RAST (radioallergosorbent) tests

These tests involve mixing small samples of the patient's blood with food extracts in a test tube. In a true allergy, the blood produces antibodies to fight off the foreign protein, which can be detected. The test can only be used as an indication of an allergy and does not determine the extent of the sensitivity to the offending food.

 

What can people do to prevent food allergy and food intolerance?

Once a thorough examination has helped to accurately identify the offending foods or food components, the only way to prevent the allergic reaction in sensitive individuals is to eliminate the food or food component from the diet. In the case of food intolerance, limiting the food to smaller servings may be sufficient to avoid symptoms. Reading the ingredient information on food labels and knowing which foods trigger the allergies, intolerance is the best defense

Professional help from a nutritionist can help ensure that no nutrients are excluded from the diet when food changes and substitutions are made. Asking about ingredients and cooking methods when taking food outside of the home can help to avoid known problem foods. When eating away from home, it is important to explain your situation and special needs to your host or food server. If necessary, ask to speak to the chef or manager of a café or restaurant.

If in doubt, play it safe and stick to plain foods such as grilled meats or prepare and carry foods you have prepared yourself. Always have a rapid-response plan and if you are, or someone else is, experiencing a severe food-allergic reaction, call immediately for medical support.