A recent post that went viral on social media said that a woman had died after consuming prawns and lemon juice together. The news said that both the common food items could react in the stomach, leading to the formation of a toxic substance. In short, food allergy is a major problem that anyone could face, leading to even fatality. There are scientific explanations for this.
What is food allergy?
Some food items contain distinct types of proteins. When such a protein enters the system, the body may react against it, considering it to be a threat. This can occur in people of all ages on any occasion.
Allergy may be caused not only by foreign proteins but also coloring agents used to make food items attractive. For eg., erythrocin and carmoisine that give red color, fast green that gives green hues, brilliant blue that makes a food item blue etc.
Ajinomoto used in Chinese food and preservatives in tinned food can also lead to allergy.
There are two types of food allergy – one that manifests itself slowly and the other a sudden allergic reaction. The latter occurs immediately after taking the food. Food allergy can lead to a condition termed anaphylaxis. It involves breathing trouble leading to even death.
Allergy to a particular food item may occur even from a young age. Sometimes, the allergy may develop during adulthood. Studies show that genetic and environmental causes lead to allergies. There are several hereditary allergies too, say experts. People suffering from conditions like asthma are more vulnerable to food allergy.
There are several causes for food allergy. The main one is to certain proteins contained in food items, as explained above. In addition, allergy can be caused by improper storage of food. When food is kept in the refrigerator for a long period, microbes may grow in it. Toxins secreted by these micro-organisms become part of the food consumed. The toxins are a type of protein which can lead to allergies. Many people eat the food kept in fridge without heating. As a result, live microbes enter the body. This could spark a sudden allergic reaction.
Food items and vegetables stored outside the fridge will also lead to this problem. In some cases, decaying parts of fruits and vegetables are discarded and the remaining portion consumed. But microbes would already have affected the apparently fresh portion also.
While buying packed items from market, check the expiry date.
Some food items when consumed together may cause allergy. They could react together and produce an allergy causing agent.
Lack of cleanliness is another cause. This could occur in two ways - using vegetables and meat without checking whether they are fresh; and cooking with unclean hands and impure water.
Care should be taken regarding allergies in children. Teachers should also be informed about it. In addition, medicines for controlling allergy prescribed by a doctor can be carried to school.
Allergy during second consumption
In some people, a food item may not cause allergic reactions when they consume it for the first time. But the problem may occur if they eat the same item a second time. The first time, body’s immune system would not have been familiar with the allergen in the food. But it can stimulate our immune system which then becomes ready to react if the same allergen is eaten again.
While eating out during celebratory occasions, care should be taken about the food served there. Speak to the chef and recognize the ingredients which may cause allergy and avoid them. You can ask the chef not to use Ajinomoto and artificial colors.
Vomiting and itching
Common symptoms of food allergy are discomfort in the stomach immediately after taking food, vomiting, itching on the body including the tongue, weak pulse, fall in blood pressure, general weakness, breathlessness and diarrhea. It is usually allergy to proteins that proves fatal.
When symptoms like itching are seen, antihistamines like Avil should be taken without delay. If the symptom does not subside or breathlessness is felt, rush to a nearby hospital where ventilator facility is available. The patient should be allowed to drink water and take rest. Loosen the dress. If a feeling to vomit is felt, do not restrain.
Tests for allergy
Intradermal tests are the best means to identify the food allergen. A minute amount of different allergens are injected separately on the skin. Reactions seen around the injected area helps to detect the type of allergen.
Though blood tests are also available, intradermal tests are more accurate.
The best preventive measure against food allergy is to identify the item causing it and keeping that food away from diet. When an allergy occurs after eating several items, it is difficult to identify the causative agent. In such cases, maintaining a food diary containing details of consumed items will help. You can refer it to pinpoint the allergen.
Beware of complications
Food allergy often causes edema in the respiratory tract. Infection may be caused to the lungs also. This may develop into serious complications like pneumonia. Fall in blood pressure may affect the heart and brain, leading to even stroke.
Things to keep in mind
Tubers: Sprouted potato causes allergy as a poison named solanine is formed in it. If only one sprout has been formed, it can be cut off and the rest of the potato used for cooking. However, if more sprouts are seen, discard the vegetable.
Another common item causing allergy is mushroom. Those having allergy to it should always be alert.
Food grains: Staples like wheat, maize, barley and oats also may cause allergy. Gluten, a protein that forms in wheat, is the causative agent. Maize, barley and oats also have small amounts of gluten. People allergic to gluten can replace wheat with rice in their diet. However, items like multigrain biscuits may not cause allergy.
Meat: Among the various types of meat, it is beef that causes allergy in most people. The causative agent is the protein formed in it. Improper storage of meat can also lead to allergy.
Nuts: Take care while tasting peanuts, which can lead to allergy. Those sensitive to it should avoid items like peanut butter also. Cashew is safe. However, avoid it too if there is mould.
Vegetables and fruits: Milk from animals can cause allergy as it contains several proteins. However, milk products like cheese, yogurt, butter and curd are usually safe. Those allergic to milk can replace it with soya milk. Liquor also causes allergy to many people as it contains sulphates and has ingredients like wheat, yeast and barley.
Fish and eggs: Fish like shrimp, crab, clams and mollusks which have shells are rich in protein and naturally may cause allergies. Eggs and items made with it like ice-cream, mayonnaise and pudding can also lead to problems. Egg white as well as yolk is an allergen, but more common is the allergy to egg white.
(Information provided by Dr T S Francis, Professor and head, Department of Medicine. MOSC medical college, Kolenchery; Dr Anitha Mohan, Nutrition specialist, Thiruvananthapuram)