Do I have a food allergy and what causes it? A question that is often asked. But is it a food allergy or a food intolerance?

To many people that are not in the know there is no difference – is there? Well, actually, yes there is.

Whilst neither condition is pleasant there is a world of difference in how they are caused, how they affect the body and of course a big difference in how they are managed. But managed they can be.


This is a reaction by the immune system to a particular food. For some reason, the body becomes sensitized to certain foods that are perfectly harmless to others. Some allergic reactions are very severe and can be life-threatening. With some people they are not so severe but in all cases a doctor should be consulted for skilled and professional opinions, advice and treatment methods.

Allergies can run in families and if you have a parent with a food allergy then there is the possibility of you having an allergy to the same or similar foods. If both parents have an allergy then the likelihood of you having it are very much greater, but not necessarily absolute.


A food intolerance is most often a problem with the digestion (or not) of certain foods. Many people have an intolerance to milk, for example, and this is not the same as an allergy to milk. We would say that these people are lactose intolerant and as we will see very shortly, lactose and lactic acid are not the same thing.


The question is, how are food allergies caused?

Without going into too deep a scientific explanation, the immune system reacts to certain foods. This is a blood system issue. Within the bloodstream we will find an antibody called immunoglobulin, that is shortened to IgE. Next, within your body tissues there are specialised cells called mast cells and these are especially present in the nose, throat, lungs, digestive system and the skin. This is why, most often, an allergic reaction will manifest itself first as skin rashes, breathing problems or digestive upsets.

Mast cells do not generally react the first time that a “naughty” food is eaten. The first time, the body will just produce a lot of IgE for that particular food. This IGe then attaches itself to the mast cells and acts like a primer charge, if you will, for the mast cells.  The next time that food is eaten, the mast cells are ready and swing into action in massive numbers. One of the substances released by the mast cells into the blood stream is histamine, which is why we take anti-histamines to counteract certain immune system reactions.

But how do the allergens that trigger a reaction get into the blood stream? Not all allergens are broken down by the heat of cooking or by digestive juices in the stomach. Some will survive the cooking and digesting process and cross into the blood stream. Once in the blood they travel very quickly to all parts of the body.

Some people say that there is a path that their reaction follows. They may become aware of itching sensations in the mouth and on the lips as a first indicator. This can be followed by nausea, possibly vomiting and sometimes diarrhoea. Once in the blood stream and triggering mast cell responses, eczema and skin irritation can follow. Breathing difficulties may develop, wheezing and shortness of breath, headaches and confusion. In extreme cases a loss in blood pressure may cause loss of consciousness and unfortunately for some unfortunate victims, death can follow.


Food intolerance is a completely different set of reactions. If we take milk intolerance, which is very common, and compare it to an allergy we will see that they are very different problems.

A food intolerance can develop at any time, even in adults. There may have been some trauma or illness that initially triggers the intolerance response. Some claim that obesity can be a trigger too.

In a normal, healthy gut, the lactose, a type of sugar in milk, is broken down by an enzyme called lactase. With a milk intolerance there is insufficient lactase being produced to fully achieve this conversion. Lactic acid results from the activity of bacteria in the gut breaking down the lactose.

So, LACTOSE should be avoided if you are milk intolerant. LACTOSE is the problem.

LACTASE is not harmful, it breaks down the lactose. Lactase is added to milk to make it lactose free.

LACTIC ACID results from bacterial activity in the gut and is normally harmless. If food contains LACTIC ACID, you should not need to avoid that food. You would not normally have an intolerance reaction.

Symptoms of intolerance to milk will include abdominal pain, nausea, bloating and diarrhoea as may be found in an allergy but the histamine release does not occur, it is a digestive problem, not a blood related problem. Whilst very uncomfortable and debilitating at the time, intolerance should not lead to breathing difficulties, skin irritations or facial swelling.


Listed here in no particular order, are some of the more common symptoms of an allergic reaction to food. The list can never be complete and the manner in which individuals react also varies. Some sufferers may only show one or two symptoms in a mild form, others may react severely with many symptoms.

1. Tingling sensations in the lips and around the mouth. A funny feeling and itching of the tongue just after eating a certain food. The mouth is the first point of contact with food and so it would be expected to be the first to react.

2. A metallic taste in the mouth is sometimes recorded. The body is beginning to react to the allergens in the food and odd sensations will begin to develop.

3. The throat may begin to swell and there can be a real danger of this affecting the casualty’s ability to breathe normally. This restriction in breathing can in itself be very worrying and can cause panic in the affected person as well as others who witness it happening, especially parents if it is a child.

4. Difficulty in swallowing may be a symptom. As the throat swells the passage way will narrow, the tissues of the throat will become sensitive, making it difficult and painful for food to pass through.

5. Abdominal pain and stomach cramps are another sign of a reaction. These can range from mild to quite severe and can be somewhat debilitating. The unfortunate casualty may need to pause what they are doing for a few minutes whilst they try to get over these stomach cramps.

6. A feeling of being bloated may manifest itself. As the food enters the digestive tract, parts of the intestines, the gut, will begin to react to the allergens.

7. Nausea and vomiting may follow as the body attempts to reject the food but there will already be allergens in the blood stream.

8. The casualty may say that they feel dizzy; they may look unstable and confused.

9. As the allergens are now in the bloodstream, difficulty in breathing may be noticed. The victim may have difficulty in speaking coherently and may have shortness of breath. They may be wheezing and it may be an audible wheeze as their lungs and breathing passage ways are becoming more and more affected.

10. Skin rashes, red blotches and hives may appear on the body. The face may become red; the eyelids begin to swell and the lips very obviously swollen.

11. Blood pressure may drop and fail to supply sufficient oxygenated blood to vital organs including the brain. The pulse may be barely detectable.

12. Anaphylaxis, the shutting down by the body of all its vital functions may follow. The casualty may lapse into unconsciousness very rapidly and death may follow.

    The effects of a food allergy, the symptoms, may range from relatively mild to very severe, even life-threatening. If an allergy is suspected then expert medical advice should be taken. If an allergic reaction is actually taking place then it may be necessary to seek immediate and expert medical attention. With severe reactions, time really does matter. Some sufferers carry small pre-charged syringes about their person for just such incidents. In all cases, treat allergic reactions with seriousness.

    The information supplied here is for information only and is not in any way a substitute for expert medical diagnosis and treatment if you have or suspect you have a food allergy. It may turn out to only be a food intolerance, or maybe not. Always have these things checked out before they become a crisis.


    Children may outgrow food allergies to milk and eggs for instance as their immune system develops. Adults however seldom do.

    This list of common food allergens shows the fourteen generally accepted problem foods. As stated earlier, every individual is different and they may have allergic reactions to other foods.

    1 – Celery

    2 – Cereals containing gluten

    3 – Crustaceans – shellfish

    4 – Eggs

    5 – Fish

    6 – Lupin – the seeds and flour

    7 – Milk

    8 – Molluscs – mussels and snails

    9 – Mustard – powder, liquid, seed, leaves and infused oils

    10 – Nuts – tree nuts

    11 – Peanuts – a type of legume

    12 – Sesame seeds

    13 – Sulphur Dioxide

    14 – Soya

    You may be wondering why peanuts are not included in nuts. Walnuts, cashews and the like are classed as tree nuts. Peanuts are actually a legume, a type of vegetable and very different.


    Seek professional medical confirmation of the foods that affect you.

    Avoid the problem/danger foods as a first choice.

    Some sufferers can eat small amounts of their trigger foods occasionally without any ill health effects, but this is to be recommended only on the say so and supervision of a doctor or medical professional, do not try it on your own.

    With food allergies, avoidance and caution really are the important words.

    There are various tests available to determine the allergens that might affect you. They range from simple skin scratch tests and hair follicle tests to the medically controlled food sampling tests. If you suspect you are vulnerable to an allergy or intolerance then the time to seek advice is now, before the allergy is triggered again. Appropriate steps and health solutions can then be put into place whilst you are in a state of health. Good luck with what you decide to do and stay healthy.

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