What is the difference between food intolerance and food allergies?
Experts have said that the number of people who believe they have a food allergy or intolerance has increased dramatically, with 20% of the UK population now believing they are affected in some way. Statistically UK hospital admissions for food allergies have increased by 500% since 1990 and 6-8% of children have a proven food allergy (National Institute for Health and Clinical Excellence 2011)*
What is a Food Allergy?
Food allergy is a reaction caused by the immune system’s reaction to a food, often causing distressing and severe symptoms. Symptoms can range from skin reactions, which include itching and rashes, swelling, stomach problems such as vomiting, tummy pain, diarrhea; respiratory symptoms such as blocked or runny nose, coughing and wheezing. These symptoms usually develop rapidly.
Usually specific IgE (Immunoglobulin E) antibodies to ‘fight off’ the allergens found in these foods are made which results in the release of histamine and other naturally occurring chemicals in the body, which subsequently cause inflammation. Skin prick tests or a specific IgE (Immunoglobulin E) blood test can only confirm this type of allergy, when they match with clinical symptoms.
The most severe reactions are called anaphylaxis and can be life threatening, requiring immediate medical attention with adrenaline injection and admission to A & E. Symptoms can include swelling of the lips, tongue or face, throat constriction, breathing difficulties and rapid pulse and heart rate. Loss of consciousness may also occur. Symptoms can start within a few minutes of eating/coming in to contact with the offending food, but can also be delayed by one to two hours. Those at risk of anaphylaxis should carry or have an adrenaline device available at all times. The GP can prescribe this if it is necessary.
There is also “Non-IgE food allergy”, which is also caused by the immune system but is not caused by a specific antibody reaction. This occurs most commonly in infants, although it occasionally persists. The symptoms are usually delayed, from hours to two to three days, but can also cause severe symptoms and inflammation to the gut, with pain, vomiting, diarrhoea or constipation. It is often associated with moderate to severe eczema, sometimes to respiratory symptoms and is rarely diagnosed as a food allergy. Non-IgE mediated food allergy requires specialist diagnosis and is difficult to manage without the initial input from a registered dietitian.
The foods that most commonly cause allergic reactions are peanuts, tree nuts (such as almonds, brazils, walnuts), eggs, milk, fish, shellfish sesame, soya, wheat.
If you’re diagnosed with food allergy you’ll be referred to a registered dietitian. It’s worth noting that some people can tolerate a well-cooked version of the food but will react to the food in its part-cooked or raw state. Experimentation must be under the guidance of an allergist or specialist allergy Dietitian.
What is Food Intolerance?
Food intolerance is not so easy to diagnose. The laboratory tests are insufficient and excluding the offending food in your diet is the gold standard rule to confirm intolerance to it
Although not life threatening, it can often make the sufferer feel extremely unwell and can have a major impact on working and social life. Ongoing symptoms can also affect the person psychologically as they feel they will never get better. The reactions do not involve IgE antibodies or the immune system and are usually delayed, occurring several hours and sometimes up to several days after eating the offending food. The symptoms caused by these reactions are usually stomach problems such as bloating, diarrhoea, constipation and IBS, and skin problems such as eczema and joint pain.
Because it is possible to be intolerant to several different foods at the same time it becomes very difficult to determine whether food intolerance is the cause of chronic illness and which foods may be responsible. Many people with food intolerance have several symptoms. Sometimes the symptoms are vague and not always easily diagnosed.
Food intolerance can be caused by different factors, such as lifestyles with erratic food intake and poor nutritional intake or high intakes of refined foods, poor intakes of dietary fibre or high fat diets. Commonly, gastro-intestinal infection can trigger ongoing symptoms such as pain or loose stools after consuming certain foods, for example lactose in milk. The duration of this varies but after excluding the problem foods, usually for some months, they can usually be slowly reintroduced in time. Some people lack the enzymes needed to digest foods, i.e in lactose intolerance, the enzyme ‘lactase’ is not produced in the stomach in large enough amounts to break down the lactose (milk sugars). Others react to the chemicals that are produced naturally in foods such as caffeine, salicylates and histamine in foods like strawberries, chocolate and ripe cheese. Another cause of food intolerance is additives in foods, such as sulphites, which are added to processed foods to give them a longer shelf life. They are also found in fruit drinks and wine. A reaction to a food that has ‘gone off’ such as salmonella poisoning is toxic reaction to a food, which will usually affect anyone consuming it.
Chemicals in foods such as caffeine, salicylates, monosodium glutamate and naturally occurring chemicals like histamine, can also cause food intolerance reactions
Getting a diagnosis
If you suspect you have a food allergy or intolerance, you should consult your GP who may refer you to a dietician, and you’ll need to keep a food and symptoms diary. Written records, dated photographs with labels of suspected packaged foods, will help to identify which foods may be causing your symptoms.