Food intolerance describes a number of unpleasant symptoms that occur in some people after they eat certain foods. Since only a small number of people have adverse reactions to food most of us can enjoy these common culprits without worry:

• spiced food
• nuts
• eggs
• caffeine
• wheat
• milk
• shellfish
• strawberries

There are different types of intolerance to food and these may be classed as 'allergic' responses and 'non-allergic' responses. An allergic reaction to peanuts, for example, could result in swelling of the lips. This type of intolerance could be identified by a blood test. On the other hand if you have a particular enzyme deficiency, you may, for example, be unable to tolerate alcohol and become red or flushed in the face after a drink. This is a non-allergic reaction that, while it can be just as unpleasant as an allergic one, has a different cause and is diagnosed differently.
 

Symptoms and diagnosis

Physical symptoms like a rash, swelling, wheezing, vomiting and diarrhoea are the hallmarks of food allergy and one or more of these symptoms may occur as a result of an allergy. Unfortunately however, these symptoms are also associated with many other medical conditions and in themselves are not enough to confirm an allergy.

The road to diagnosing a food allergy is long and requires expert help from both a medical and nutritional practitioner who are experienced in the area. Once a food allergy is suspected a detailed food/symptom diary will help narrow the field in the search for possible 'problem foods'. Family history details will also prove useful as allergies tend to run in families.

Where there is a suspicion that a particular food is the cause of a reaction, this can be confirmed with a blood test, a skin prick test and finally a food challenge. Any one of these tests in isolation is not considered diagnostic and they should be used in combination to establish a confident diagnosis. These various tests and consultations with qualified practitioners can be costly, but, it is better to know exactly what the problem is and to receive the correct treatment.

True food allergies are much less common than many believe. Often people assume they have an allergy because when they compare notes with a friend they find they have similar symptoms and experiences, and then diagnose their own allergy. These self-diagnosed cases usually turn out not to be an allergy at all. This can lead to restrictive diets that are completely unnecessary and unbalanced. These diets may even lead to health problems down the road such as low iron stores and low bone density. It is always important to discuss your concerns and symptoms with your GP and ask to be referred to a specialist for treatment.
 

Restricting your diet

Once a specific food allergy has been diagnosed a Dietician can draw up a special diet. Following a restrictive diet is quite difficult at first. It is important to take your time when shopping and examine food labels carefully. Most foods have an ingredients list, but if there is no information on a product or you are in any doubt, the best advice is to avoid that particular food.

Below is an outline of what to do if you have an allergy to wheat, peanuts or lactose;

Wheat - free diet
Wheat and wheat derivatives are found in a wide range of foods. The following is a brief guide to a wheatfree diet. You should also seek the help of a Dietician for individual advice.

Foods to avoid	Alternatives
Stout and lager	Revolution Red Beer
Ice cream, tart, crumble, pancakes, semolina	Fresh fruit, meringue, rice pudding, custard, yogurt (meusli flavour)
Tortilla wraps, spring rolls, kebabs, sausuages, black and white pudding, meat pies, meat loaf, fish or chicken in batter and breadcrumbs	Grilled or roast meat, chicken and fish (sauce made with cornflour)
Pizza, lasagne, quiche, scotch eggs	Fresh vegetables, eggs, cheese
Breakfast cereals eg puffed wheat, weetabix, shredded wheat, branflakes cheerios, meusli, alpen	Porridge, rice krispies, cornflakes
Pasta, spaghetti, couscous	Rice, potato
Biscuits, buns, cakes and pastry made from ordinary flour	Flour, soya flour or potato flour
All bread and crackers made from ordinary flour	Bread, biscuits, buns, cakes and pastry made from rice

Nut-free diet

Peanut allergy is one of the most serious forms of food allergy because the degree of sensitivity can be so high. In some cases peanut dust can cause symptoms, as can handling nuts or even contact with trace amounts of nuts. Not only can sensitivity be high, but the severity of symptoms ranges from swelling, to a severe shock-like reaction (anaphylaxis) which can be life threatening. Some people with nut allergy, on the advice of a GP or specialist, will carry adrenaline with them in case of accidental exposure to nuts.

When you are eating out ask to speak with the chef about nut-free choices on the menu, as the waiting staff may not be as informed as you need. The following is a list of nuts and food products that should be avoided if you have a nut allergy. Always read food labels carefully and avoid foods if you are in doubt:

hazelnuts, brazil nuts, pistachio nuts, cashew nuts, macadamias, chestnuts, filberts, cob nuts, peacans, almonds and marzipan, walnuts, ground nuts, pine nuts, peanuts, pesto sauce, praline, franqipani, nut pastes, chopped nuts, nut oils, mixed nuts and blended vegetable oils

Lactose intolerance

Lactose intolerance is caused by a deficiency or total lack of the enzyme lactase which is needed to digest lactose in food. Lactose is a sugar and it is principally found in milk and milk products such as yoghurt and in trace amounts in cheddar cheese (not butter). However, it is also found in many processed foods and medicines and labels need to be checked carefully for milk as an ingredient.

Milk solids and skimmed milk powder also contain lactose. Some foods such as pizza, lasagne, custard and rice clearly contain lactose but other foods such as sausages, hamburgers and soup may not be so easy to guess, so be careful.

Lactose intolerance often causes a reaction like nausea, diarrhoea, bloating or bowel discomfort when excess lactose is consumed and so sufferers can tolerate small amounts of lactose at each meal. Recent research has shown that individuals have their own lactose threshold which in most cases is not exceeded by a small glass of milk at each meal.

Everyone will find his or her own tolerance level by trial and error. However the important finding from this research is that the lactose intolerant sufferer does not have to completely avoid lactose. Cheese such as cheddar cheese is usually well tolerated because it only has a trace amount of lactose and the lactose in yoghurt is mostly pre-digested and so it is also fine.

Soya milk, goats or sheep milk are not a suitable substitute for cows milk as they all contain lactose.