he elimination diet is a way of identifying which foods may be causing adverse reactions. Managed properly it can be an extremely accurate way of diagnosing specific food intolerances and is often used by GPs.
There are four steps to the diet:
- Eliminate/ exclude all suspect foods from the diet.
- Replace them with new/rarely eaten foods or Artificial Nutrition Support (ANS).
- See if symptoms clear up.
- Reintroduce suspect foods one at a time to find out which ones were causing the symptoms.
GPs vary in their approach to the diet. Some prefer to eliminate only the most common problem foods whilst others exclude almost everything. (The latter is often referred to as a 'rare-food', 'few-food' or 'caveman' diet.) It is important that the approach is flexible. It unusual for the general population to have more than 5 intolerances, so there is little point excluding all foods to discover they only have a problem with milk and caffeine. However a strict exclusion diet may be the only way to diagnose all intolerances for someone with multiple sensitivities.
Why Exclude so Many Foods?
It will be a lot easier to correlate specific foods with specific symptoms if there is a period of time with no symptoms at all. Eliminating only one food at a time will make no difference to your health if you are reacting to many foods, especially if the worst offenders are being eaten every day.
Ideally no-one should try an elimination diet without medical support. Eliminating a large range of foods all at once can lead to nutritional problems, especially if they are not replaced. In addition, the symptoms of food intolerance can also be caused by a number of serious illnesses. Before starting an elimination diet, it is wise to seek advice from your GP, especially if you are already in poor health.
Hypersensitive sufferers need to be aware that they may develop further sensitivities to the few foods they have left as, during the exclusion phase, these foods will need to be eaten more regularly and in larger amounts. Under these circumstances it is useful to consider replacing all foods with a form of Artificial Nutrition Support (ANS). These drinks can be expensive, but you may be able to get them on prescription if you suffer from bowel disease. For more information about drink supplements, see Food Substitutes.
Occasionally, there are instances where no medical support is available. In such a case, an excellent guide to preparing and carrying out an elimination diet can be found in chapter 14 of The Complete Guide to Food Allergy and Intolerance by J. Brostoff & L. Gamlin (ISBN 0-7475-3430-6). The step-by-step instructions are suitable for individuals who suspect either one, or many food intolerances and includes advice for investigating sensitivities in toddlers and babies.
Which Foods to Suspect?
There are foods that people react to more commonly than others. These include wheat, milk, oranges, chocolate, eggs, nuts, fish, shellfish, sugar, yeast and soya. However it is possible to become intolerant of absolutely any food substance: preservatives, colourings, even sugar and salt. So the first suspects should be foods that are eaten most frequently, for example wheat and milk. Before you start the diet, keep a diary to find out which foods you eat most often as the results can be surprising. Make sure you list the ingredients of any processed foods.
Ironically, you should also suspect any food that you cannot bear to stop eating, that cheers you up, or that makes you feel better. The body often produces 'feel good' hormones as a reaction to problem foods, so be warned - cutting these out takes a great deal of self control!
Starting the Diet
Think about when would be the most suitable time to start the diet. It is likely to take a minimum of two weeks, so choose a time when you are not going to be away from home. If you go out, you may need to take your own food with you. It is important to plan ahead as you need to strictly avoid all traces of your suspected problem foods. Starting the diet twice should be avoided as it can occasionally lead to even more food intolerances.
Before you begin, try to deal with any environmental allergies such as pollen, moulds, pet dander, or chemical sensitivities. Reactions to these can often be very similar to those of food intolerance and if not dealt with can confuse the results of your diet.
Before starting the elimination diet, it is helpful to have an understanding of how foods are related to each other. Occasionally when an individual reacts to a particular food, they can also develop sensitivities to foods that are botanically related. When setting up an elimination diet it can be helpful to exclude these related foods.
It is usual to feel a lot worse during the first few days of an elimination diet. You may feel grumpy, develop headaches, or flu-like symptoms. You might not feel 'full' after eating, may crave the very food you are trying to avoid, or might find that your symptoms get worse. All these are signs that you are on the right track and that food intolerance is contributing to your ill health. Once the offending foods are completely out of your system, there is likely to be a fairly spectacular recovery. It can take anything from 3 days to several weeks. If there is no change to symptoms after two weeks, you need to question whether you are reacting to the remaining foods in your diet; undetected chemical or environmental allergies; or simply that your condition is not caused by food intolerance.
After the Diet
If after completing the elimination diet you find you have multiple sensitivities, you may want to consider eating your remaining foods on a Rotation Diet. This means eating each food only once every 4 - 7 days and should minimise developing further intolerances. You should also consider the underlying reason for your sensitivities, and whether there is anything you can do to alleviate them. For further information see Dealing With the Underlying Cause.
Food intolerances can change over time, so it may be worth retesting foods every 6 - 12 months. However, if you suspect you have a true allergy to a particular food, (especially nuts or seeds) see your GP for immediate testing and avoid the food completely. For more details see Allergy/ Intolerance.
Before you begin the diet, see your GP for a general healthcheck to rule out other illnesses.
Ask your GP or dietician to help you plan the diet. If they are unwilling, read chapter 14 of The Complete Guide to Food Allergy and Intolerance by J. Brostoff & L. Gamlin (ISBN 0-7475-3430-6).
Before starting the diet, try to eliminate any chemical or environmental allergies and rule out hyperventilation. Symptoms from any of these can easily be confused with those of food intolerance.
Do not start an elimination diet without full preparation; starting the diet twice can lead to further sensitivities.
Don't cut out foods until you've found something to replace them with; another week of symptoms is far preferable to worsening health or developing total food intolerance.
Keep a diary before, during and after the diet to keep track of any new symptoms or intolerances.
Test culprit foods twice before excluding them permanently; you may have been reacting to something other than the food.
After the diet, rotate all foods to prevent further sensitivities.
Get your eventual menu checked out by a dietician to ensure there are no nutritional inadequacies.
See your GP to check you do not have true food allergies to the eliminated foods.
Remember, food intolerances DO change; consider retesting eliminated foods after six months.