How To Do An Exclusion Diet

If you think you, your child or your baby may have a food allergy or intolerance, you may decide to do an exclusion diet.  This means cutting out any foods you think you/your child may be reacting to for a few weeks to see if symptoms improve, and then reintroducing the food(s) one at a time to see if the symptoms return.  (Note: if your baby has had an immediate and/or severe reaction do not reintroduce the foods until you have spoken to a doctor).  In my last post I talked about the symptoms of food allergy in babies, and if you are a breastfeeding mum this means changing your own diet.  Please remember to discuss any changes to your diet with your doctor or other healthcare provider.  If you are excluding foods from your diet (or your child’s) you may need a referral to a dietitian.

Why do an exclusion diet?

Allergy testing via blood test or skin prick test is another option.  However these can be distressing for babies and children.  The results are not always reliable, which means they may not detect an allergy even if it is present.  It is also only possible to test for IgE-mediated allergies via blood test (which are usually immediate reactions) or skin reactions via skin prick test.  There are other types of tests for food allergies and intolerances (such as IgG, kinesiology and hair analysis) but there is no scientific evidence that they actually work.  An exclusion diet is considered the ‘gold standard’, meaning it is the best possible way to test for food allergies and intolerances.  It can also be done easily at home, and will provide you with evidence if you are struggling to get your doctor or healthcare provider to listen to you.  Sadly not all doctors are clued up about food allergies.

My daughter has multiple food allergies, diagnosed by a paediatrician, based on symptoms and an exclusion diet.  I have been through all of these steps myself, as she was breastfed so I cut the foods out of her diet and mine.  She has also had blood tests, which showed that she does have allergies, but not what she is allergic to (she has high IgE antibodies which confirms allergies, but all of the individual food tests came back negative!).

Step 1: Choose your suspects

Make a shortlist of foods you think you/your child may be reacting to.  In the UK, the most common food allergies in babies and children are milk, egg, peanuts, tree nuts, fish and shellfish.  In adults, the most common food allergies are peanuts, tree nuts, fish and shellfish.  Wheat, gluten, soy, sesame and kiwi can also commonly cause problems.  If your baby’s symptoms occur every day it may be a food that you eat daily like dairy or wheat.  If it occurs less often it may be worth keeping a food and symptoms diary to help you narrow down the trigger food.  To do this, write down everything you eat plus any symptoms for 1-2 weeks.  Then, when the symptoms occur look at the previous 1-2 days and see if you can spot any foods that were not eaten on the other days (with no symptoms).  Also consider any existing or previous food allergies within the family.

If you have a few foods that you think you or your little one may be reacting to, in the short term it is harder to cut out lots of food at once, but you will see results faster than cutting them out one at a time.  Being allergic to one food increases your chances of having more food allergies, so it is very possible to be allergic to more than one thing, and your symptoms won’t improve fully until all problem foods are eliminated.  It may seem overwhelming at first, believe me I understand, but you will soon learn what you can eat safely.

Step 2: Prepare

Go through your cupboards and check ingredients.  Think about what products you need to replace and what alternatives you will use instead.  If you are cutting out dairy, do not switch straight to soya as it is very common to be allergic to both.  Use almond, coconut or hemp milk instead.  Be aware that ‘free from’ products tend to be very processed and not necessarily particularly healthy, but it may help to buy a few treats while you complete the exclusion diet so you don’t feel too deprived.  If you’re working you may find it easier to pack lunches for a few weeks.  You may also like to make a meal plan.  Make sure your fridge and cupboards are stocked with plenty of things you can eat.  You might also like to get some support – for example there are lots of allergy groups on Facebook for cow’s milk allergy (CMPA), gluten-free diets, coeliac disease etc where you can find recipe ideas, restaurant reviews and lists of ‘safe’ foods, as well as asking questions or advice.

Step 3: Eliminate suspects from your diet

Stop eating all of the foods you identified in step 1 for 2-6 weeks.  Dairy can take around 2 weeks to get out of your system, gluten can take 6 weeks.  See if you notice any improvement in symptoms.  Make sure you check the packets of everything you eat and check before eating out.  Most chain restaurants have allergen information available online.  All restaurants are required by law to provide information on any of the 14 most common allergens used as ingredients in their food so it is still possible to eat out safely.

Step 4: Evaluate and Reintroduce

If you have seen a noticeable improvement in symptoms over the 6-week period, then an allergy or intolerance is the most likely cause.  Try reintroducing each eliminated food, one at a time, to see if symptoms reoccur. Choose one of the foods you have excluded and eat it every day for a week.  If the symptoms do not reoccur then it is safe to include that in your diet again.  If they do reoccur then this confirms the allergy and you should remove the food from your diet immediately and discuss this with your doctor or healthcare provider.  They will be able to advise you on how to reintroduce the food gradually and safely to test your tolerance level.

I’ll be honest, doing an exclusion diet is hard.  it’s a steep learning curve as you have to learn which foods are safe.  Your supermarket shop will take twice as long as you check the labels on everything.  But soon you will know what’s ok to eat, and it does get easier.  Eating out can be tough as well.  When we first started our exclusion diet we all went out to a cafe and I sat and watched my husband and older daughter tucking into chocolate cake while I had to make do with a packet of raisins.  I’ve got used to it now, and although I do enjoy an allergy-safe cake now and then, it doesn’t bother me when I can’t because I know how ill and miserable it would make my younger daughter.  Plus I feel much healthier now myself as I eat much less junk food, I cook most things from scratch, and I’ve also lost 2 stone without having to count calories or points.  In fact, I think I could quite happily live without gluten, dairy and soya permanently (although I do miss eggs!).  So although it’s hard work at first, it does get easier over time and it’s well worth it in the long run.

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