The challenge of elimination diets
The ‘Gold Standard’ way of diagnosing an adverse food reaction (food allergy or intolerance) is by a process of elimination and If there is a relapse following challenge, then a diagnosis of adverse food reaction can be made.
It is a very similar process for our pets. Keeping a food diary for your pet is a great idea in addition to discussing the full clinical dietary history with the vet. This includes the actual food rations, treats, supplements, the sneaky morning bit of toast and marmalade, what you pop inside toys to make them interesting when your pet is left alone and what any children or visitors given them on special occasions. All of these count. In animals, dietary trials usually begin with the selection of a single novel protein source and a single novel carbohydrate source (ones not previously eaten by the animal) or a hydrolysed diet (where the food is processed in such a way the body doesn’t recognise the proteins that may cause a problem). The selection of appropriate foods for an elimination diet can be much harder in pets, especially those with varied diets or whose dietary history is unknown. This is where serological food antibody tests, which look at the pet’s antibody responses (both IgE and IgG antibodies) to commonly eaten foods, can help. By selecting those foods to which the animal has no antibody response (i.e. no positive scores), the likelihood of a reaction to the elimination diet is lessened and the time taken for diagnosis could be shortened. Just like with people, if an improvement occurs, then the old diet, or rather components of it, are reintroduced to check the benefit was due to the dietary change and not something else entirely. Only at this point, can a diagnosis of an adverse food reaction be made.
Not so easy, huh? For us humans, given how varied all our diets are these days, and the sheer number of ingredients in some of our food products, identifying the trigger foods can be as easy as finding a needle in haystack, so maybe the animal approach of removing everything but one protein source and one carbohydrate source is actually easier if you can face it!
I was lucky to undergo food intolerance blood testing for serological IgG (antibody) responses 18 months ago. I’ve always suffered with symptoms of IBS – bloating, stomach cramps, constipation, lethargy – but put it down to ‘one of those things’. I was unsure of what my trigger foods could be. Until I started to give it some serious thought. My love of lunchtime cheese sandwiches (Cranks do an amazing Wensleydale and chutney on granary bread mmm…) that left me sluggish all afternoon could be to blame I suppose? Highly likely to be the gluten as everyone is gluten intolerant these days, right? Wrong! Only 5-10% of the adult population is gluten intolerant, with 1% coeliac sufferers. My blood test showed IgG antibody responses to cows’ milk, corn and yeast. Not gluten. So based on this yes, it seemed sensible to take those lunchtime cheese sandwiches off the menu to see if it made a difference. Many years ago I had identified vanilla as a migraine trigger (thank you Green and Blacks ice cream!) and interestingly my test also showed an increased antibody response to vanilla.
Being a human, I set about performing my elimination diet, basing my menu on the foods I didn’t feel I’d had responses to, and cutting out all dairy (fairly easy), corn (super easy) and yeast (super tricky). As mentioned before, in pets the approach would have been to select just one protein source and one carbohydrate for the diet and feed nothing else. Yeast is in more food stuffs than you think and not labelled as an allergen. I lost weight, my symptoms vanished and I felt great. Some people and pets who follow the elimination diet see their symptoms improve either instantaneously, or gradually over a few weeks. These symptoms can include gastric problems, skin problems, headaches and lethargy for humans. Dogs with adverse food reactions frequently present with skin problems, gastro-intestinal problems, otitis and sometimes a combination of all three.
So, having identified the potential culprits, removed them from the diet, eliminated or reduced the symptoms, it’s time to add the foods back to the diet and see what happens. This was essential to check it wasn’t something else entirely that caused my improvement.
I had managed to cut out or reduce the foods I suspected were the trigger in my diet. This was made easier by the fact that lots of restaurants and shops are now allergen aware (even my local chippy!), and I felt great. Until this week that is. I had the ultimate diet challenge when I unwittingly ate crackers and crisps loaded with dried yeast extract. Yeast is often added to savoury foods to add flavour, especially things like beefy or bacon flavoured crisps that are vegetarian friendly. I paid the price as I swelled up like a space hopper and struggled to breathe as my insides crushed my diaphragm. And, oh my word, the pain. I was in agony, agony I tell you! But at least I was aware of what was happening. Unlike our furry-friends who struggle to understand how that stolen sausage could lead to tummy troubles or super-itchy paws. Twenty-four hours later I was back to normal, more aware of my yeast intolerance than ever. Given my fun this week, I’m not planning on adding cows’ milk, corn or yeast back into my diet any time soon!
Written by Nicola Kingswell– Head of Laboratory Operations
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