Today is the last day of Food Allergy Awareness Week. To celebrate, let’s review the gold standard method for uncovering hidden food allergy and intolerance reactions.
The elimination / rechallenge diet is elegant in its simplicity, if difficult in practice. To get started, we’ll need to track a symptom that we suspect to be related to a dietary trigger. This symptom might be a skin disorder, a nasal allergy, or something more vague like fatigue. The more specific the symptom, the better.
Once we have a symptom (or several symptoms) to track, we can begin the elimination phase of the diet. An elimination diet includes very few foods, and these foods are chosen based on their low likelihood for triggering reactions. Rice, non-citrus fruits, green vegetables, turkey, and lamb tend to be the reliable staples of an elimination diet.
This phase usually goes for about two weeks. If the symptom being tracked improves by 50% or more during this period, it is likely (although by no means certain - symptoms can wax and wane on their own, after all) that food is playing a role. If little to no improvement is seen, on the other hand, dietary triggers are probably not significant contributors to the problem.
After the elimination phase comes the rechallenge portion of this program. To rechallenge, a particular food is added to this minimal elimination-style diet in its purest form. For example, to rechallenge eggs, eat a boiled egg, not an egg muffin sandwich. Similarly, dairy can be challenged with a glass of milk or wheat with a bowl of creamed wheat cereal.
If our tracking symptom worsens by 50% or more with the introduced food, this is a positive result, and this food should be minimized or removed from the diet going forward. If the change is marginal or confusing, this is probably a negative result. If there is confusion about the result, the rechallenge should be repeated.
That’s all there is to it. As long as the nutrient and calorie composition of the diet stays appropriate, this is a program that almost anybody can do safely. I do not recommend this exercise for people at risk of weight loss due to serious health challenges (metastatic cancer, for example) or a recent history of eating disorder, however.
The most common problem I see with this protocol is that people become so worried about a potential reaction that they start limiting their diet in ways that this exercise really doesn’t support. For people who perceive multiple and mild reactions to several of the foods that are introduced, I tend to recommend looking at gastrointestinal health, rather than following a dangerously restricted diet going forward.