Allergy or Intolerance? Same same, but different

Allergies are on the rise

The rate of allergies has more than doubled in 50 years – from 3% in 1960 to 7% in 2018 – in parallel to other immune-mediated diseases (autoimmune diseases and atopic disease like asthma and eczema). And what about intolerances? Every other person seems to have one of those now… is it an allergy or intolerance? Why do some of us seem intolerant one minute and not the next? Why can someone with a supposed intolerance sometimes still eat some of that food? You’ll often notice people using the words allergy and intolerance interchangeably but, as we’ll see, they couldn’t be more different. Let’s dive in…

What’s the same?

It’s easy to see why allergies and intolerances are often confused. After all, both have to do with food causing symptoms. In both cases, these can be local symptoms in the gut itself (digestive upset) or systemic symptoms beyond the gut.

What’s different?

Allergies immune response to food

With allergies, we’re talking about the immune system reacting to specific foods. There are 8 foods responsible for the vast majority of allergic responses, and they’re the ones you’ll be used to seeing in bold on food labels and restaurant menus: peanuts, tree nuts, fish, shellfish, eggs, milk, wheat & soy. There are a couple of other more ‘exotic’ ones too like celery, mustard and lupin…

Symptoms are rarely just digestive and may include itching, rash, hives, runny nose, chest tightness, wheezing, swelling of the eyes, lips, mouth or throat etc. These can develop very quickly and be mild through to severe or even life-threatening.

The tiniest amount of the allergen can trigger this aberrant immune response in affected individuals, which is why peanuts can’t be consumed in an aeroplane cabin and most schools are nut-free zones.

Intolerance – do not involve the immune system

Most intolerances relate to digestive problems; the immune system is not involved.

Symptoms often include excess gas, bloating, cramps, nausea, changes in bowel movements etc. after eating certain foods. Common examples are lactose in milk (affects 75% of people globally, but far lower rates in Northern Europe), the “FODMAPs” (fermentable carbohydrates), wheat and gluten. Histamine intolerance is another good example – one I’ll tackle in another post as it’s a bit more involved.

Often, a threshold amount of the particular food is required to trigger symptoms. This threshold is different for every person, and even varies within the same person from day to day depending on other factors. Maybe you’re gluten intolerant but if you’re chilled out on holiday you can eat half a croissant with no issues…yet a sandwich at work and you’re doubled up with cramps!

Testing for allergy or intolerance

Your GP can test or refer you to an allergist to diagnose allergies. This will often involve a blood test to look for IgE antibodies which the immune system is making to specific allergens. Skin-prick patch tests and diet modification may also be used.

Where intolerances are concerned, we enter murkier waters. At this moment in time, there are no truly accurate tests you can buy that will tell you if you are intolerant to a given food (except lactose). Many claim to do so, by looking at IgG antibodies or worse (please don’t buy a hair analysis test!). The issue is that IgG is actually an indicator of repeated exposure. If anything, having these antibodies actually suggests tolerance to the food concerned! Many individuals suffering from digestive issues will buy into these tests looking for a solution, but sadly come away with a long list of things they supposedly can’t eat, even more confused & fearful around food and with a more restricted diet than before! An all-round terrible outcome.

The only real way of knowing if you are truly intolerant to a food is a good old elimination diet. This basically involves temporary restriction of the suspect food, paying close attention to any change in your symptoms and then reintroducing that food (preferably placebo-controlled, think like a scientist!)to see what happens. This can be a long and arduous process – especially if you have many possible intolerances or no real idea what is causing your symptoms! A registered Nutritional Therapist can be invaluable for guidance and support.

The good news is that, unlike allergies, intolerances can very often be “fixed”. In some instances (like histamine intolerance I mentioned), genetic variants can make this difficult – but genetic reasons do not apply to the majority of us.

Why most intolerances aren’t about the food

Often, disturbances in the microbiome (our gut bugs) are the actual problem. This is called “dysbiosis”. Certain types of bacteria are particularly good at helping us process and digest our food by producing digestive enzymes for example. One example is the lactase enzyme which breaks down lactose in milk. If we are one of the people who, for genetic reasons, don’t make enough lactase in our small intestine, our gut bacteria could potentially become more efficient at producing it for us when the lactose reaches them (in the colon) undigested. This suggests there is potential for a lactose intolerant person to consume more of the problematic milk over time by “training up” their microbes…

Many people, with IBS for instance, struggle with certain fermentable carbohydrates known as FODMAPs. Common problem foods include onions and garlic, beans, cruciferous veggies and stone fruits. Although cutting out or reducing some of these can provide temporary symptom relief, restricting these fibre-rich foods in the long-term makes the problem a whole lot worse! Why? Because it alters the composition of our microbiota (the types of bugs that live there and in what numbers) so we can have a harder time when we do re-introduce these foods or occasionally indulge in some gluten/dairy or whatever. It’s very much a case of “use it or lose it”!

Similarly, we now know when mum restricts potential allergens (assuming she herself is NOT allergic) during pregnancy it increases the chance of baby having food allergies. Equally when we introduce possible allergens early on in weaning at 6 months (or for little ones who are most at risk, even earlier under an allergist) you decrease the risk of food allergies.You you may have noticed this advice has gone 180 degrees since we were kids!

Finally, we can’t ignore the power of the the “nocebo” effect: If we expect to have horrible symptoms when we eat a particular food, our brain communicates with our gut ensuring we will have physical symptoms! This was perfectly illustrated in a systematic review that found 40% of people who believed they were gluten intolerant (this was me too for 5+ years!) had the same or worse symptoms with the placebo that didn’t contain any gluten (because they thought it did).

So how should you handle an intolerance?

In general, as long as we’re not talking about an intolerance and not an allergy, cutting out the food concerned is usually not the best approach. At least not for longer than a few weeks. More diversity – that means eating more different foods – is key to gut health. Fibre is so important, which is why a FODMAP diet maintained beyond the recommended initial phase can be so detrimental. If you’re in a place of restriction, start low and go slow when you begin eating more fibre or suspected culprit foods. A registered Nutritional Therapist can help you improve the integrity of your gut lining (support an overly “leaky gut”) and reduce chronic low-grade inflammation. This is the secret to happy microbes and a happy tum (for most of us).

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