The problem with allergy testing

Food allergies and intolerances are on the rise. There are tons of theories to explain why this is happening, but I won’t even pretend to know the answer – because I don’t. But what I do know is that many people are being diagnosed based on allergy testing that may not be all that accurate.

The problem with allergy testing

There are a few standard tests used by health professionals that are known to be accurate. These include skin pricking, blood tests for IgE antibodies, food challenges (suspected foods are fed to you under medical supervision), and food elimination challenges (foods are eliminated and then reintroduced one at a time). To say for sure that you have an allergy, usually more than one of these tests will be done. Taken alone even these standard tests many not get it right.

What makes things even more complicated is the fact that there are also many tests used that do not have scientific evidence behind them. One of these tests is a blood test for IgG antibodies. This sounds legitimate, right? But there is actually no evidence that this test is accurate. In fact, IgG antibodies are thought to actually be a normal response in your body to food! So if an IgG antibody test comes back positive for wheat, for example, it’s probably because you’ve recently eaten wheat. But it doesn’t mean you’re allergic to it! Other alternative tests like hair analysis, muscle response tests, and pulse tests are also lacking any evidence to say they are useful.

The problem with allergy testing

Many people still use these tests though, which concerns me as a dietitian. Because these tests often tell people that they are “allergic” to foods when they didn’t even notice any symptoms to begin with, leading to unnecessary elimination of foods. And when eliminating foods, especially multiple foods or entire food groups, there is always risk of nutritional deficiencies. Plus, allergies are no fun (this is coming from someone with allergies). Why submit yourself to a life of restriction when you may not need to?

So if you have a suspected food allergy, your best bet is to make an appointment with an allergist for accurate testing. And for people with food allergies, especially young children, I strongly encourage seeing a Registered Dietitian for help selecting a safe, nutritionally adequate diet!

Note: If your allergy tests come back negative but are experiencing unpleasant symptoms, you may be intolerant to the food. A food intolerance is different from a food allergy because it is not immune based. If you’re interested in food intolerances, let me know and I’ll write a post about it!


Filed under nutrition

18 Responses to The problem with allergy testing

  1. It is kind of crazy how so many people are allergic to things now. I think people are also just likely to self diagnose. Like if you eat a big meal and you’re bloated (because you ate a big meal) it’s like “ohh I must be allergic to something.” But it would be a bummer to eliminate a whole food group for no reason!

    • Chelsea

      Yes I think self diagnosing is definitely a big problem! I mean I definitely support people avoiding foods that make them feel bad, but it’s important to determine your allergies/intolerances with the help of a professional so that foods aren’t unnecessarily cut out!

  2. Not going to lie- hearing people speak of their self-diagnosed allergies do my head in…especially when it’s to do with gluten & dairy as chances are, it’s only because eliminating both seems to be the “cool” thing to do lately. Rather than official tests, I think our bodies are the best indicator in telling us what foods suit and don’t suit us. And I personally also think we need to keep experimenting as our bodies keep evolving- so what may have not worked well in the past may actually be handled well now (at least in small doses).

    • Chelsea

      That’s true! I don’t think it’s widely known that some children grow out of allergies (like milk allergies) by the time they’re 10, so it’s always a good idea to get retested!

  3. Jamie

    It sounds like we don’t have a good understanding of food allergies. Are intolerances better understood?

    • Chelsea

      I’d say allergies are pretty well understood when standard tests are used. Of course there’s still some work to be done – if we understood them perfectly we’d have a treatment for them!

      Our understanding of intolerances varies. Some we have a pretty good grasp on (such as lactose intolerance), but others still need a ton of research (like FODMAPs).

  4. Ah, this was a great read. Post more stuff like this! You make all the science very ‘readable’. :) I’m currently on Whole30, which is essentially an elimination diet, and I’m a bit nervous (and excited!) about the reintro phase next week!

  5. Great post! True allergies are terrifying and it’s important for people to get tested and not self diagnose… no unneccessary restrictions, please!

  6. Molly

    Can blood tests for allergies be administered by your family doctor? I had always been going to see an allergist but he retired this year. Usually I just get the skin test but would be interested in getting the blood test as I haven’t had that type of test done in a few years. Also, do you know anything about growing into allergies? I grew into mine in grade 4 and at the time was told it was linked to hormones – but I wasn’t sure if you knew whether that was true or just a hypothesis!

    I agree with the above comments – I love the more nutrition related posts :) Very helpful (Although don’t do away with personal posts because those are fun too!).

    • Chelsea

      Family doctors don’t tend to the bloodwork themselves – they refer you to a lab. And I’m not sure if labs can do blood tests for allergies or not. My guess is no, but you never know. :)

      In order to have an allergy to something your body has to become sensitized to it. You can’t be allergic to something you’ve never eaten before! Did you eat a lot of nuts/seeds before age 4?

      I suppose I’ve been slacking a bit on personal posts lately. Although I try to intertwine personal tidbits with my recipe posts. Let me know if there’s anything in particular you’d like me to post about though!

  7. LOVE these posts, Chelsea. It’s so prevalent amongst some HLB’s where they claim to be a or b without any proper testing or just following a trend- I’d love to see a post on food intolerances- I developed one to oats for ages because I used it as my carb source for like, two years. Worst.

    • Chelsea

      Yeah it’s hard to tell whether people truly believe they have an allergy to a food or if they’re just following what’s trendy!

  8. Allergies and intolerances are such a tricky topic, especially in the HLB community where a lot of people like to cut things out because someone else did and “noticed” a positive result. Like… how much of that is legit and how much of it is just placebo? And what makes things even more frustrating is that even if we have a slight intolerance or allergy to something, our body can still handle it fine if we’re generally healthy… but as soon as we get more stressed or tired or whatever, our symptoms can act up even more. There are just way too many factors when it comes to diet… it can drive ya crazy.

  9. Pingback: . link love 2/22 . - . running with spoons .

  10. This was enlightening and fascinating. It also explains why so many allergies are cropping up because of these false positive tests. Geesh, this is also why I’m so grateful I don’t have allergy issues. Actually that’s not entirely true. I’m fairly certain, based on my bodies reaction, I’m allergic to something in alcohol although the reaction is never horrible: hives and heat, so I just ignore it and indulge in a cocktail from time to time. I’ve never had any lasting problems from my approach either.

  11. Pingback: Friday Favourites + Weekly Reads | Mango About Town

Leave a Reply