Have you ever heard of hair allergy tests? Essentially, they’re promoted as methods of detecting food allergies or sensitivities by analyzing a few strands of hair. While that seems amazing – no blood tests and can be done in the comfort of your home! – they are unfortunately not regarded as evidence-based or accurate.
Let’s break down the differences between allergies and intolerances, why hair testing is not appropriate for either, and what is actually useful in these situations.
Disclaimer: This post is for information purposes only and should not be construed as medical advice. Always consult your doctor if you have questions regarding a food allergy or intolerance.
Food Allergies and Testing Methods
When my son couldn’t tolerate dairy (or eggs or soy) in his first year of life, I because fairly interested in the world of food allergies and intolerances. Even as a dietitian, it took quite a bit of learning to understand some of the different conditions out there.
Most of the time, the term food allergy is thrown around in reference to a number of conditions. But in the medical field, a food allergy generally refers to an immune response (via IgE antibodies) to a particular food protein. That immune response is what causes symptoms like hives, itching, or anaphylactic shock.
IgE-mediated food allergies are diagnosed either via skin prick tests or blood tests.
Skin prick tests use a very small needle (lancet) that ever-so-slightly penetrate the skin’s surface with a very small amount of the potential allergen. Doctors can see if there was any response – swelling, redness, itchiness – to the skin.
According to the Mayo Clinic, are certain people that shouldn’t undergo skin allergy tests. These include those who have previously experienced a very severe allergic reaction, or people who are on certain medications. Similarly, severe eczema can make it difficult to find a large patch of clear skin to perform the test.
Those who aren’t a good fit for skin prick testing will be given a blood test. You might hear terms like ELISA, RAST, or ImmunoCAP testing thrown around; these are all different types of blood tests (RAST used to be used frequently but it is less common today).
Blood tests will measure the amount of IgE antibodies specific to a certain food. The higher the levels, the more likely it is that you have an allergy.
Wondering if these same results can be assessed with hair samples? According to the Cleveland Clinic, there is no IgE in hair samples. As such, providing a hair sample for an at home test (or holistic test in a doctor’s office) cannot provide accurate results for IgE-mediated food allergies.
If you believe you or your child has a food allergy, see a doctor to discuss evidence-based testing options like skin prick or blood testing.
Food Sensitivities, Intolerances, and Testing
Not all reactions to food, however, are based on IgE mediated responses.
For example, a non-IgE mediated cow’s milk protein allergy is common among infants, which typically results in gastrointestinal upset and mucous or blood in the stool. This type of condition is thought to involve a cellular reaction.
Similarly, FPIES –food protein-induced enterocolitis syndrome – is a non-IgE allergy that results in severe vomiting and diarrhea within a few hours of ingestion of a trigger food.
There are also the broader terms like “food intolerance” and “food sensitivity.” Some food intolerances have a standard medical definition. For example, lactose intolerance has nothing to do with the proteins in milk, but instead has to do with lacking the enzyme necessary to break down sugar in milk.
Food sensitivities do not have a standard definition (but this term is often used for non-IgE allergies, as well as other food reactions). These could cause an adverse reaction when eating a certain food (for example, an upset stomach or headache). These are not well understood yet.
While these conditions are very real, and some can be very serious, none involve the IgE response that traditional allergy tests measure. As such, a traditional allergy skin prick test or blood test can’t tell you if you have them.
There are two conditions under this broad category that have validated testing methods:
- lactose intolerance, which can be diagnosed via a hydrogen breath test or lactose tolerance test for blood sugar levels, and
- celiac disease, sometimes called gluten intolerance, which can be diagnosed via an endoscopy to assess damage to the intestines.
However, right now, the rest of the conditions that fall under this section do not have specific tests for diagnosis that are widely accepted by the scientific community. (This includes hair tests – though more on that in the next section).
There are some professionals that support the use of MRT testing – a mediator release test which is a type of blood test. This looks at certain inflammatory chemicals released in response to different foods.
As a dietitian, what is being tested here does seem to make the most sense to me. It also involves working with a certified LEAP therapist after the test in order to make dietary changes, which is much more powerful than a simple handout of foods to avoid.
However: there is no peer reviewed research that I can currently find that supports the use of MRT for assessing food sensitivities, and the overall scientific community not accepted the use of this test at this point. (Anecdotally, though, I acknowledge some professionals have had success with their clients).
So what’s the best steps when confronted with a possible food sensitivity? The generally accepted clinical approach is focused on:
- identifying symptoms and trigger foods,
- ruling out other conditions, and
- testing the results of elimination diets to see if symptoms improve.
Hair Testing and IgG – Is it Legit?
Most hair tests claim to be able to be able to detect food sensitivities or intolerances by measuring levels of IgG. IgG is another type of antibody that your body produces; in fact it’s the most common one.
However, IgG tests have not been shown to identify food allergies, intolerances, or sensitivities. They are not proven to be accurate, and insurance companies typically do not cover them for this reason.
In fact, IgG prevalence in response to a particular food could simply indicate that an individual has exposure to that food. Just because IgG is created in response to eating a food, doesn’t mean that it leads to their blood cells creating an inflammatory response. (source)
Similarly, there are some pathways to food sensitivity that may not involve IgG, which would render an IgG test less than helpful.
Several scientific bodies have spoken out against these tests. For example, the Canadian Society of Allergy and Clinical Immunology put out a position statement in 2012 which stated:
“The literature currently suggests that the presence of specific IgG to food is a marker of exposure and tolerance to food, as seen in those participating in oral immunotherapy studies. Hence, positive test results for food-specific IgG are to be expected in normal, healthy adults and children.” (source)
Similarly, the American Academy of Allergy Asthma and Immunology has stated:
“It is important to understand that this test has never been scientifically proven to be able to accomplish what it reports to do. The scientific studies that are provided to support the use of this test are often out of date, in non-reputable journals and many have not even used the IgG test in question. The presence of IgG is likely a normal response of the immune system to exposure to food. In fact, higher levels of IgG4 to foods may simply be associated with tolerance to those foods.” (source)
Another issue with hair tests is that the specific laboratory protocol for even assessing IgG response likely varies considerably.
And of course the major problem with these tests is that they may cause you to unnecessarily eliminate foods that you don’t have to remove from your diet.
Imagine my surprise when a Groupon popped up for a “Food Allergy and Sensitivity Test from The Allergy Testing Company” when I was thinking about writing this article. At $26, I bought it to test it out solely for the purposes of blogging about it.
First off, you should know I personally do not have any food allergies or known intolerances. I’m generally healthy and don’t have any ongoing symptoms or medical concerns that would make me question whether I had issues with a particular food. I was curious to see what the test would show.
The process was pretty simple. You printed out a sheet of paper from the company, and mailed it in along with a few strands of your hair that you plucked out and placed in a plastic bag. Honestly, it took about 3 minutes to get it all ready and sealed up in the envelope to send out. (I’m slightly nervous that my hair is being kept in some storage front to frame me for a crime someday, but who knows.)
That’s where the “good” news ends.
This company has no information at all about how the testing is actually conducted. I don’t think it even listed anywhere that it was an IgG test, though I admittedly may have missed that.
In the FAQ section of their website, they describe how their test compares to allergy blood tests: “A blood test is testing for IgE mediated allergies and will only produce results listing reactions in the immunoglobulin system (these are estimated at only 2% of all allergies). Our hair sample test is examining changes at a cellular level because the latest science shows that up to 43% of allergies are in fact a reaction in T cells.”
First off, those stats are misleading – I cannot find any scientific literature to support these claims. And second, still no specific details as to how the hair is analyzed.
When I received my results, the packet offered slightly more information: “Food sensitivity is an immune response by the IgG antibody which is the largest circulating antibody in our immune system…There are many studies that suggest that up to 20% of the population may have sensitivities to certain foods and that these sensitivities can contribute to symptoms such as Irritable Bowel Syndrome, headaches, insomnia, headaches, certain types of arthritis, autism, ADD/ADHD, eczema, chronic ear infections, gut malabsorption and many other chronic conditions.”
There’s a lot in that statement that is untrue – but I feel especially compelled to clarify that food sensitivities are not a cause of autism.
Anyway – moving on to the actual results. Here’s what they told me:
Out of curiosity, I eliminated all of the red ones for a few weeks.
The result? I had no changes at all in how I felt. Since I didn’t have any medical issues to begin with, there was nothing really to change – but I didn’t feel like I had more energy or anything like that either.
Plus, some of these results just don’t make sense in my head. Let’s take a look at one of the high reactivity options – high fructose corn syrup. This is a sweetener made from corn starch. There are several forms, but the most common is 55% fructose and 42% glucose. To give comparison, sucrose (aka table sugar) is about a 50/50 split of each.
One would expect that if I was displaying a “high” food sensitivity to high fructose corn syrup, that I’d also display a sensitivity to either a) caramelized sugar syrup (essentially the same ingredients, albeit slightly different proportions as HFCS), b) corn, or c) perhaps a fruit that was high in fructose. Instead, their own test results claim I did not have a problem with any of those other foods.
Obviously I’m an N=1 here, and personal anecdotes do not mean scientific proof. But I thought some might find it interesting to see a first-hand experiment.
The Bottom Line on Hair Allergy Tests
Hair tests cannot diagnose a food allergy.
They are typically advertised for food intolerances or sensitivities, claiming to assess IgG levels. However, IgG has not been proven to be directly connected with specific food sensitivities.
In addition to spending unnecessary money, these tests may lead to extreme limitations on foods that can cause nutrition imbalances.
And of course, it can take away the enjoyment from meals. For example, I love walnuts and mushrooms – if I trusted my IgG results, I’d have to eliminate them, when in reality there’s no scientific reason to do so.
What Should You Do From Here?
- If you believe you or your child has a food allergy: It’s best to consult your doctor or allergist for a skin or blood test.
- If you believe you or your child has non-IgE mediated allergies or food sensitivities: My best recommendation is to work with your doctor and dietitian that can help you with an elimination diet based on symptoms and diet history.
- Wondering about MRT instead? I’m still very hesitant to recommend MRT based on the lack of research. I do think that theoretically, the idea of the test (i.e. assessing the end point, rather than one avenue to the end point) offers more value than IgG tests. Ensuring that you work with a professional is valuable too. However, down the road we may see that this is simply another non-validated test that is not worth the money (or maybe we’ll be surprised and see evidence to support use). Only time shall tell.
As always, the choice is yours when it comes to your own health. If you feel better eliminating certain foods or you want to spend money on a test even if it’s not accurate just to check it out – by all means, go for it. My hope is simply that you’ll have a better understanding of all the information and limitations.