What the Science Says: This Dietitian's Honest Thoughts on Food Sensitivity Blood Tests
Are you considering a food sensitivity blood test, or had one done previously? If so, listen up!
These tests are often advertised at medical clinics (hello, Life Labs!), leading us to assume that they must be evidence-based and worthy of our consideration. In addition, they are often recommended by natural or alternative healthcare practitioners for those with digestive/hormone/energy issues, without a second thought.
So you have digestive symptoms, persistent headaches and a nagging skin issue that you can't seem to get to the bottom of, you might be considering getting a food sensivity blood test.
But is it worth your time? And would a Digestive Health Dietitian recommend it for your gut-health journey?
Before diving into the evidence, let's get the basics straight...
Food Allergy vs. Intolerance vs. Sensitivity
Did you think these are all the same? Well think again! Let’s discuss the differences between each of these food related triggers before we get into how to identify them.
FOOD ALLERGY
A food allergy is an immune response to a certain food that your body identifies as an invader. When this occurs, your body triggers cells to release an antibody (IgE) to help neutralize the allergen. These IgE antibodies also alert cells to release histamines which are responsible for the allergic symptoms.
Food allergy symptoms can be mild or life-threatening and affect all parts of the body including the skin, respiratory system, and gastrointestinal tract. Some of the more common symptoms include hives, swelling of the mouth, wheezing, shortness of breath, and vomiting.
The most common food allergies are:
Eggs
Fish
Shellfish
Milk
Peanuts
Soy
Tree nuts
Wheat
FOOD INTOLERANCES
A food intolerance is the body’s inability to digest certain foods. They are either caused by the body not having enough of a certain enzyme to break down a certain food component resulting in reactions in the digestive tract such as bloating, pain and gas. They can also occur by a reaction to a type of food chemical component or additive, such as sulphites or histamine.
As you can see, there are two main differences between a food allergy and a food intolerance. First, an intolerance’s symptoms are not life-threatening, and occur in the digestive tract. However, an allergy’s symptoms can be life-threatening and can occur all over the body. Second, an intolerance is not caused by an immune reaction, whereas an allergy is.
Let’s take lactose intolerance as an example. For a reminder, lactose intolerance is an individual’s inability to digest the sugar in milk called lactose. As we age, our ability to digest dairy decreases because our intestines produce less of the enzyme called lactase. Lactase works to break down lactose. When there is less lactase present in our body, there is less lactose broken down. Therefore, there is more lactose sitting in our digestive tract. In doing so, symptoms such as bloating, inflammation, or diarrhea arise. Lactose intolerance is a very common form of food intolerance, much like gluten intolerance.
It’s also important to note that with food intolerances, people have different tolerance levels. Some people with a fructose intolerance for example, may be able to digest small amounts of foods with fructose, but then experience symptoms when higher amounts are consumed.
FOOD SENSITIVITY
Food sensitivity actually has no standard medical definition, and it can be used to mean any reaction to a food. Sometimes this term is used interchangeably with food intolerances or allergies. For example stating that someone has a ‘histamine sensitivity’.
It is commonly said that food sensitivities are caused by an immune reaction, resulting in many symptoms such as headaches, fatigue, rashes, and even joint pain. There is likely more factors going on here, such as underlying dysbiosis and permeability (aka small gaps or perforations) in the digestive tract that may result in inflammation-type responses to certain foods consumed.
Should You Take a Food Sensitivity Test?
As discussed above, food sensitivities are NOT food allergies, but a condition that causes symptoms over a longer period of time (skin changes, migraines, digestive issues, etc.). Whereas allergies are a very immediate response (itchy skin, rashes, hives, etc.).
Our body produces DIFFERENT antibodies for sensitivities vs. allergies. IgE antibodies are produced in food allergies whereas IgG antibodies are produced for food sensitivities. Therefore, IgG blood tests (aka those food sensitivity blood tests) are performed to diagnose food sensitivities (rather than IgE tests).
IgG tests look for the presence of IgG antibodies in the blood. HOWEVER (take note...) the immune system makes IgG antibodies to proteins found in the food you regularly eat regardless of if you’re intolerant/sensitive to them!
This means it is NORMAL to have IgG antibodies to foods that you are tolerant to. For example, if you eat dairy regularly, IgG testing can detect IgG antibodies for lactose regardless of if you’re sensitive or not. As you can see... those food sensitivity tests can often result in a false positive!
As a result, food sensitivity test results can lead to over-restricting and fearing foods unnecessarily. Not to mention they are expensive - a test kit can cost around $250-300 CAD.
The problem I often see in my practice is that client’s are recommended to take these tests and expect to “uncover their trigger foods” but instead are left with a long and daunting lists of foods they need to cut out. This can trigger increasing fear and stress around food, and in the long term result in nutrient deficiencies and an unneccesarily restricted diet.
As I chat about in my FREE masterclass ‘5 Secrets to Find Freedom From IBS & Painful Bloating’. - excessive food restriction can affect the health of our gut-microbiome which can further worsen digestive health for the long term.
So what can you do to identify your food intolerances and sensitivities instead?
Rather than hopping on these expensive blood tests, the gold standard for determining food sensitivities or intolerances is a structured elimination diet, under the guidance of a Registered Dietitian.
Getting to the Root of Your Symptoms
So if you’re trying to figure out if you have an allergy, intolerance, or sensitivity and what might be causing it, the first thing to do is look at your symptoms. If your symptoms are digestive issues chances are you have an intolerance. If your symptoms include swelling, breathing complications, or hives it is most likely an allergy. All other symptoms (migraines, mood swings, acne), or a combination of them, could point to a food sensitivity.
However, for food sensitivities or food intolerances (rather than expensive food sensitivity blood tests), the gold standard for determining food sensitivities or intolerances is a structured elimination diet. Please keep in mind that this form of diet should be performed under the guidance of a trained Dietitian, so that you can ensure it is evidence-based and you are meeting your nutritional needs.
As always if you aren’t sure what is going on, chat about this with a Medical Doctor and Registered Dietitian.
Closing Thoughts
Now you better understand the differences between a food allergy, food intolerance, and a food sensitivity, as well as how to find out which the culprit is.
So where you do you go from here? The next step is getting the appropriate help to match! If you are having reactions and aren’t sure what the culprit is, make sure to consult with your medical doctor.
If you are specifically having issues tolerating foods, identifying the source of the sensitivity or intolerance, and/or need help planning your diet to ensure you are meeting nutritional requirements, feel free to reach out so we can chat more about your history and if it is a good fit to work together. Together we will look deeper into your diet and lifestyle, identify your specific triggers, and create a plan to help you increase your diet diversity and build up your gut microbiome while finding freedom from uncomfortable and persistent symptoms.
Hope you found this article insightful! If you have any questions, feel free to post a comment below.
P.S. Want to save TIME, STRESS and MONEY while optimizing your gut health and wellness with a proven meal planning and prepping system? Get my complete guide to Gut-Friendly Meal Planning & Prepping Workshop + Resource Bundle! You won’t want to miss this!
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