Debunking Food Sensitivity Tests: What the Science Says
I recently gave a few presentations on the gut-brain connection, and I briefly mentioned that food sensitivity tests are more of a marketing scam than anything scientifically supported. Needless to say, this sparked a few inquiries, including a friend/colleague suggesting I debunk this in one of my blogs. So here we are!
I’m excited to share this insight, hoping it saves you from unnecessary food fears and spending.
And if you’ve already done a food sensitivity test, please know you’re not alone and there is zero judgment here. These tests are heavily marketed and can seem like a helpful solution when you’re not feeling your best. It makes complete sense to want answers and relief.
And likely - if you’ve tried food sensitivity testing - you’ve ended up with a long list of foods you can’t eat. This is a common story, and also (unfortunately) not supported by reliable scientific evidence - despite the marketing claims.
Let’s break down what these tests are really telling you (and what they’re not).
First, Let’s Define the Terms
It’s common for people to use food allergy, food intolerance, and food sensitivity interchangeably, but they’re quite different. Let’s review those differences:
Food Allergy: This is an immune response involving IgE antibodies - think: hives, throat swelling, or even anaphylaxis. This happens when your immune system overreacts to a specific food protein. While some food allergy responses can be mild, many can be life-threatening; people with food allergies typically carry EpiPens with them at all times.
Food allergies show up quickly after eating the food (minutes to hours) and should always be taken seriously and diagnosed by an allergist. Sometimes people grow out of these, but a lot of the time they’re with you for life.
Example: For someone with a peanut allergy, even airborne exposure - like being near peanut dust or the smell of peanut butter - can trigger a severe reaction and/or require hospitalization. 🥜
Food Intolerance: This is not an immune response; it’s more about the digestive system or specific reactions to chemicals in foods. Your body often struggles to break down certain foods or chemicals, which can lead to symptoms like bloating, gas, stomach pain, brain fog, fatigue, or even migraines.
Symptoms of food intolerance typically take anywhere from a few hours to a full day to set in because they’re based on the speed at which food is digested within your body. Food intolerances can still make you feel pretty uncomfortable, but they are not life-threatening.
Example: Someone with lactose intolerance is missing lactase - the enzyme needed to break down lactose (a sugar found in milk and dairy products). As a result, the lactose stays in the gut, draws water towards it, and can result in intense diarrhea and gas.
Food Sensitivity: Here’s where things get a little fuzzier. Sensitivities are thought to involve the immune system in a non-allergic (non-IgE), delayed way. A particular food prompts the immune system to create internal inflammation, which can lead to a host of symptoms - including digestive, skin, or cognitive issues, along with joint pain.
Symptoms may show up hours or even days later, making it harder to identify, and again, these are not life-threatening. These also tend to be temporary - your body, immune system, and gut microbiome are continually changing, and what may not sit well today may be fine after a period of time. By the way, the science overall is a bit vague, simply because “food sensitivities” are not an actual medical diagnosis, and there is no accurate way to test or classify “food sensitivities” in the first place.
Example: Someone with undiagnosed Celiac Disease eating gluten might develop intestinal permeability (leaky gut), and start reacting to a variety of foods (aside from gluten), but once gluten is removed and the gut begins to heal, many of those sensitivities can improve or disappear entirely.
What Do Food Sensitivity Tests Test For?
Most at-home or practitioner-ordered food sensitivity tests measure IgG antibodies - a type of immune marker that shows your immune system has seen a food before. If you have “high” IgG antibodies to a food, that’s interpreted as having a “sensitivity” to that food.
Here’s the thing: Having IgG antibodies to a food is not a bad thing - in fact, IgG is more of a sign of food tolerance, not intolerance!
Many of us would show IgG reactivity to the foods we eat regularly because our immune system is doing its job and recognizing them as familiar. And “higher” IgG levels simply means it’s a food you eat often or have recently eaten…which is why so many folks’ favorite foods end up “high” on these tests.
There’s no solid evidence that IgG levels correlate with negative symptoms or sensitivity, and these tests aren’t scientifically validated for diagnosing food issues - this includes genetic tests, which make similar claims.
Major Allergy & Immunology health and medical organizations across the globe (U.S., Canada, Europe, and Australia) have all issued statements (some quite strong!) against using IgG testing to diagnose food sensitivities.
If the above isn’t enough, there is actually a pretty big class action lawsuit that was just filed last month against one of the biggest food sensitivity testing companies on the market - essentially noting everything I mentioned above about how scientifically inaccurate and misleading they are.
Risks of Food Sensitivity Testing
Aside from the dent in your wallet and the unnecessary food eliminations, there are other risks to consider when following the (unsupported) results:
Increased Risk of Malnutrition: These tests often come back with dozens of foods and/or food groups to eliminate. This can eventually lead to nutrient deficiencies and digestive changes that may cause or worsen food intolerances over time. And the overall reduction in food diversity is counterproductive to supporting your gut health.
Heightened Food Anxiety: Receiving a long list of “reactive” foods can create fear and stress around eating, leading to increased anxiety and hypervigilance at meals.
Disordered Eating Patterns: Restrictive eating prompted by these tests may contribute to binge eating, food obsession, or other eating disorder/ disordered eating behaviors - especially when variety becomes too limited.
False Sense of Control: Test results may offer the illusion of clarity, but they often distract from addressing deeper issues like stress, gut health, or overall lifestyle factors that affect digestion and well-being.
Delay in Accurate Diagnosis: Relying on misleading test results can delay getting an accurate diagnosis - whether it’s a food allergy, intolerance, GI condition, or something else entirely - keeping you stuck in symptom management instead of real solutions.
What to Consider Instead
If you’re struggling with symptoms you suspect might be food-related, here are some suggestions to consider, instead of relying on (unreliable) food sensitivity tests:
Consider it a yellow/red flag if someone recommends this test to you: People who are practicing evidence-informed nutrition won’t be recommending food sensitivity testing based on the current existing scientific literature. If someone does, it might be time to look for another provider. This question is also great to ask a provider if you’re considering working with them.
Support your gut: Many food reactions are linked to issues like intestinal permeability (“leaky gut”), stress, or dysbiosis (an imbalance of gut flora) - not the foods themselves. Focusing on gut support can help reduce sensitivities.
Keep meals balanced and nourishing: Rather than cutting foods out, think about what you can add to support your gut - like fiber-rich veggies, cooked foods, adequate protein, and anti-inflammatory nutrients.
Address the bigger picture: Sleep, stress, nervous system regulation, and digestion all influence how your body responds to food. Sometimes the issue isn’t the food - it’s how your body is currently processing it.
The Bottom Line
Food sensitivity testing companies are profiting off your health concerns and I’m not here for that. At best, they’re a marketing scam and a waste of money; at worst, these tests often lead to unnecessary restriction and confusion, without actually addressing the root cause of your symptoms.
If you think certain foods might be at play regarding your health issues, give yourself permission to slow down, gather quality information, and take it one small step at a time. Real solutions rarely require long “do-not-eat” lists; a flexible, nourishing approach will always take you further than restriction.
Here’s a helpful list from Food Allergy Research and Education of other unproven tests related to food allergies/sensitivities, so you can save yourself going down any of these other pseudoscience paths, too!