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Your Tiredness + Brain Fog May Be Caused By An Underlying Food Sensitivity — Here, The Best At-Home Tests To Find Out

Two doctors weigh in on who should test, which test to use and how to interpret results

These days you can test for anything at home, from COVID to urinary tract infections and strep throat, as well as measuring your hormone levels and more. Now, at-home food sensitivity tests, which gauge how your body reacts to different foods, are becoming increasingly popular. But the tests aren’t cheap, so many people are wondering, are these tests accurate, and should you even be doing them without a healthcare practitioner to help you interpret the results and track a course forward? And if so, which is the best at home food sensitivity test? Read on for all the answers, then see how food sensitivity tests helped one woman heal after year of fatigue and brain fog.

What are food sensitivity tests?

These tests determine which foods your body responds to with unpleasant symptoms, typically caused by inflammation (as opposed to food allergies, which can be potentially life-threatening reactions). The tests can be a powerful health tool, says functional medicine expert Jill Carnahan, MD, author of Unexpected. “I think: more power to the consumer. It used to be the physician had all the authority and information. I love that the playing field has been evened so patients have more data.”

And there’s little harm that can come from a test like this. “It is really just a guide of what to try eliminating,” explains Dr. Carnahan. “It gives you a map. The real test after is trying 30 days or longer without, see if you feel better, then reintroduce.”

Who should take at home food sensitivity test?

Even if you don’t have any diagnosed food allergies, your body can react to different foods in ways that make you feel unwell. “Some reasons people may be interested in food sensitivity tests are gut health symptoms such as bloating or indigestion after eating, change in bowels such as constipation or diarrhea or acid reflux,” says Erica Armstrong, MD, founder and CEO of Root Functional Medicine in Grand Rapids, MI. (Click through to learn how constipation can cause back pain.) “However, food sensitivities can also cause a chronic low-grade inflammation that leads to other symptoms like brain fog, skin rashes, headaches or joint pain.” 

An at home food sensitivity test can help you determine if certain foods are causing your symptoms and provide you with a direction forward toward healing.

How at home food sensitivity tests work

Most of the tests available today measure whether your immune system is producing any antibodies in response to foods. There are two common antibodies that are measured, depending on the test: IgE and IgG. “IgE is produced when you have a true allergy to the food,” says Dr. Carnahan. The body produces IgG, on the other hand, in response to lots of foods. That said, not all of the foods that cause an IgG reaction necessarily cause noticeable symptoms. But all at-home food sensitivity tests that use a blood sample measure IgG.

Are at home food sensitivity tests accurate?

Yes…and no. “Total IgG tests will catch a lot of foods that you don’t have a severe reaction to,” Dr. Carnahan explains. “Some people’s tests light up and they can have 20 or 40 or 60 positive results.”

This is one of the reasons that Dr. Armstrong doesn’t use them in her practice. “Typically, IgG tests will show positive results to foods you have eaten recently, and the result does not necessarily mean there is a sensitivity to the food.”

Indeed, Dr. Carnahan stresses the necessity of using these tests not as a diagnostic tool but as an information-gathering mission. “People can get really restrictive and villainize good foods, which can be harmful. The key is temporarily reducing foods, but you don’t want to stop eating them all together.”

How to take an at-home food sensitivity test

To get the best results on an at home food sensitivity test, you need to be eating a pretty varied diet to begin with. “If there are foods you haven’t touched for two years, you won’t see those react,” Dr. Carnahan says. “You want to expose yourself for at least three days, or even a week or two, before you do the test because it’s somewhat reliant on that.”

Also important to remember: If you suspect a gluten sensitivity, these tests will show if you have a gluten sensitivity, but they do not test for celiac disease. “No reaction to wheat on these tests does not rule out celiac,” says Dr. Carnahan, noting that people with celiac disease experience a different immune response than the one being tested.

What to do with the results

Once you’ve taken an at home food sensitivity test, you can try cutting out the foods that showed an immune response. “It can give clarity to which foods are triggers and when you take them out temporarily you do get relief,” Dr. Carnahan says.

But perhaps the more crucial step is adding the foods back into your diet after 30 days or so. If symptoms return, you’ll know which foods triggered them. And if you feel fine, you can go back to eating those foods freely.

Dr. Armstrong stresses that any dietary changes you make after reviewing your results should be temporary. “A common pitfall we see with these tests is that people start avoiding their favorite foods in an attempt to feel better and then they struggle to reintroduce those foods,” she says. “Then they end up with an over-restricted diet, stress over this limited diet, nutrient deficiencies and more. Elimination diets are meant to be temporary to calm inflammation while we work on improving overall gut health and the microbiome.”

The 4 best at home food sensitivity tests

If you want to try an at home food sensitivity test, give one of these a shot. Note: Other tests on the market use hair samples and mouth swabs to test food sensitivities; we’re focusing on blood tests because those are the ones the physicians we spoke to use and recommend. If your health insurance plan includes a Flexible Spending Account or a Health Savings Account, the tests may be eligible for coverage. Simply submit a claim to your insurance company or use the funds from your FSA or HSA account.

Best combination doctor-prescribed/at home test: Vibrant Wellness Food Sensitivity Complete ($384)

Unlike traditional at home tests you can order online, your healthcare provider has to order this one for you. Dr. Carnahan is a fan of this test. Once your doctor orders the test, it is sent directly to your home for sample collection (you’ll prick your finger and fill a blood spot card) and shipping to the lab. Then a few weeks later, you’ll receive your personalized results directly, which will include reactions to 209 common foods and food additives.

Reviewers’ favorite test: Everlywell Food Sensitivity Test (order on Amazon, $199)

With more than 3,700 five-star reviews on Amazon, users love this fully at-home test. Using a finger prick, it tests your reactivity to 96 foods and provides a digital report of results, usually within a week.

Best budget test: Genova Connect Food Sensitivity Test (buy at GenovaConnect, $144)

Dr. Carnahan likes this brand, which also offers a Food Sensitivity+ test that a doctor can order). The at home test checks sensitivity to 80 foods.

Most comprehensive test: 7Drops Allergy and Food Intolerance Test, (Buy at 7Drops, $299)

This test measures both IgE and IgG antibodies in response to 295 common allergens and 286 possible food intolerance triggers to provide information on both allergies and food sensitivities. Plus, you’ll receive personalized dietary recommendations with your results that can help inform your food choices going forward.

If you’d rather have your doctor do the testing, Dr. Carhanan likes Cyrex Labs Array 10 Multiple Food Immune Reactivity Screen, which costs $700. “Cyrex Labs is one of the best,” says Dr. Carnahan, who has ordered this blood test for her patients. It tests for hundreds of foods and additives, some in both their raw and cooked forms.

Food-sensitivity test success story: Jill Hietpas

Jill Hietpas, who solved fatigue with at home food sensitivity testing
Tiffany Lamers

What is wrong with me…I shouldn’t be this fuzzy,” Jill Hietpas told herself as she struggled to remember what she was in the middle of doing. “I began worrying about how frequently I was unable to maintain focus or stay on track in both conversation and in my work as a physician assistant,” she recalls. “Tip-of-tongue syndrome became part of my everyday life, as I was constantly struggling to recall or remember words as well as details that I’d normally know like the back of my hand.

Fatigue and brain fog took over Jill’s life

“At first, my brain fog began as the occasional bout of forgetfulness. I chalked it up to working a lot and being busy, not eating well or taking care of myself like I should. But for years, the fuzziness grew and became so intense that it began affecting me at work and at home with my family.

“I had word-finding problems, memory problems and difficulty focusing, staying on task and multitasking. At every physical, the doctor said I was perfectly healthy, yet my mind felt like mush and I was always fuzzy and mentally exhausted.

“I also saw a neurologist who did a multitude of labs and MRI scans, all of which were normal. While I was relieved those tests didn’t indicate a problem, I grew frustrated that no one could explain — or treat — my brain fog.

When doctors couldn’t help, Jill did her own food sensitivity testing

“Because I developed other health issues like headaches and joint pain, I decided to perform food sensitivity testing and stool testing on my own, which I could do at the doctor’s office where I worked. When I received those results, suddenly I had hope the fog might eventually lift! I learned that I had a sensitivity to ­certain foods, including many typically deemed ‘healthy’ like some veggies, and as a result, I had an unhealthy gut microbiome and a leaky gut. (Click through for simple swaps to heal leaky gut.)

“These issues led to inflammation within my body and throughout the gut/brain axis, which was causing my brain fog and other symptoms. This diagnosis was a big surprise for me. I had often heard the advice to limit dairy and gluten, which we’re told are the typical offenders of digestive issues, but it turned out I wasn’t sensitive to those.

“I immediately stopped eating the foods I was sensitive to, including corn, beets, cucumber, onion, pumpkin, squash, chickpeas, ­honeydew, cauliflower, lettuce and eggs. At the time, I had been eating most of those foods daily.

“I also eliminated inflammatory oils, processed foods and sugar and instead drank more water and added a probiotic, fiber and lots of vegetables and whole foods.

Feeling clear-headed and energized again

“Within two or three weeks, I felt tremendously better, and that’s when I realized that my brain fog was like when you have vision problems that aren’t severe. At first, you can get by, but then you get corrective lenses that show you how you should be seeing and you see the world in a whole new way. After a full month, I was thrilled that I felt clear-minded again.

“But changing my entire way of eating was tough. It took some energy for me to prep my foods and clean out the house so I didn’t cheat and grab foods I was sensitive to. I followed an 80% rule, where I ate the best I could 80% of the time, avoiding most of the foods I could, but sometimes I couldn’t prep appropriately due to my schedule. Other times we were out socializing and I didn’t have as much control.

“After about six months of eliminating them, I was able to reintroduce many of the foods I was sensitive to, and thankfully, the fog hasn’t returned. I restarted the foods one at a time to see how I would react.

“I still can’t believe that food sensitivities were the cause of a decade of brain fog! I never would have stopped eating those healthy foods if I hadn’t had those labs done to identify them.

“Now that my gut is healed, my thoughts are sharp, it’s easier to multitask, I have little to no fatigue or headaches and I’m able to clearly verbalize my thoughts without word-finding problems and trouble staying focused.

“I feel younger and more energetic now than I did when I was in my early 30s! I truly wish I would have known about food sensitivities sooner!”

This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.

For more stories about sneaky GI conditions:

If You Suffer From Bloating, Constipation and Blue Moods, This Yogurt May Be the Delicious Cure You’ve Been Waiting For

The Hidden Food Sensitivity That Could be Causing Fatigue and Gut Issues

An Undiagnosed Gluten Sensitivity Can Impair Your Thyroid Function — Here’s How to Fix It

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