Do At-Home Food Sensitivity Tests Really Work?

If you are someone who deals with weird — and gassy — stomach issues who turns to the Internet to symptom search, chances are your social media feeds have been graced with ads for at-home food sensitivity tests.

Marketed as convenient ways to test your own stomach without going to the doctor, they're particularly tempting for anyone who wants answers but doesn't have a lot of time.

Some popular brands are Everlywell, myLAB Box and YorkTest Laboratories. These tests typically cost between $100 and $250 and come with instructions for how to take them and read the results on your own.

"These [tests] are new health-empowerment tools where people get the chance to test their own lab work and see if something's not working in their body," says Terrell Smith, MD, founding physician and director of clinical development at Spora Health.

Once you receive a test kit in the mail, you swab the inside of your mouth or take a small blood sample and send it back to the company's laboratory. Your results are emailed back to you within weeks.

But, do these tests ‌really‌ work?

Here, learn more about whether at-home food sensitivity tests are worth trying, and what experts suggest to do when you have a true food sensitivity.

Before spitting into a test tube or taking a blood sample for these at-home food sensitivity tests, it helps to know what a food sensitivity actually is.

A food sensitivity occurs when a person has difficulty digesting a particular food, according to the American Academy of Allergy, Asthma & Immunology (AAAI).

Symptoms of food sensitivity include, per the Cleveland Clinic:

• Gas
• Abdominal pain
• Bloating
• Diarrhea
• Nausea and/or vomiting
• Fatigue
• Headache and/or brain fog
• Acne or rash

This is different from a food intolerance (where your body lacks the digestive enzyme needed to break down ingredients like lactose and fructose) and a food allergy, where your "immune system builds an antibody response to a particular food," says Kien Vuu, MD, a California-based performance and longevity physician.

Food allergies can involve your entire body, and can "make you break out in hives, feel short of breath or [experience] throat closure," Dr. Vuu says, which requires emergency care.

In other words, the immune system isn't involved with a food sensitivity or an intolerance, but it ‌is‌ involved with an allergy. Sensitivities will mostly only cause digestive issues, Dr. Vuu says, but some, such as to lactose and gluten, may trigger symptoms other than digestive upset, such as fatigue, migraines and joint pain.

You know food sensitivities cause your tummy troubles, but what's actually happening inside your body when you're sensitive to a food? That's what these tests claim to measure.

At-home food sensitivity tests detect the level of immunoglobulins, or proteins that function as antibodies, in the bloodstream. These proteins fight off germs like viruses and bacteria, according to the National Library of Medicine (NLM).

Specifically, these tests detect immunoglobulin G (IgG) — the most abundant immunoglobulin in the bloodstream, per the NLM.

Your results may show you have higher IgG when you eat any number of things, like milk or bread or broccoli, for example. This may encourage you to cut that food out of your diet.

The problem with this? Your IgG levels increase after eating ‌any‌ food. This doesn't necessarily mean you are sensitive to them, Dr. Vuu says.

"High IgG levels after eating a certain food doesn't always mean it's bad for your body," he says. "It just means you've been exposed to it. There is currently no clear correlation between increased IgG levels and food sensitivity in the medical community," he adds.

It's true. Studies that support the use of food sensitivity tests are often out of date, in non-reputable journals and don't even use the test in question, according to the AAAI. In fact, there is ‌no one‌ test for any intolerances or sensitivities, per the AAAI.

There are no IgG-equivalent food sensitivity tests offered by allergists or primary care physicians, Dr. Vuu says.

Instead, doctors use tests that detect immunoglobulin E (IgE).

If you have a true food allergy, your immune system overreacts to that food by producing IgE. This increase is what causes an allergic reaction, per the AAAI.

IgE tests typically require multiple "skin pricks" or blood samples to determine the variety of foods you are allergic to.

While at-home food sensitivity tests cannot detect true food sensitivities, there's at least one benefit to trying one of these tests if you are curious and your budget allows: It could be a way to start a conversation with your doctor about your health.

Don't be afraid to bring the results to your primary care physician if you've already taken one, Dr. Smith says.

"We won't be upset by you bringing this information," he says. "We are humans, too, and are interested in learning all we can about health."

Together you can discuss what the results do or do not tell you, which open doors to deeper conversations about your symptoms and a plan to address them.

It should come as no surprise that tests without enough scientific evidence have more risks than benefits. These risks include:

"Many patients come to me with at-home tests and have ruled out pretty much everything but water," Dr. Vuu says. He cautions that this is too drastic of an approach.

Cutting out entire food groups because your test detected high IgG when you ate them, especially for long periods of time, can distort your relationship with food, leading to some harmful disordered eating tendencies, says Tamar Samuels, RD, a New York-based dietitian and co-founder of Culina Health.

"When you cut out foods like wheat, for instance, you miss out on fiber important for gut health," she says. "You can also become afraid to eat certain things, which affects quality of life."

"These tests give expensive and misleading results," Dr. Vuu says. "Without doctor supervision, you may be unnecessarily cutting things out."

That said, not everyone feels comfortable visiting the doctor due to factors like anxiety, lack of health insurance, language barriers and systemic racial injustice. These barriers can lead people to become susceptible to health "tools" advertised online, instead.

But test results that are only shared online, or through an app, can leave people without the full picture of their results, according to the American Medical Association's Journal of Ethics. People may even decide to self-treat their condition with supplements or medication they do not need.

What's more, you might turn to the Internet to interpret your results, which can lead to a wealth of false information and anxiety if you don't know where to look.

When you eliminate foods from your diet, you may miss out on essential nutrients needed for optimal gut (and overall) health, per St. Luke's Health.

For example, cutting out dairy products when you are not actually sensitive could cause vitamin D deficiency. And cutting out gluten can lead to vitamin B, iron and magnesium deficiency, according to St. Luke's Health.

This is why it's important to only eliminate foods (and then slowly reintroduce them) under doctor supervision.

While there is no official test to determine food sensitivity, there are a variety of ways doctors can help you detect and address them.

A gastroenterologist would be able to determine a gluten, lactose or other food intolerance through endoscopies, Dr. Smith says. But most intolerances can be determined by a primary care physician if you bring a log of symptoms. They can refer you to an allergist if needed.

Your doctor may suggest a test for food intolerances such as lactose, fructose or sucrose intolerance called a hydrogen breath test, per the University of Michigan Health.

Prior to the test, your doctor will ask you to drink a solution of lactose, fructose and sucrose. Then, you'll breathe into a test tube that checks your level of hydrogen and methane gas — byproducts of intolerance, per University of Michigan Health.

The results will determine your course of treatment, which could include an elimination diet.

While elimination diets are an important part in determining whether you have a food sensitivity, it's the reintroduction of these foods that will give you answers, Samuels says.

When you add eliminated foods back into your diet, you can track your symptoms to determine if that particular food is the culprit.

Samuels recommends:

• Eliminating all the foods you think are causing symptoms.
• Reintroducing one food at a time.
• Supplementing with other types of food. For example, if you eliminated bread or wheat, try adding other complex whole grains like rice or quinoa to your diet.
• Keeping a food diary to report symptoms and findings to your doctor.

If you are sensitive to certain foods, you can try over-the-counter medications called digestive enzymes, Samuels says. These allow you to continue eating said foods without pain and digestive discomfort.

Some popular brands are GlutenEase (Amazon, $24.22) and Lactaid (Amazon, $12.46). Both make it easier for your stomach to break down gluten and lactose, respectively, Samuels says.

There's also a digestive enzyme called alpha-galactosidase (sold as Beano, $16.95) that helps people digest roughage like beans and raw vegetables.

If you do have a food sensitivity and have eliminated that food from your diet, there are supplements you can take to help make up for any lost nutrients.

Doctors frequently recommend the following, according to Samuels, but only for people who are truly deficient (otherwise too much can cause issues):

• Calcium
• Vitamin B12
• Vitamin D
• Iron

At-home food sensitivity tests don't work like they claim.

While these tests work by detecting IgG levels, that information doesn't accurately determine which foods you may be sensitive to. It can simply tell you what foods you've recently eaten and been exposed to.

What's more, these tests are expensive, and results can be difficult to understand without a doctor's guidance. That's why many experts, like Dr. Vuu and Samuels, do not recommend at-home sensitivity tests to their patients.

If you believe you are sensitive to certain foods, it's best to visit your doctor or a registered dietitian and follow a professionally administered elimination diet.