In the not-so distant past, if you felt like a certain food was causing digestive issues (say you got, ahem, gassy every time you ate dairy), your options were either to:

A. Cut said food out of your life and see if you feel better.

B. Go to your doctor for testing. (And unless you’re flat out allergic, chances are they’ll make you do an elimination diet anyway.)

Thankfully, there is now an Option C: at-home testing. While having access to a good gastroenterologist is invaluable, there’s a lot of detective work you can do yourself thanks to a wide variety of high-tech, gut-focused tests that you can do in the comfort of your own home. But the proliferation of options makes choosing what to try a bit confusing. Should you hold your nose and go for a stool test? Prick your finger and mail in a blood sample? Or is a breath test the way to go?

“The first question you have to ask yourself is, ‘What am I looking for?,'” says double board certified functional integrative doctor Bindiya Gandhi, MD, who is based in Atlanta, Georgia. With this in mind, she offers up her insight here—along with the makers of a few trending at-home tests—to better understand your options.

Option 1: Breath test

Used for: FODMAP issues

If someone is experiencing gas, bloating, constipation, or diarrhea on a regular basis, it’s not uncommon for their doctor to put them on a low-FODMAP diet. (FODMAPs are groups of short-chain carbohydrates found in certain foods that can cause digestive discomfort for some people.) Adhering to a low-FODMAP diet can help alleviate symptoms, but the diet rules are so complicated that a lot of people just eliminate all six FODMAP groups because they can’t figure out which one or ones are causing problems. Enter FoodMarble (starting at $159), a breath test that says it can more easily pinpoint which FODMAP groups are the culprit—so people can rule out which specific FODMAP foods are causing issues, rather than just cutting all of them out entirely.

FoodMarble uses a breath test to measure the amount of hydrogen in your body. Why hydrogen? Basically, if your body has trouble digesting food, it moves into your large intestine and just…sits there, attracting bacteria. The bacteria eats the food, causing fermentation and creating hydrogen gas in the body, says gastroenterologist James Brief, MD, who serves as the company’s chief medical officer. And all that hydrogen, he says, can lead to bloating, gas, and other unpleasant symptoms.

“With this device, when you record your fermentation and you record your symptoms, I can say, ‘Hmm I was bloated in the evening and there was a big spike [in fermentation levels] a couple hours earlier. Then I can link that to what I ate that caused it,” Dr. Brief says.

This specific test has two options for consumers to choose from. You can just purchase the straight breathalyzer for $159, and take the test four times an hour for three hours after eating. The results get logged into the app, and you can track your digestion and fermentation levels in real-time.

The other option is a $29 add-on that comes with four powdered blends of each FODMAP group (like lactose and fructose). Test-takers mix the solution at home, one at a time, into water and then breathe into the device roughly four times an hour for three hours. Dr. Brief says this is the most precise way to use the test because it allows the user to compare their baseline fermentation level with the specific FODMAP groups individually, rather than try to pinpoint what’s causing excess fermentation on their own. “Until now, patients could only do this type of test at the doctor’s,” Dr. Brief says, which often requires multiple trips to test each FODMAP group. “Now people can do it while hanging out at home, or at work.”

Option 2: Blood test

Used for: Food sensitivities

Maybe FODMAP foods aren’t the prob. Maybe you have a hunch gluten is causing your brain fog or you feel sick every time you eat eggs. For this, you can take a finger-prick blood test like EverlyWell ($159) which tests for the 96 most common food sensitivities. (The company also offers a few other at-home tests like vitamin D levels and thyroid function.)

“Blood tests work by measuring the levels of IgG antibodies in the body,” Dr. Ghandi explains. “If you eat something causing inflammation in your body, it will raise your antibody levels, because that’s your defense system.” On the consumer end, all it takes is filling out an online profile, pricking your finger, and drip five small drops of blood onto a collection card, which you then mail in to the company. The blood sample is exposed to their panel of 96 sensitivities, which has enzymes of various triggers (such as nuts, lactose, or gluten). If the IgG levels in the blood sample go up in response to one of these triggers, the company says that means a person has a sensitivity. If the blood doesn’t react to the enzymes, the company says a person is likely not sensitive to it. With the results, Everlywell suggests certain diet changes to avoid those particular triggers it identified.

This type of blood test (offered by many different kinds of services) is controversial; the American Academy of Allergy, Asthma, and Immunology says that IgG tests for food sensitivities are not supported by sound scientific evidence and does not recommend them. In a statement emailed to Well+Good, a rep for EverlyWell said: “The laboratory developed test that EverlyWell provides access to looks at IgG antibodies to determine if there is a non life-threatening reaction to a certain food. The same test has been in practice for over two decades and is ordered by thousands of health providers in the US every year. Research supports using this test in conjunction with an elimination diet and add-back challenge.” The company also emphasize that they do not screen for food allergies, which can be life-threatening.

Everlywell is also not available in New York, New Jersey, Maryland, and Rhode Island because of local regulations (in New York, for example, lab tests can only be ordered by a licensed physician).

Option 3: Stool test

Used for: Parasites, SIBO, and other gut conditions

In her clinical practice, Dr. Bindiya uses stool testing to check for parasites, yeast overgrowth, and levels of good and bad bacteria. When that balance is out of whack, that’s when your gut lining starts to break down and can potentially lead to inflammation and other health issues. The at-home stool tests on the market, like uBiome (price varies depending on your health insurance plan) and Viome ($399) can offer similar insight.

“We are finding people with different ailments from Hashimoto’s to acne using the test,” Viome founder Naveen Jain says. “All these things are really symptoms of chronic inflammation caused by our gut microbiome. Our microbial activity and what they are producing is largely responsible for our immune system response in our body. At least 70 percent of our immune system is in our gut lining.”

After you mail your sample in, Viome analyzes the bacteria present in the stool. “We’re taking into account the specific components of food and looking at two things,” says Tom Malterre, CN, CFMP, Viome’s nutritional scientist who has been studying the microbiome for over a decade. “One, which organisms do they feed? And two, what are the characteristics coming out of these organisms?” Basically, the test looks at what types of microbes are living in your gut and assesses whether the substances they release have a positive, negative, or neutral impact on your body. Ubiome operates in a similar way, although they have slightly different technology behind their tests. Once the testing is done, both Viome and uBiome recommend ways to digest (pun intended) this information like suggesting certain probiotics to take or diet tweaks to try.

Viome is available in all 50 states. Ubiome is only available through your healthcare provider (you request a test, and your doctor signs off on the test before you complete it and send it off to the lab).

So I got my test…now what?

If you decide that you want to try and take one of these at-home tests, Dr. Ghandi recommends talking to a doctor about the results. “One, it might have provided insight into something serious going on you need to work with a doctor with, and two, it’s helpful to go over any lifestyle or dietary changes you need to make,” she says, regardless of whether the company provided their own suggestions. They can help you unpack the results and get more information to make sure any lifestyle changes you make are truly necessary.

Dr. Ghandi points out that while breath, blood, and stool tests are all available at a doctor’s office, the at-home tests work slightly differently. A doctor may do a stool test to specifically look for parasites, SIBO, or yeast overgrowth, a breath test for FODMAP sensitivities, and a blood test for food sensitivities, but far and large, the way they are going to test for food allergies is with an elimination diet. Given that the technology is still so new (and the brands mentioned above don’t have any study results publicly available on their products’ efficacy), it’s unclear how accurate the at-home versions of these tests really are. But Dr. Ghandi sees big promise with this industry. “As time goes on, these tests are going to get better and even more accurate,” she says. But it’s still best to go over results with a pro IRL to make sure you’re understanding them correctly.

It’s a brave new world—and our digestion will be better off because of it.

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