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Breathalyzers That Grade Your Gut Health? Yes, They Exist

These devices promise insights into your metabolism, food sensitivities and more. But do they work?

Jessica Rendall Wellness Reporter
Jessica is a writer on the Wellness team with a focus on health technology, eye care, nutrition and finding new approaches to chronic health problems. When she's not reporting on health facts, she makes things up in screenplays and short fiction.
Expertise Public health, new wellness technology and health hacks that don't cost money Credentials
  • Added coconut oil to cheap coffee before keto made it cool.
Jessica Rendall
5 min read
Lumen's metabolism test
Lumen/James Martin

The wellness world is rife with gut news, and rightfully so: Researchers learn more every day about how the microbes living in our gut give us important clues on how our body uses energy as well as our overall health. 

But actually pinning down what's going on within your digestive system, and your metabolism's relationship to weight and health, can be difficult. This makes it hard to find the root cause of an upset stomach or symptoms of irritable bowel syndrome. That's why handheld devices like FoodMarble's Aire digestive breath tester and Lumen's metabolism tracker were born: to help people understand what the gut is doing and how our body uses food as fuel.

Home metabolism tests aren't new -- there are a number of home tests that measure hormone levels that can affect metabolism through blood or saliva samples. There are also home food sensitivity tests available, though the cost effectiveness of these might be up in the air since it's difficult to determine what's a food sensitivity, intolerance or allergy without a lot of trial-and-error (and possibly a pile of medical bills).

But a vape-like device you can slip into your pocket that promises to give you metabolic and digestive clues is particularly promising. These gut breathalyzers work by reading your breath for the different gasses being emitted and beaming that information to your phone to give you actionable insights. 

Here's what we know about how they work, and whether they're worth it.

A digestive breath tester for people with stomach issues 

FoodMarble's founder, Aonghus Shortt, had an engineering background when he started looking for a better solution for his wife following her diagnosis with irritable bowel syndrome, so he created FoodMarble's AIRE sensor. Specifically, he wanted to help her and others with food-related symptoms understand how they're digesting food, so that they know what sets off their symptoms and what foods are probably fine to eat. You can read our full review of the device here.

To use the FoodMarble, you exhale into the device for 5 seconds, and molecules in your breath will flow over special sensors that signal different levels of gasses present in the breath, Shortt says. In this case, high levels of hydrogen and methane indicate a lot of what FoodMarble calls fermentation – what's given off when your digestive system and your gut microbes are, well, digesting.

"Instead of you digesting the food, you've got your gut microbes and they're breaking it down," Shortt said. "In a sense, they're digesting it instead."

When paired with the FoodMarble app, the device will give you information on what foods are causing higher levels of fermentation, which presumably also result in more digestive upset symptoms, such as bloating. The goal is to help you narrow down foods that cause less fermentation or fewer gasses, and which are therefore easier on your gut. 

FoodMarble also has a food library, where you can search for easier-to-digest foods based on the information collected by the breath tester. This may make it easier to go grocery shopping or decide where to eat out when you're perusing restaurant menus ahead of time.

A photo of FoodMarble's breathalyzer

FoodMarble's digestive breath-testing system.


A device that claims to crack your metabolism code 

Lumen's portable metabolic test, which advertises insight that may help you lose weight or have more energy, also starts with an exhale into the device. A carbon dioxide sensor measures the level in your breath, supposedly indicating the type of fuel your body is using to produce energy. The goal is better metabolic flexibility, or your body's ability to transition between different types of fuel.

Lumen says its device is based on a type of test that's historically been reserved for testing athletes athletes in a clinical setting. The device tells you whether you're burning mostly fat or carbs, and the paired app suggests a day or meal plan for you, as reported in a review by Wired. Understanding how your body is using energy may help promote a healthier or more sustainable weight-loss plan, or increase your energy.

Grading the gut-health graders 

Dr. Niket Sonpal, a gastroenterologist based in New York, says that hydrogen breath tests aren't new. They're commonly used to diagnose digestive health conditions, including IBS, lactose intolerance and small intestinal bacterial overgrowth. And a tool that helps people narrow down foods that trigger their symptoms can be a useful thing. Sonpal says that, with patients where lactose intolerance might be expected, he proposes a "lactose and chill" method, which is essentially sitting down to a movie while eating ice cream and cheese, then waiting to see whether you develop bloating, diarrhea or cramping.

However, knowing how much hydrogen or fermentation you're producing after eating isn't equally valuable information to everyone. Certain foods naturally produce more hydrogen. And if you have a higher hydrogen level with no symptoms, according to Sonpal, there shouldn't be a cause for concern. Indeed, FoodMarble says on its website that the breath-testing devices are for people with SIBO, IBS or digestive problems -- so, not for people who are curious but have no symptoms. 

But Sonpal adds that people with digestive problems may have another existing, or potentially more serious, health condition. About one-third of people with IBS also have another condition such as celiac, malabsorption syndrome or Crohn's, he says. 

"How many people are going to buy this, tailor their foods, but possibly be delaying a diagnosis of something more serious?" 

Like the platter of other health-tracking devices out there, breath testers and sensors that offer digestive or metabolic clues will be useful for many people, but not everyone. Perhaps, they're best for people who already have an accurate medical diagnosis and are looking for tools to help manage their symptoms, or people who are simply passionate about health technology and love keeping tabs on their metrics, including their digestive or metabolic health. 

Also, you're breathing into a device, not adding a drug or supplement to your body and introducing the potential for side effects. So using one as a first step could be helpful, if you're willing to spend the money. But weight loss can be more complicated than food selection.

"Food tracking devices are one component for the multifaceted diamond that is weight loss," Sonpal said. 

Generally speaking, digestive and food-related problems may be hard to diagnose for the same reason devices that make them important targets for new devices to glean insight: It's a complicated system, and related symptoms often overlap with with each other. But more information is better than less, and technology is keeping pace with our growing interest in gut health. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.