Are Home Gut Microbiome Tests Accurate?A Lab Test of 7 Services

Home gut microbiome kits ask you to mail in a stool sample and send back a report on your bacteria, often with advice attached. A key question comes before any advice: if two companies test the same sample, do they get the same answer?

The same sample, seven answers

Scientists at the US National Institute of Standards and Technology made a standardized human stool reference material and sent it to seven consumer microbiome services.¹

• The results showed major discrepancies, both between companies and within the same company.¹
• The differences between providers were about as large as the natural differences between different people.¹
• The researchers blamed differences in methods and a lack of quality control.¹

In other words, a report could say more about which company you chose than about your gut.

Why results vary

An earlier project sent blinded stool and artificial samples to 15 laboratories, which analyzed them using nine different data methods.² Results depended on how the sample was handled, how DNA was extracted and how the data were analyzed.² Reproducibility has been a challenge in microbiome science for years.²

How these tests are regulated

The NIST researchers note that consumer kits sit between strictly regulated medical devices and loosely regulated wellness products, a difference buyers may not notice.¹ They called for standards so results can be trusted.¹

What experts recommend

An international panel of 69 experts from 18 countries found insufficient evidence to recommend microbiome testing widely, and discouraged ordering tests directly without a clinical reason.³ They also said people shouldn’t stop their therapy because of a test result.³ See what the expert panel says about gut microbiome kits.

A better use of the money

If bloating, gas or bowel changes are the reason you’re curious:

1. Track your symptoms and meals for a week or two to see a pattern.
2. See a clinician if symptoms persist, to check for things that do have reliable tests, such as celiac disease. See could I have celiac disease?

Try: “I was thinking of buying a gut microbiome test to understand my bloating. Is there a test that would actually help, or should we start somewhere else?”

Bloated by Dinner covers tests sold to worried guts in Chapter 9, “The Food Detective,” in a section called “The Test You Can Skip.” Its Belly Clock is a free alternative: a week or two of meal and symptom times that shows your own pattern. See the book.