There Is No Such Thing as a “Perfect” Microbiome (So Save Your Money on the Tests)
For a few hundred dollars, companies will "grade" your gut microbiome. The problem: there is no agreed "perfect" microbiome to grade against — and experts say so.
There is no scientific or clinical consensus on what a "healthy" microbiome is, and no single metric like cholesterol, so at-home gut tests have nothing reliable to grade you against — experts call them "essentially meaningless" clinically. Save your money and eat a wide variety of fibre-rich plants and fermented foods instead.
For a few hundred dollars, a growing number of companies will mail you a kit, ask you to send back a stool sample, and return a glossy report “grading” your gut microbiome — often with supplement recommendations conveniently attached. It is a seductive idea: a report card for your gut, like a cholesterol number. There is just one problem. There is no agreed-upon “perfect” microbiome to be graded against — and the experts who study this for a living will tell you so.
The uncomfortable truthNobody can define a “healthy” microbiome
This is not our opinion; it is the current scientific consensus, which is essentially that there is no consensus. As a June 2026 NPR round-up of the field summarised it, there is “no clinical or scientific consensus around what constitutes a healthy microbiome.” Everyone’s gut community is different — shaped by diet, geography, genetics, age and more — and a mix that looks great in one healthy person can differ wildly from another equally healthy person. There is no single “good” species list to hit.
Why it is not like cholesterolNo single number
The reason a cholesterol or blood-pressure reading is useful is that decades of research tie specific numbers to specific risks and treatments. The microbiome has nothing equivalent. Per the same NPR reporting, “there’s no single metric that can deliver a reasonably straightforward assessment of your gut health like there is for cholesterol or blood pressure.” So when a report hands you a “gut health score” of 74 out of 100, the honest question is: 74 compared to what, exactly? The number looks precise. It is not the same as meaningful.
A “gut health score” of 74 looks precise. But 74 compared to what? There is no agreed healthy microbiome to grade against.
What the tests are actually good forResearch, mostly — not you
This sequencing technology is genuinely powerful, and it is doing real work in research, where scientists compare thousands of samples to hunt for patterns (that is how promising leads like health-associated bacteria get found in the first place). The gap is between that and a clinically useful readout for one individual. NPR’s bluntest line: what the direct-to-consumer industry is promoting has “leapfrogged the evidence,” and the tests are “essentially meaningless” from a clinical standpoint. Your results can also change week to week based on what you ate, making the “retest to see your progress” model especially good for the seller.
What to do insteadFeed it, do not audit it
Here is the liberating part: you do not need a report to do the things that actually support a gut microbiome, because the advice does not depend on knowing your exact species mix. Eat a wide variety of plants; the single best-supported lever is the number of different fibre-rich foods you eat in a week. Add fermented foods. Go easy on ultra-processed food. That is the whole evidence-based playbook, and it costs nothing to run. Save the a few hundred dollars — or put it toward groceries, which will do more for your gut than any score.
If you have real, persistent digestive symptoms, the answer still is not a consumer kit — it is a doctor, who can order tests that are actually validated for specific conditions. A microbiome report cannot diagnose disease, and treating one like a medical result can send you chasing problems you do not have. This is educational, not medical advice.