Stool vs blood: the new era of gut-health testing

Get to know your gut — and take charge of your health

The body is like a finely tuned engine. And your gut? It’s the power plant that keeps that engine humming. From the food you eat to the nutrients you absorb — and even how your immune system responds — your gut holds a central role.

A short history: How our understanding of the gut has evolved

Not too long ago, talking about gut microbes sounded exotic — but the story goes back further than you might think. Research into intestinal microbes started in the 1840s, with scientists exploring the bacterial inhabitants of the gut. Fast forward to the 21st century: the term microbiome was coined in 2001 to describe the ecological community of microbes living in and on us. Large-scale initiatives begun in 2007 further expanded our knowledge of the microbial world inside us. With all this progress, though, the way we test and interpret gut health is still shifting — and that’s important to keep in mind.

It’s not just who is there — it’s what they’re doing

In the early days, much of the focus in gut health was on diversity: the more microbial species present, the better — or so it seemed. But emerging research shows that the story is richer. It’s not enough to catalogue the microbes; we need to understand their function. In other words: what are the gut bacteria doing for you?

The range of roles microbes perform in the ecosystem may be more predictive of health than simply counting species. So when we talk about gut-health testing, the good news is that we’re moving beyond just “which bacteria do you have?” to “what’s your gut ecosystem actually doing?”

Fueling the workforce: Diet, fiber & metabolites

Here’s where things get personal. Because your gut microbiome is an entire ecosystem, deeply shaped by your everyday diet and lifestyle. Think of the bacteria as a workforce: you provide the raw materials (food, fiber, other nutrients), and they process it, producing molecules that affect you.

Take fiber as an example. When you eat high-fiber foods, your beneficial gut bacteria break them down and produce metabolites that help protect you. Studies link diet-gut microbiota relations to health outcomes and note that different diets drive different microbial profiles and functional potentials. So yes — what you eat matters a lot, not just for you, but for what your microscopic partners are doing.

Why gut health matters beyond digestion

We often think of digestion when we talk about gut health, but the implications ripple farther:

Around 70% of the body’s immune system resides in or interacts with the gut — meaning gut health impacts not just digestion and nutrient absorption but how well you handle external stressors and immune challenges.

The gut-brain axis also plays a key role: we now know that gut microbes send signals that affect mood, stress response, energy, even sociability. From metabolism to overall health, what’s happening in your gut can affect your stamina, how you age, and your vitality.

Gut-health testing: The old way vs the new way

Traditional stool-based gut tests is a direct way to provide useful information about the types and diversity of microbes present — and they’ve been the foundation for much of what we know about the microbiome today. But stool testing also comes with practical and scientific limitations. Collecting and shipping samples can be messy and inconvenient, and the results only capture part of the picture — mainly what’s happening in the lower gut. They can miss activity in the small intestine or along the gut lining, where many critical processes take place. Most importantly, stool tests show which bacteria are there, but not their function, what they’re doing.

That’s where the new, blood-based method comes in. It offers a more complete view by measuring the biochemical signals and metabolites produced by the gut microbiota — helping us understand not just composition, but actual function.

Old way (still common): A stool microbiome sample that tells you which microbes live in your gut and gives you a diversity score (“your microbial diversity is high/low”).

Limitations of stool testing:

It shows only a snapshot: what’s present, not what’s active.

It may miss parts of the gut (some microbes live in niches that a stool sample doesn’t fully capture).

Merely knowing species counts doesn’t always translate to meaningful health predictions.

Newer way (emerging): Zinzino’s Gut Health Test is pioneering the next generation of testing by looking not only at microbial composition but at functional signals — the metabolites, microbial-derived molecules, and blood biomarkers indicating how the gut is influencing your body.

The idea: Are your gut microbes turning the food you eat into fuel and beneficial signals — or are they triggering your body’s stress responses?

This shift from “who is there” to “what they are doing” is the frontier of gut-health testing.

Why you should care

Your gut is unique. Not even identical twins have the exact same gut microbiota. So generic diets or supplements that “worked for someone” might not work for you. When you test and interpret your gut, you gain hard facts about your inner ecosystem. You can then tailor your diet, lifestyle, and habits to your gut’s needs. Testing gives you a springboard — a starting point for action.

Your personal four-step gut-health journey

Here’s a simple, actionable roadmap you can follow when taking our Gut Health Test. Think of it as your gut-care protocol.

Step 1 — Take a blood sample and get a baseline.

Your test reveals markers the gut metabolism leaves behind in your blood  — telling you whether your food is fueling your body beneficially or triggering stress responses.

Step 2 — Decode the results and make them actionable.

You’ll get a gut health test report translated into meaningful insights that you may use to map a diet and lifestyle routine tailored for your gut: How is your gut influencing your diet? How are your habits (sleep, stress, physical activity) showing up?

Step 3 — Fuel your gut with the right food and habits.

Bring in high-fiber foods, a diverse diet, and habits that support your microbial workforce — regular movement, better sleep, lower stress. Let your microbiome do the heavy lifting.

Step 4 — Repeat and refine.

Gut health isn’t a one-time test; it’s a journey. Retesting every four months helps you track meaningful changes, fine-tune your nutrition, and stay aligned with your body’s evolving needs.

The bottom line

If you want a long, vital, healthy life, start in your gut. Your gut is where your energy, balance, even your mood and stress are managed. Treat it like the engine service it deserves — individually and intentionally. Testing can help you understand it instead of guessing. But remember: not all tests are created equal. Some still focus only on species counts. The wiser move is to choose a test that captures function — what your microbes are doing. And always, your food is the main signal your microbes receive. Respect that power. You’re unique. Your gut is unique. Let’s help your gut help you.