It's completely understandable to feel confused if the gut microbiome score you received wasn't what you expected. Perhaps you eat plenty of vegetables but received a below-average score, or maybe you have gut issues but scored highly. It's easy to doubt the results, but that’s because the picture of your gut health is rarely straightforward.
What’s the science behind your score?
Your microbiome score is backed by ZOE's own science, using data from the world's largest microbiome study and the most advanced technology available. That’s why we’re confident in its accuracy.
1. How accurate is our technology?
While many tests use 16S technology (examining only one gene), ZOE uses Shotgun Metagenomic Sequencing. This allows us to look at over 5 million marker genes and accurately identify thousands of bacterial species, including many new to science. If there were any issues with your sample during testing, our lab team would inform us, and we would ask you to send another sample.
2. How is your score calculated?
Your microbiome score reflects the balance of good and bad bacteria we detect in your stool sample. It is based on 100 specific species (50 good, 50 bad) that show the strongest, most robust association with overall cardiometabolic health (factors like blood sugar, BMI, and heart disease risk). We determined these key associations through the largest microbiome study of its kind in the world, analysing over 34,000 stool samples. In science, a large dataset means the data is more robust.
Each of the 100 species plays a role in your score, but some have a bigger impact on your overall score than others. For example, a high abundance of a single strongly weighted bad species could outweigh a high total abundance of many weaker good species.
3. Are all the species in my gut included in my score?
This score focuses only on the 100 species we believe are most associated with cardiometabolic health markers, but it is not a complete census of every species in your microbiome. You may have many other beneficial species doing good work that are simply not part of this specific ranking.
What does my score mean?
Your Gut Health Score runs from 0 to 1,000. A higher score reflects a microbiome with a better balance of the good and bad bacteria most strongly associated with cardiometabolic health - things like blood sugar regulation, healthy weight, and heart disease risk.
Most people's scores sit somewhere in the middle of the scale. A low score doesn't mean your gut health is beyond improvement - it simply shows where your microbiome is today, and gives you a baseline to measure progress against. A high score shows that, right now, your gut bacteria are well balanced.
If you completed your first ZOE test before the ZOE 2.0 update, your original score was out of 100. All scores are now on a 0-1,000 scale. To compare your old score to your new one, multiply your original score by 10. A score of 500/1,000 is equivalent to 50/100.
Why do scores vary between people?
No two microbiomes are alike - and that's completely normal. Your score reflects the unique microbial community you've built over your entire lifetime, shaped by factors stretching back to the first years of life.
This is why two people following identical diets can have very different scores. It doesn't mean one person's results are wrong - it means their microbial baseline, history, and biology are different. Your score is personal to you, and comparing it to someone else's is rarely meaningful.
Some microbiome compositions are also naturally more stable and resistant to change than others. For these people, it may simply take longer for even consistently healthy diet changes to shift the score.
What factors can affect my score?
Diet is the single biggest lever you can pull to improve your microbiome - but it doesn't act alone. A wide range of factors influence your gut bacteria, some of which can temporarily shift your score even when your diet is excellent:
Stress - chronic stress measurably changes the composition of gut bacteria. The gut-brain axis is a two-way system; psychological stress affects the gut directly.
Sleep - poor or disrupted sleep is one of the most significant non-diet stressors on the microbiome. Even a few nights of poor sleep can shift bacterial populations.
Antibiotics and medications - even a short course of antibiotics in the months before testing can substantially alter your microbiome composition. Many medications (including some common painkillers, antacids, and metformin) also have documented effects on gut bacteria.
Illness - a gastrointestinal illness, or even a significant respiratory illness, can temporarily disrupt your microbiome.
Activity levels - exercise has a positive effect on microbiome diversity. A period of reduced activity can offset dietary gains.
Season and environment - research shows seasonal variation in the microbiome, and changes in your environment or travel can introduce new variables.
Early-life history - how you were born, whether you were breast or bottle fed, early antibiotic use, and exposure to diverse environments in childhood all set a lifelong microbial baseline.
Your microbiome also has a natural setpoint - a range of bacterial abundance it tends to return to. Short-term changes shift it temporarily, but the long-term pattern matters more than any single snapshot.
Why might your score not match your diet?
Although diet is the main modifiable factor that can influence your microbiome as an adult, your gut bacteria are influenced by many other things.
Your microbiome score is also shaped by long-term influences, such as early-life experiences (e.g., birth mode, childhood antibiotic use), exposure to diverse environments, and even pet ownership. Additionally, individual microbiomes may have varying levels of stability, with some taking longer to respond to diet and lifestyle changes even with healthy habits.
Your microbial community is built over your entire lifetime, with the first three years being the most critical. This means your microbiome composition (and score) is heavily influenced by historic factors that set your microbial baseline, such as how you were born, whether you were breast or bottle fed, early antibiotic use, and even whether you had pets and where you grew up.
Some microbiome compositions are naturally more stable and resistant to change than others. For these people, it may simply take longer for even the most consistently healthy diet changes to shift the microbial composition.
As an adult, factors like stress, sleep, exercise, antibiotic use, time spent outdoors and medication all play a role in shaping your microbial community.
Regular exercise and spending time in natural environments can further promote microbial diversity, while reducing sources of stress and ensuring quality sleep can create better conditions for gut health.
Focus on incremental improvements.
Your microbiome score now is not your score for life. Your microbiome is a living thing - it can change as quickly as in days, but these changes will only stick if your lifestyle and diet changes are consistent. Focus on the incremental changes over the next few months.
Focus on introducing high-fiber foods like legumes, whole grains, nuts, seeds, and vegetables. Incorporating fermented foods like kefir or kimchi and diversifying plant intake can further enhance microbial diversity.
You may notice changes in your digestion, energy, or mood before you see a change on your retest. This is all still progress! Keep focusing on the small consistent steps and your gut bacteria will thrive.
Remember to monitor your energy levels, digestion, and overall mood as early indicators of progress before retesting your microbiome score.
Read more about the main dietary factors that make the biggest difference in your gut health here.