Combined Fermentation Score Explained
Understanding Your Fermentation Score
Your fermentation score (or F-score) reflects the combined levels of hydrogen and methane gases in your breath. These gases are produced when microbes in your gut ferment food, and together they give us a picture of what’s happening in your digestive system.
Both hydrogen and methane contribute to fermentation. Their combined effect is stronger than either one alone — so even if each gas is low individually, the total score may place you in the medium range.
Example:
A total score of 6.0 with a 1:1 hydrogen to methane ratio means:
- Hydrogen = 3.0
- Methane = 3.0
Each gas is low on its own, but together they indicate a medium level of fermentation.
📈 Score Ranges in the App
To make scores easier to interpret, the FoodMarble app uses the following categories:
Range | Score | Description |
|---|---|---|
Low | 0.0 – 3.4 | Minimal fermentation activity |
Medium | 3.5 – 6.7 | Moderate fermentation |
High | 6.8 – 10.0 | High fermentation activity |
These ranges help you spot trends over time and see which foods or other factors may lead to higher fermentation.
⚙️ How the Scale Works
The fermentation score is shown on a 0–10 scale, representing how much gas is being produced in your gut at any time. The scale is divided evenly into low, medium, and high.
To prevent the score from maxing out at 10 too quickly, it increases more gradually once the gas levels are high — a bit like inflating a balloon: it gets harder to add more air as it fills up.
This means there’s a bigger difference between 9 and 9.5 than between 8 and 8.5.
Rest assured, though — anything in that top third of the scale can be taken as high.
💡 Important Insights
- Some people naturally have higher baseline methane levels. In these cases, hydrogen spikes may be more closely linked to symptoms such as bloating or discomfort.
- On challenge days, it’s usually fine to continue even if methane is elevated — as long as hydrogen remains low. The challenge data will still be valid and meaningful.
🔍 Putting It All Together
It’s normal for your scores to fluctuate — this doesn’t mean something is “wrong.” What matters most are the patterns you uncover over time.
By combining your fermentation scores, food logs, and symptom tracking, you can build a clearer picture of what your body tolerates best.
Every breath, meal, or symptom logged is a step toward greater understanding. Over time, these small pieces of data can lead to valuable insights that support your comfort and confidence day to day.
Updated on: 05/11/2025
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