Study analysis · European Journal of Nutrition · 2008
This cereal lowers insulin more than sugar—here's why that changes everything.
Eating fermented barley or oat cereal spikes your blood sugar and insulin way less than eating pure sugar.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at what happened to 13 people's blood sugar after they ate special barley and oat breads. It found their blood sugar didn't spike as high as when they drank sugar water. But it didn't test if the breads caused the lower spike — maybe they just happened to eat them on days when they were more active or slept better.
What’s the bottom line?
Scientists tested two special cereals made from fermented barley and oat — both packed with fiber and special starch — to see how they affect blood sugar and insulin after eating.
How strong is this study?
This study tried to be careful by measuring blood sugar at exact times and using the same amount of carbs, but it didn't randomly assign meals or hide which food people were eating. With only 13 people, it's like guessing the favorite ice cream flavor by asking three friends — it might be right, but we can't be sure it's true for everyone.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
33 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=13)+1.3/20
- Follow-up+10/10
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a single-group, within-subjects cross-sectional study with no randomization, unclear blinding, and a very small sample size. Without a control group comparison or random assignment, it cannot rule out confounding factors or establish cause-effect relationships.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the study text. No industry ties or funder involvement were identified.
The study lacks any declared funding sources or conflict of interest statement. While this absence does not confirm bias, it limits transparency. The research appears academically conducted with no apparent industry influence based on available text.
Key takeaways
- 01
Barley cereal lowered blood sugar a lot (GI=30, vs.
- 02
100 for sugar).
- 03
Oat cereal lowered insulin even more (II=21, vs.
- 04
55 for barley).
- 05
Both were much better than plain sugar.
- 06
Yes — eating these cereals instead of refined carbs means your body doesn’t need to pump out as much insulin, which helps avoid energy crashes and long-term metabolic problems.
Surprising findings
- Oat cereal lowered insulin more than barley—even though both lowered glucose similarly.Most assume glucose and insulin responses move together, but here, oat decoupled them—reducing insulin demand without sacrificing glucose control.
- Barley’s glycemic index of 30 is lower than most legumes and even some non-starchy vegetables.People think only non-carbs are low-GI, but this fermented barley is as good as broccoli for blood sugar control.
Practical takeaways
Swap sugary breakfast cereals for tempe-fermented barley if you want to control blood sugar, or fermented oat if you want to reduce insulin spikes.
This study used specially bred high-amylose barley and high-beta-glucan oats—common store-bought oats may not have the same effect.
medium confidenceTry making your own fermented grain porridge using tempeh starter or koji to mimic the study’s method.
The study used 25g of available carbs—equivalent to about 1/2 cup cooked cereal—so portion size still matters.
medium confidenceWhy this study matters
Barley Crushes Blood Sugar
Fermented high-amylose barley reduced the glycemic index to just 30—compared to 100 for pure glucose—meaning it causes a fraction of the blood sugar spike. This effect was strongest in the first 60 minutes (p < 0.0001).
Most people think all whole grains are equal, but this shows specific processing and grain type can turn a carb into a blood sugar stabilizer—perfect for energy control and avoiding crashes.
Oat Beats Barley at Lowering Insulin
Despite similar glucose-lowering effects, fermented oat cereal had an insulin index of 21—less than half of barley’s 55—meaning your pancreas releases far less insulin after eating oat.
This flips the script: you can choose your grain based on whether you want to tame glucose (barley) or insulin (oat)—a game-changer for metabolic health and fat storage.
Fermentation Is the Secret Weapon
Both cereals were tempe-fermented, which likely produced organic acids and altered starch structure—key factors in slowing digestion and reducing post-meal spikes.
Fermentation isn’t just for probiotics—it’s a powerful tool to make carbs healthier. This turns everyday breakfast into a metabolic upgrade.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tested two special cereals made from fermented barley and oat — both packed with fiber and special starch — to see how they affect blood sugar and insulin after eating.
Research results
Barley cereal lowered blood sugar a lot (GI=30, vs. 100 for sugar). Oat cereal lowered insulin even more (II=21, vs. 55 for barley). Both were much better than plain sugar.
What this means - more context
Yes — eating these cereals instead of refined carbs means your body doesn’t need to pump out as much insulin, which helps avoid energy crashes and long-term metabolic problems.
This study evaluates whether fermented whole-grain barley and oat cereals with high amylose and beta-glucan content can reduce postprandial glucose and insulin responses in healthy adults.
Fermented whole-grain barley and oat cereals significantly lowered postprandial glucose and insulin responses compared to glucose. Barley reduced glucose more (GI=30), while oat reduced insulin more (II=21), suggesting grain-specific metabolic effects.
Methods Used
Thirteen healthy adults consumed 25g available carbohydrate portions of glucose, tempe-fermented high-amylose barley, and tempe-fermented high-beta-glucan oat in a crossover design. Blood glucose and insulin were measured at 0, 15, 30, 45, 60, 90, and 120 minutes; GI and II were calculated per FAO/WHO standards.
Main Finding
Barley tempe reduced glycemic index to 30 (vs. glucose reference), and oat tempe reduced insulin index to 21 (vs. barley tempe’s 55), with both showing significantly lower glucose and insulin responses than glucose (P<0.0001 and P<0.002, respectively) during the first 60 minutes.
Confidence Level
Moderate — small sample size (n=13), no randomization, but within-subject design, controlled meals, and statistically significant results with reported p-values and effect sizes (GI/II) enhance reliability.
Study Flags
Red Flags
- •Small sample size (n=13)
- •No randomization of meal order
- •No confidence intervals reported
Surprising Findings
Oat cereal lowered insulin more than barley—even though both lowered glucose similarly.
Most assume glucose and insulin responses move together, but here, oat decoupled them—reducing insulin demand without sacrificing glucose control.
Practical Takeaways
Swap sugary breakfast cereals for tempe-fermented barley if you want to control blood sugar, or fermented oat if you want to reduce insulin spikes.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at what happened to 13 people's blood sugar after they ate special barley and oat breads. It found their blood sugar didn't spike as high as when they drank sugar water. But it didn't test if the breads caused the lower spike — maybe they just happened to eat them on days when they were more active or slept better.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Controlled meal conditions with standardized carbohydrate portions
- Repeated blood sampling at multiple time points
- Use of validated FAO/WHO standards for GI and II calculation
Weaknesses
- No randomization
- Blinding status unknown
- No control group (only compared to glucose load, not other cereals as controls)
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tested two special cereals made from fermented barley and oat — both packed with fiber and special starch — to see how they affect blood sugar and insulin after eating.
Research results
Barley cereal lowered blood sugar a lot (GI=30, vs. 100 for sugar). Oat cereal lowered insulin even more (II=21, vs. 55 for barley). Both were much better than plain sugar.
What this means - more context
Yes — eating these cereals instead of refined carbs means your body doesn’t need to pump out as much insulin, which helps avoid energy crashes and long-term metabolic problems.
This study evaluates whether fermented whole-grain barley and oat cereals with high amylose and beta-glucan content can reduce postprandial glucose and insulin responses in healthy adults.
Fermented whole-grain barley and oat cereals significantly lowered postprandial glucose and insulin responses compared to glucose. Barley reduced glucose more (GI=30), while oat reduced insulin more (II=21), suggesting grain-specific metabolic effects.
Methods Used
Thirteen healthy adults consumed 25g available carbohydrate portions of glucose, tempe-fermented high-amylose barley, and tempe-fermented high-beta-glucan oat in a crossover design. Blood glucose and insulin were measured at 0, 15, 30, 45, 60, 90, and 120 minutes; GI and II were calculated per FAO/WHO standards.
Main Finding
Barley tempe reduced glycemic index to 30 (vs. glucose reference), and oat tempe reduced insulin index to 21 (vs. barley tempe’s 55), with both showing significantly lower glucose and insulin responses than glucose (P<0.0001 and P<0.002, respectively) during the first 60 minutes.
Confidence Level
Moderate — small sample size (n=13), no randomization, but within-subject design, controlled meals, and statistically significant results with reported p-values and effect sizes (GI/II) enhance reliability.
Study Flags
Red Flags
- •Small sample size (n=13)
- •No randomization of meal order
- •No confidence intervals reported
Surprising Findings
Oat cereal lowered insulin more than barley—even though both lowered glucose similarly.
Most assume glucose and insulin responses move together, but here, oat decoupled them—reducing insulin demand without sacrificing glucose control.
Practical Takeaways
Swap sugary breakfast cereals for tempe-fermented barley if you want to control blood sugar, or fermented oat if you want to reduce insulin spikes.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Human Cross-Sectional
Subject
Moderate probability
on the GRADE evidence scale
This study looked at what happened to 13 people's blood sugar after they ate special barley and oat breads. It found their blood sugar didn't spike as high as when they drank sugar water. But it didn't test if the breads caused the lower spike — maybe they just happened to eat them on days when they were more active or slept better.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Controlled meal conditions with standardized carbohydrate portions
- Repeated blood sampling at multiple time points
- Use of validated FAO/WHO standards for GI and II calculation
Weaknesses
- No randomization
- Blinding status unknown
- No control group (only compared to glucose load, not other cereals as controls)
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study tried to be careful by measuring blood sugar at exact times and using the same amount of carbs, but it didn't randomly assign meals or hide which food people were eating. With only 13 people, it's like guessing the favorite ice cream flavor by asking three friends — it might be right, but we can't be sure it's true for everyone.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
33 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=13)+1.3/20
- Follow-up+10/10
100 / 100
54 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 544 / 100
Probability of being correct
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
This design cannot establish causation — the findings describe an association, not a cause. This is a single-group, within-subjects cross-sectional study with no randomization, unclear blinding, and a very small sample size. Without a control group comparison or random assignment, it cannot rule out confounding factors or establish cause-effect relationships.
No Conflicts
No conflicts of interest identified
No conflicts of interest or funding statements were disclosed in the study text. No industry ties or funder involvement were identified.
The study lacks any declared funding sources or conflict of interest statement. While this absence does not confirm bias, it limits transparency. The research appears academically conducted with no apparent industry influence based on available text.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Max German cite this study, drawing 1 claim from it.
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence