Rye and blood sugar markers in 31 randomized trials
What it found
In 31 randomized trials in people, rye did not change fasting, post-meal or overall blood glucose.
It did lower the overall insulin response after meals.
What they found
Studies in people
Fasting glucose
Across 8 trials, rye made no difference to fasting glucose. The result stayed the same when single studies were removed.
Post-meal glucose
Across 12 trials, rye had no overall effect on glucose after eating. Two subgroups showed a trend toward higher post-meal glucose: people over 50 and short interventions of 270 minutes or less.
Glucose AUC
Across 18 trials, rye did not change the overall glucose response. There was a trend toward a lower glucose response at rye fiber doses of 12 g or more.
Insulin AUC
Across 16 trials, rye lowered the overall insulin response after meals. This was seen at rye fiber doses of 12 g or more, but not below 12 g.
Fasting and post-meal insulin
Rye did not change fasting insulin or post-meal insulin overall. In two trials of normal-weight people, fasting insulin rose slightly.
Animal and lab studies
Possible mechanism
Lab and animal studies suggest compounds in rye such as lignans and alkylresorcinols may affect insulin. Gut bacteria may play a role, but this is not proven in people.
What the authors conclude
- They say rye consumption may reduce insulin levels without affecting glucose markers.
How it was done
Rye has the most fiber of any cereal, and fiber is thought to help control blood sugar. The authors wanted to see if rye specifically helps glucose and insulin markers.
They pooled 31 randomized controlled trials with 922 adults, mostly healthy, comparing rye products like bread and porridge against refined wheat or cereals. Trials lasted from 90 minutes to 12 weeks.
What it can’t tell you
- The trials were mostly short and in healthy people, so they cannot show long-term effects on diabetes or other diseases.
- Most trials were done in Europe, so the results may not apply to people in other regions.
- The trials could not be blinded because rye was eaten as food, which may affect how results were reported.
Who paid
- Conflicts
- Declarations. Ethics approval and consent to participate: Not applicable. Competing interests: The authors declare no competing interests.
- Authors work at
- Shiraz University of Medical Sciences, Iran; Kerman University of Medical Science, Iran
The paper
- Title
- Effect of rye consumption on markers of glycemic control: evidence on the "rye factor": a systematic review and meta-analysis of randomized controlled trials
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Ghazvini M, Ghanbari-Gohari F, Foshati S, Akhlaghi M (2025). Effect of rye consumption on markers of glycemic control: evidence on the "rye factor": a systematic review and meta-analysis of randomized controlled trials. Nutrition & metabolism. doi:10.1186/s12986-025-00901-8Free full textPubMed 40165312DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error