Rye compounds linked to weight and insulin changes
What it found
In a 12-week trial in people with overweight or obesity, a high-fiber rye diet changed many blood compounds and gut bacteria compared with refined wheat.
Some of these changes were linked to greater reductions in weight, fat mass, BMI, or fasting insulin.
What they found
Studies in people
Rye compounds in blood
The rye group had higher levels of benzoxazinoids (DIBOA-S), phenylacetamides (2-HPA-S and 2-HHPA-S), and other compounds like indolepropionic acid, 2-aminophenol, enterolactone, pipecolic betaine, and gallic acid-4-sulfate compared with the wheat group.
Gut bacteria changes
The rye diet increased Eubacterium xylanophilum and Agathobacter and decreased Ruminococcus torques and Romboutsia in the gut.
Weight and fat loss
Greater reductions in body weight, body fat, BMI, and waist circumference were seen in the rye group compared to the wheat group. Some blood compounds, like gallic acid-4-sulfate and phenylacetamides, were linked to these reductions even after adjusting for rye intake markers.
Blood sugar and insulin
The intervention had no overall effect on fasting insulin or glucose, but higher levels of gallic acid-4-sulfate and phenylacetamides were associated with lower fasting insulin levels.
Inflammation marker
Plasma CRP concentrations were lower in the rye group compared to the wheat group after 12 weeks.
What the authors conclude
“Phenylacetamide metabolites (2-HPA-S and 2-HHPA-S), gallic acid 4-sulfate, and succinylglycine may constitute biomarkers of wholegrain rye cardiometabolic effects.”
Also in their conclusions
- They conclude that a 12-week high-fiber rye intervention increased specific plasma metabolites and changed gut bacteria, and that these changes were sufficient to describe the intervention effects regardless of clinical characteristics.
- They suggest that phenylacetamide metabolites (2-HPA-S and 2-HHPA-S), gallic acid 4-sulfate, and succinylglycine may be biomarkers of wholegrain rye cardiometabolic effects.
- They call for more studies to validate these metabolites as biomarkers of rye intake or its health effects.
How it was done
The authors wanted to find reliable markers in blood that reflect rye intake or its metabolic effects, and to understand how these markers relate to gut bacteria and heart and metabolic risk factors.
They ran a 12-week randomized trial in 207 adults with overweight or obesity, comparing a hypocaloric diet with high-fiber rye products (108 people) or refined wheat products (99 people). Blood and stool samples were collected at the start and end of the 12 weeks.
What it can’t tell you
- This study cannot show whether these blood markers or gut bacteria changes directly cause the health effects, only that they are linked.
- The results may not apply to other populations or to longer-term rye consumption.
Who paid
- Authors work at
- Universitat de Barcelona, Spain; Instituto de Salud Carlos III, Spain; Chalmers University of Technology, Sweden
The paper
- Title
- Metabolite Biomarkers Linking a High-Fiber Rye Intervention with Cardiometabolic Risk Factors: The RyeWeight Study
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Unión Caballero A, Meroño T, Åberg S, et al (2025). Metabolite Biomarkers Linking a High-Fiber Rye Intervention with Cardiometabolic Risk Factors: The RyeWeight Study. Journal of agricultural and food chemistry. doi:10.1021/acs.jafc.5c01415Free full textPubMed 40838659DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error