Sourdough rye crispbread, appetite and blood sugar in 24 adults
What it found
Sourdough-fermented rye crispbread lowered hunger compared with wheat crispbread, but unfermented rye crispbread led to the lowest insulin response.
This was measured in 24 healthy Swedish adults after a single breakfast.
What they found
Studies in people
Hunger and desire to eat
People felt less hungry and had less desire to eat after the sourdough-fermented rye crispbread compared with the wheat crispbread. Both types of rye crispbread lowered the desire to eat more than the wheat version did.
Insulin levels after eating
Insulin levels were lowest after eating the plain rye crispbread without sourdough. The sourdough-fermented rye crispbread and the wheat crispbread produced similar insulin responses.
Blood sugar levels
Blood sugar levels were about the same after all three breakfasts. The type of crispbread made no clear difference to glucose readings over the test period.
Gut hormone GLP-1
Levels of the gut hormone GLP-1 did not differ between the three breakfasts. This hormone is linked to feelings of fullness.
Animal and lab studies
Fibre breakdown during digestion
In lab tests simulating chewing and stomach digestion, the sourdough-fermented rye crispbread broke down faster than the plain rye version. The plain rye crispbread also became much thicker and stickier during digestion, which may explain why it led to lower insulin levels.
What the authors conclude
- They conclude that sourdough-fermented rye crispbread may reduce hunger but does not improve blood sugar or insulin responses compared with plain rye crispbread.
- Their results suggest that the way rye bread is processed changes its structure and fibre, which then affects how the body responds after eating.
- They call for future studies to look at other common food processing methods and their long-term effects on health.
How it was done
Obesity is rising worldwide and foods that keep people feeling full might help limit overeating. The authors wanted to see how sourdough fermentation changes the way whole grain rye crispbread affects hunger, blood sugar and insulin.
Twenty-four healthy Swedish adults each ate three different breakfasts on separate days, at least six days apart. Each breakfast included either sourdough-fermented rye crispbread, plain rye crispbread or refined wheat crispbread. Researchers tracked self-rated hunger and took blood samples for up to six hours after eating.
What it can’t tell you
- This trial only tested a single breakfast, so it cannot show what happens when people eat these crispbreads every day over months or years.
- All participants were young and healthy adults, so the findings might not apply to older people or those with metabolic conditions.
- Participants could tell the crispbreads apart by taste and appearance, which might have influenced how hungry they reported feeling.
Who paid
- Authors work at
- Swedish University of Agricultural Sciences (SLU), Sweden; Uppsala University, Sweden
The paper
- Title
- Impact of sourdough fermentation on appetite and postprandial metabolic responses - a randomised cross-over trial with whole grain rye crispbread
- Type
- Randomised controlled trial
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Zamaratskaia G, Johansson DP, Junqueira MA, et al (2017). Impact of sourdough fermentation on appetite and postprandial metabolic responses - a randomised cross-over trial with whole grain rye crispbread. The British journal of nutrition. doi:10.1017/S000711451700263XFree full textPubMed 29185930DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error