A new international study shows that simply replacing regular bread with a specially formulated oat β-glucan-enriched bread does not significantly improve long-term blood sugar control in individuals at risk of type 2 diabetes.
The 16-week randomized controlled trial, known as the CarbHealth study, involved nearly 200 participants across Germany, Norway, and Sweden. Participants were asked to replace their commonly consumed bread by study bread (a ß-glucan enriched or a wholegrain control bread) and to consume at least 3 slices 6 days a week, mimicking real-life conditions.
The study bread was specifically designed at The Norwegian food research Institute (Nofima). It qualifies for an EFSA health claim for foods containing oat beta-glucan that can reduce post-prandial (after-meal) glycemic (blood sugar) responses.
Despite previous evidence from controlled clinical studies suggesting that oat β-glucans can reduce blood glucose and cholesterol levels, this large-scale effectiveness trial found no significant improvements in key metabolic markers such as HbA1c, fasting glucose, insulin, or blood lipids.
“We designed a high-fiber ß-glucan enriched oat bread specifically for this study, aiming to test whether a simple dietary swap could yield measurable health benefits in everyday life,” said lead researcher Dr. Therese Hjorth.
“However, our findings suggest that changing just one food item—even one with proven short-term benefits—is not enough to improve long-term glycemic control.”
The results contrast with earlier efficacy studies conducted under ideal conditions, which formed the basis for health claims approved by the European Food Safety Authority (EFSA). These studies showed that β-glucans can lower postprandial blood glucose and cholesterol levels. The CarbHealth trial, however, highlights the gap between controlled research environments and real-world dietary behavior.
“Our study underscores the importance of a whole-diet approach rather than relying on single-food substitutions,” said co-author Professor Jutta Dierkes. “Even though the oat bread met EFSA’s criteria for β-glucan content, the flexible, real-life consumption patterns likely diluted its potential impact.”
“Functional foods like β-glucan-enriched bread can assist in consuming a healthy diet” explains Professor Anette Buyken, “yet broader dietary changes as well as environments facilitating healthy choices are needed to achieve meaningful health outcomes”.
About the Study
The study was led by researchers from Chalmers University of Technology, the University of Bergen, Nofima AS, Paderborn University and the University of Leipzig
The CarbHealth trial was funded by the Research Council of Norway, the Swedish Research Council Formas, and the German Federal Ministry of Education and Research, under the European Joint Programming Initiative “A Healthy Diet for a Healthy Life.” The study is registered at ClinicalTrials.gov (NCT04994327).