Effect of a regular consumption of traditional and roasted oat and barley flakes on blood lipids and glucose metabolism-A randomized crossover trial

Sarah Reiners; Sandra Hebestreit; Lisa Wedekind; Michael Kiehntopf; Anne Klink; Silke Rummler; Michael Glei; Stefan Lorkowski; Wiebke Schlörmann; Christine Dawczynski

doi:10.3389/fnut.2023.1095245

Effect of a regular consumption of traditional and roasted oat and barley flakes on blood lipids and glucose metabolism-A randomized crossover trial

Front Nutr. 2023 Feb 2:10:1095245. doi: 10.3389/fnut.2023.1095245. eCollection 2023.

Authors

Sarah Reiners^{1

2}, Sandra Hebestreit¹, Lisa Wedekind³, Michael Kiehntopf⁴, Anne Klink⁵, Silke Rummler⁵, Michael Glei⁶, Stefan Lorkowski^{2

7}, Wiebke Schlörmann⁶, Christine Dawczynski^{1

2}

Affiliations

¹ Junior Research Group Nutritional Concepts, Institute of Nutritional Sciences, Friedrich Schiller University Jena, Jena, Germany.
² Competence Cluster for Nutrition and Cardiovascular Health (nutriCARD) Halle-Jena-Leipzig, Jena, Germany.
³ Institute of Medical Statistics, Computer and Data Sciences, Jena University Hospital, Jena, Germany.
⁴ Institute of Clinical Chemistry and Laboratory Diagnostics, Jena University Hospital, Jena, Germany.
⁵ Institute of Transfusion Medicine, University Hospital Jena, Jena, Germany.
⁶ Department of Nutritional Toxicology, Institute of Nutritional Sciences, Friedrich Schiller University Jena, Jena, Germany.
⁷ Department of Nutritional Biochemistry and Physiology, Institute of Nutritional Sciences, Friedrich Schiller University Jena, Jena, Germany.

Abstract

Background: Regular consumption of the soluble dietary fiber β-glucan is associated with decreased total cholesterol (TC), low-density lipoprotein (LDL) cholesterol and blood glucose. Barley and oat flakes as natural sources of β-glucan were roasted to improve sensory quality. The aim of this study was to investigate whether roasting of barley and oat flakes changes the physiological impact of the β-glucan-rich flakes on glucose and lipid metabolism.

Method: A five-armed randomized crossover trial design was used. The intervention study was conducted from May 2018 to May 2019 and included 32 healthy subjects with moderately increased LDL cholesterol (≥2.5 mmol/L). During the 3-week intervention periods, 80 g of roasted or traditional barley or oat flakes, or four slices of white toast bread per day were consumed for breakfast. At the start and the end of each intervention, fasting and postprandial blood was taken. The intervention periods were separated by 3-week wash-out periods.

Results: During the interventions with the cereal flakes, TC and LDL cholesterol concentrations were significantly reduced compared to baseline values by mean differences of 0.27-0.33 mmol/L and 0.21-0.30 mmol/L, respectively (p < 0.05), while high-density lipoprotein (HDL) cholesterol was only reduced after the intervention with barley flakes (p < 0.05). After the intervention period with toast, TC and HDL cholesterol increased (p < 0.05). The fasting levels of triglycerides, fasting blood glucose and insulin did not change in any group. The effects of traditional and roasted varieties on blood lipids did not differ between the groups.

Conclusion: The regular consumption of traditional or roasted barley and oat flakes contributes to the management of cardiovascular diseases by improving TC and LDL cholesterol.

Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT03648112, identifier NCT03648112.

Keywords: barley; blood lipids; cardiovascular risk factors; oat; roasting; β-glucan.

Associated data

ClinicalTrials.gov/NCT03648112

Grants and funding

This IGF project of the FEI was supported via AiF within the program for promoting the Industrial Collective Research (IGF) of the German Ministry of Economic Affairs and Climate Action (BMWi), based on a resolution of the German Parliament. We acknowledge the support by the German Research Foundation in this IGF Project (19351 BR). We also acknowledge support by the German Research Foundation Project-Nr. 512648189 and the Open Access Publication Fund of the Thueringer Universitaets-und Landesbibliothek Jena.