Insoluble Fraction from Brewer's Spent Grain reduces hypercholesterolemia in Mice fed a Western style Diet
Authors: Raza Ghulam Shere , Maukonen Johanna , Mäkinen Markus J. , Niemi Piritta , Niiranen Laura , Buchert Johanna , Herzig Karl‐Heinz 
Published: June 2021

Background

Hypercholesterolemia and obesity are major risk factors for cardiovascular & metabolic diseases. Dietary fibers offer several health benefits like improvement of the serum lipid profile, glucose tolerance, immune functions and promote weight loss. Brewer's Spent Grain (BSG) is most abundant byproduct of industrial brewing. INS is an insoluble fraction from BSG, consists of lignin 40%, arabinoxylan 25% and glucan 11%. The effect of INS was studied in Western style diet (high fat and <0.05% fiber) fed mice in terms of metabolic diseases.

Methods

Male mice (C57BL6) were fed with Western style diet (WD, 60% Kcal fat, <0.05% fiber) ± 20% INS, cellulose or their combination (INS‐Cellulose 1:1) or a control diet (10% Kcal Fat) for 14 weeks. Body weight and food intake were monitored during the entire feeding trial. Insulin sensitivity after 12 weeks, and fasting plasma cholesterol, triglycerides and IL‐6 were measured after 14 weeks of feeding. The cecal microbiota and gene expression in liver tissue were analyzed, and fecal bile acid were measured. Histological examination and computer‐assisted morphometry of liver was performed to access hepatosteatosis

Results

INS, cellulose and their combination feeding significantly reduced body weight gain (p<0.05) (12.1±1.4g 13±0.9g, 11.9±0.9g vs WD 16.7+1.1 g) respectively, while there were no significant changes observed in food intake. INS and INS‐cellulose feeding significantly (p<0.01) reduced total plasma cholesterol by 15% and 12%, respectively but no significant change in plasma triglyceride. INS did not improve insulin resistance; in contrast cellulose and INS‐cellulose significantly (p<0.05) ameliorated it. Fecal bile acid excretion was significantly (p<0.01) increased in all fiber fed up to 250% compared to WD fed mice. Plasma IL‐6 was significantly decreased with INS and cellulose as compared to WD. Fat accumulation in the liver was significantly reduced by the fiber feeding. WD significantly (p<0.05) diminished the numbers of cecal bacteria within the following taxa: Ruminococcaceae, Bacteroides spp., Coriobacteriaceae ‐ predominant bacteria as compared to the control diet. Ruminococcacace were increased in all the fiber fed mice compared to WD fed. Bacteroides spp. and Coriobacteriaceae increased only in INS, while cellulose feeding reduced Coriobacteriaceae compared to WD. Furthermore, the following genes Hmgcr, Ldlr, Pparα, Fxr and Pxr were significantly upregulated in liver tissues of mice fed INS as compared to WD fed mice.

Conclusion

INS attenuated the hypercholesterolemic effects of the Western style diet in mice. These effects may be due to bile acid binding activity of INS, changes in the microbiome and increased expression of fatty acid metabolizing genes. Therefore, the insoluble fraction from BSG, consisting of lignin, arabinoxylan and glucan, might be suitable for alleviating the cholesterolemia and thus metabolic diseases.

Support or Funding Information

N/A

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.