Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.
Food Funct. 2020 Jan 29;11(1):514-523. doi: 10.1039/c8fo02507j.
Mixed linkage (1→3),(1→4)-β-d-glucan (BG) is a soluble fibre available from oat and barley grains that has been gaining interest due to its health-promoting role in cardiovascular diseases and its ability to modulate the glycaemic index which is beneficial for people with diabetes. This study investigates the effect of three purified barley BGs, with different molecular weight and block structure, on faecal bile acid excretion in hypercholesterolaemic rats. Wistar rats (48 male) were divided in four groups: Control group fed with the cellulose-rich diet (CON); Glucagel group fed with the commercial BG (GLU, 100 kDa), and rats fed with low molecular weight BG (LBG, 150 kDa) and medium molecular weight BG (MBG, 530 kDa). The bile acid profiles of rat faecal samples were measured using gas chromatography-mass spectrometry (GC-MS). A metabolite profiling approach led to the identification of 7 bile acids and 45 other compounds such as sterols, fatty acids and fatty alcohols. Subsequent application of ANOVA-simultaneous component analysis and Principal Component Analysis revealed that all three BG diets increased bile acid faecal excretion compared to the control group. The bile acid excretion was found to be different in all three BG diets and the MBG group showed a significantly higher level of faecal secondary bile acids, including deoxycholic acid, hyodeoxycholic acid, and lithocholic acid. We hypothesise that the hydrophobic surface of the secondary bile acids, which are known to cause colon cancer, has high affinity to the hydrophobic surfaces of cellulosic blocks of the BG. This in vivo study demonstrates that the molecular weight and/or block structures of BG modulate the excretion of secondary bile acids. This finding suggests that developing diets with designed BGs with an optimal molecular structure to trap carcinogenic bile acids can have a significant impact on counteracting cancer and other lifestyle associated diseases.
混合键（1→3）、（1→4）-β-葡聚糖（BG）是一种可从燕麦和大麦谷物中获得的可溶性纤维，由于其在心血管疾病中的促进健康作用以及调节血糖指数的能力，对糖尿病患者有益，因此越来越受到关注。本研究调查了三种不同分子量和嵌段结构的纯化大麦 BG 对高胆固醇血症大鼠粪便胆汁酸排泄的影响。将 48 只雄性 Wistar 大鼠分为四组：对照组（CON）喂食富含纤维素的饮食；Glucagel 组喂食商业 BG（GLU，100 kDa），以及喂食低分子量 BG（LBG，150 kDa）和中分子量 BG（MBG，530 kDa）的大鼠。使用气相色谱-质谱联用仪（GC-MS）测量大鼠粪便样本中的胆汁酸谱。代谢物分析方法鉴定了 7 种胆汁酸和 45 种其他化合物，如甾醇、脂肪酸和脂肪醇。随后应用方差分析-同时成分分析和主成分分析表明，与对照组相比，所有三种 BG 饮食均增加了胆汁酸的粪便排泄。发现所有三种 BG 饮食中的胆汁酸排泄都不同，MBG 组粪便中次级胆汁酸，包括脱氧胆酸、去氧胆酸和石胆酸的水平显著升高。我们假设，已知会导致结肠癌的次级胆汁酸的疏水面与 BG 的纤维素嵌段的疏水面具有高亲和力。这项体内研究表明，BG 的分子量和/或嵌段结构调节次级胆汁酸的排泄。这一发现表明，开发具有最佳分子结构的设计 BG 饮食以捕获致癌胆汁酸，可能会对对抗癌症和其他与生活方式相关的疾病产生重大影响。
