Department of Endocrinology and Diabetes, University Hospitals Coventry and Warwickshire NHS Trust, United Kingdom.
Centre of Applied Biological & Exercise Sciences, Coventry University, Coventry, United Kingdom.
J Nutr. 2018 Jan 1;148(1):7-12. doi: 10.1093/jn/nxx008.
Large prospective cohort studies consistently show associations of a high dietary fiber intake (>25 g/d in women and >38 g/d in men) with a 20-30% reduced risk of developing type 2 diabetes (T2D), after correction for confounders. It is less well recognized that these effects appear to be mainly driven by high intakes of whole grains and insoluble cereal fibers, which typically are nonviscous and do not relevantly influence postprandial glucose responses [i.e., glycemic index (GI)] or are strongly fermented by the gut microbiota in the colon. In contrast, a dietary focus on soluble, viscous, gel-forming, more readily fermentable fiber intakes derived from fruit and certain vegetables yields mixed results and generally does not appear to reduce T2D risk. Although disentangling types of fiber-rich foods and separating these from possible effects related to the GI is an obvious challenge, the common conclusion that key metabolic effects of high-fiber intake are explained by mechanisms that should mainly apply to the soluble, viscous type can be challenged. More recently, studies in humans and animal models focused on gaining mechanistic insights into why especially high-cereal-fiber (HCF) diets appear to improve insulin resistance (IR) and diabetes risk. Although effects of HCF diets on weight loss are only moderate and comparable to other types of dietary fibers, possible novel mechanisms have emerged, which include the prevention of the absorption of dietary protein and modulation of the amino acid metabolic signature. Here we provide an update of our previous review from 2008, with a focus on mechanistic insights of how HCF diets may improve IR and the risk of developing T2D.
大量前瞻性队列研究一致表明，高膳食纤维摄入量（女性>25 克/天，男性>38 克/天）与 2 型糖尿病（T2D）风险降低 20-30%相关，在纠正混杂因素后。但人们较少认识到，这些作用似乎主要归因于全谷物和不可溶性谷物纤维的高摄入量，这些纤维通常是非粘性的，不会显著影响餐后血糖反应（即血糖指数（GI）），或者在结肠中被肠道微生物群强烈发酵。相比之下，关注可溶性、粘性、凝胶形成、更易发酵的纤维摄入量，这些纤维来自水果和某些蔬菜，其结果喜忧参半，通常不会降低 T2D 风险。尽管将富含纤维的食物进行分类，并将其与与 GI 相关的可能影响分开是一个明显的挑战，但高纤维摄入的主要代谢作用是通过主要适用于可溶性、粘性的机制来解释的这一普遍结论可能受到挑战。最近，人类和动物模型的研究集中在深入了解为什么高谷物纤维（HCF）饮食似乎能改善胰岛素抵抗（IR）和糖尿病风险的机制。尽管 HCF 饮食对体重减轻的影响仅为中等，与其他类型的膳食纤维相当，但可能出现了一些新的机制，包括防止膳食蛋白的吸收和调节氨基酸代谢特征。在这里，我们提供了我们 2008 年的一篇综述的更新，重点介绍了 HCF 饮食如何改善 IR 和 T2D 风险的机制见解。
