La Torre Danique, Verbeke Kristin, Dalile Boushra
Translational Research Center in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases and Metabolism, Faculty of Medicine, KU Leuven, Leuven, Belgium.
Leuven Brain Institute, KU Leuven, Leuven, Belgium.
Gut Microbiome (Camb). 2021 Sep 8;2:e3. doi: 10.1017/gmb.2021.3. eCollection 2021.
Dietary fibre is an umbrella term comprising various types of carbohydrate polymers that cannot be digested nor absorbed by the human small intestine. Consumption of dietary fibre is linked to beneficial effects on cognitive and affective processes, although not all fibres produce the same effects. Fibres that increase short-chain fatty acid (SCFA) production following modulation of the gut microbiota are thought to be the most potent fibres to induce effects on cognitive and affective processes. SCFAs can exert their effects by improving central, peripheral and systemic immunity, lowering hypertension and enhancing intestinal barrier integrity. Here, we propose additional mechanisms by which dietary fibres may contribute to improvements in affective and cognitive processes. Fibre-induced modulation of the gut microbiota may influence affective processes and cognition by increasing brain-derived neurotrophic factor levels. Depending on the physicochemical properties of dietary fibre, additional effects on affect and cognition may occur via non-microbiota-related routes, such as enhancement of the immune system and lowering cholesterol levels and subsequently lowering blood pressure. Mechanistic randomised placebo-controlled trials are needed to establish the effects of dietary fibre consumption and the magnitude of explained variance in affect and cognition when incorporating measurements of microbiota-dependent and microbiota-independent mechanisms in humans.
膳食纤维是一个统称，包括各种类型的碳水化合物聚合物，这些聚合物不能被人类小肠消化或吸收。膳食纤维的摄入与对认知和情感过程的有益影响有关，尽管并非所有纤维都产生相同的效果。那些在调节肠道微生物群后增加短链脂肪酸（SCFA）产生的纤维被认为是对认知和情感过程产生影响的最有效纤维。短链脂肪酸可以通过改善中枢、外周和全身免疫、降低高血压以及增强肠道屏障完整性来发挥作用。在这里，我们提出膳食纤维可能有助于改善情感和认知过程的其他机制。纤维诱导的肠道微生物群调节可能通过增加脑源性神经营养因子水平来影响情感过程和认知。根据膳食纤维的物理化学性质，对情感和认知的额外影响可能通过与微生物群无关的途径发生，例如增强免疫系统、降低胆固醇水平并随后降低血压。需要进行机制性随机安慰剂对照试验，以确定膳食纤维摄入的影响以及在纳入人类微生物群依赖性和微生物群非依赖性机制测量时情感和认知中可解释变异的程度。
