Professor Yu Yinghua/Zheng Kuiyang from Xuzhou Medical University reveals that the lack of dietary fiber causes cognitive dysfunction

Click on the blue letters to pay attention to our dietary fiber and whole grains containing unique biologically active ingredients, including resistant starch, vitamins, minerals, phytochemicals and antioxidants
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The World Health Organization (WHO) recommends a fiber intake of 25-35 grams per day
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The current per capita fiber intake is about 15 grams per day in the United States, 13.
6 grams per day in the United Kingdom, and about 11 grams per day in China
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Dietary fiber is composed of complex carbohydrates, which are neither digested nor absorbed in the gastrointestinal tract, but fermented in the colon and cecum to produce short-chain fatty acids with anti-cancer properties
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Clinical studies have shown that the dietary fiber intake of children aged 7 to 9 is positively correlated with cognitive function
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But the specific mechanism is unknown
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On November 10, 2021, the team of Professor Yu Yinghua and Professor Zheng Kuiyang from Xuzhou Medical University Jiangsu Provincial Key Laboratory of Immunity and Metabolism published an article in Microbiome, revealing the mechanism by which dietary fiber-deficient eating habits cause cognitive dysfunction through the brain-gut axis
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Dietary fiber-deficient diet causes cognitive dysfunction.
Researchers have found that after 15 weeks of dietary fiber-deficient diet, mice have cognitive dysfunction, gain weight, and decrease synaptic density in the CA1 region of the hippocampus
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At the same time, the number of microglia in the hippocampus increased, the phagocytic ability was enhanced, and the phagocytic synapses also increased, which indicates that the loss of synapses mediated by hippocampal microglia after the loss of dietary fiber causes cognitive dysfunction
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In order to further find out which synaptic protein in the hippocampus mediates the memory impairment caused by the lack of dietary fiber, they found through mass spectrometry proteomics that there are 31 proteins in the dietary fiber-deficient mice that are associated with synaptic signaling pathways, among which calcium/ The calmodulin-dependent protein kinase II δ (CaMKIIδ) protein is the most critical, and the expression of this protein decreases after the loss of dietary fiber
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Intestinal flora plays a key role in regulating brain function, and dietary fiber can affect the composition of intestinal flora
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Dietary fiber-deficient diet mice showed increased intestinal inflammatory factors, decreased expression of antibacterial peptide Reg3γ, destruction of the integrity of the epithelial barrier, increased intestinal permeability, and decreased intestinal flora diversity.
A series of intestinal dysfunction changes
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Microglial phagocytic synapses increase short-chain fatty acids through the expression of GPR41 and GPR43 receptors in the intestinal epithelium to regulate host metabolism
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The serum acetate, propionate, and butyrate (all short-chain fatty acids) of mice on a dietary fiber-deficient diet decreased by 60%
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In GPR41 or GPR43 receptor knockout mice, tight junction protein expression is reduced, intestinal permeability is increased, while cognitive dysfunction is shown, and hippocampal synaptic density is decreased
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After 15 weeks of continuous supplementation of short-chain fatty acids in dietary fiber-deficient mice, the researchers can significantly improve cognitive function, increase the density of synapses in the hippocampus, reduce the activation of microglia, and partially improve intestinal function
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In summary, this article reveals the mechanism by which long-term dietary fiber-deficient diets cause cognitive dysfunction in mice: the loss of synapses mediated by microglia in the hippocampus
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Reasonable dietary fiber can reduce the risk of diet-related cognitive dysfunction
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[References] https://doi.
org/10.
1186/s40168-021-01172-0 The pictures in the article are from the references