Skip to 0 minutes and 8 secondsBut what exactly do these bacteria, fungi and so on do? Do they affect more aspects of our lives than we think they do? Take a look at a simple illustration of the bidirectional communication pathways between the gut microbiota and the brain. We saw a range of molecules originating in the gut that are involved in the upstream part of the communication system.

Skip to 0 minutes and 35 secondsMicrobiota produce: - Short-chain fatty acids (SCFA), which affect lipid, glucose and cholesterol metabolism in various tissues, as well as regulate Treg cells induction in the colon and control satiety hormones. ‐Neuropeptides and neurotransmitters - microbiota is associated with the synthesis of neuroactive molecules like serotonin, which is responsible for anxiety, happiness and mood. Microbiota is involved in the "fight or flight" response driven by the activation of the sympathetic nervous system. We nearly understand how exposure to that response plays an important role in the deregulation of the intestinal ecosystem. We divide microbiota into potentially harmful bacteria like Clostridia, which produce enterotoxins; Staphylococus, Proteus, Pseudomonas aeruginosa, which produce toxins.

Skip to 1 minute and 32 secondsAnd potentially good bacteria like Bifidobacterium and Lactobacillus, which help in digestion and have antitumor activity; Eubacterium, Fusobacterium, which produce short­chain fatty acids, and Campylobacter jejune - a potential tumor marker. Dysbiosis of gut bacteria has been implicated

Skip to 1 minute and 55 secondsin: intestinal diseases like colorectal cancer and inflammatory bowel disease; systemic diseases like diabetes, metabolic syndrome, kidney toxicity, atopy, type 2 diabetes and hypertension; and neurological diseases like Parkinson’s, Alzheimer’s, multiple sclerosis or autism. The microbiome acts as an organ. It maintains homeostasis. It contributes to the protection from pathogens, hosts fat storage, regulates brain physiology and behavior, as well as regulates food digestion and metabolism rate. This “job” is dependent of food quality. A healthy diet lets microorganisms exist in the eubiosis state. Increased number of Bacteroidetes and Firmicutes increase microbial diversity and concentration of short-chain fatty acids. Normal levels of neurotransmitters are observed, the same as the physiological immune response. Intestine has normal tight junctions.

Skip to 3 minutes and 11 secondsThere is a healthy level of inflammatory cells in circulation. In summary, a healthy Central Nervous System functioning is observed. How a high-fat diet changes microbiome response? A decrease in the number of Bacteroidetes and Firmicutes is observed, and a decrease in the microbial diversity. Altered number of neurotransmitters is also observed, what causes the increase of anxiety, depression, sensitivity to stress, and a decreased learning and memorizing performance. Leaky gut causes inflammatory response, what influences neuro-inflammation and dysregulates Central Nervous System functioning. Chronic infection with Helicobacter pylori, responsible for stomach ulcer, induces anxiety-like behavior in mice and reduces food intake. Definitely, microbiome influences the gut-brain axis. Bacteria produce enzymes which help to digest substrates from food, especially saccharides.

Skip to 4 minutes and 13 secondsHehemann’s group found the new glycoside hydrolase - the enzyme which helps to digest porphyrin in human stool as a gene of Bacteroides plebeius. The data showed that it is present only among a Japanese population, not that of USA. It suggests that microorganisms have “tools” to help digest some substrates and to modify the human genome. Gut bacteria are the main source of vitamin K and some B-complex. They have a cognitive function. Bacteria give a human the opportunity to receive some micronutrients and phytonutrients from plants. Bacteria have an impact on our immune system, as they enrich immune cells, mucus and immunoglobulin A.

Skip to 5 minutes and 11 secondsIt was found that a high-fat diet and a high-sugar diet shift the immune response into inflammation, and decrease the number of CD4 cells, which help to keep homeostasis. To conclude, human microbiome is the place where our body operates with the outside world. The microbiome acts as the frontline of our immune system, as it is constantly exposed to new microbes and compounds which come with the food.

Skip to 5 minutes and 47 secondsIn summary let’s cite Hippocrates: ”Let food be thy medicine and medicine be thy food”. And Jean Brillat-Savarin “Tell me what you eat and I will tell you what you are”.

Microbiome role in the gut-brain axis, part II

Does microbiome affect our body? Are there any connections between microbiome and brain function?

This lecture shows the connections between gut microbiota and the brain. It stresses the importance of microbial products that affect several aspects of our life such as metabolism, immune response, happiness, mood, and many more.

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This video is from the free online course:

Food for Thought: The Relationship Between Food, Gut and Brain

EIT Food