Original Academic Latitude Academic Latitude 2024-06-30 08:05 Shanghai
In our gut, there are countless intestinal microbes, and these invisible bacteria, fungi and even viruses constitute a complex microbiome environment, many of which are mutually beneficial and symbiotic with humans. Gut bacteria, for example, can metabolize food to produce molecules such as vitamin B, vitamin K, and short-chain fatty acids, which help reduce intestinal and body inflammation levels, while also stimulating the immune system to defend against pathogens. In recent years, studies on the gut-brain axis have also revealed the interaction between the gut and the brain, as well as the regulatory mechanism of the gut on the brain, and the gut microbiota is a key part of it.
Because of this, the effects of lifestyle, diet or medications on gut bacteria are not limited to the gut. A recent paper in Nature Medicine found that changes in the gut microbiota can lay the foundation for the development of diabetes, and the research team conducted the most comprehensive analysis of type 2 diabetes and the microbiome to date with the help of gut microbiome data from more than 8,000 volunteers from different regions of the world.
They found that 19 bacterial species were associated with the risk of type 2 diabetes. Overall, the intestinal flora of patients with type 2 diabetes produces more molecules that cause immunogenicity, butyric acid fermentation is reduced, and the glycolysis process is disrupted. In particular, the study mentioned Prevotella copri, which is often found in too many levels in diabetic patients, who metabolize to produce high levels of branched-chain amino acids, which have been linked to an increased risk of obesity and diabetes in many studies. The authors speculate that changes in gut bacteria may precede the onset of diabetes symptoms, and that the risk of diabetes may be reduced by timely supplementation of those species that have decreased.
▲Studies have found that changes in the microbiome are associated with diabetes risk (Image source: Reference [1])
In addition to the intervention strategy of supplementing specific intestinal bacteria, the way we can protect intestinal bacteria on a daily basis is actually very simple, that is, "eat and drink well"! This is not to say how high-end the diet is, but to achieve a balance of meat and vegetables, failing which the intestinal bacteria will turn from beneficial to harmful.
Tryptophan is an essential amino acid obtained through food, and it is found in large quantities in meat, eggs, and dairy foods, so daily supplementation of this type of food is essential. But if you only eat meat, tryptophan is indeed enough, but they are going in a harmful direction in intestinal metabolism.
A study in Nature Microbiology mentions the nutritional battle for intestinal bacteria - tryptophan competition. There are many species of intestinal bacteria that absorb tryptophan for nutrient metabolism, such as the well-known Escherichia coli (Escherichia coli), and Clostridium sporogenes is also the main force of tryptophan intake. The difference is that the tryptophan metabolites of the two are different, the former produces indole, and the latter produces 3-indoleacetic acid (ILA) and 3-indolepropionic acid (IPA), which is such a little difference, but the outcome is completely different.
Excessive accumulation of indole is often harmful, and the occurrence of chronic kidney disease is often associated with high levels of indole. On the other hand, ILA and IPA can protect the intestinal mucosa, reduce inflammation levels, and improve the body's tolerance to dietary antigens. If only meat is consumed, and they are provided with a large amount of tryptophan at one point, then the level of indole will continue to be high.
So is there a way to change that? The study gave a positive answer, and dietary fiber should be supplemented from fruits and vegetables. The addition of fiber does not directly affect E. coli, but the fiber-loving Bacteroides thetaiotaomicron has a large source of fiber metabolism, which continuously breaks down fiber into simple sugars and releases them around.
Image source: 123RF
When E. coli sensed the monosaccharide molecule, it immediately changed its attitude, because it prefers carbohydrates to tryptophan. As a result, excess tryptophan flows to Clostridium sporatogenes, which is not affected by the level of monosaccharides, and they continue to produce ILA and IPA, which have more beneficial effects on the individual.
The authors point out that dietary fiber supplementation can not only affect the composition of the intestinal microbiota, but also change the metabolic behavior of the intestinal microbiota. A proper combination of different food types will contribute to a healthier gut, thereby reducing the risk of gut microbiome-related diseases.
Resources:
[1] Dietary fibre directs microbial tryptophan metabolism via metabolic interactions in the gut microbiota, Nature Microbiology (2024). DOI: 10.1038/s41564-024-01737-3.
[2] Mei, Z et al. Strain-Specific gut microbial signatures in Type 2 Diabetes Revealed by a Cross-Cohort Analysis of 8,117 Metagenomes, Nature Medicine (2024). DOI: 10.1038/s41591-024-03067-7