Variation and transmission of the human gut microbiota across multiple familial generations

We supposedly get our first dose of gut microbes from our mother during birth – but how do our gut microbes change over time in relation to the female relatives that live with us or apart from us? A new study investigated how gut microbiota is transmitted across generations of women in a family. The researchers found that women from the same family do tend to share microbes. And while some microbes appear to transmit across up to four generations (perhaps through the birth process), living in the same household was a stronger predictor of shared microbial strains.

Predicting the Role of the Human Gut Microbiome in Constipation Using Machine-Learning Methods: A Meta-Analysis

The gut microbiome may play a role in constipation: not only does the gut microbiome in individuals with constipation differ from that of healthy individuals, but gut microbiota functions can also affect biological functions, such as gut motility. A recent metalysis looked at 3056 fecal samples from five research studies and found that alpha diversity of the microbiota was significantly higher in the subjects with constipation. Differences in composition were also observed between the two groups. At the genus level, Serratia, Dorea, Aeromonas, and Hungatella were most abundant in subjects with constipation. These findings underscore an exception to the rule that diversity in the gut microbiota is a marker of health -- because this meta-analysis shows a diverse microbiota is typical of constipation.

Effect of Gut Microbial Enterotypes on the Association between Habitual Dietary Fiber Intake and Insulin Resistance Markers in Mexican Children and Adults

Nowadays it’s very easy to test your gut microbes, but the results are difficult to interpret. How can we group 'types' of gut microbiotas in a useful way? Enterotypes use a categorization method that assigns an individual’s microbial profile to one of several clusters in an effort to classify the complex ecosystem. Martinez-Medina and colleagues examined gut microbial enterotypes in Mexican school-aged children and adults to determine if enterotypes predict the way dietary fibre intake affects metabolic health. This cross-sectional study found that in children and adults with the Prevotella enterotype, hemicellulose intake correlated negatively with markers of insulin resistance. This was not observed in the other enterotypes. Further work may show that having fibre in the diet confers benefits differently depending on the gut microbial makeup.

In vitro study of the effect of quinoa and quinoa polysaccharides on human gut microbiota

Quinoa is recognized as a functional food due to its important nutritional value and its bioactive components. Zeyne et al. used an in vitro fermentation model to determine the effects of cooked and uncooked quinoa after simulated human digestion, the effects of quinoa polysaccharides (QPs) on the gut microbiota, as well as the (purportedly beneficial) short-chain fatty acids produced by the human fecal microbial communities. Quinoa substrates enhanced the growth of beneficial bacteria from groups such as Prevotella and Bacteroides. Moreover, quinoa polysaccharides could be prebiotic candidates due to their ability to increase Bifidobacterium and Collinsella. The analysis revealed that cooked and uncooked quinoa, and quinoa polysaccharides, had significantly different modulatory effects on gut microbiota, correlating with short-chain fatty acid production.

Gut microbiota-mediated secondary bile acids regulate dendritic cells to attenuate autoimmune uveitis through TGR5 signaling

We know about the gut-brain axis, the gut-lung axis, and more. Is there a gut-eye axis? The autoimmune eye disease referred to as uveitis is a form of eye inflammation that causes eye redness, pain, and blurred vision, and it can even lead to blindness. New research suggests that differences in the gut microbiota and bile acids may play a key role in this inflammatory condition. This mechanistic study by Hu et al. tested bile acids and examined the gut microbial composition in an animal model of uveitis. The researchers found that secondary bile acids were decreased in the stool and blood of the mice with the uveitis. Then when the researchers restored the microbe-derived bile acids and deoxycholic acid, the severity of the uveitis decreased, which was through the reduced production of pro-inflammatory mediators in dendritic cells.

Oral microbiome findings challenge dentistry dogma

For a long while, scientists thought that specific bacteria called S. mutans caused dental cavities. But now that we know more about the oral microbiome, it’s clear that those bacteria are neither necessary nor sufficient for cavity development. Check out Kristina’s Nature Outlook article here to find out how science on the oral microbiome is changing some fundamental understandings in the field of oral health.