July 09, 2022 8 min read
The human gut microbiome is fundamental for human health, and it’s not just digestive health that benefits from the unique ecosystem in your colon. Even your immune system receives some ‘training’ from your microbiome, and that’s the point, the world over is packed with micro-organisms that work hard to play a part in the wider ecosystems that are key to the health (and disease) of the planet.
Humans and bacteria have co-evolved together over millions of years, so it’s no surprise that they play such a key role in our lives.
The human gut microbiome is comprised of mostly bacteria but also protozoa, fungi, archaea, viruses and their collective genomes.
It is estimated to be made up of up to 1014microbial cells.
To quantify that — if you wrote the number out — it would look like this: 100000000000000.
Yes, that’s huge.
The gut’s ecosystem is highly diverse and is composed of 3 main phyla, Bacteroidetes, Firmicutes,and Actinobacteria[i].
In this article, we are going to home in on one particular genus, Roseburia, a member of the Firmicutesphylum.
The Roseburia genus is named after the American microbiologist Theodor Rosebury who studied microorganisms native to human beings. It is made up of gram-positive anaerobic bacteria that, when observed under a microscope, looks slightly curved and rod-shaped.
They also have multiple tail-like projections, called flagella, which allow them to be motile (move).
In the human gut, Roseburia species are commensal, which means they live inside you and cause you no harm. Instead, they bring you some benefits by producing short-chain fatty acids, particularly butyrate which is known for its anti-inflammatory properties and immunity maintenance[ii].
Although the Roseburia genus is less represented than more famous gut inhabitants like Bifidobacteriaand Lactobacillus, it is an important member of the gut microbiome with equally important roles.
That’s right, Roseburia produces important metabolites for human health through the fermentation of indigestible dietary carbohydrates, mainly plant fibres. One of these important metabolites is butyrate and Roseburia is one of the most abundant butyrate producers in the human gut[iii].
In fact, one study conducted in 2014 found that a reduction in a specific strain, Roseburia hominis as well as Faecalibacterium prausnitzii was indicative of dysbiosis in patients with ulcerative colitis[iv].
An important role of butyrate is its involvement in energy production for the cells that line the gut, called colonocytes. Butyrate also helps to protect against certain chronic illnesses as well as protecting the body from pathogens that may have the potential to make you sick.
Roseburia sp. CAG: 182is a newly discovered strain that was found in the gut of just over 40% of the PREDICT 1 study participants[v]. Although scientists don’t know too much about this particular strain yet, the PREDICT researchers have found an association with this bacterium’s presence and lower insulin secretion and increased healthy fat levels.
That’s why Roseburia sp. CAG: 182has been identified as one of the 15 good gut microbes identified by the PREDICT program.
The Roseburia genus is associated with lean individuals, perhaps because of its ability to produce butyrate in the gut[vi]. Butyrate is associated with maintaining the integrity of the gut barrier by upregulating tight junction proteins.
In other words, it helps to keep bad things like toxins, pathogens, and undigested food particles from entering the bloodstream and causing you harm.
As well as the findings from the PREDICT 1 study, other researchers have found an association between Roseburia sp. CAG: 182and inhibitory control, which may further explain its protective role against obesity.
Inhibitory control is a specific type of cognitive function and is conceptualised as the ability to suppress or inhibit a specific thought, action, or feeling[vii]. Inhibitory control is important especially if you want to stick to long-term goals and, in the case of Roseburia sp. CAG 182,inhibitory control is important for sticking to healthy eating plans and avoiding giving in to the temptation to foods that may not be healthy.
In the study published in Gut,the composition and functionality of the gut microbiome, as well as plasma and faecal metabolomics in association with cognitive tests measuring inhibitory control, were analysed in a discovery cohort consisting of 156 participants and an independent replication cohort made up of 970 participants.
The results showed that some bacterial species were positively associated with better inhibitory control, including Roseburia sp. CAG: 182[viii].
Interestingly, this could mean that the composition of the gut microbiota may play an important role in specific cognitive functions and behaviours associated with obesity such as impulsive food-reward related choices.
In another study conducted in 2021, Roseburia sp. CAG:182 was identified as one of five bacterial species associated with positive nutritional and cardiometabolic health markers[ix].
Furthermore, the gut microbiome has also been linked to the therapeutic benefits of immune checkpoint inhibitors (ICIs) in some cancer patients.
In a meta-analysis of real-world cohorts published in Nature Medicine, it was shown that Roseburia sp. CAG:182 increased in all responders to ICI therapy.
More research is needed, but the study helps to confirm a link between the gut microbiome and ICI response which may be significant for future cancer treatment.
When it comes to the composition and diversity of your gut microbiome, diet is a major influencer. In fact, plant-based diets or those that are rich in plant fiber, are associated with increased levels of Roseburia,which in turn is linked to better health outcomes.
Research shows that adherence to the Mediterranean Diet is associated with an increased abundance of Roseburia[x].Typically, the Mediterranean Diet comprises of a regular consumption of olive oil, plant based foods such as fruit, vegetables, nuts, seeds, and cereals, a moderate consumption of fish, seafood and dairy, and a low consumption of red meat[xi].
Because it can improve quality of life and has gained recognition for being one of the healthiest living patterns available, the Mediterranean Diet is endorsed by most medical professionals across the world.
So, if you want to ensure the diversity of your gut microbiome, the best thing you can do is eat a healthy, balanced diet, packed full of dietary fiber.
During the first months of life, breast milk is associated with the development and composition of the infant gut microbiota more than the introduction of solid food. Human breast milk is packed with human milk oligosaccharides, or HMOs, and has been shown to be highly beneficial to babies because they help the infant gut and immune system to mature over time.
However, HMOs are advantageous to adult humans, too. HMOs are indigestible carbohydrates, so the human body is ill-equipped to break them down. Thus, much like dietary fiber, HMOs travel to the colon where they are nourished by good bacteria such as Bifidobacteria, and, in turn, Bifidobacteria helps to feed other microbes, particularly butyrate producers like Roseburia,a microbial activity known as cross-feeding.
Recent research has shown that specific Roseburia species can grow on distinct human milk oligosaccharides[xii].
Overall, HMOs can help to support the immune and digestive systems as well as regulate weight. Their function as a prebiotic may help to promote good health in the gut and beyond.
Roseburiais a bacterial genus belonging to the Firmicutesphylum, which is known for its prolific butyrate-producing capabilities. In the recent PREDICT program, researchers identified a particular strain, Roseburia sp. CAG: 182, to be one of the 15 ‘good’ gut microbes that are associated with good health outcomes.
The research into this particular strain is limited because it has only recently been discovered. However, emerging research has found that Roseburia sp. CAG: 182may influence a specific cognitive function, called inhibitory control which may have an important role in the development of obesity. The strain may also have promising effects for targeted cancer treatments, so the future look promising for this Roseburiastrain.
A science writer who specialises in human health and enjoys writing about all things related to the gut microbiome.
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[v] What Is Roseburia sp. CAG:182? [Internet]. Joinzoe.com. 2022 [cited 2022 Jul 6]. Available from: https://joinzoe.com/learn/roseburia-sp-cag-182
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[x] Haro C, Montes-Borrego M, Rangel-Zúñiga OA, Alcalá-Díaz JF, Gómez-Delgado F, Pérez-Martínez P, Delgado-Lista J, Quintana-Navarro GM, Tinahones FJ, Landa BB, López-Miranda J, Camargo A, Pérez-Jiménez F. Two Healthy Diets Modulate Gut Microbial Community Improving Insulin Sensitivity in a Human Obese Population. J Clin Endocrinol Metab. 2016 Jan;101(1):233-42. doi: 10.1210/jc.2015-3351. Epub 2015 Oct 27. PMID: 26505825.
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