April 21, 2024 8 min read
A recent study published in the Journal - Cell, has found that some specific gut inhabitants may influence your heart disease risk.
Gut microbiome and metabolome profiling in Framingham heart study reveals cholesterol-metabolizing bacteria. Cell, 187(8), 2024, 1834-1852.
Cardiovascular diseases are the world’s biggest killer, responsible for 17.9 million deaths each year[i], highlighting the need for greater preventative measures. Here, we’ll discuss what cardiovascular disease is, and how some species of the gut microbiota could reduce the risk by consuming cholesterol.
Cardiovascular disease is a broad umbrella term used to describe any disease that affects the heart or blood vessels, including:
There are several common risk factors for the development of cardiovascular disease, such as: Tobacco smoking, Blood fat imbalances including cholesterol (dyslipidemia), Obesity, High blood pressure, Poor diet, Alcohol consumption, Physical inactivity.[ii] The problem is that in the vast majority of cases, heart disease presents with no physical symptoms, lending it the nickname of ‘the silent killer’. [iii].
It’s no secret that scientists have long been investigating the association between the overall composition and function of the gut microbiome and its potential in chronic disease development.
To date, associations have been made between the intestinal ecosystem and other metabolic conditions, including diabetes and obesity. For example, data from studies conducted in North America, Europe, and Asia have found a reduction in butyrate-producing species in the gut of type 2 diabetic individuals, and strains of the Bifidobacterium, Faecalibacterium,and Akkermansia genera alongside an increase in Ruminococcus, Fusobacteria,and Blautia[iv].
Obesity, on the other hand, is a further global health crisis and the gut microbiota has been identified as a major player in its onset and development[v]. Research has shown that an increased abundance of the next-generation probiotic, Akkermansia, for example, is associated with a decreased risk of obesity[vi].
Importantly, both of these conditions are precursors or risk factors for the development of cardiovascular disease, and the composition of the gut microbiome may influence their development. Therefore, begging the question, does the human gut microbiota impact the development of cardiovascular disease?
The short answer to this question is yes. Research has shown that the gut microbiota has the power to influence almost all of the cardiovascular risk factors, as we demonstrated with just two in the previous section.
Sun et al., (2019) found that the abundance of several specific bacteria genera, including Catabacter and Robinsoneilla,were positively linked with high systolic blood pressure[vii]. Dysbiosis can also influence the health of your heart, including the development of atherosclerosis, a condition that causes the narrowing of blood vessels due to the deposition of fatty plaques on the vessel walls, constricting blood flow[viii].
Furthermore, bacterial metabolites, such as trimethylamine (TMA), and animal-based food products like trimethylamine-N-oxide (TMAO) found in eggs, meat, milk, and fish, also promote the development of atherosclerosis through a variety of mechanisms. Examples include a reduction in bile acid synthesis and cholesterol accumulation in the immune cells, specifically macrophages[ix].
Although these are examples of how an out-of-balance gut could increase your risk of developing heart-related conditions, new and emerging evidence suggests that some bacteria may have a protective role to play.
A recent study published in the journal, Cell,identified that the gut bacteria species, Oscillibacter, is associated with lower blood and fecal cholesterol. Therefore, this microbe could have potential benefits for blood fat homeostasis and cardiovascular health.
The study analysed the microbial genomes and metabolites of more than 1400 Framingham Heart Study participant's stool samples – a specific and long-running study looking at cardiovascular disease risk factors.
One of the significant findings of the study was that the presence of Oscillibacter was linked to reduced cholesterol levels in feces and blood plasma. It was found that the bacteria could metabolise the cholesterol in the gut, and as a result lower its presence in the body[x]. Therefore uncovering a potential therapeutic benefit that could help target high cholesterol and mitigate cardiovascular disease risk in the future.
Cholesterol is a waxy type of fat that’s present in the blood. Although it has accumulated a bad name for itself, the human body needs some cholesterol to function, for example for producing hormones and building cell membranes[xi].
In the blood, cholesterol is transported around the body via lipoproteins, including high-density lipoprotein (HDL) and low-density lipoprotein (LDL). HDL is known as good cholesterol because it transports the excess from the body back to the liver for processing, while LDL is considered bad because it transports cholesterol to the arteries, where in high amounts it can collect on the artery walls.
If a large amount of cholesterol can gather on the artery walls, it can lead to complications. For example, these plaques can restrict blood flow or break off and travel to other areas of the body, increasing the risk of heart attacks and strokes[xii].
Although the abundance of several bacterial species was associated with cardiovascular blood markers, including triglycerides and blood sugar, it was the link between Oscillibacter and cholesterol that stood out.
The researchers found that Oscillibacter can convert cholesterol into intermediate products that other gut bacteria can break down and remove from the body. Interestingly, the study found over 16,000 links between gut microbes and metabolic characteristics. Individuals in the study who had several Osciliibacterspecies present had lower cholesterol levels than those who didn’t.
The study also identified another species, Eubacterium coprostanoligenes, which also contributes to lowering cholesterol. Previous research has shown that coprostanol-forming microbes are associated with reduced cholesterol levels in people who have these bacteria in high abundance[xiii]. That’s because these species can convert cholesterol into coprostanol, a type of stanol that cannot be absorbed and is instead excreted from the body[xiv].
The novel study by Li et al., (2024) found that Oscillibacter and Eubacterium may work synergistically to lower cholesterol. For example, Oscilibacter may possess the enzymes and genes needed to transform and process cholesterol, leading to its subsequent removal.
The cholesterol-metabolising properties of Oscillibacter and its potential to work alongside other species that carry cholesterol-processing genes are not only fascinating but could have potential therapeutic uses for the treatment of high cholesterol, which would have a beneficial effect on cardiovascular disease risk.
This is particularly pertinent as next-generation probiotics, that is live bacteria or live bacteria products that have been identified by comparative microbiota analyses and provide targeted prevention or treatment of a disease[xv], are gathering traction in the scientific world.
Some common examples include Akkermansia muciniphila, identified for its anti-obesity and anti-diabetic benefits and Faecalibacterium prausnitzii, known to improve gut diseases[xvi]. Interestingly, research by Thingholm et al., (2019) found that obesity was characterised by changes in the composition of the gut microbiome, including a reduced number of Akkermansiaand Oscillibacter[xvii].
As research into the targeted and therapeutic use of probiotic bacteria species increases, this study pinpoints the potential for Oscillibacter to treat high cholesterol in the future.
Currently, there are no Oscillibacter probiotics available on the market. However, your gut might already contain trace amounts of Oscillibacter, and the best strategy is to adopt a healthy, prebiotic-rich diet to boost its abundance.
According to gut microbiome test data from two of our HMO consumers, their Oscillibacter levels were boosted from 0.53% to 0.80% and from 0.09% to 0.14%. They have used Ombre to test their stool and have been taking HMO for at least 23 days. Disclaimer: this is preliminary consumer data only.
Overall, the study by Li et al., (2024) identifies the potential metabolic pathways that Oscillibacter employs to lower cholesterol abundance in the human body. The gut microbiome is proving to be instrumental in the development and prevention of many chronic diseases, and its potential to positively influence cardiovascular disease, the world’s biggest killer, is promising.
Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.
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