Can The Gut Cause Cardiovascular Disease?

Welcome to my blog post ‘Can The Gut Cause Cardiovascular Disease?’ where I discuss some of the research exploring the connection between our gut microbiota and cardiovascular disease..

You may also be interested in the section of my blog dedicated to gut health, click here, in particular:

• The Gut Microbiome In Multiple Sclerosis: What Bacteria Are Involved
• Psychobiotics: Probiotics For Mood And Mental Health

Accumulating evidence has indicated that intestinal microbiota is involved in the de- velopment of various human diseases, including cardiovascular diseases (CVDs). In the recent years, both human and animal experiments have revealed that alterations in the composition and function of intestinal flora, recognised as gut microflora dysbiosis, can accelerate the progression of CVDs.

Moreover, intestinal flora metabolises the diet ingested by the host into a series of metabolites, including:

• Trimethylamine N-oxide
• Short chain fatty acids
• Secondary bile acids
• Indoxyl sulfate

All of which affects our physiology by activation of numerous signalling pathways.

Coronary Artery Disease

The composition and functions of the gut microbiome are affected by external factors that are associated with increased CVD risks, including aging, obesity, a sedentary lifestyle and dietary patterns. In turn, the composition of the gut microbiome may affect the development of CVD.

The observation that DNA from various species of bacteria is found in atherosclerotic lesions and in the gut of the same individuals suggests the gut microbiota may be a potential source of atherosclerotic bacteria and is therefore likely to participate in the pathogenesis of coronary artery disease. Jie et al demonstrated the relationship between the gut microbiota and atherosclerotic CVD. They identified that the composition of gut microbiome, including members of the Enterobacteriaceae and Streptococcus spp, was higher in atherosclerotic CVD than in the healthy controls.

Karlsson et al used shotgun sequencing of the gut metagenome to reveal that intestinal microbial communities in patients with symptomatic atherosclerosis were different from those in healthy controls. Patients had increased numbers of the genus Collinsella, while the gender- and age-matched controls had an increased abundance of Eubacterium and Roseburia

Five species (Eubacteria, Anaeroplasma, Roseburia, Oscillospira and Dehalobacteria) have been shown to be effective in preventing atherosclerosis. Similarly, experiments per- formed by Stepankova et al demonstrated the protective effects of intestinal bacteria on the progression of atherosclerotic lesions.

How Does The Microbiome Effect Cardiovascular Disease?

A study by Li et al revealed that the TMAO level in acute coronary syndromes was an independent predictor of both short-term (30 days and 6 months) and long- term (7-year) major adverse cardiac events. Other studies have also highlighted the participation of TMAO in the development of CVD in a variety of patient cohorts. Collectively, mounting evidence suggests that TMAO is part of an important mechanism by which the intestinal microflora influence CVD.

High Blood Pressure (Hypertension) And The Microbiome

Thus, blood pressure is closely linked to the diversity, richness and evenness of the microbiome living in the gut and it is affected by the F/B ratio.

The gut microbiota consists of four major phyla: Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. Firmicutes and Bacteroidetes account for a large part of the intestinal microflora. The ratio of Firmicutes (F) and Bacteroidetes (B) (F/B) is considered a biomarker for gut dysbiosis. Yang et al demonstrated that microbial richness, diversity and evenness were decreased not only in spontaneously hypertensive rat models but also in a cohort of patients with high blood pressure.

Additionally, an increased F/B ratio and decreased numbers of acetate- and butyrate-producing bacteria were observed.

This indicates that hypertension is linked to gut dysbiosis and that improving gut microbiota may be a target for future therapies for hypertension

Heart Failure And The Gut Microbiome

Heart failure encompasses a group of complex clinical syndromes that result in damage to the structure or function of the heart. Heart failure is the end stage of many CVDs. Although pharmacological and non-pharmacological therapies can delay the progression of heart failure, the short‐ and long‐term mortality rates remain high.

Our understanding of the pathophysiological mechanisms of heart failure has changed greatly in the recent years. The main concept shift is from haemodynamic changes to neurohumoural-immune regulation. The role of gut microbiota in inflammatory and immune response has drawn attention to the link between the gut microflora and heart failure.

Pasini et al compared the bacteria and fungi in the faeces of heart failure patients with those of healthy controls.

The results showed that patients with chronic heart failure (CHF) were colonised by more pathogenic bacteria than the control patients.

Candida, Campylobacter and Shigella species were proven to be positively correlated with the severity of disease.

Leaky Gut And Heart Failure

Compared with healthy controls, intestinal permeability (IP) increased for 78.3% of the patients with CHF. The gut was more permeable in patients with moderate and severe CHF than patients with mild CHF.

This prompted researchers to propose the ‘gut hypothesis’.

How Do I Improve Gut Health For Cardiovascular Health?

• A diverse diet with plenty of fresh fruit, vegetables and thus dietary fibre.
• Probiotics
• Prebiotics
• Do daily physical exercise
• Manage stress levels
• Prioritise sleep

So Can The Gut Cause Cardiovascular Disease?

• Trillions of bacteria reside in the human gut, mainly divided into probiotics, neutral bacteria and pathogenic bacteria.
• Among them, the Firmicutes and Bacteroidetes families occupy the high- est proportion and the F/B ratio is a vital parameter reflecting intestinal disorders.
• Factors such as lifestyle, drug application and intestinal environment disorders may contribute to gut dysbiosis, promoting the occurrence and development of CVD.
• Changes in the gut microbiota of individuals with coronary artery disease, hypertension and HF have been observed.
• Because the gut microbiota is closely related to CVD, new ways to treat CVD based on the gut microbiota are emerging.
• For patients with CVD, reasonable adjustment of diet structure and optimisation of diet composition are particularly important for maintaining physical health. Prebiotics can promote the growth of probiotics and inhibit the growth of pathogen. Supplement of prebiotics and/or probiotics may be effective and feasible in the treatment of CVD.

References of ‘Does The Gut Microbiome Cause Cardiovascular Disease?’:

1. The role of intestinal microbiota in cardiovascular disease: click here.
2. The gut microbiome in atherosclerotic cardiovascular disease: click here
3. The gut microbiome and cardiovascular disease: current knowledge and clinical potential: click here.
4. Gut microbiota derived metabolites in cardiovascular health and disease: click here.
5. Intestinal Microbiota in Cardiovascular Health and Disease: JACC State-of-the-Art Review: click here.