How a gut-healthy diet affects your heart

Heart disease remains the leading cause of death worldwide, with millions of people affected by conditions like high blood pressure, high cholesterol, and obesity. While traditional risk factors such as genetics, exercise, and diet have long been recognised, emerging research suggests that the gut microbiome - the trillions of bacteria living in our digestive system - plays yet another important role in the body to help support heart health.¹ The latest evidence shows that following a gut-friendly diet can lower the risk of cardiovascular disease (CVD) by influencing cholesterol levels, reducing inflammation, and improving metabolic health.¹

The gut-heart axis

The connection between the gut and the heart is often referred to as the gut-heart axis. The gut microbiota, made up of beneficial and harmful bacteria, influences the absorption of nutrients and the production of key compounds like short-chain fatty acids (SCFAs), which have been linked to improved cardiovascular function.¹ A balanced microbiome can help regulate blood pressure, reduce harmful cholesterol, and lower systemic inflammation - all of which are key contributors to heart disease.

However, an imbalance in gut bacteria, often caused by diets high in processed foods, refined sugars, and unhealthy fats, can lead to increased production of harmful metabolites such as trimethylamine-N-oxide (TMAO). Studies have linked high TMAO levels to an increased risk of atherosclerosis, a condition where arteries become clogged, restricting blood flow and raising the likelihood of heart attacks and strokes.²

What does a gut-healthy diet look like?

A gut-healthy diet primarily consists of whole, nutrient-dense foods that support beneficial bacteria while limiting the growth of harmful microbes. The following dietary patterns have shown the most promise in improving both gut health and cardiovascular health:

1. Plant-rich diets

Plant-based diets, including Mediterranean and vegetarian diets, are rich in fibre, polyphenols, and antioxidants. These nutrients support the growth of beneficial bacteria such as Faecalibacterium prausnitzii and Roseburia, which are known for producing SCFAs like butyrate. Butyrate has anti-inflammatory properties that may help prevent artery damage and improve overall heart health. A systematic review found that individuals following plant-rich diets saw significant reductions in total cholesterol (by an average of 6.77%) and low-density lipoprotein (LDL) cholesterol.¹

2. Whole grains 

Whole grains such as brown rice, oats, quinoa, and whole wheat contain high amounts of fibre, which acts as a prebiotic - food for good gut bacteria. Studies have shown that whole grain consumption increases the abundance of Bifidobacteria and Lactobacilli, both associated with lower blood pressure and improved cholesterol levels.³ Additionally, whole grains reduce systemic inflammation, a key driver of heart disease.

3. Polyphenol-rich foods

Polyphenols, found in foods like berries, dark chocolate, green tea, and red wine (in moderation), support a diverse gut microbiome. Research suggests that polyphenol-rich diets increase beneficial bacteria while reducing harmful strains that contribute to heart disease.⁴ Polyphenols have been linked to lower blood pressure, improved circulation, and a reduced risk of heart attacks and strokes.⁴

4. Fermented foods

Fermented foods such as yoghurt, kefir, kimchi, and sauerkraut introduce live beneficial bacteria into the gut. These probiotics help maintain gut barrier integrity, reducing inflammation and lowering the risk of heart disease.⁵ A diet rich in fermented foods can also lower LDL cholesterol and improve blood sugar control - both important factors for cardiovascular health.⁵

How an unhealthy diet affects gut and heart health

Just as certain foods can promote heart health, others can do significant damage. Diets high in processed foods, saturated fats, and refined sugars have been shown to:¹

• Increase harmful gut bacteria linked to inflammation

• Raise levels of TMAO, which contributes to artery plaque buildup

• Lead to insulin resistance, obesity, and high blood pressure

Restrictive diets, such as ultra-low-fat or fasting-based regimens, may result in short-term weight loss and improvements in triglyceride levels, but they can also negatively impact gut microbiota diversity if not carefully balanced.⁶

The best diet for gut and heart health

Transitioning to a gut-healthy diet doesn’t mean a complete overhaul overnight. Small, sustainable changes can make a significant impact:¹

• Increase fibre intake: Aim for 25–30g per day from vegetables, fruits, legumes, and whole grains.

• Diversify your diet: Eat a variety of plant-based foods to support a diverse microbiome.

• Incorporate fermented foods: A daily serving of yoghurt or kimchi can provide beneficial probiotics.

• Reduce processed foods: Minimise consumption of refined sugars, fried foods, and ultra-processed meals.

• Stay hydrated: Drinking plenty of water supports digestion and gut health.

The future of the gut-heart connection

Ongoing research continues to explore the intricate relationship between gut health and cardiovascular disease. While current evidence strongly supports the benefits of gut-friendly dietary patterns, further studies will help fine-tune dietary recommendations for optimal heart health.

One emerging area of interest is personalised nutrition—using microbiome analysis to tailor dietary recommendations based on an individual’s gut bacteria composition.¹ This could change the way we look at heart disease prevention and treatment in the coming years.

The numan take

A diet rich in fibre, polyphenols, and fermented foods supports a diverse and healthy gut microbiome, reducing inflammation and improving heart health. While no single diet works for everyone, adopting a plant-rich, whole-foods-based eating pattern can offer long-term benefits for both the gut and the heart. 

References

1. ^{Yu J, Wu Y, Zhu Z, Lu H. The impact of dietary patterns on gut microbiota for the primary and secondary prevention of cardiovascular disease: a systematic review. Nutr J [Internet]. 2025;24(1). Available from: http://dx.doi.org/10.1186/s12937-024-01060-x}

2. ^{Zhu Y, Li Q, Jiang H. Gut microbiota in atherosclerosis: focus on trimethylamine N‐oxide. APMIS [Internet]. 2020;128(5):353–66. Available from: http://dx.doi.org/10.1111/apm.13038}

3. ^{Xu D, Feng M, Chu Y, Wang S, Shete V, Tuohy KM, et al. The prebiotic effects of oats on blood lipids, gut Microbiota, and short-chain fatty acids in mildly hypercholesterolemic subjects compared with rice: A randomized, controlled trial. Front Immunol [Internet]. 2021;12. Available from: http://dx.doi.org/10.3389/fimmu.2021.787797}

4. ^{Iqbal I, Wilairatana P, Saqib F, Nasir B, Wahid M, Latif MF, et al. Plant polyphenols and their potential benefits on cardiovascular health: A review. Molecules [Internet]. 2023;28(17):6403. Available from: http://dx.doi.org/10.3390/molecules28176403}

5. ^{Leeuwendaal NK, Stanton C, O’Toole PW, Beresford TP. Fermented foods, health and the gut microbiome. Nutrients [Internet]. 2022;14(7):1527. Available from: http://dx.doi.org/10.3390/nu14071527}

6. ^{Grembi JA, Nguyen LH, Haggerty TD, Gardner CD, Holmes SP, Parsonnet J. Gut microbiota plasticity is correlated with sustained weight loss on a low-carb or low-fat dietary intervention. Sci Rep [Internet]. 2020;10(1). Available from: http://dx.doi.org/10.1038/s41598-020-58000-y}