The gut-heart connection refers to the communication that happens between the gut and the heart.
They might seem like an unlikely pair, but studies show that the health of your heart seems to be linked to the health of your gut.
But how do the gut and heart ‘talk’ to one another? Although scientists are still trying to answer this question, it’s thought that the communication travels in one direction – from the gut to the heart.
This communication is thanks to the trillions of microbes that reside in your gut – known as the gut microbiome. Gut microbes can produce healthful and harmful compounds that trigger positive or negative health effects on different organs of the body, including the heart.
In fact, recent research suggests that gut microbes can alter heart structure and function in different ways. Let’s dig into the science a bit more.
The power of gut microbes – the good
A group of compounds that seem to be key for gut-heart connection harmony are short-chain fatty acids (SCFAs) - the main ones being butyrate, acetate, and propionate. These are produced when gut microbes break down nutrients, such as fibre and plant chemicals, like polyphenols.
A proportion of SCFAs can enter the bloodstream and circulate around the body. SCFAs are known for their anti-inflammatory effects. In other words, they dampen inflammation.
For example, SCFAs can bind to cells that line blood vessels and cause them to widen (called vasodilation). In doing so, SCFAs can help to lower blood pressure.
SCFAs can also influence fat metabolism. For example, they have been shown to reduce total cholesterol and LDL ‘bad’ cholesterol levels by lowering the rate of cholesterol production in the liver.
In fact, studies have shown a link between lower numbers of butyrate-producing microbes in the gut and an increased risk of heart disease.
SCFAs can also act as messengers and influence behaviour of the autonomic nervous system (ANS) – the complex network of nerves throughout the body that controls all involuntary processes, such as heart rate.
The power of gut microbes – the bad
Gut microbes can also produce compounds that are considered harmful for heart health. A key compound that seems to disrupt gut-heart connection harmony is Trimethylamine N-oxide (TMAO).
Gut microbes produce a compound called trimethylamine (TMA) when they break down nutrients such as lecithin, choline, and carnitine which are abundant in red and processed meats. TMA is converted to TMAO by some types of gut microbes and then enters the bloodstream.
TMAO is known for its pro-inflammatory effects. In other words, it drives inflammation.
For example, TMAO triggers the release of inflammatory compounds (called cytokines) from immune cells. Over time, this causes damage to blood vessels.
TMAO also influences fat metabolism, but in the opposite way to SCFAs - TMAO encourages build-up of cholesterol in blood vessels.
In fact, higher levels of TMAO in the blood is linked with a higher risk of heart disease – the most common one being coronary artery disease and increased risk of heart attacks.
Interestingly, other animal products also contain nutrients such as lecithin, choline, and carnitine, but they are not linked with a higher risk of heart disease.
This includes eggs, white meat (e.g. chicken) and fish. This might be because other compounds in these foods are considered cardioprotective – in other words, they protect the heart. For example, omega 3 fatty acids in oily fish.
Supporting the gut-heart connection
What you eat plays a key role in shaping your gut microbiome. This can affect your heart health - for better and for worse.
Heart disease is largely preventable, so prioritising your gut health is one important way to support your heart health.
Here are some top tips:
- Focus on fibre-filled foods including wholegrains, nuts, seeds, fruit, vegetables, legumes, herbs and spices. Here are some recipes to get you started.
- If you eat red and processed meat regularly (i.e. nearly every day), think about reducing it down to a few portions a week or less. Keep portions to 70g or less. This is about two rashers of bacon or three slices of ham.
- Choose foods containing healthy fats including avocados, nuts, seeds, oily fish, and extra virgin olive oil.
- Try including fermented foods such as sauerkraut, miso, kefir, and tempeh.
To learn more about other gut health topics, visit Symprove’s Gut Hub.
Sources
Unlocking the gut-cardiac axis: a paradigm shift in cardiovascular health. NLM. Link.
Short-Chain Fatty Acid Propionate Protects From Hypertensive Cardiovascular Damage. NLM. Link.
Short Chain Fatty Acid Receptors and Blood Pressure Regulation. NLM. (2023) Link.
Short-chain fatty acids are potential goalkeepers of atherosclerosis. Frontiers. (2023). Link.
Butyrate-producing bacteria and the gut-heart axis in atherosclerosis. Science Direct. (2020). Link.
From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Science Direct. (2016). Link.
Methodological considerations for the identification of choline and carnitine-degrading bacteria in the gut. Science Direct. (2018). Link.
Trimethylamine N-Oxide (TMAO), Diet and Cardiovascular Disease. Springer Nature. (2021). Link.
TMAO as a biomarker of cardiovascular events: a systematic review and meta-analysis. Springer Nature. (2020). Link.
Effect of egg ingestion on trimethylamine-N-oxide production in humans: a randomized, controlled, dose-response study. Pub Med. (2018). Link.
Impact of chronic dietary red meat, white meat, or non-meat protein on trimethylamine N-oxide metabolism and renal excretion in healthy men and women. European Heart Journal. (2018). Link.
Implication of Trimethylamine N-Oxide (TMAO) in Disease: Potential Biomarker or New Therapeutic Target. NLM. Link.
Fermented foods and cardiometabolic health: Definitions, current evidence, and future perspectives. NLM. Link.
