🍵Tea Time! for the Heart

In our latest edition of Tea Time we delve into the benefits of tea for the heart and how this simple beverage can improve your health.

It is recognised that green tea is healthy. Many have even described it as a ‘superfood’ due to its antioxidant properties. This is particularly true of matcha, which originates from Japan. Interestingly, Japan is home to one of the world’s blue zones, and has a famously high life expectancy. Could there be a link? The quizzical mind will ask if there is any evidence for this, what exactly about tea is so beneficial? If you haven’t already be sure to check out our previous ‘Tea Time!’ blog post where we go into the chemistry behind tea’s properties.

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The health benefits of catechins, the active ingredient in tea are broad and have been implicated in diseases such as cancer, neurodegenerative diseases and even COVID-19. However, in today’s Tea Time we’re going to look more closely at the impacts of tea in cardiovascular disease.

What is a Cardiovascular disease?

Cardiovascular disease is really an umbrella term that includes several medical conditions that effect the heart. For example, coronary heart disease (CHD), congenital heart disease, and peripheral arterial disease are all types of cardiovascular disease.

This condition is the leading cause of death worldwide especially in highly developed countries, which tend to have older populations with higher rates of obesity. Now that we known a little bit about the context, we’re going to have a closer look at three types if of cardiovascular disease, namely CHD, Heart Failure (HF).

A diagram of the heart including the names of the major arteries, veins, and chambers.

A diagram of the heart including the names of the major arteries, veins, and chambers.

Coronary Heart Disease

Firstly, let’s talk about what CHD actually is, according to the NHS.

Coronary heart disease is the term that describes what happens when your heart's blood supply is blocked or interrupted by a build-up of fatty substances in the coronary arteries.

This constricting of the arteries leads to reduced oxygen supply to the heart and results in symptoms of angina (heart pain), shortness of breath and nausea.

Published in 2018, one clinical trial tried to establish a link between tea catechin and the risk of stroke and CHD. The study included men and women, aged 40-69, that had no previous history of heart disease, stroke or cancer. Unfortunately, no significant direct link was established between catechin intake and the likelihood of stroke or CHD. However, it was observed that non-smoking men that had high catechin blood levels did have a reduced risk of stroke. This lead to the researchers proposing that catechins provide a protective effect against stroke.

Heart Failure

Heart failure is a serious medical condition that results in the inability of the heart to pump blood to the tissues of the body, which can be fatal. The disease is also defined by the NHS as:

Heart failure means that the heart is unable to pump blood around the body properly. It usually happens because the heart has become too weak or stiff.

It has been established that a particular catechin known as EGCG, which we met in the previous publication of Tea Time, is the active ingredient in tea. Investigators used a technique known as echocardiography, which is just a technical way of saying using sound to measure the heart. Using this measurement method, they showed that EGCG reversed myocardial fibrosis, oxidative stress and cardiomyocyte apoptosis, which are all causes damage to the heart and are up-regulated during heart failure. For those that may be unfamiliar, myocardial fibrosis is a pathological condition that means a scarring of the heart tissue, which leads to heart failure. Oxidative stress is essentially damage caused to tissues by toxic chemicals known as reactive oxygen species (ROS). In healthy individuals the body has mechanisms of moping up these ROS. However, in older patients and smokers ROS increases and can contribute to HF. Finally, cardiomyocyte apoptosis is just the medical jargon for heart cell death, which needless to say is not good. Importantly, the chemicals in tea help to combat these physiological pathologies.

As we’ve just seen it seems that catechins could have a really beneficial impact on heart health. We’ve even seen that in the case of heart failure, and to a lesser extend CHD, green EGCG can act as a kind of preventative medicine.

So why isn’t the NHS giving us prescription Matcha paid for by the HM Treasury?

Well, there are a few reasons. Firstly, many of the studies that we’ve looked at have been conducted in animal models instead of humans so it’s not entirely clear if the effects will translate. Also, many of these studies use isolated EGCG instead of tea. This means that the dose that is being given to these animals is not necessarily comparable to the dose you might find in your average matcha latte. This is why we need more research in humans to see if these food products can have genuinely beneficial impacts on our health.

Nonetheless, I hope that the next time you make yourself that delicious green beverage you’ll remember all of the amazing molecules it contains and the fantastic science that it has allowed us to discover.

On a final note, this is one in a series of articles looking at the health benefits of tea. So, make sure to read our previous articles and look out for more in future publications of ‘The Pink Zone’.

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Yegor Lisle (he/him) is a UCL MSci Pharmacology student. He is curious about the nature of biology, the origin of life, and the biochemistry of the universe. In particular he wants to understand more about the interface between biology, chemistry and physics.

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