Tea and gut health – what’s your favourite cuppa?

Black tea (with or without milk) is the UK’s favourite drink – we drink as much tea as we do water. Samuel Pepys is the first known Briton to indulge in this now very British tradition – in 1665, he sat down with colleagues to discuss ‘war & peace’ with his new-found ‘China drink’ – and the practice caught on!

The most frequently consumed variety of tea in the UK is black breakfast tea – 45% of all the tea we drink. It is particularly popular in the over 55 age group, with 10% drinking 6 cups per day. Earl Grey (black tea flavoured with oil from the rind of bergamot orange) comes in second with around 19% of us consuming this on a daily basis.

In this blog, we look at the contents and types of tea available to us and how they may help to support gut health.

What is tea?

Tea comes from the Camellia sinensis plant and is made using the leaves of the plant in a step-by-step process of withering, rolling, fermenting, drying and sorting. 

  1. The leaves are withered to reduce the moisture content
  2. The leaves are then rolled to start the oxidation and fermentation processes
  3. Fermenting then increases oxidation, which helps to reduce the bitter taste of the leaves.
  4. The leaves are then dried so they can be stored for long periods.
  5. The tea is sorted into different grades

Black, green, white, Pu-erh and oolong teas are all from the same plant and the difference in type and taste is based on how the leaves are processed after being picked. For example, the differences between green, oolong and black tea are based on oxidation – the extent to which the enzymes in the leaves react with oxygen in the air. They all follow the same production process, but are oxidised to different levels.

These three teas are also fermented to different levels – green tea is not fermented, black tea is completely fermented and oolong tea contains a mixture of both fermented and non-fermented leaves.

What’s in tea?

Tea comprises a number of active components, including caffeine, but also a number of other ingredients

  • Caffeine is a natural stimulant, which stimulates the brain and central nervous system and helps us to remain alert. It is naturally found in coffee, cacao and all teas made from the Camellia sinensis plant. 

The different teas contain the following estimated caffeine amounts, although these can vary depending how the tea is brewed:

  • Black Tea – 37mg of caffeine per 100ml
  • Oolong and green tea – 31mg/100ml
  • White tea – 27mg/100ml
  • Pu-erh – 21mg/100ml
  • Matcha – 126mg/100ml
  • Rooibos – caffeine free
  • Fruit teas – caffeine free
  • Herbal teas – caffeine free
  • Tea polyphenols

Polyphenols are naturally occurring organic compounds found in plants that confer benefits on the plant and are thought to be beneficial micronutrients for humans.

One class of polyphenols is known as flavonoids and a sub-category of flavonoids, known as catechins and epicatechins, is found in the tea plant. Green tea is thought to have the highest levels of the most potent tea polyphenol (epigallocatechin-3-gallate or EGCG) and most research has been done with green tea, but this polyphenol is also present in black tea. 

Another flavonoid, known as quercetin is also found in both black and green tea.

  • Tannins

Catechins are also known as tannins and are what gives tea its dry, bitter flavour. They are believed to act as a protective mechanism in plants and have also been shown to have antimicrobial, antiviral and antifungal properties.

Tannins have also been shown to have a potential role in weight management and are known to interfere with the absorption of certain nutrients, such as iron. Over-consumption or consumption on an empty stomach may also lead to nausea.

Is tea good for my gut health?

There is some evidence to show that green tea may help to increase levels of Bifidobacterium and suggestions that black, oolong, Pu-erh and Fuzhuan teas (microbially fermented ‘dark tea’) can affect the diversity of microbes in the gut. 

What are fermented teas?

Whilst black tea goes through a fermentation process, there are specific teas that are designed to be ‘aged’ to encourage microbial fermentation. Pu-erh and Furzhuan teas are fermented teas from specific regions of China that have been used by the Chinese for centuries to aid in digestion after meals.

Kombucha is a fermented drink made from sweetened tea and a bacterial culture known as a ‘scoby’. The resulting fermented, fizzy beverage contains live lactic acid bacteria and has a distinctive sour taste. It is widely available to buy in supermarkets and many brands now sell different ‘flavours’ of kombucha – it is also relatively easy to make at home.

Other types of tea

We are also increasingly aware of herbal ‘teas’, which are growing in popularity and now make up 9% of all tea consumed in the UK – mainly by the 16-28 year old age range, who drink fruity or herbal teas 65% of the time. 

These teas are actually herbal infusions as they are not made from the ‘tea’ plant and infusions that may be helpful in supporting digestion include fennel, licorice root, chamomile, lemon and ginger and peppermint – all herbs that have been shown to have beneficial digestive properties.

The most frequently consumed variety of tea in the UK is black breakfast tea – 45% of all the tea we drink. It is particularly popular in the over 55 age group, with 10% drinking 6 cups per day. Earl Grey (black tea flavoured with oil from the rind of bergamot orange) comes in second with around 19% of us consuming this on a daily basis.

In this blog, we look at the contents and types of tea available to us and how they may help to support gut health.

What is tea?

Tea comes from the Camellia sinensis plant and is made using the leaves of the plant in a step-by-step process of withering, rolling, fermenting, drying and sorting. 

  1. The leaves are withered to reduce the moisture content
  2. The leaves are then rolled to start the oxidation and fermentation processes
  3. Fermenting then increases oxidation, which helps to reduce the bitter taste of the leaves.
  4. The leaves are then dried so they can be stored for long periods.
  5. The tea is sorted into different grades

Black, green, white, Pu-erh and oolong teas are all from the same plant and the difference in type and taste is based on how the leaves are processed after being picked. For example, the differences between green, oolong and black tea are based on oxidation – the extent to which the enzymes in the leaves react with oxygen in the air. They all follow the same production process, but are oxidised to different levels.

These three teas are also fermented to different levels – green tea is not fermented, black tea is completely fermented and oolong tea contains a mixture of both fermented and non-fermented leaves.

What’s in tea?

Tea comprises a number of active components, including caffeine, but also a number of other ingredients

  • Caffeine is a natural stimulant, which stimulates the brain and central nervous system and helps us to remain alert. It is naturally found in coffee, cacao and all teas made from the Camellia sinensis plant. 

The different teas contain the following estimated caffeine amounts, although these can vary depending how the tea is brewed:

  • Black Tea – 37mg of caffeine per 100ml
  • Oolong and green tea – 31mg/100ml
  • White tea – 27mg/100ml
  • Pu-erh – 21mg/100ml
  • Matcha – 126mg/100ml
  • Rooibos – caffeine free
  • Fruit teas – caffeine free
  • Herbal teas – caffeine free
  • Tea polyphenols

Polyphenols are naturally occurring organic compounds found in plants that confer benefits on the plant and are thought to be beneficial micronutrients for humans.

One class of polyphenols is known as flavonoids and a sub-category of flavonoids, known as catechins and epicatechins, is found in the tea plant. Green tea is thought to have the highest levels of the most potent tea polyphenol (epigallocatechin-3-gallate or EGCG) and most research has been done with green tea, but this polyphenol is also present in black tea. 

Another flavonoid, known as quercetin is also found in both black and green tea.

  • Tannins

Catechins are also known as tannins and are what gives tea its dry, bitter flavour. They are believed to act as a protective mechanism in plants and have also been shown to have antimicrobial, antiviral and antifungal properties.

Tannins have also been shown to have a potential role in weight management and are known to interfere with the absorption of certain nutrients, such as iron. Over-consumption or consumption on an empty stomach may also lead to nausea.

Is tea good for my gut health?

There is some evidence to show that green tea may help to increase levels of Bifidobacterium and suggestions that black, oolong, Pu-erh and Fuzhuan teas (microbially fermented ‘dark tea’) can affect the diversity of microbes in the gut. 

What are fermented teas?

Whilst black tea goes through a fermentation process, there are specific teas that are designed to be ‘aged’ to encourage microbial fermentation. Pu-erh and Furzhuan teas are fermented teas from specific regions of China that have been used by the Chinese for centuries to aid in digestion after meals.

Kombucha is a fermented drink made from sweetened tea and a bacterial culture known as a ‘scoby’. The resulting fermented, fizzy beverage contains live lactic acid bacteria and has a distinctive sour taste. It is widely available to buy in supermarkets and many brands now sell different ‘flavours’ of kombucha – it is also relatively easy to make at home.

Other types of tea

We are also increasingly aware of herbal ‘teas’, which are growing in popularity and now make up 9% of all tea consumed in the UK – mainly by the 16-28 year old age range, who drink fruity or herbal teas 65% of the time. 

These teas are actually herbal infusions as they are not made from the ‘tea’ plant and infusions that may be helpful in supporting digestion include fennel, licorice root, chamomile, lemon and ginger and peppermint – all herbs that have been shown to have beneficial digestive properties.

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