Flavonoids: The Secret Ingredient in Earl Grey Tea!

Black tea, bergamot, and hot water, right? That’s all you need to make the perfect Earl Grey blend. 

But, wait! Earl Grey tea has a whole host of unseen ingredients. 

And that includes flavonoids.

But what are flavonoids? And how did they end up in your cup of Earl Grey tea? 

Here’s a full breakdown of flavonoids (AKA Vitamin P) to mull over with your morning cuppa.

flavonoids in Earl Grey tea
There are over 2000 different bioactive ingredients in Earl Grey tea.

Table of Contents

What Are Flavonoids?

Earl Grey tea is brimming with tannins, alkaloids, catechins, carotenoids, amino acids, vitamins, minerals, and (you guessed it) flavonoids. 

And many of these bioactive components are why Earl Grey is so healthy

So what are flavonoids? And what makes them so noteworthy?

Sometimes called Vitamin P, flavonoids are a group of phenolic plant-based compounds (phytochemicals). 

And they’re found in much of the food we eat.

There are currently over 6000 types of flavonoids, with six primary subtypes.

Main Dietary Flavonoid Subtypes Include:

  • Flavanols
  • Flavan-3-ols
  • Flavones
  • Flavanones
  • Isoflavones
  • Anthocyanins

Other Common Subtypes Include:

  • Chalcones
  • Aurones
  • Flavanonols
  • Proanthocyanidins
  • Leucoanthocyanidins

Each breaks down in the body differently. And thanks to their many antioxidant properties, flavonoids are pretty good for you. 

Are Flavonoids a Vitamin?

Don’t let the ‘Vitamin P’ name fool you, though. Flavonoids aren’t vitamins!

First discovered in the 1930s, scientists believed flavonoids were a new kind of vitamin

It turned out they were wrong. 

But the name (Vitamin P) stuck around until the 1950s. And it’s still around today – albeit less common.

Other terms for flavonoids include polyphenols,  phytonutrients, phytochemicals, and bioflavonoids.

What’s the Purpose of Flavonoids?

This group of phytonutrients (plant chemicals) play an important role in the health, growth, and development of plants. 

And they do this in several ways.

  • Fighting off Infection
  • Filtering Ultra Violet Rays
  • Symbiotic Nitrogen Fixation
  • Attracting Pollinators
  • Regulating Cell Growth
  • Environmental Stress Defence (e.g. drought)

Flavonoids are also responsible for the deep-coloured pigmentation in fruits, vegetables, leaves, and flowers. 

These vivid colours help to attract pollinating insects and animals.

Most flavonoids are yellow in colour. And that’s where the flavonoid name comes from. The Latin word ‘flavus’ means yellow.

But there are a few exceptions.

Anthocyanins and Anthocyanidins:

One of the main dietary classes of flavonoids, anthocyanin provides the blue, black, purple, violet, and magenta pigments in fruits, vegetables, and flowers (e.g. cornflowers, açaí, black beans). When sugar-free, this flavonoid type is called anthocyanidin.

Theaflavins and Thearubigins:

Part of the flavan-3-ols (catechins) sub-group, theaflavins and thearubigins are the reddish brown pigment in black tea.


Sometimes used as a food additive, anthoxanthin is a water-soluble pigment that’s either colourless, white, or cream (e.g. potatoes, turnips, cauliflower).  And they’re part of the flavanols and flavones flavonoid subtype.

Flavonoids in Earl Grey Tea

There are six primary types of dietary flavonoids. And each of these has its own set of subcategories and related benefits. 

Seriously, it’s like going down a never-ending rabbit hole!

And you can find them in foods like tea, coffee, wine, cocoa, fruits, legumes, nuts, seeds, herbs, and vegetables.

Both the black tea and bergamot (a citrus fruit) in Earl Grey contain flavonoids.

And according to this 2017 study, Earl Grey tea was rich in Quercetin, Rhamnetin, Naringin, and Rutin (among others). Epigallocatechin-3-gallate was also present.

Tea Flavonoids

There are three main subclasses of flavonoids in black tea – Flavanols, Flavan-3-ols, and Oligomeric Flavonoids (OPCs)

And it’s thought that the flavonoids in tea may help to reduce chronic health issues. For example, cardiovascular disease, stroke and, type 2 diabetes.

Between the years 1999-2002 and 2007-2010, the CDC conducted a National Health and Nutrition Examination Survey (NHANES). 

In this study, they found that a whopping 80% of flavonoid intake came from tea (flavan-3-ols). This makes tea one of the main sources of flavonoids in US adults aged 19 years and over. 

Both green and black tea typically contains between 138mg and 118mg of flavonoids per 100ml. 


Flavanols are touted for their antioxidant and cardioprotective properties. 

Unlike other flavonoids, they’re mostly colourless. And they’re mainly present in tea, wine, stone fruits, and vegetables.

While their role in plants isn’t fully understood, it’s believed that they help protect against common climate stresses (e.g ultraviolet light).

Main Flavonol Types:
  • Kaempferol
  • Myricetin
  • Quercetin
  • Isorhamnetin
Flavonol Rich Foods:
  • Black Tea
  • Green Tea
  • Onions
  • Grapes
  • Wine
  • Peaches
  • Tomatoes
  • Lettuce
  • Scallions
  • Kale
  • Berries
  • Broccoli

Flavan-3-ols (Catechins)

All teas from the Camellia sinensis plant are rich in the flavonoid, flavan-3-ols. 

This subclass of flavonoids has a high nutrient content. And it’s one of the most common dietary subclasses found in the human diet.

Due to the oxidation process, black tea is typically higher in theaflavins and thearubigins (tannins).

While green tea is higher in catechins (e.g. epigallocatechin gallate and epicatechin). And Oolong sits somewhere in between.

Main Flavan-3-ols Types:
  • Epicatechin
  • Epigallocatechin
  • Thearubigins
  • Theaflavins
  • Proanthocyanidins
  • Epigallocatechin Gallate
  • Epicatechin Gallate
Flavan-3-ols Rich Foods:
  • Black Tea
  • Oolong Tea
  • White Tea
  • Green Tea
  • Cocoa
  • Apples
  • Grapes
  • Blueberries

Bergamot Flavonoids

In 1930, scientists extracted a new substance from oranges. This substance turned out to be a flavonoid (rutin). And not a new kind of vitamin, as they first thought.

So it’s no surprise that bergamot (citrus bergamia) contains its own set of flavonoids (polyphenols). 

95% of bergamot contains neoeriocitrin, neohesperidin, naringin, melitidin, and brutieridin. Rhoifolin, diosmin, and poncirin make up the rest. And they’re all part of the flavanones subgroup. 


Found almost exclusively in citrus fruits, flavanones are responsible for the bitter taste of their flesh, juice, and peel. 

Also referred to as dihydroflavones, flavanones have antioxidant, anti-inflammatory, blood lipid-lowering and cholesterol-lowering properties. 

They’re also known to help with weight loss and fighting off the free radicals.

Main Flavanones Types:
  • Hesperetin
  • Eriodictyol
  • Neoeriocitrin 
  • Neohesperidin
  • Naringin
Flavanones Rich Foods:
  • Lemons
  • Limes
  • Oranges
  • Grapefruit
  • Bergamot

Health Benefits of Flavonoids

Flavonoids are considered nonessential nutrients. But consuming flavonoids may hold the key to better health. 

Here are some of the health benefits of flavonoids.

  • Improved Cardiovascular Health
  • Cancer Prevention
  • Antimicrobial and Antihistamine Properties
  • Memory Enhancement
  • Mood-Boosting Properties
  • Reduces Levels of Serum Insulin
  • Eases Perimenopausal and Postmenopausal Symptoms
  • Reduces Osteoporosis Risk
  • Slows Destruction of Collagen
  • Fights Gum Disease
  • Lower Blood Pressure

And by drinking a citrus-infused blend (like Earl Grey tea), you can increase the phenolic content of tea. 

Especially if you add an extra slice of lemon in there. 

Thus super-charging your antioxidant intake.

Does Adding Milk to Earl Grey Make a Difference?

So, will adding milk reduce the polyphenol properties of Earl Grey tea?

Luckily, researchers at the Rowett Research Institute and the University of Aberdeen decided to test that theory.

First, they gathered a small group of healthy volunteers. The participants were given tea without milk, tea with added water, and just milk and water. 

Researchers then measured the blood levels of each volunteer.

Not only was tea found to increase the antioxidant levels in the blood. But, most importantly, milk didn’t affect the flavonoid content.

If that’s not enough to convince you, one study in China demonstrated that adding milk to tea lowered the risk of oral cancer. 

So What Does This All Mean?

To date, researchers have only just begun scratching the surface. 

But the health benefits of flavonoid-rich foods are undeniable. 

And with new flavonoids discovered each year, it’s only a matter of time before we uncover their full potential. 

However, the way our bodies metabolise food may limit these health benefits.

As such, the best way to get the most out of flavonoids is by eating a variety of plant-based foods. And (of course) drinking plenty of Earl Grey tea.