EGCG, Catechins and Polyphenols
FAQ Guide

What are EGCG, catechins and polyphenols, and their health benefits and side effects? How much to consume? Best product and brand to buy?

1. What are tea polyphenols?

Polyphenols is a much abused term. Strictly speaking, it refers to a class of micronutrients that is presents in most vegetables and fruits. In recent years, they have attracted much scientific scrutiny due to their antioxidant properties and health benefits.

There are many types of polyphenols, of which the most well-researched are flavonoids. Flavonoids themselves are further divided into six sub-classes:

  • Flavanols
  • Flavonols
  • Flavones
  • Isoflavones
  • Flavanones
  • Anthocyanidins.

Flavonoid is a fascinating subject. To learn more about it and which is the richest source of food for flavonoids, read

Green Tea Catechins and Flavanoids Explained

Tea contains lots of polyphenols but it also contains other compounds. Confusingly, tea seller tends to use the word polyphenols interchangeably with green tea extract, which can be misleading, as you shall learn later.

What's In Polyphenols?

According to a 1992 study by Harold Graham, one third of dried tea extract is flavanols such as catechins. Another 10-14% are flavonols such as kaempferol, quercetin, and myricetin. This is explained further in the article below:

Green Tea Ingredients and Chemistry Explained

2. What are catechins?

When buying a green tea extract, instead of looking at polyphenols, you should focus on how much catechins it contains.

Catechins are what make green tea special. They make up the bulk of green tea's antioxidants and its healing potential.

Let's say you come across an exciting product that says "300 milligrams of polyphenols". You may be led to believe it contains 300 milligrams of catechins. You could be wrong.

A standardized green tea extract contains only about 30% catechins. So 300 milligrams of polyphenols may only contain 90 milligrams of antioxidants, not the 300 milligrams that you expect

Green Tea Versus Black Tea

Catechins are unoxidized. When black tea is made, catechins oxidize to form more complex compounds called thearubigins and theaflavins. Between the two, only theaflavins contain significant antioxidant potential.

Green tea contains about 30% catechins, whereas black tea contains only 4% of theaflavins. Both are powerful antioxidants. But green tea has far more in quantity, which explains why it is associated with more health benefits.

3. What is EGCG?

Okay, now you understand what catechins are, the rest is easy.

Green tea contains six types of catechins: EGCG, EGC, ECG, EC, GC and C. Among the six, there is some evidence that EGCG and ECG are the most potent.

However, what makes these catechins so interesting is not their potency, but their abundance. About half of the catechin content of tea is EGCG. Just a small quantity of tea leaves will steep many cups of tea.

It is this relative abundance that makes green tea special. No other food or beverage contain this much antioxidants!

EGCG is the focus of almost every scientific study, and has been associated with most of the newly discovered green tea benefits!

4. What are the health benefits?

While the Chinese people have been drinking green tea for the last 2,000 years, green tea extract is a recent invention. How can we be sure that ingesting it will give the same benefits as drinking green tea?

While long term population studies tend to use beverages, short duration laboratory and human trials tend to use green tea extract for consistency.

Remember the last time you heard about a newly discovered green tea benefit? Chances are this study was performed using green tea extract.

The health benefits of EGCG are deep and wide ranging, literally covering every part of your body. The following article covers this in some details feel free to scan through it:

Green Tea Health Benefits -16 Things That Make Miracles Possible

The Ohsaki National Health Insurance Cohort Study is one of the largest population studies ever conducted - 40,530 Japanese adults were questioned over the course of 11 years.

Researchers found those who drank 5 or more cups of green tea a day were 16% more likely to live longer than those who drank less than one cup a day.

Heavy green tea drinkers are also 26% less likely to die from heart disease.

EGCG Health Benefits - 6 Discoveries You Can't Ignore

5. Can it help me lose weight?

The weight loss effects of green tea are slow but significant and there is real scientific evidence to justify its inclusion as one of the top ingredients in many reputable weight loss products.

It can help you lose weight safely and effectively in three ways:

  • Increase metabolism

  • Burn fat

  • Reduce fat storage

Many scientific studies have indicated that it can have some big benefits to overall health, especially because it can help you lose weight.

EGCG Weight Loss - Green Tea 3-Way Magic

However, unless you get your ingredients and dosage right, scientific studies have shown that simply consuming EGCG won't help you lose weight.

These four studies show that you need to consume somewhere between 300 to 700 milligrams of catechins or EGCG a day to have any weight loss effect.

If you are consuming towards the lower end of the scale (say 300 milligrams), then make sure your formulation contains a significant amount of metabolic stimulants such as caffeine.

Green Tea Extract Weight Loss - Dieter's Slimming Guide

If you are interested in drinking tea beverage to lose weight, read Green Tea Diet - How To Be A Successful Loser.

6. Does it have any side effects?

Green tea itself has few side effects.

After all, the Chinese people have been drinking tea for thousands of years. It has been officially proven by study that green tea is the second most consumed beverage in the world after water.

It is water-soluble, which means if you overdose, it is unlikely to build up. The excess simply gets flushed out of your body.

There is only one caveat: Be careful when you are pregnant or consuming lots of sub-quality processed products (such as tea powder or dietary supplement).

Side Effects - Green Tea Extract Consumers Beware!

How to Maximize Benefits

7. Which foods and beverages contain the highest levels of this compound?

When choosing the healthiest tea beverage to drink, always go for the least processed option.

A 2007 report published by the US Department of Agriculture (USDA) analyzes nearly 400 foods for their EGCG content. It shows that regular green tea contains the highest concentration of antioxidants.

It is followed by decaffeinated green tea, flavored green tea and instant or bottled tea.

EGCG Content in Green Tea - USDA Study

The same study shows why green tea is probably the best way to ingest antioxidants.

One gram of green tea steeped in 100 milliliters of water yields 127 milligrams of catechins.

In comparison, 100 grams of dark chocolate contains 54 milligrams, blueberries 52 milligrams and black grapes only 22 milligrams!

Green Tea Catechins - Best Food and Beverage Sources

8. So green tea contains the highest concentration of EGCG. Should I take a green tea extract supplement or drink green tea?

This is an open-ended question, much depends on the quality of the green tea or supplement product you are comparing.

For those of you who can't tolerate caffeine all, caffeine-free supplement is a viable option.

That aside, I personally prefer to drink green tea consisting entirely of young tea buds plucked from the top of the tea bush in the first three days of spring. I think these high grade green teas offer the best value in term of taste, nutrition and avoidance of side effects.

Taking supplement is not quite the same as drinking green tea. Supplements are not regulated by the FDA, there are plenty of rogue traders out there pushing lots of sub-standard products.

Product quality is highly dependent on the intermediate processing steps used. Even the raw ingredients are different: Highest quality tea farms make high grade green tea for drinking, while low quality tea farms make tea extract.

It all boils down to the rule of thumb that you want to use the least processed product.

You can tell a cup of green tea is high quality by looking at it and tasting it. You can't do the same for a green tea extract supplement. When buying one, you have to trust the manufacturer. You have to go with the reputation of the supplement maker.

Also, scientific study has shown that the potency of a supplement is often over-stated. For further analysis on this subject, please read the following article:

Green Tea Supplements Vs Drinking - Pros and Cons

9. How about matcha green tea powder?

For a tea lover, I love matcha for its emerald green, rich flavors and ceremonial grace. However, if you are considering matcha as a health food, and as a replacement for a cup of high quality tea, I think you should go in with a more realistic expectation.

Just like green tea, there are many grades of matcha tea powder.

A high grade tea powder is made from young tea buds plucked in the early spring, just like a high grade green tea. However, additional labors is needed to grind the tea buds into powder form, which means a high grade matcha is more expensive than the tea itself.

It is nice to add low grade tea powder to smoothie or instant iced tea. However, one should only buy the tea powder from reputable sources as much of Japanese tea powder is sourced from China.

This is further explained in Matcha Powder Health Benefits Vs Green Tea Leaves.

10. Which dietary supplement do you recommend?

I personally believe that drinking green tea will always offer better value for money than dietary supplement. However, you may prefer a supplement for other reasons such as convenience, being caffeine-free or for clinical reasons.

In the following article, I review the green tea supplements that currently exist in the marketplace. Read to discover which is the reputable "gold standard" EGCG brand that you can trust!

Green Tea Catechins - Supplement Brands Reviewed

11. How much should I consume daily?

The golden rule here is to following the manufacturer's instructions and take great care not to overdose.

In East Asia, people drink 3 to 6 cups of green tea daily. This is equal to a daily intake of 300 to 900 milligrams of catechins a day, depending on the quality of the green tea being steeped.

However, taking green tea supplement is not exactly the same as drinking green tea. This is explained in the Green Tea Supplement Side Effects article, where three studies have found green tea extract to be toxic at high doses.

On the other hand, you don't want to consume too little or else you will lose out on the health benefits.

In the Green Tea Extract Weight Loss article, we examine four scientific studies, which found that you need to consume somewhere between 300 to 700 milligrams of catechins or EGCG a day to have any weight loss effect.

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Harold N, Graham PD (1992). Green tea composition, consumption and polyphenol chemistry. Journal of preventive medicine and hygiene. 1992 May;21(3):334-50.

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