What is Green Tea Extract (And Side Effects)

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Green tea extract has become quite a craze, with health brands offering green tea extract tablets, capsules, pills, liquids and powders for us to consume. Whether you whisk yours up into a smoothie or take a green tea extract pill with a swig of water, are you completely certain of what you’re ingesting?

In this short, to the point and (hopefully) helpful guide, we’re going to take you through what’s in green tea extract, the side effects, and whether you should be worried or not.

Spoiler: you shouldn’t be worried as long as you’re sensible and follow these tips!

What is In Green Tea Extract?


Green tea extract is made from dried green tea leaves. It may simply be compacted green tea, or it might be concentrated with extra doses of caffeine, antioxidants, and flavonoids found naturally in green tea. Some green tea extracts might even have extra ingredients added for health benefits.

What they all have in common is the green tea component, which is what we’re exploring. In green tea, there is:

  • Antioxidants (these fight free radicals, which otherwise damage your body and can cause certain types of cancer).
  • Vitamins and minerals (predominantly vitamin C, B2, E, and folic acid).
  • Caffeine (there’s 30mg of caffeine on average in a cup of green tea, the amount in green tea extract varies from 5mg to 40mg – always check the label!).
  • L-theanine (blocks stress receptors in your brain for a relaxed, focused feeling).
  • Catechins (these are polyphenols in green tea that give it an astringent flavor, the most interesting is EGCG or epigallocatechin gallate).

Most green tea extracts and health pills in general focus on that last component, the EGCG catechin. There’s a lot of research into EGCG with evidence showing that “pronounced cardiovascular and metabolic health benefits can be obtained by regular consumption of 5-6 or more cups of green tea per day”, like this study into green tea and EGCG benefits. Put simply, it’s good for your heart and it can help you lose weight.

Of course, drinking 5 to 6 cups of green tea per day is too much for some people (although we could do it happily!) so the green tea extract pill was created. It contains all the EGCG health benefits you want without the time and effort needed to make 6 cups of green tea.

Side Effects of Green Tea Extract Pills


Compressing 6 cups of green tea into one small pill does come with some negative effects that you’ll want to avoid. The first that we’d like to point out is dehydration. 6 cups of tea is a lot of water. Replacing those cups with small pills and a mouthful of water to wash it down isn’t the same. If you’re switching from drinking tea to taking the extract, make sure you’re drinking enough water to keep yourself hydrated too!

Caffeine Sensitivity

The recommended daily limit of caffeine is 400mg for healthy adults or 200mg for pregnant women. That doesn’t mean you can safely consume 400mg of caffeine at once, however! There’s a huge difference between having small doses of caffeine throughout the day and having it all in one go.

150mg of caffeine in a green tea extract pill might give you jitters and shakes, headaches and even stomach upset if you’re sensitive to it. It’s definitely enough to keep you wide awake at night if you consume it in the evening.

But 3 cups of black tea (3x 50mg of caffeine) spread out is easy. For many people, that’s average. Just one cup of tea with each meal.

So, when you’re taking green tea extract make sure you know how much caffeine is in it. Even if you can comfortably handle that much caffeine over a day, that doesn’t mean you won’t feel a reaction when you take it all at once.

Liver Damage

This is where we see the side effects of consuming large amounts of EGCG. The European Food Safety Authority conducted a study to find out how much EGCG is too much, and the side effects of taking large doses.

They discovered that:

  • By drinking green tea infused in water, you receive between 90mg and 300mg of EGCG.
  • By taking 1 green tea extract pill, you receive between 5mg and 1000mg of EGCG depending on the brand.
  • Consuming 800mg or more of EGCG per day results in liver damage.

Their study was based on drinking at least 3 cups of green tea per day (1 cup has 30mg of EGCG on average).

To damage your liver, you’d need to drink at least 27 full cups of green tea in one day, or take 1 green tea extract capsule containing 800mg of EGCG.


Liver damage is bad enough, but green tea extract can also be toxic. If you go way over the 800mg per day limit, you could need dialysis or even a liver transplant due to toxicity. This isn’t an exaggeration; this has happened to ordinary people!

Many factors influence our bodies. Genetics and diet can also impact your chances of liver damage and toxicity from taking too much green tea extract.

The key thing to understand here is that everything is about moderation. Green tea is good for you, in moderation. So is EGCG. Taking too much or not realizing what is in the green tea extract you’re taking is where the problems lie.

More:Best Green Tea (How to Choose And Where to Buy)

Benefits of Taking Green Tea Extract


Despite the serious side effects of taking too much green tea extract, there are some benefits to it. These are the benefits you could have if you take your green tea extract sensibly along with a healthy diet and plenty of exercise:

  • Improved heart health by lowering cholesterol, decreasing blood pressure and reducing heart inflammation.
  • Faster metabolism. Catechins and caffeine in green tea regulate hormones that encourage your body to burn calories more effectively.
  • Prevent cancer by introducing antioxidants that fight free radicals.
  • Reduce the visual signs of aging, e.g. wrinkled and dull skin, with those cheeky antioxidants again. Improve elasticity and reduce acne by applying green tea skincare products or by consuming green tea extract.
  • Get the vitamins you need (particularly if you are deficient and/or the extract is enriched with extra vitamins).
  • Improve brain function with antioxidants (yes, again!) and by decreasing the action of heavy metals. This can also potentially protect you from Parkinson’s, Alzheimer’s and dementia.

More research is needed into how the health benefits of green tea extract differ from those of simple infused green tea.

Be Sensible with Green Tea Extract

To make sure that you are sensible with your green tea extract, follow these tips:

  • Maintain a healthy diet and exercise regime instead of fasting or replacing meals with the green tea capsules.
  • Read the small print and find out what exactly is in the extract and how it is made.
  • Don’t take the capsules on an empty stomach.
  • Don’t exceed more than the recommended dose (which should have less than 800mg of EGCG in it).
  • Drink plenty of water to stay hydrated.
  • Consult your doctor if you have an existing medical condition, dietary restriction or deficiency before taking green tea extract. And, of course, seek medical help immediately if you have a bad reaction to the capsules you take.

It’s simple to stay safe and reap the benefits when you know how!

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