Amount of Evidence: High Potential Benefits: Reasonable Safety: Very High
TABLE OF CONTENTS
What is green tea extract?
Green tea extract is a supplement with the polyphenols found in green tea. EGCG (Epigallocatechin gallate) is the main catechin in green tea extract and is responsible for most of the supplement’s beneficial effects, such as fat loss, improved cholesterol levels, reduced chance of cancer, and more. Usually, around 50% of the extract is EGCG, which is why the extracts are sometimes simply called EGCG. In this article, we will look at the main benefits of a green tea extract, potential side effects, and how to use it the right way.
Potential benefits
It is important to note that all of the potential benefits mentioned below are dose-dependent. In general, the higher the dose you take, the more pronounced the effects will be. However, they do reach a plateau at a certain point. We will discuss the best dosing protocol later in this article.
Also, there are many additional benefits and side effects associated with green tea that have to do with caffeine. The benefits mentioned below in this article are specifically related to green tea extracts without caffeine.
Major benefits
Improved cholesterol levels – Green tea extracts have been shown to both increase HDL cholesterol and lower LDL cholesterol. The lowering of LDL appears to be more notable than the increase in HDL. One study also found that green tea catechins reduce the oxidation of LDL to a small extent.
Fat loss – Unfortunately, this effect is not as strong or reliable as some people claim it to be. Tea appears to be quite effective for fat loss but that seems to be because of the combination of catechins and caffeine.
Antioxidant effects – EGCG and other catechins in green tea extract have been shown to decrease oxidation in the body. This is probably the main reason why many types of tea appear to lower the chance of cancer.
Minor benefits
Improved skin quality – A high intake of green tea catechins leads to an improvement in skin quality. Specifically, they are able to reduce acne.
Improved dental health – Green tea has been shown to have anti-microbial properties and can specifically protect your gums.
Increased photoprotection – Photoprotection means protection of the skin from the sun. This effect applies to all green tea catechins, not just EGCG.
Reduced muscle soreness – This benefit is most notable if you overtrain or if you are a beginner at resistance training.
Increased blood flow – While the effect is not significant, EGCG has been shown to increase blood flow.
Increased longevity – Green tea catechins have been associated with a 6% increase in longevity in mice. Unfortunately, there are not enough human studies yet to know what the effect of these polyphenols is as far as slowing down aging.
Increased insulin sensitivity – EGCG has mixed effects on insulin sensitivity but in general, it usually leads to an increase. This effect is most notable in unhealthy people with insulin resistance. Green tea catechins have been linked to a reduction in fasting blood glucose levels but not fasting insulin levels.
Lowered blood pressure – The polyphenols can greatly reduce blood pressure, especially the blood pressure increase from caffeine.
Increased cognition – This effect is most notable in people who have a poorer cognition at baseline.
Protection from DNA damage – Green tea has been shown to reduce DNA damage. This effect appears to be most notable in unhealthy individuals, such as diabetics.
Lowered heart rate – This effect is likely caused indirectly and appears to be a byproduct of EGCG’s ability to burn fat and lower blood pressure.
Metal chelation – Green tea catechins (including EGCG) act as metal chelators and can help you detoxify from heavy metals.
Reduced iron absorption – Green tea extract supplements can lower iron absorption by around 10-30%. This can be seen as a benefit for those who have too much iron in their bloodstream, which is just as common (if not more common) as iron deficiency.
Increased well-being – Unfortunately, this effect has only been noted in unhealthy individuals. It may, however, apply to healthy people as well.
VO2 max – Interestingly, green tea extracts have been shown to increase VO2 max levels to a small extent. This effect applies mainly to untrained people.
Unproven benefits
The effect of EGCG on these parameters is either not sufficiently researched or the science shows little to no efficacy in these areas.
Metabolic rate – Green tea extracts have not been correlated with increased metabolism. Green tea and other types of tea can lead to a small increase in metabolism but that mostly has to do with caffeine, not EGCG or other polyphenols.
Estrogen – There doesn’t seem to be any significant connection between a green tea extract and estrogen levels.
Triglycerides – No influence on fasting or postprandial triglycerides was ever noted.
Bone health – Green tea does not significantly influence bone mineral density.
CRP (C-reactive protein) – No strong connection between green tea catechins and CRP has been observed.
Liver health – The evidence is somewhat weak in this regard. However, there is at least some amount of data that shows green tea may be beneficial for liver health in the long term.
Possible side effects
These side effects are dose-dependent and the risk for them increases (most often linearly but sometimes exponentially) as the dose is increased. Some of the side effects are relevant only at very high doses.
Decreased absorption of certain minerals – Specifically, EGCG and other catechins in tea worsen the absorption of iron by 10-30%, which may and may not be a concern to you. Since a somewhat high percentage of people are deficient in iron, you may want to avoid EGCG close to your meals to minimize this effect, especially if you are experiencing signs of iron deficiency. On the other hand, this effect can also be viewed as a benefit since many people have too much iron in their bloodstream, which can lead to iron toxicity and faster aging.
Lowered testosterone – EGCG appears to be able to both increase and decrease testosterone, depending on multiple factors. The most important variable is the dose, where low doses have been shown to increase testosterone and high doses to decrease it.
Nausea – Doses of over 1200 mg commonly cause nausea. This is the most notable short-term side effect for most people. Nausea caused by EGCG is not linked to stomach damage.
Diarrhea – This effect can happen even at relatively low doses and varies from person to person.
Who should not take EGCG?
You should probably avoid taking a green tea extract if you:
already drink a lot of tea – Extra catechins would not be as beneficial in that case.
suffer from an iron deficiency – Green tea catechins have been shown to decrease the absorption of iron by 10-30%.
are on a budget – Even though EGCG supplements are relatively cheap, there are more cost-effective supplements on the market.
Who will benefit the most?
You should definitely consider taking a green tea extract if you:
have iron overload – EGCG and other green tea catechins can help you flush the excess iron out of your system.
have a high budget for supplements – Even though the benefits of EGCG may not be as significant as those of some other supplements, the supplement is so safe that the benefits should outweigh the potential side effects in the vast majority of people.
Other sources of tea catechins
Beware that the amount of EGCG and other catechins can vary greatly from brand to brand when it comes to both tea and dietary supplements. While there are many more sources of this EGCG, the main ones include:
Green tea extract – Green tea extract supplements usually contain around 50% EGCG. They are usually a better choice than isolated EGCG supplements.
Green tea – This is the most popular source. An average cup contains 50-100 mg of EGCG.
Matcha green tea – Matcha is significantly higher in catechins than other forms of green tea. Or, more precisely, you get to consume more of them since you ingest the powder.
Decaf green tea – Decaffeinated green tea contains on average 60 mg of EGCG per cup.
Black tea – Unfortunately, black tea contains significantly less EGCG than green tea. To be exact, 6-10 mg has been found in most brands.
Pu-Erh – Pu-Erh is comparable to black tea as far as its caffeine and catechin content.
Oolong tea – Oolong tea has around 40 mg of EGCG per cup.
White tea – White tea has around the same level of catechins as green tea and contains an average of only 10 mg of caffeine per cup. This is potentially a very good thing because it allows you to drink a lot of white tea and reap more benefits connected to EGCG and other catechins in it.
Fruits – Certain fruits contain a reasonable amount of EGCG. For example, apples contain on average 5 mg per 100 grams, and berries usually around 6 mg per 100 grams.
One important thing to mention when it comes to tea is that you can greatly influence the amount of catechins in the tea by how long you let it steep in water. The longer you do, the more catechins will get dissolved into the water and the more benefits you will get to derive from them.
How much green tea extract should you take?
Most of the studies that were done on EGCG use doses of 100-800 mg. Since around 50% of green tea extract is EGCG, we need to multiply this dose by 2.
In general, 500-1000 mg seems to be the sweet spot dose where you should derive most of the benefits without meaningful side effects.
While you could probably derive slightly more benefits from a higher dosage, taking more than 600 mg is by no means necessary and could just be a waste of money.
It is important to note that the effects of a green tea extract are cumulative. Therefore, you need to take it on regular basis to notice long-term benefits.
Best time to take green tea extract
The time of the day you take the supplement doesn’t matter. However, there are two rules you need to follow:
1) Take the supplement on an empty stomach (food worsens the absorption of the catechins in a green tea extract). 2) Do not take the supplement too close to your meal (because EGCG, as well as the other catechins in tea, decrease absorption of iron)
Also, if you consume caffeine, it is best to take a green tea extract with it since these two compounds have a synergistic effect.
Interactions with other supplements
Caffeine The catechins in a green tea extract negate some of the potential side effects of caffeine. The combination also appears to be quite effective for fat loss and a few other effects.
Green tea A green tea extract has been shown multiple times to have a synergistic effect with regular green tea. The synergistic effect specifically applies to reducing the risk of cancer and the rate of its progression.
Vitamin C Vitamin C appears to enhance the absorption of green tea catechins. It can also protect iron from becoming less bioavailable after you consume green tea catechins.
Ubiquinone Ubiquinone (a metabolite of CoQ10) increases the anti-oxidative effects of EGCG. Green tea catechins also increase CoQ10’s ability to protect the liver during reserpine toxicity.
Turmeric This combination appears to be very effective at preventing or slowing down the growth of colon cancer.
Iron Since green tea extracts inhibit the absorption of iron by around 10-30%, they may increase your iron needs. If you notice a sign of deficiency or are prone to it, you may want to increase your iron intake and supplements are one way to go. Do not take iron together with green tea or its catechins though, so the absorption isn’t decreased. Also, do not take this as a call to action to start taking iron if you are not deficient because some people tend to have too much iron in their system. Excess iron in the blood can also lead to health complications.
Phytic acid Phytic acid (found primarily in nuts, seeds, legumes, and grains) and green tea have been shown to significantly decrease tumor growth when ingested together. So far, the tumor-suppressing effect has only been found in the colon but likely applies to other tumor cells as well.
Lemon Lemon (probably because of the citric acid in it) significantly increases the beneficial effects of tea.
Omega 3 Omega 3 fatty acids increase the bioavailability of EGCG and other catechins.
Piperine Piperine (found in black pepper) seems to increase the bioavailability of green tea extract supplements to at least some extent. However, more studies are needed to confirm this effect.
L-Theanine This combination may protect you from cognitive decline to some extent.
Quercetin Quercetin can increase the absorption of catechins.
Soy isoflavones The combination seems to lead to AMPK activation, which may have a positive effect on increasing lifespan.
Whey protein Whey protein negates many of the beneficial effects of green tea catechins.
Where to buy a green tea extract
Amazon seems to be the best option for ordering green tea extract supplements in most countries. They offer some very affordable products that are backed by many positive reviews. Also, you can choose from a wide range of brands there without having to spend time searching through other markets on the internet.
One thing to pay attention to if you decide to buy EGCG supplements in capsule form is that some brands display the dosage per serving and not per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.
FAQ
It is not yet known if you develop a tolerance for a green tea extract over time. For this reason, it is best to cycle the supplement and not take it every once in a while. For example, you can take it on weekdays and not take it during the weekend.
Yes, assuming it is caffeine-free. The catechins do not impact your sleep in any negative way.
The catechins are stable molecules but they can lose potency over time.
Keep your green tea extract supplements in a cold, dark, and dry place and they will remain just as potent for many years.
In the short term, the peak plasma concentrations of EGCG are reached 1-2 hours after you take it. After that, the concentrations start slowly diminishing until they become undetectable, which usually takes around 24 hours.
In the long term, it takes around a month to start noticing the benefits of a green tea extract. It is important to note that the effects of the supplement are cumulative. Therefore, you need to take it on regular basis to notice long-term benefits.
Fruits are the highest food source of this catechin. Specifically, apples, kiwis, and berries contain most of it. Nuts would be the second richest food group in EGCG. It is important to say, however, that even the richest food sources cannot compare to green tea and other forms of tea when it comes to the EGCG content.
The peak plasma concentrations of epigallocatechin gallate are reached 1-2 hours after you take it. After that, the concentrations start slowly diminishing until they become undetectable, which usually takes around 24 hours.
The compound is extremely safe if you stick to the regular doses. With that said, 8+ grams a day could potentially lead to acute toxicity and cause harm to certain organs.
Gyokuro is the type that appears to be the highest in EGCG and other catechins. Whichever type of green tea you are consuming, choosing a powdered form (matcha) will allow you to get the most catechins out of it. Therefore, matcha gyokuro appears to be the winner.
No, it is perfectly fine to take green tea extract during a fast. In fact, the antioxidants in it are actually going to increase some of the benefits of fasting.
References
Most of the information provided in this guide is based on scientific research that can be found and verified in the PubMed medical library. We excluded from consideration studies that are either confounded or have a high conflict of interest.
Anecdotal evidence (from reports on Reddit, YouTube, and other sources) is also taken into account unless it contradicts scientific research.
