What Are Green Tea Supplements?

With hundreds of millions of regular users, green tea is one of the most popular caffeinated beverages in the world.  Consequently, its extract is also featured in hundreds of different dietary supplements and is taken by millions of people.     

Green tea extract is not surprisingly derived from green tea leaves, which come from the Camellia Sinesis plant.  Like the drink, green tea extract also contains caffeine along with natural compounds called catechins.

While plenty of research has demonstrated the positive effects of caffeine, there is also an ample body of evidence to suggest that catechins may offer several additional health benefits.  

What Benefits Are Associated with Green Tea?

Boost Energy

Many different energy drinks and pills feature green tea extract as one of their central ingredients.  That’s because countless studies have shown that caffeine helps to improve everything from alertness and cognition to reaction time and overall sports performance.   

Caffeine primarily works by inhibiting the action of the biochemical adenosine, which amongst other things, helps to produce feelings of tiredness when it’s released.  There is also some evidence that caffeine helps to boost levels of serotonin and epinephrine in your brain as well, which is why it’s considered a nootropic substance.        

It’s an Antioxidant

The other central ingredient in green tea — catechins — act as antioxidants, helping to block the build-up of free radicals.  Free radicals are unstable molecules that can cause cellular damage, increase oxidative stress, and raise your risk of illness and disease.  

Several studies, however, have shown that catechins like epigallocatechin-3-gallate (EGCG), which is the most abundant catechin found in green tea, help to reduce oxidative stress and improve cellular health and longevity. (1)(2)(3)

May Improve Brain Function

Catechins also appear to have neuroprotective properties helping to reduce oxidative stress and inflammation in the brain.  Catechins like EGCG help to prevent brain cell damage by blocking the build-up of free iron on your brain’s neurons, which may aid in improving your performance when it comes to memory and cognition-related tasks.(4)(5)

Support Cardiovascular Health

On top of reducing oxidative stress, research shows that catechins may benefit your cardiovascular health in several ways as well.  A number of studies have found that green tea intake helped to reduce LDL cholesterol levels in study participants.(6)(7)

Other research has also demonstrated that green tea may help to lower your blood pressure and reduce inflammation in your arteries, which in turn may help to lower the risk of cardiovascular disease.(8)

May Help With Weight Loss

In addition to keeping your heart healthy, there is also some evidence that catechins may help to promote weight loss, although the study results are mixed. (9)(10)

Some researchers argue that EGCG helps to increase the physiological process known as thermogenesis.  Thermogenic compounds like catechins help you to burn more calories by increasing how much heat your body generates.(11)

However, it’s important to point out that the number of extra calories you burn off as a result of ingesting green tea is likely pretty small.  While it might be a helpful tool for some, eating right and exercising regularly are far more effective when it comes to weight loss.  

Are There Any Risks Associated With Green Tea Supplements?

While there are a number of potential benefits associated with green tea, the National Institute of Health (NIH) suggests that green tea extract may pose some potential dangers that regular tea does not.   

More specifically, the NIH has reported over 50 cases of acute liver injury resulting in individuals who took dietary supplements containing green tea extract.  While most people were able to recover with treatment, several fatalities have been reported. (12)

In most cases, liver injury occurred inside of 4 months with symptoms typically arising anywhere from 10 days to several months afterward.   The issue appears to be linked to an excessive intake of EGCG. While they may be beneficial to your health at lower levels, research shows that catechins can be toxic for your liver at high dosages.    

Catechins make up about 10% of green tea extract, with EGCG being the most abundant catechin.  The concentration of green tea extract can vary significantly from one product to another, which may help to explain why some weight loss products have been directly associated with liver injury while others have not.  

Many products containing green tea extract also don’t clearly state how much EGCG is in each dose, which makes it much more difficult to know how much you’re taking in per day.            

This can be problematic especially when it comes to individuals taking green tea extract for weight loss.  In fact, nearly all cases of liver injury reported by the NIH were directly linked to weight loss products such as Hydroxycut, Dexatrim, and Slimquick.  

For instance, a case study published in the Annals of Internal Medicine reported that a 37-year-old woman with no history of liver disease developed jaundice along with abdominal pain and nausea around 4 months after she began taking a weight-loss product containing green tea extract.(13)  Lab test ultimately revealed that her serum aminotransferase (ALT) levels were 20 times greater than normal and a liver biopsy showed significant necrosis and inflammation.

A 2015 study published in the Journal of Food and Chemical Toxicology explored the effects of green tea extract in postmenopausal women at risk for breast cancer.(14)  While the researchers did report some positive findings, they also found that 6.7% of the study participants who were given green tea extract ultimately demonstrated elevated aminotransferase (ALT) levels, which can be a sign of liver injury — when your liver is damaged, it often releases more ALT in your blood.  

Research suggests that things like fasting, obesity as well as some vitamin and mineral deficiencies may increase the risk of liver injury when it comes to consuming green tea extract.    

In addition, taking green tea extract with other medications can significantly increase the risk of liver toxicity as well.  For example, one of the authors did not realize that he was combining green tea extract with 4 other known liver toxins and suffered reversible hepatitis.

Such common medications that may inadvertenly add significant risk include:

  • Tylenol (acetominophen)
  • Amoxicillin and Augmentin (antibiotics)
  • Antidepressants like Paxil, Wellbutrin, and Lexapro
  • Asprin
  • Anit-viral agents like Acyclovir for Herpes
  • Aloe-Vera
  • Maca
  • Niacin
  • Red Yeast Rice and Statins

There are literally over 1000 medications and supplements that can increase the likelihood of liver injury when combined with green tea extract.

While there is still some debate when it comes to tolerability, research suggests that the chances of liver damage start to increase significantly when you go over 21 mg of green tea extract per kilogram of body weight each day.   The NIH reports that the maximum dose tolerated in humans is 9.9 grams per day — that breaks down to over 20 cups of tea.  

So Should You Take Green Tea Extract?

While there does appear to be more risk involved in using green tea extract compared to just having a cup of tea, there are several things you can do to minimize the danger.  

When it comes to boosting your energy level, one of the easiest ways to minimize the risks associated with green tea extract is simply to get your caffeine from another source.  If switching over to a cup of tea or coffee is not for you, then you may want to consider an energy supplement without green tea extract.  

With that being said, if you’re more interested in it for the health benefits, there are several things you can do to make sure you’re consuming green tea extract safely and effectively.  The first thing to do is look for reputable products that clearly state how much EGCG is in each dose.   

On top of that, you can also take green tea extract with other substances that help to reduce the risk of liver damage.  For instance, doctors commonly recommend n-acetylcysteine (NAC) and milk thistle to drug overdose patients to help reduce liver toxicity.(15)