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Green Tea – Not Just for Dieting

Green Tea - Not Just For Dieting
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Green Tea comes from the leaves of the Camellia Sinensis tree. The same tree supplies the leaves which make White Tea, Oolong Tea and the English favourite, Black Tea, the difference is caused by how the leaves are processed. Green Tea leaves are in their purest form, having been picked and dried, Oolong, Black and White Tea Leaves are all oxidised and fermented to different degrees. The process of fermentation changes the levels of active compounds in the leaves, all of which are linked with different health benefits.

As the focus of this article will be Green Tea, we’ll take a closer look at the active compounds involved and their mechanisms of action within the body. We’ll also do our best to distinguish the reliable, evidence-backed science from some of the bro-tastic hearsay we come across in our industry!

As a starter for 10, let’s take a look at the active components of Green Tea (hereafter referred to as GT). Bear with me here, there’s going to be a lot of similar-looking words, however the rest of the article should be a lot clearer as a result!

Caffeine

Ever tried caffeine? Of course you have. Caffeine needs little explanation, it improves alertness, concentration, reduces the rate of perceived exertion during exercise and is strongly associated with increased rates of fat oxidation. Winning. Actual levels of caffeine in GT vary widely across brands and will depend on growing conditions & the amount of time you leave the teabag to steep. As a guideline you’re looking somewhere from 35-70mg per 200ml cup of the green stuff. By way of comparison, a black Americano from your favourite chain will contain somewhere around 160mg to a staggering 400mg of caffeine.

L-Theanine

This amino acid is also found in green tea. Theanine is regarded as having an antagonistic effect to caffeine and is associated with feelings of calmness. Considering the relatively low caffeine content combined with L-Theanine, you’ll generally get a nice, gentle boost from GT.

GT Polyphenols

Polyphenols are a class of organic compounds which are found naturally in fruits, vegetables, herbs and other plants. Different classes of polyphenols have different effects on the body, but generally, in short, they’re good for you, get more of them in your diet. The main class of polyphenols in GT are known as catechins.

Catechins

Just to make life complicated, there are a lot of these. They all have similar structures and similar names. The main ones are as follows:

  • Catechin (probably could have guessed that one). This accounts for around 1-2% of the total catechin content of GT.
  • Epicatechin (EC) – This accounts for around 7-10% total catechin content.
  • Epicatechin Gallate (ECG) – Around 6-8% total catechin content.
  • Epigallocatechin (EGC) – Around 35% total catechin content.
  • Epigallocatechin-3-Gallate (EGCG). This is the catechin that’s received the most attention from research. It typically accounts for 40-50% of the catechin content in GT (although this can be a lot higher in certain teas) and is the one that’s made GT and Green Tea Extract (GTE) synonymous with dieting, weight loss, fat burning, thermogenesis and ‘toning’ (my least favourite word).

The above catechin values were taken from Henning et al (2003) who analysed five different brands of GT. The total average catechin content per 200ml cup of GT was found to be 306mg. As we know, efficacy for GT and EGCG supplementation and weight loss is good, really good, but that’s not the point of this article. So, what else can these compounds do?

Muscle Growth?

So let’s knock this on the head now, drinking tea does not give you muscles. If it did then the British stereotype would look very different. GT does however contain Epicatechin which has some very interesting connections to muscle growth & development. Specifically, it is proposed that it can reduce levels of the protein myostatin in the body by increasing levels of the protein follistatin. Myostatin and follistatin are naturally occurring proteins. In loose terms myostatin is capable of limiting the rate of muscle growth, follistatin binds to myostatin, rendering it inactive (Cash et al 2009). Reducing myostatin has been touted as a way of increasing muscle growth and preventing sarcopenia. In even looser terms, try googling ‘myostatin deficient cow’ and marvel at a load of ultra-jacked cattle!

In a pioneering study human subjects were supplemented with 25mg EC per day for 7 days (Gutierrez-Salmean et al 2014). The ratio of follistatin to myostatin in the blood was shown to significantly increase, which could hold implications for supplementation for muscle growth. Even more interesting was the fact that subjects’ strength was shown to increase by 7%. We shouldn’t get carried away with this as the study only observed six subjects, but it definitely warrants further research.

Cognitive Benefits?

The headline ‘tea makes you happy’ is a lot more believable than ‘tea gives you muscles’. How many times have you brewed a cuppa, taken a sip and smiled? Well, there might be more to that than you think… EGCG and L-Theanine are able to cross the blood brain barrier and are both considered to have roles within the brain itself.

Supplementation with 300mg EGCG was demonstrated to increase overall alpha, beta and theta activity in the brain in a group of young, healthy adults. The subjects were dosed with a caffeine-free GT Extract in pill-form, left to brew for two hours and were then strapped onto an EEG device. Not only was overall brain activity increased, self-reported scores for calmness improved and self-reported feelings of stress decreased when compared to placebo (Scholey et al 2012). It is worth mentioning also that in a general population study of over 42000 Japanese adults, there was an inverse association noted between GT consumption and psychological distress – i.e. the more GT you drink, the less likely you are to be distressed (Hozawa et al 2009).

L-Theanine is strongly associated with feelings of calmness and relaxation. A dose of 200mg tends to be regarded as optimal for these outcomes. Unfortunately you won’t be getting anywhere near this level from GT, Keenan et al (2011) reported that average concentrations were 7.9mg L-Theanine per cup. However, it is still possible that there could be a synergistic effect from EGCG and L-Theanine happening.

Endurance Exercise

Now, this is where some of the fat oxidation potential of GT comes into play. When undertaking endurance exercise your body will be burning a mixture of fat, carbohydrate and protein as fuel. Unless you’re starving, the level of protein oxidised for energy will remain fairly constant but the ratio of fat to carbohydrate that’s burned can change. A couple of major factors which can affect this are the relative intensity of the exercise (the nearer your max you are, a higher proportion of carbs will be burned) and the food that’s been consumed pre-exercise (consume carbs pre-exercise and you’ll burn more carbs).

During exercise the carbohydrates that are burned will come from free glucose in the blood and from liver & muscle glycogen. We can only carry a finite amount of glycogen and stores of this can become exhausted. It is for this reason you’ll typically see endurance competitors knocking back high carbohydrate gels and drinks during exercise. Running out of carbohydrates mid race will largely equate to ‘hitting the wall’ and be the end of your race day.

As we know, fats and protein can be converted to carbohydrate within the body, but this takes time. So, what would happen if we could promote fat oxidation during exercise and effectively ‘reserve’ our glycogen stores for later?

GT has been investigated on a few occasions as to whether it can improve endurance exercise performance, so far the results are equivocal. One study by Dean et al (2009) observed no difference in the exercise performance of elite male cyclists when dosed with 270mg EGCG per day for 6 days. However; in the 24 hour before each cycling trial, the subjects were consuming somewhere between 670 – 690g carbohydrate and only 35g fat. It therefore isn’t that surprising that the subjects saw no difference as they’d have an awful lot of carbs to be burning!

Roberts et al (2015) did show an effect on performance with GT supplementation. A standardised extract which provided 400mg EGCG was given to regular, active men for 1 month. Improvements were observed in the rate of fat oxidation during submaximal exercise and 40 minute cycling time trial performance. This is really promising for people like most of us, who aren’t elite athletes and just want to be able to run a bit further or burn a bit more fat.

However, there are a couple of things that should be pointed out; there were only 6 participants per group (6 on GTE & 6 on placebo) and the subjects performed the submaximal exercise & time trial after a 12 hour fast. Unless you’re poorly prepared or really don’t like yourself, you’ll never go into an endurance event fasted. However, anyone who enjoys fasted cardio in the morning (I’m using the word ‘enjoys’ very loosely here) may like to look into taking a couple of our Super Strength Green Tea Capsules before exercise, this would provide 405mg EGCG.

Antioxidant / Pro-Oxidant?

The topic of antioxidants is always an interesting one as the gut reaction is to associate antioxidants as good and pro-oxidants as bad. It’s not quite that straightforward. Whilst the average person could probably do with making some dietary amends to increase their antioxidant intake, Reactive Oxygen Species (ROS) such as Superoxide and Hydrogen Peroxide also play a role in cell signalling for training adaptations at the cellular level (tiny gainz).

On the whole GT, GTE and EGCG are strongly associated with having an antioxidative effect on the body. However, recent research has shown that this may not exactly be the case. EGCG is especially interesting as it appears to be able to function as both an antioxidant and a pro-oxidant, depending on the situation. Jówko et al (2015) reported that supplementation with a mega-dose of GTE (1000mg GTE, of which 548mg was EGCG) was able to prevent oxidative stress induced by repeated sprints in healthy, athletic male subjects. Subjects’ overall total antioxidant capacity also increased following 4 weeks of supplementation. This is the type of action that one would expect to see from standard, chronic, highly-dosed antioxidant supplementation.

Kim et al (2014) reported on some of the other functions EGCG can have in the body; namely the pro-oxidative ones. It appears that in certain cellular conditions, EGCG is able to trigger the production of hydrogen peroxide. As mentioned earlier in this section, despite being a reactive oxygen species, hydrogen peroxide also functions as a cellular signalling molecule, this would suggest that GT may in fact aid training adaptations. A compound that was able to prevent oxidative stress from training without blunting cellular signalling necessary for growth and development would be a very interesting compound indeed. GT, GTE and EGCG are gaining popularity amongst competitive athletes, so this could be a key area to watch in the future.

Take Home Message

GT is good for you and definitely not just relevant for those of us looking to lose weight. This article has outlined some of the other benefits associated with the active compounds but this is by no means exhaustive. GT, GTE and EGCG are really hot topics for research currently, so it’s entirely possible we’ll see an expansion on the associated benefits in the near future. For anyone wanting to get some green goodness into their diet, we currently sell Green Tea Extract, Matcha Green Tea Powder and Super Strength Green Tea Capsules.

References

Cash, J.N. et al (2009). The structure of myostatin:follistatin 288: insights into receptor utilization and heparin binding. The EMBO Journal. 28(17), 2662-2676.

Dean, S. et al (2009). The effects of EGCG on fat oxidation and endurance performance in male cyclists. International Journal of Sport Nutrition and Exercise Metabolism. 19(6), 624-44.

Feng W.Y. (2006). Metabolism of green tea catechins: An overview. Current Drug Metabolism, 7(7):755–809.

Gutierrez-Salmean, G. et al (2014). Effects of (−)-epicatechin on molecular modulators of skeletal muscle growth and differentiation. The Journal of Nutritional Biochemistry. 25(1), 91-94.

Henning, S.M et al (2003). Catechin content of 18 teas and a green tea extract supplement correlates with the antioxidant capacity. Nutrition and Cancer. 45(2), 226-235.

Hozawa, A. (2009). Green tea consumption is associated with lower psychological distress in a general population: the Ohsaki Cohort 2006 Study. The American Journal of Clinical Nutrition. 90(5), 1390-1396.

Jówko, E. et al (2015). The effect of green tea extract supplementation on exercise induced oxidative stress parameters in male sprinters. European Journal of Nutrition. 54(5), 783-791.

Keenan, E. et al (2011). How much Theanine in a cup of tea? Effects of tea type and method of preparation. Food Chemistry. 125(2), 588-594.

Kim, H.S. et al (2014). New insights into the mechanisms of polyphenols beyond antioxidant properties; lessons from the green tea polyphenol, epigallocatechin 3-gallate. Redox Biology. 2, 187-195.

Roberts, J.D. et al (2015). The effect of a decaffeinated green tea extract formula on fat oxidation, body composition and exercise performance. Journal of the International Society of Sports Nutrition. 12(1).

Scholey, A. et al (2012). Acute neurocognitive effects of epigallocatechin gallate (EGCG). Appetite. 58(2), 767-70.

About the Author

Jack (MSc Sports Nutrition, BSc Hons Sport and Exercise Science) works within the BULK POWDERS® product team. His role includes all aspects of new product development, from recipe concept and formulation, to website content and legislation. He also really likes tea.

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