Green tea : the perfect thermogenic beverage

Green tea is a fantastic beverage, and quite surprising one : well known for it's numerous virtues, it is also an interesting beverage when it comes to fat burning. (the famous thermogenesis)
Tea is not originated from India...but from China, around 4500 years ago. While many stories exist about that, the most famous one came from China.
It is said the emperor Shen Nung, while he was asleep against a tree (the Camelia Sinensis) had leaves from that tree which felt in his hot water recipient. When he woke up, the sweet smell attracted him, he decided then to taste it...thus the green tea was born.
Nowadays, tea is the most consumed beverage, with 15 000 cups per second around the world

# Varieties
The Camelia sinensis is the origin of all the different varieties :
- greens
- whites
- oolong
- black
It exists around 3000 varieties of tea world-wide, the three main exporters being India, China and Sri-Lanka. While most have their qualities, the Green tea remain the most interesting one. Simply put, not any transformation is made to it, so all it's virtues are preserved.

# Composition
The color of the tea is determined by the way it is manufactured. Black tea is largely oxidized, oolong tea partially, while the Green tea is prepared in ways to prevent it's polyphenols (we'll see that later) oxidation.
The composition is determined by :
- The soil conditions
- The season
- The methods used to process the tea
- The way leaves are harvested.

Roughly, tea contains :
For 100 g :
- 300 mg of Vitamine-C
- 100 mg of Vitamine-E
- 11 mg of Vitamine-B
- 15 mg of Vitamine-A

and from 3 to 4,3% of Caffeine, 0,02 to 0,04% of theophylline, and from 0,15 to 0,20% of Theobromine.

One other interesting component for us, fitness people, green tea contains Theanine, which is a water-soluble amino-acid which is converted by catechin by sunglight.
The greatest theanine content is found in the "Gyokuro", a high-grade tea in Japan, a marvellous one :-) . Gyokuro is cultivated without sunlight, giving it it's particular taste.

# Green tea and polyphenolic compounds
Green tea contains many polyphenols. These last have very interesting antioxidants virtues : polyphenols can fight against the free-radicals formation (substances that enhance the cells aging), not to mention obvious capacities to prevent diseases, while researches today don't know totally how they work.
Here are several virtues, (other well documented exist of course) :
- Against cardiovascular diseases, polyphenols block bad cholesterol (LDL) oxidation
- Against cancers, by preventing tumours formation.
- Against osteoporosis, by acting as hormons, (I'm thinking about Soya isoflavones here), though it's still a work in progress in the amongst the Scientists
-etc... in fact so many benefits, but it is out of my scope here

The most abundant polyphenolic compound (more than 50% of all polyphenols) is the EGCG (catechin epigallocatechin gallate) (Others being : EC, ECG and EGC). Let's see why the EGCG is interesting...

# Green tea and Thermogenesis
Scientists found green tea stimulates thermogenesis, but this effect cannot be simply related to the caffeine content, since the thermonogenic effect of green tea is greater than the same amount of caffeine.

Dullo, a scientist, found that the EGCG catechin increased the Respiration rate of the brown fat (fat that stimulates the thermogenesis). He led another test, which involved 10 "healthy" subjects, who received on three separate occasions :

#1- 50 mg of caffeine + 90 mg of EGCG (125 mg of catechins)
#2- 50 mg of caffeine only
#3- A placebo

Every trial was made in a 24 hours window, with a 10 days intervals between each test. Beware thought this study didn't imply obese people (we'll show later why I'm talking about that), only men from 8 to 30% bodyfat. The results varied, but 6 men over the ten had their daily energy expenditure (EE) increased from 266 to 836 kJ !
Even more interesting, they didn't found any link between the percentage of bodyfat and the magnitude of the thermogenic response.

# Green Tea and Respiratory Quotient
Diurnal EE increased significantly for the subjects, the nocturnal one not so much, but something interesting happened :
The green tea produced lower Respiratory Quotients (RQ).
The RQ conditionates the fat burning. Interesting
The lower is your RQ, the more fat you burn - that is sometimes named "substrate usage", "substrate oxidation", or even "fuel mix". I found very promising that such a small dose of EGCG produced such impressive effects on the RQ. The contribution of fat oxidation was significantly higher for the green tea treatment over the placebo one (31,6% of contribution for 41,5%).
You already must have read about RQ, when it comes to aerobic (both lactic and alactic) exercices, and how low intensity cardio burns more fat, but only rely on a given EE conditionned by the RQ. By stimulating it, we can do better

# Green Tea and obese people
Obese people burn more CHO and less fatty acids that *healthy* people (obesity is a disease). Why ? Because of biochemical and hormonal deffects which make the noradrenaline and adrenaline triggering defficient. As we saw, the EGCG catechin modify the RQ - but in fact, it does more ephedrine and caffeine normalize the release of adrenaline/noradrenaline, plus the correction of the RQ. (The other part of the results showed more lipid was oxidized during ephedrine treatement).

You may have already saw over the internet such statement regarding the CHO and FAT oxydation defficiency, but I think, you could turn it the other way :
- You simply can use Green tea for regulating the hormons releases rather than cutting on fatty acids - You would drive slowly with you car if it was diagnosticed broken, but it would not be the real solution. Through the studies, there is a direct evidence on how the thermogenesis induced by green tea helps obese people by normalizing their defective substrate utilization

# ...but not for everyone ?
Despite all it's virtues, BUT because all these properties, it exists some counter-indications
- Constipations
- Pregnancy (studies still in progres I think)
- Breastfeeding
- Insomnia (that's me)
- Ulceres
- Anemia, Green tea preventing iron assimilation
- Heart palpitations

# Sources :
http://www.ncbi.nlm.nih.gov/pubmed/10584049?dopt=Abstract
http://www.ncbi.nlm.nih.gov/pubmed/10702779?dopt=Abstract
http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1997.tb51852.x/full
http://www.ncbi.nlm.nih.gov/pubmed/3512957?dopt=Abstract