Why you should be drinking Green Tea
Team Aegis – Personal Trainers London
When it comes to weight loss there are endless articles and ‘revelations’ in the media about the latest and greatest fat loss supplements and secrets. Many of these are given with a fair amount of hyperbole and imagery that alludes to marvellous effects. The reality is that many of the recommended supplements really lack compelling evidence for use, while others are shrouded in mystery or uncertainty over their safety or efficacy. However, there are other dietary interventions that are easily achievable, relatively low cost, clinically safe, and proven at being an effective part of a weight loss programme. Probably leading the field in this market is Green Tea, which is one of the first things to go onto any client shopping list when discussing weight loss, or health improvement in general.
Of course, every once in a while I am challenged on this advice, so what better way to deal with that than by putting together an article that summarises the reasons behind my recommendation and why it can have so many positive effects on your health.
So, what is it that is so good about tea? Well, it all stems from compounds in tea called flavonoids. You might have heard this term more recently as their importance for our overall health becomes better understood, at the same time their depletion over recent years in the average diet is also becoming more obvious. They were first discovered by a Hungarian chap – Szent Gyorgi, who also discovered Vitamin C, and when we look at plants with high levels of certain types of flavonoids we can see where many ‘natural’ remedies get their roots from. For example you may have heard of Milk Thistle for helping the liver? It’s the flavonoids in Milk Thistle that help protect against free radical damage there, making it a good choice for anyone who likes a drink or two (although in my opinion Betaine is even MORE valuable). Most of these good guys are found in the skins, peel, and seeds of what we eat and are quickly destroyed by processing and pasteurisation (ever heard of a certain drink that innocently talks about its amazing health properties but after processing go on to pasteurise their drink, pretty much eradicating all the benefits?). Many eminent health writers and researchers now believe that these compounds, and their recent decline in modern diets, plays a large part in the causes of many chronic health problems that have reached almost epidemic levels, such as heart disease (still the number one killer in the UK) and cancers. This is worrying when you consider that the UK leads the way in death rates for strokes, and heart disease, often by considerable amounts over other developed countries. It’s about the only league table we seem capable of getting to first place on. Flavonoids have been linked to so many health conditions that it is impossible to cover them all here, so just trust me when I tell you that they are REALLY important to ensuring good health.
But, lets get back to green tea and the flavonoids it contains. Flavonoids basically work in two roles, that of anti-oxidants and also as anti-inflammatory agents. Tea contains specific flavonoids that are called catechins, the most often seen of which is called Epigallocatechingallate (not easy to say even without a few drinks), which is typically abbreviated to EGCG. EGCG is now being seen in more and more supplements and health products ranging from toothpaste to anti-ageing remedies, and not without some good reason, so lets go on to explore some of the proven benefits to date.
Now, I’m just getting going, but this first section is about a much less publicised, although no less cool part of how green tea can help improve body composition and health. First we need to quickly visit nutritional biochemistry and talk about an enzyme called Aromatase. Enzymes basically speed up chemical actions in the body, which can be a good thing or a bad thing, depending on the process. Similarly the things we eat or the drugs we take can inhibit or promote a particular enzymes activity. An example would be ACE Inhibitors, often given for high blood pressure. These drugs prevent the enzyme that is responsible for increasing angiotensin II, which can cause constriction of the blood vessels.
Aromatase is one of those enzymes you don’t want to be helping out. In fact, you’d do well to try and reduce it, particularly if you are male and interested in avoiding the dreaded man boobs or someone (female or male) concerned about breast cancer (and lets be honest, who isn’t concerned about cancer with it affecting 1 in 3 of us?). Now, this is in danger of getting complicated but stick with me. Aromatase is responsible for the conversion of testosterone (which is present in men and women, albeit in considerably smaller amounts in the latter) into estrogen, specifically estradiol – the most potent of the estrogen metabolites. This is not good news, particularly if it is sped up by having excess fat or by drinking alcohol.
Excesses estrogens are rarely good, ask any woman going through the menopause whose rapid progesterone decline has led to a predominance of estrogen in her body. Aesthetically, as a man, it will cause you to store fat around the chest area, and reduce your ability to gain muscle - hardly the ambition of any man I know. This has been highlighted recently by the Biosignature system designed by strength coach Charles Poliquin that considers the relation of skinfolds to hormone levels. However, there are some far more sinister effects beyond aesthetics, in particular its effect on cancers, some of which are very sensitive to estrogen and will proliferate in its presence. For women, this excess of estrogen can also contribute to lower body fat storage. By now, I am guessing I have made my point and you probably can guess what I am going to tell you next? That’s right, green tea actually inhibits the action of aromatase, slowing it down, so it may actually help you get a better looking chest and more importantly help lower your risk of cancer, in particular breast cancer. There are also some links to green tea being protective against other cancers although the research isn’t quite as clear for these as isolating prevention to a variable such as this in a large population cohort is difficult to achieve.
Now, if you are one of the men reading this, you’ll want to keep paying attention, because if the threat of man boobs isn’t enough, then how about prostate cancer, baldness, skin ageing and a host of other issues that green tea can help prevent? Again, this can get complicated, but simply put (well as simply as possible), green tea compounds inhibit (slowing down) the action of an enzyme (5a Reductase) that converts your testosterone into 5a - DHT. DHT isn’t the kind of substance you want replacing your testosterone, in fact from first glance, there doesn’t seem to be anything good about it at all! Excess DHT production can not only reduce the flowing barnet you had as a youngster, but is also linked with other far nastier androgen related issues, not least to mention that a reduction in testosterone is counter-productive for building muscle and having a healthy sex life.
Now, lets move on and talk about green tea and fat burning. Green tea is probably one of the most research proven things you can drink to enhance efforts to improve body composition. There are two main ways that green tea does this, the first is through actually increasing fat oxidation and energy expenditure (check out the references at the bottom if you don’t believe me), and the other is through actually reducing the amount of fat triglycerides that the body absorbs. There is a ton of research in fact that shows green tea and in particular EGCG can have a positive effect on body composition. It also goes without saying that if you are trading a high calorie drink – such as the aforementioned fruit juices – for a zero calorie option such as green tea then you will be reducing the intake of dietary sugars that are metabolised into triglycerides and stored in the fat tissue as well as cutting back on calories – another associated benefit.
When considering energy consumption it is interesting to see that the effect of green tea isn’t purely down to the caffeine either, as control groups taking only caffeine did not see the same results. Part of this may be down to Green tea’s effects on an enzyme called Catechol-o-methyl transferase. COMT degrades norepinephrine, which is not desirable if you are looking to lose bodyfat. Although we can be sure that an increase in 24-hour energy consumption is definitely one of the reasons, there are almost certainly a few more others. For example the Journal of Phytomedicine (a riveting read I can assure you) published a paper that showed green tea (or a specific extract called AR25) to actually inhibit both pancreatic and gastric lipases, while the Journal of Biofactors (another equally satiating read) found that green tea affected the glucose uptake mechanisms, lowered fatty acids and cholesterol, and suppresses the formation of fat tissue (this study was in rats…). Other rat studies have theorised that leptin (a hormone linked to appetite) and appetite reduction play a role in producing favourable body composition changes. Fascinating stuff I hear you say? Now, it is important to remember that not all this research is done on humans, and it isn’t all done with drinking green tea, in fact quite a bit is based on capsules, topical application or injections.
So, where does this all leave us? Well, we know that when it comes to supplements that can help with weight loss there are certainly some audacious claims made by many manufacturers. We also know that in many cases, weight loss products include ingredients that are either unsupported with sufficient evidence or are in doses far lower than those used in the studies used to support their inclusion. We often don’t hear about the potential dangers of some commonly seen ingredients and it is my belief that the efficacy of some of these products is sometimes overstated. We would do well to remember that when it comes to weight loss, there are often psychological and emotional factors to consider around eating behaviours before we start handing out magic bullets for it. However, with that rather length caveat well discussed, let’s take a look at the facts for green tea.
Firstly, I am a big believer in herbal products that have stood the test of time and show a long and prevalent anecdotal history. An excellent example of this is fish oil, which many of us will remember being spoon fed as a youngster by our grandparents, who often swore by it for helping bones and joints. They were clearly onto something as we now know it to be one of the most truly beneficial supplements for just about anyone to take. Green Tea is similar, it is well established as being safe for just about anyone (although care is warranted in young children, pregnant women, and other specialist populations, where there may be altered physiology), and is largely well supported by the clinical evidence for a wide range of health benefits. Can it be effective for weight loss? Yes, I truly believe that if drank in sufficient quantities then it can be one of the more effective weight loss supplements and I routinely recommend it as part of my weight loss plans.
References:
Liao S (2001) The medicinal action of androgens and green tea epigallocatechin gallate. Hong Kong Medical Journal 2001;7:369-74
Caltagirone S et al (2000) Flavonoids apigenin and quercetin inhibit melanoma growth and metastatic potential. International Journal of Cancer 87(4):595-600
Kao Y (2000) Modulation of Endocrine systems and food intake by Green Tea ECGC. Journal of Endocrinology 141(3):980-987
Berube-Parent et al (2005) Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men. British Journal of Nutrition 94(3): 432-436
Shixian et al (2006) Green Tea Extract Thermogenesis-Induced Weight Loss by Epigallocatechin Gallate Inhibition of Catechol-O-Methyltransferase. Journal of Medicinal Food 9(4):454-458
Chantre (2004) Recent findings of green tea extract AR25 (Exolise) and its activity for the treatment of obesity. Journal of Phytomedicine 9(1):3-8
Kao Y (2000) Modulation of Obesity by a Green Tea Catechin. American Journal of Clinical Nutrition 72(2):1232-1233
Ashida et al (2004) Anti-obesity actions of green tea: Possible involvements in modulation of the glucose uptake system and suppression of the adipogenesis-related transcription factors. Journal of Biofactors 22(1-4): 135-140
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