Friday, December 2, 2011

Green Tea Extracts for Building Strength & Size and Losing Weight - Fact or Fraud? Or, Why It is Always Worth Taking a Look at the Data that Is NOT in the Abstract.

Image 1: If the watery green tea is healthy, then a potent extract must be even more healthy, right? This may well be just another instance of "supplementational idiocy"...
I know people love their Green Tea! After all, Camellia sinensis is one of the staples that has not yet been debunked as another hoax of the supplement of pharmaceutical industry - a real healthfood, right!? Well, you will probably be familiar with my skepticisms towards the notion that taking tons of the polyphenols you are "supposed" to get in relatively small quantities from 2-3 cups of green tea in supplemental form must necessarily be a good thing, just because epidemiological data suggests that people who consume green tea (for those who only now this stuff in capped form: Green tea is actually a beverage ;-) in moderation are overall healthier than people who abstain from drinking hot water extracts (=tea) from minimally oxidized (=green) Camellia sinensis leaves.
Did you miss my previous blogposts on the negative effects of high dose green tea extracts on testosterone levels and male fertility? If so, I suggest you read up on that one before adopting the (stupid) more-is-more principal and popping the whole box of green tea caps at once.
Two recent studies do confirm the notion that green tea, even as a supplement, may be a worthwile addition to your dietary (I suggest you drink the tea not use the supplement) or supplemental (if you cannot stand the taste of the brew) regimen. The first one comes from scientists from the University of Warsaw in Poland (Jówoko. 2011). In a small-scale study with 35 subjects, Ewa Jówoko and her co-workers investigated the effect of 1280mg of green tea polyphenols (from a standardized GTE supplement by Olimp Sports) had on the adaptational response to a standardized 4-week strength training regimen (cf. figure 1)
Figure 1: Summary of the study design - participant characteristics, training and supplementation regimen.
If you look at the summary of the study protocol in figure 1, you may notice that there are two factors which contribute to the real-world significance of the study. Firstly, the subjects followed a semi-standardized diet (90g protein; 270g carbs; 104g fat), because they had to eat at the University's cafeteria. Secondly, the training, as well as the supplementation protocol are similar to what a real beginner would be doing in the gym, when he strives to build lean muscle tissue. On the other hand, this also means that we will probably see different (I would bet even less pronounced) results in trained athletes / advanced strength trainees with an optimized diet and a highly sophisticated supplement regimen - so bare that in mind, when you interpret the following results.
Figure 2: Changes in back squat and bench press 1-RM max and repetition max after 4-weeks of strength training with and without GTE supplement (data calculated based on Jówoko. 2011).
It should not surprise you that 4 weeks of training led to increases in squat and bench press performance. The inter-group differences, as well as the increase in maximal repetition number on the bench, however, did not reach statistical significance. In other words, what we are seeing here are effects of the exercise regimen, independent of GTE supplementation.
Figure 3: Changes in blood pH, base excess and lacate subsequent to the initial (Term I) and post (Term II) muscular endurance and max strength tests (data calculated based on Jówoko. 2011).
Similarly, the changes in blood ph, base excess and lacate subsequent to the initial (Term I) and post (Term II) muscular endurance and max strength tests (cf. figure 3), were not statistically different between groups. But if you followed the SuppVersity news lately, you will already know that blood ph is the domain of plain baking soda... so why even bother with green tea in this regards? After all its not even supposed to be a H+ buffer, but a powerful anti-oxidant, so what we should see are decreased rates of oxidation...
Figure 4: Lipid hydroxyperoxides at rest, 5min and 24h after a strength and endurance test before and after the 4-week intervention (data based on Jówoko. 2011).
And in fact, if you take a very close look at the data in figure 3, you may be able to see (I highlighted the bar for you ;-) why the title of the study, "Green tea extract supplementation gives protection against exercise-induced oxidative damage in healthy men", is not totally off: The degree of lipid peroxidation at rest(!) remained constant (within statistical margin) in the GTE group, while it increased by +27% in the non-supplemented group. In view of the non-existent differences in terms of strength or endurance gains between the groups, it is yet very questionable whether this "protective" effect is worth the 16$ (based on the price of the original supplement used in the study that is only available in Europe) it would cost to mimic the supplementation regimen used in the study - especially for someone who does meet the dietary requirements for vitamin E, which is something the study participants with their cafeteria food didn't.

Scientific fraud in the name of marketing

The results of the second study, which investigated the effects of decaffeinated green tea extract (DGE: 2x530mg per day; 800mg catechins per day, total) on body weight changes in 69 overweight subjects (sedentary males, aged 40–69 years, with BMI > 28 and < 38 kg/m²) are similarly dazzling. In their abstract, A. L. Brown and his collegues from Unilever (do I have to say anything else) summarize the results of their 6-week placebo controlled cross-over study as follows (Brown. 2011):
Despite a similar increase in estimated energy intake during intervention period 1, body weight decreased by 0.64 (SD 2.2) kg and increased by 0.53 (SD 1.9) kg in the DGT and placebo groups, respectively (P< 0.025), suggesting a protective effect of green tea catechins on weight gain.
Does not sound earth shattering, but -0.6kg weight loss does at least appear to be more desirable than +0.53kg weight gain. But even if you do not have access to the full-text (as I do) and are thus able to debunk this as a blatant manipulation of the facts (which, by the way, is the result of selecting data from the more favorable 2 weeks of the 6-week study period), the standard-deviations of 2.2kg in the DGE and the 1.9kg in the placebo group should ring an alarm. If you do have the full-text, and take a closer look at table 3 (cf. excerpt)...
Table 1: Excerpt from table 3 in Brown, 2011
... you should start sensing fraud. After all, the table clearly states that the mean body weight loss over the whole study period was -0.038kg for the placebo and -0.327kg for the decaffeinated green tea group. If you now scroll a few pages down and read the last paragraph...
The authors are all employed by Unilever Research & Development, which is a division of Unilever plc, a company which has a significant commercial interest in tea. Unilever plc provided all funding for the study.
... it should become obvious that, even in the case of something as "innocent" as green tea, you better not believe everything you hear and read about "superfood" and respective extracts on the Internet. So, instead of buying decaffeinated capped bullshit from Unilever, you better go to your local grocery store, get yourself some quality green tea and make tea-time a relaxing part of your probably hectic daily routine ;-)