Coffee Lengthens, While Caffeine Shortens Your Telomeres: An Essential Paradox? The Latest Evidence Reviewed

If life "begins with coffee", will it also help you end later with coffee?

If you follow the SuppVersity on Facebook, you will be aware that the majority of studies indicates that the chronic consumption of coffee (even in amounts of 5+cups/day) has potent health benefits - at least in normal, healthy individuals. Accordingly, you may not consider the observation Larry Tucker (2017) made when he evaluated the relationship between caffeine intake and coffee consumption and leukocyte telomere length, in his latest study surprising. After all, a drink with overall beneficial effects on one's health, shouldn't have negative effects on our telomere length, a biomarker of the senescence of cells.

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What is surprising about Tucker's cross-sectional study, however, is that his analysis of data of 5826 adults from the National Health and Nutrition Examination Survey (NHANES) shows that the consumption of coffee's main active ingredient was inversely related to telomere length (F = 15.1, P = 0.0005) - or, to be more precise that the subject's telomeres were 35.4 base pairs for each 100 mg of caffeine they consumed on a daily basis; and that after adjusting for the covariates.

Caffeine shortens and coffee lengthens your telomeres - How's that possible? 

Well, the most probable answer is that other substances in coffee, such as chlorogenic acid, ameliorate the negative effects caffeine will have on the length of your telomeres.

Figure 1: The caffeine intake is negatively associated with the length of the telomeres according to the data from 5826 adults from NHANES (1999–2002) in both coffee drinkers and abstainers (Tucker. 2017).

And indeed, the data from the study seems to confirm just that. After all, a re-analysis of the link between caffeine consumption and telomere length revealed that...

• each 100 mg of caffeine consumed by coffee drinkers was associated with telomeres that were 36.7 base pairs shorter than the cohort average (F = 9.0, P = 0.0054), while 
• each 100 mg of caffeine consumed by non-coffee drinkers was associated with telomeres that were 40.0 base pairs shorter (F = 8.5, P = 0.0067).

This observation alone can't explain that coffee intake, in general, was positively related to telomere length (F = 12.6, P = 0.0013), independent of the covariates. If we take into consideration that coffee is not the only source of caffeine in the average American's diet, however, another factor that may interfere with the telomere length emerges: sodas, energy drinks & co.

A short telomere length correlates with an increased risk of mortality and with the (subjectively) rated health status of older subjects in Njajou (2009).

What does telomere length have to do with (healthy) aging: Over the course of your life-cycle, your telomeres naturally shorten. Part of the telomeric DNA does not replicate each time a cell divides. This is commonly referred to as the "end replication problem," and short telomeres generally lead to negative health consequences. Accordingly, the ever-shortening length of your telomere caps limits the number of cell divisions which is why it's only logical that a study in nearly 20,000 participants found that one's telomere length correlates with a 25% greater risk of early death (Weischer. 2012).

Telomeres don't just count in the years before you die, though, Njajou et al. (2009) showed that telomere length is also predictive of years of healthy life, too. Eventually, the research on the predictive accuracy of telomere length on life expectancy and/or health is yet in its infancy.

With sodas, energy drinks & co. being staples and ever-more popular contributors to the American diet, respectively, one could thus assume that the correlation is driven by the ill effects of other ingredients of this beverages - first and foremost sugar - on one's average health and thus telomere length. Whether that's a valid hypothesis, however, appears questionable in view of the fact that Frary, et al. (2005) report, based on USDA data from 1994 to 1996 and 1998, that the "[m]ajor sources of caffeine [in the US population are] coffee (71%), soft drinks (16%), and tea (12%)".

Figure 2: Caffeine intake (mg/d) from beverages and foods by age group, NHANES 2011–2012 (Drewnowski. 2016) 

Similar results have been reported more recently based on NHANES data from 2011-12 by Dewenoski, et al. (2016 | see Figure 2). It would thus be too easy to do what everybody appears to do today and to blame blame the ill effects of caffeine on the consumption of soda & co and thus eventually the obesogenic "sugar boogeyman".

While caffeine is the #1 ingredient in energy drinks, taurine has recently emerged as more important contributor to their effects than everybody may have thought | learn more

So what do you have to remember: The first thing to remember certainly is that the study at hand is only one out of at least three epidemiological studies showing a positive association between coffee consumption and (increased) telomere length (I've reported many of them in the SuppVersity Facebook News | e.g. Lee. 2015; Liu. 2016).

Accordingly, the most important thing to remember is that the study at hand adds to the evidence that your coffee addiction (if kept within reasonable limits <10 cups/day) will positively affect your telomere length and could thus even have life-extending effects.

The fact that pertinent epidemiological studies, like the one at hand, consistently show beneficial effects of caffeinated coffee and taking into account that Takahashi, et al. (2017) showed only recently that, in a rodent model, caffeine adds to the anti-aging effects of coffee, is the second thing you should remember.

The one thing you should not do, however, is to blame sugar for the surprising difference between the telomere-lengthening effect of caffeine intake and coffee that was observed in the study at hand. After all, Figure 2 should remind you that the vast majority of caffeine comes from coffee and tea, and only small quantities from sugary soda & co | Comment on Facebook!

References:

• Drewnowski, Adam, and Colin D. Rehm. "Sources of caffeine in diets of US children and adults: Trends by beverage type and purchase location." Nutrients 8.3 (2016): 154.
• Frary, Carol D., Rachel K. Johnson, and Min Qi Wang. "Food sources and intakes of caffeine in the diets of persons in the United States." Journal of the American Dietetic Association 105.1 (2005): 110-113.
• Lee, J. Y., et al. "Association between dietary patterns in the remote past and telomere length." European journal of clinical nutrition 69.9 (2015): 1048-1052.
• Liu, Jason J., et al. "Coffee Consumption Is Positively Associated with Longer Leukocyte Telomere Length in the Nurses’ Health Study." The Journal of nutrition 146.7 (2016): 1373-1378.
• Njajou, Omer T., et al. "Association between telomere length, specific causes of death, and years of healthy life in health, aging, and body composition, a population-based cohort study." The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 64.8 (2009): 860-864.
• Tucker, Larry A. "Caffeine consumption and telomere length in men and women of the National Health and Nutrition Examination Survey (NHANES)." Nutrition & Metabolism 14.1 (2017): 10.
• Weischer, Maren, et al. "Short telomere length, myocardial infarction, ischemic heart disease, and early death." Arteriosclerosis, thrombosis, and vascular biology 32.3 (2012): 822-829.

Native Whey, a Superior Muscle Builder? Recently Observed Impressive Absorption Rates Tell You Nothing About 'Gains'

Do you have to replace your whey protein concentrate with "native whey" product to avoid missing out on massive gains? The study to answer this question has not yet been, done, but the study at hand certainly does not warrant this conclusion.

You will probably have seen the results of the latest study from a recent paper by scientists from the Norwegian School of Sport Sciences (Hamarsland. 2017). The one, where 20g of native whey protein showed significantly faster amino acid absorption than 20 g of whey protein concentrate 80 (WPC80), hydrolyzed whey (WPH), microparticulated whey (MWP), and milk proteins (Milk) after being administered to thirteen healthy male subjects (age: 26.6 ± 7.4 years, height: 180.8 ± 6.3 cm, weight: 80.8 ± 6.3 kg) in a single-blinded, randomized, five-way crossover, controlled study - a study, of which I am pretty sure that various snake oil vendors are already (ab-)using it to sell expensive "native", i.e. unprocessed whey protein as "superior" anabolic".

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Fortunately (for your wallet), Hamarsland's study does not provide evidence that the accelerated amino acid absorption would translate into real-world muscle gains in a long-term study.

Figure 1: Graphical illustration of the events on the five testing days (Hamarsland. 2017).

As you can see in the graphical illustration of the events on the five testing days in Figure 1, the Norwegian scientists had their subjects meet at the lab at 07:00 am on each of the five study days that were separated by at least 14 days fasted. When the subjects arrived at the lab, ...

"[t]hey received a standardized breakfast consisting of oatmeal and a glass of orange juice (1855 kJ: 9.2 g fat, 69.3 g carbohydrates and 16.6 g protein). [...] Two hours after breakfast, the participants performed the standardized resistance exercise session in 40 min and consumed one of the five protein supplements within 6 min after the end of the session. Blood serum and plasma samples were collected at 0, 30, 45, 60, 90, and 120 min after ingestion of the protein supplement. Additional blood samples were collected at 22 and 30 h on the study days when milk and native whey were ingested. During the study days with milk and native whey, recovery of muscle function was measured as changes in maximal isometric voluntary contraction knee extensions (MVC), counter movement jump (CMJ) 30 min prior to, and 0, 6, 22 and 30 h after the exercise session. The 0 h time point was immediately after the workout and about 20 min after the last set of leg exercise" (Hamarsland. 2017).

Unlike some of you would probably have expected before reading (about) the paper, hydro whey, which is often advertised as the "fastest whey protein your money can buy", did not rank first in the authors' analysis of the blood samples (see Figure 2).

Figure 2: Blood concentrations of total amino acids (a), essential amino acids (b), BCAAs (c) and leucine (d) before and after a bout of strength training and intake of 20 g of protein from milk, microparticulated whey (MWP), whey protein hydrolysate (WPH), whey protein concentrate 80 (WPC-80) or native whey (NW) in young men (Hamarsland. 2017).

Rather than that, the rarely studied "native whey", which is eventually nothing than cross-flow micro-filtrated (CFMF) raw milk produced the highest amino acid levels - and that despite the fact that WPC, which is usually produced by ultra-filtration of the "cheese whey", a byproduct of cheese manufacturing and was thus exposed to enzymatic processes and (optionally) pasteurization, and "native whey" have virtually identical amino acid profiles.

Previous acute response studies say: speed doesn't determine protein synthesis

If we rely on the often-heard claim that faster protein absorption would translate into increased gains, this would imply that the fractionate protein synthetic response to native whey should be higher than that we'd see in response to any other of the five tested proteins. Now, unfortunately, this response was not measured in the study at hand.

Figure 3: The faster absorption and increased aminoacidemia of whey vs. milk protein in Mitchell et al. (2015) did not translate to (A) significantly increased acute (A) and aggregate (B) myofibrillar protein synthesis.

From previous studies, we do know, however, that an increase in aminoacidemia as it was also observed in Mitchell's 2015 comparison of whey and milk protein concentrate does not translate to an increase in skeletal muscle protein synthesis (see Figure 3).

Previous "real world" (=longitudinal) studies say: speed doesn't build extra muscle

Now, the acute protein synthetic response can be misleading. A similar, but longitudinal, comparison of the effects of whey protein concentrate and hydrolysate supplementation on lean mass gains in 56 resistance-trained men by Lockwood et al. (2016) found no increase in the skeletal muscle hypertrophy response to 8 weeks of resistance training either.

Figure 4: Total lean mass (kg) before and after 8 weeks of standardized resistance training and supplementation with whey protein concentrate (WPC), WPC + lactoferrin and whey protein hydrolysate (WPH) in Lockwood et al. (2016).

In conjunction with the lack of effect the 4 sets of 10RM repetitions of leg press and knee extensions, and 3 sets of 10RM repetitions of bench press and seated rowing had on the subjects' countermovement jump (CMJ) performance in the study at hand, the existing evidence does, therefore, refute the conclusion that the results of the study at hand would imply that native whey protein is a better muscle builder (or a more effective recovery promoter) than any of the other dairy proteins Hamarsland, et al. tested.

Previous research suggests that faster amino acid absorption don't translate to increased gains and the observed increase fat loss w/ hydro whey is probably a result of its bio-active peptides | learn more  

So what does all that mean? While it may appear as if you'd have to get rid of your beloved whey protein concentrate, isolate or hydrolysate brand, the one you chose, as I have previously suggested, based on taste, price, and credibility, and buy some "native whey". There are two reasons why I believe this would be a mistake,

Reason #1 can be found in the study itself. After all, the authors readily admit that "[they] were not able to show any differences in recovery of muscle function after consumption of native whey compared to milk after a bout of heavy load strength training" (Hamarsland. 2017) - practically relevant effects on your workouts do thus not exist.

Reason #2 can be found in the literature, which shows consistently that there's no relevant increase in protein synthesis (and long-term gains) with so-called "fast(er)" proteins (Mitchell. 2015). Now, this doesn't mean that you can be sure a long-term study would not reveal other differences, such as the increased fat loss Lockwood et al. (2016 | reviewed here) observed when they compared regularly to faster absorbing hydrolyzed whey - this effect, however, has nothing to do with accelerated amino acid absorption and all with the different concentration of bioactive peptides (learn more), which could be present in "native whey", as well. After all, it is subjected to less processing steps than regular whey proteins | Comment on the SuppVersity Facebook Page!

References:

• Hamarsland, Håvard, et al. "Native whey induces higher and faster leucinemia than other whey protein supplements and milk: a randomized controlled trial." BMC Nutrition 3.1 (2017): 10.
• Lockwood, Christopher M., et al. "Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males." Journal of the American College of Nutrition (2016): 1-12.
• Mitchell, Cameron J., et al. "Consumption of milk protein or whey protein results in a similar increase in muscle protein synthesis in middle aged men." Nutrients 7.10 (2015): 8685-8699.

20% Calorie Deficit + BB Split + Whey = Strength ↑, Fat ↓ + Muscle ↕ | Preconditioning and Cryotherapy for Strength

Whey protein can help you shed body fat while upping your PB on squats. 

If you're looking for the latest papers on building muscle, running faster, lifting more and getting jacked look no further, today's installment of the Strength and Conditioning Update (Feb'17) discusses all interesting papers from the latest / upcoming issues of the venerable Journal of Strength and Conditioning Research. Papers that investigate the size and time-course of low-intensity 'pre-conditioning' that could make the difference between victory and defeat at the Olympic Games and elsewhere, the lean mass preserving, fat loss promoting and strength increasing effects of whey protein supplementation during diet phases and, last but not least the immediate strength boost of cooled muscles.

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• 24h-pre = optimal timing for performance enhancing low-intensity 'pre-conditioning' (Tsoukos. 2017) -- In their latest study, US and Greek researchers examined the often-overlooked delayed effects of a power type training session on explosive performance.
  
  Seventeen well-trained male power and team-sport athletes (age: 22.7+/-5.5 y, height: 181+/-8 cm, body mass: 80.7+/-8.6 kg, body fat: 9.2+/-1.7 %, 1-RM half-squat: 163+/-29 kg) performed four sessions (2 experimental and 2 control) one week apart in a randomized and counterbalanced order. Explosive performance was assessed before, 24 and 48 h following a low-volume, power-type training session (5 x 4 jump squats at 40% 1RM with 3 min rest), as well as before and after 24 and 48 h of rest (control).

  

  Figure 1: Time course of changes in countermovement jump (CMJ) performance (Tsoukos. 2017).

  If you're now asking yourself why it would be important to know that, following training, CMJ was improved by 5.1 +/- 1.0% and 3.0 +/- 1.0% at 24 and 48 h, respectively, you are probably no professional athlete or trainer. Those small, but significant performance gains you see 24h and 48h after the last training session could, after all, make the difference between winning the gold medal and flying home without a trophy for Olympic (and obviously other) athletes.
  
  In that the scientists observations that, compared to baseline, the reactive strength index (RSI) improved by 10.7 +/- 2.1% only at 24 h, provides additional evidence that 'pre-conditioning' w/ a low volume workout 24h before a competition is the way to go "before competition or a high-quality training session to improve their performances" (Tsoukos. 2017).
• Whey for strength, no carbohydrate for endurance improvement while dieting? (Wesley. 2017) -- A recent study from the College of Charleston yielded not on, but two noteworthy results: (a) the pre- and post-supplementation with 2x28g of whey protein will non-significantly enhance your body fat loss (over isocaloric carbohydrate control) and help you maintain lean mass, and it will (b) also allow you to keep gaining strength while dieting.
  
  In their 8-week study, Wesley et al. put sixteen resistance trained men (24+/- 1.6 years of age), who had been on a regular, consistent resistance training for at least two years prior to the onset of the study, and were currently engaging in whole body resistance training, on a combined diet + exercise (bodybuilding split style resistance-training, 60-90 min 4 days per week | Chest/Triceps, Day 2: Legs, Day 3: shoulders, Day 4: Back/Biceps) regimen. All subjects...

  

  Table 1: Diet card for an off-day (Wesley. 2017).

  "[...] completed a 4 d/wk body building style split resistance training program for eight weeks in conjunction with a pre, peri-, and post-exercise ingestion of whey protein (WHEY) nutritional supplement or carbohydrate (CON) based nutritional supplement [while consuming a highly standardized diet containing] 30% carbohy-drates, 35% protein and 35% fat on training and 25%carbohydrates, 40% protein and 35% fat on off days" (Wesley. 2017)

  Each individual’s daily caloric and macronutrient intakes were determined using the Harris Benedict formula with an activity factor of 1.35 (lightly active individual engaging in light exercise 1-3 days/week) for workout days and 1.125 (sedentary individual) for off days. Practically speaking, the subjects did thus consume ~13% and 27% less, on the workout and off days, respectively, than they should need according to the Harris Benedict formula (the mean deficit on a weekly basis was thus 19%).
  

  

  Figure 2: Absolute changes (kg) in lean and fat mass (Wesley. 2017).

  As you'd expect in a well-designed study, there were no differences in body mass change between the WHEY and CON groups. Over the course of the study, this, and more importantly, the subjects' body composition changed: While both groups lost body mass (p<.05), the WHEY group maintained their lean mass (LBM) while the CON group lost (p<.05) lean mass, and the WHEY group lost FM (p>.05) and the CON group did not, though the change in FM between groups was not different.
  

  

  Figure 3: Changes in squat and bench press performance (Wesley. 2017).

  Furthermore, both the WHEY and CON (p<.05) groups significantly increased lower body strength, only the WHEY group, however, increased upper body strength (p<.05) while the CON group saw a non-significant decline in bench press strength (see Figure 3).
  
  So, whey is vastly superior? Well, I guess "vastly" would be too much. After all, not all differences are statistically significant and the higher CHO intake in the CON group even allowed for a statistically significant increase in lower body and upper body repetitions to fatigue in the CON group (p<.05). For people focussing on strength endurance, the 2x28g of whey protein are thus not necessarily the best choice. For almost all other variables gymrats are interested in (body composition, bench press & squat strength etc.), the provision of 2x28g of whey protein before and after workouts is yet the better of the two supplementation options.

• 

  Figure 4: In contrast to what you would expect from a study assessing the effects of cooling on handgrip strength, the scientists used an expensive whole body cryo-therapy device, the "Space Cabin" by the "Criomed Ltd" (de Nardi. 2017). 

  Cryotherapy before workouts or competitions could up your strength, study in healthy non-athletes claims, but... (De Nardi. 2017) -- Cooling is usually thought of as a means to recover faster - a means with sign. downsides as discussed in previous SuppVersity articles - it can yet also be used acutely right before a workout and/or competition; and if the results of the latest study from the Universities of Genoa and Turino translate from recreational athletes' handgrip strength to the average gymrats' and/or professional strength athletes' quads, biceps and other muscles this is a quite effective means to achieve potentially relevant strength increases in no time...
  
  Don't go mad if you don't own a "Space Cabin" (see Figure 2), it's not yet worth it. After all, the question whether the results translate to more relevant muscle parts is not the only issue one can have with the study at hand. With an inter-group difference of only 1.9kg (treatment) vs. 0.52 kg (no treatment), the absolute change is very small.
  
  But let's not get judgemental before we have at least looked at the study design: For practical reasons, the authors of the study at hand tested the change in maximum handgrip strength (JAMAR Hydraulic Hand dynamometer), not the previously mentioned quads or biceps in two-hundred healthy, who were randomly assigned to be treated with single partial-body cryotherapy (PBC) session before the test or no treatment [a placebo treatment would have been nice, but honestly, how would you do that - after all, the subjects would certainly have noticed if the Space Cabin by Criomed Ltd the scientists used (see Figure 4) was not even turned on, no?].
  

  

  Figure 5: Pre- (T0) vs. post-test (T1) handrgrip strength (de Nardi. 2017).

  When the authors compared the post-PBC strength test data to the previously measured initial handgrip strength, they found that a single 150 seconds session of PBC (temperature range between -130 and -160 *C; the subjects wore swimwear, a pair of gloves, woolen socks and wooden clogs to isolate the tested hand), they found a significant increase in handgrip strength in both groups - the effect that the T0 vs. T1 (pre vs. post) difference in the PBC group was higher, i.e. 39.48 kg vs. 40.01 kg in control and 39.61 kg vs. 41.34 kg, however, lead de Nardi, et al. to conclude that their study would "provide the first evidence that a single session of PBC leads to the improvement of muscle strength in healthy people" (de Nardi. 2017).
  
  In view of the fact that (a) grip strength is usually not the rate limiting parameter in sports, and that (b) the improvements are not exactly impressive, though, you may agree with me that the word "preliminary" are of great importance, here and that it is thus too early to conclude that "[t]he results of the study implies that PBC could be performed also before a training session or a sport competition" (de Nardi. 2017).

Can you even have too much whey? Find out in "Too Much Whey Today, Type II Diabetes Tomorrow " | more

So what do you have to remember? Whey protein works. It's as simple as that. After all, the study by Wesley et al. is only one in a long line of studies showing benefits not just during "cuts" (i.e. while you're trying to lose body fat), when it conserves lean mass and augments fat mass losses, but also during the various "bulk" or "maintenance" studies I have discussed in the 20+ articles about whey on the SuppVersity in the past years.

Whey does thus have something the strength pre-conditioning in Tsoukos- and, even more so, the cryotherapy in the De Nardy-study do not have. Ample of practically relevant evidence of its efficacy | Comment on Facebook! 

References:

• De Nardi, et al. "Acute effects of partial-body cryotherapy on isometric strength: maximum handgrip strength evaluation." Journal of Strength & Conditioning Research: Post Acceptance: January 20, 2017.
• Tsoukos, et al. "Delayed effects of a low volume, power-type resistance exercise session on explosive performance." Journal of Strength & Conditioning Research: Post Acceptance: January 24, 2017.
• Wesley, et al. "Effect of Whey Protein in Conjunction with a Caloric-Restricted Diet and Resistance Training." Journal of Strength & Conditioning Research: Post Acceptance: September 10, 2015

26% Body Fat, Zero Lean Mass Loss W/ HIIT + 3x500mg Green Tea Supp in 10Wks | Is EGCG Liver-Toxic?

Lean, not skinny: In the long run HIIT + GTE could take you there, but there's one caveat... at least w/ the green tea.

The social networks are full of women complaining that they are not losing fat. If you ask them what they have tried to ignite body fat loss, the answer usually is: reduced energy, fat/carb intakes and, if any sport at all, endless cardio sessions... now, while studies show that this approach to fat loss works, it's (a) mostly the caloric deficit that determines the loss of body weight and (b) is often accompanied by significant lean mass losses.

An attractive alternative would be (i) not having to diet, (ii) not having to do endless cardio sessions and (iii) having a fat loss supplement that actually works.

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Well, guess what, Afzalpour et al. have an ahead-of-print paper they tagged with the keywords "HIIT;
Catechins; SRIT1; PGC-1 "(Afzalpour. 2017) that appears to suggest that this 'attractive alternative' does actually exist - at least for those women who have the most body fat to complain about for whom the scientists speculated that it could be the combination of "green tea consumption along with HIIT training" that "would improve body composition in overweight individuals and would show significantly greater improvements compared green tea consumption or HIIT training alone" (Afzalpour. 2017) - without dieting (or I should say: without prescribed dieting, the scientists did not access the women's food intake over the 10-week period; there was just a baseline reading)!

Table: Anthropometric characteristics of the subjects in the three groups (Afzalpou. 2017); note: there were no significant baseline differences in body composition and fitness between the three groups of young women.

To assess the validity of this hypothesis, the researchers from the University of Birnjad, in Iran, recruited thirty overweight young women (21.07 ± 1.2 years, BMI: 27.5 ± 1.3 kg/m²2 and body fat percentage: 34.1 ± 1.5%) and randomly assigned them to 3 groups (cf. Table 1):

• HIIT plus 1.5g/day green tea in 3x500mg servings with meals (HIIT+G),
• HIIT plus placebo (HIIT), and
• no training and supplementation control group (CON).

Said HIIT training program included 3 sessions of high-intensity interval training (HIIT) performed per week for 10 weeks with the intensity of 85—95% HR max. More specifically, ...

Figure 1: Overview of the HIIT parcours and the periodization scheme (Afzalpour. 2017).

"[t]he protocol of HIIT required the participants to finish a determined path (20 meters) with their maximum speed within 30 seconds. The starting point of the test was exactly in the middle of the obstacles, i.e., 10 meters from each obstacle. 

The training included running from the middle line to the first obstacle and then returning a 20-meter path to the second obstacle. After each run, there was an active rest for 30 seconds (Figure 1). 

In the first and second weeks, the training was performed with 4 repeats, in the third and fourth weeks with 5 repeats, in the fifth and sixth weeks with 6 repeats, in the seventh and eight weeks with 7 repeats, and in the ninth and tenth weeks with 8 repeats (Figure 1). In each session before the training protocol, the participants had [to] warm up for 5—10 minutes, and they cooled down for 5—10 minutes at the end of each session." (Afzalpour. 2017).

The intensity of training within the activity was controlled by measuring the heart rate during
the activity by pulse meter and using maximum heart rate formula (220-age). Besides, the Borg scale (6—20) was used to ensure greater control over the intensity of training.

Rodent studies clearly confirm the hepatoxicity of high doses of green tea; with the often-hailed EGCG having the most significant impact on the liver health of mice - with death being a consequence of the injection of a human-equivalent-dose of "only" 12mg/kg, or 850mg - luckily, the oral bioavailability of EGCG is low (Galati. 2006).

Weren't there recent studies showing ill-health effects of green tea? Well, "recent" is relative. I guess it all started w/ the testosterone-reducing effects of green tea I discussed back in 2011, already.

More recently, however, there have 24 case-reports of liver problems in response to the consumption of green tea supplements in man from 1999 to 2009, only (Mazzanti. 2009) - a response of which scientists say that it is due to (-)-epigallocatechin gallate (EGCG) or its metabolites "which, under particular conditions related to the patient’s metabolism, can induce oxidative stress in the liver" (Mazzanti. 2009).

Whether that's actually the case in the human case studies is particularly difficult to tell (Molinari. 2006), because it is well possible that "[i]n a few cases, toxicity related to concomitant medications could also be involved" (Mazzanti. 2009) - especially because EGCG messes significantly with the cytochrome P450 cascade, inhibiting, CYP1A2, CYP2D6, CYP2C9, and CYP3A4, which metabolizes not just all sorts of anti-depressive drugs, but also estrogen and could potentially explain the T-reductions in the previously mentioned 2011 study. In addition to that, a more recent series of studies (James. 2016) suggests that

"EGCG treatment induced hepatotoxicity [is dose dependent] and it induced oxidative stress by inhibiting antioxidant response. Mitochondrial function was impaired based on reduced biogenesis and inhibition of complexes following EGCG treatment." (James. 2016)

As bad as it may sound, this can (a) explain why it worked in the study at hand - practically speaking it did the opposite of what the anti-oxidants which hampered the gains in Bjornson et al. (2015 | discussed in detail, here), did it added to the pressure to adapt - and (b) and must be reconciled with the already low and chronically decreasing bioavailability of EGCG with chronic administration.

One important advice I want to give you at this point is still: do not fall for the notion that 'more helps more' (toxicity of really high doses of GTE in rodents has been proven multiple times), do not buy a pure EGCG product and stop using your green tea supplements if you notice the first symptoms of liver problems (usually otherwise inexplicable fatigue).

An intensity that yielded impressive effects, not only, but especially in terms of the subjects' body at loss that was not unreliably assessed with BIA, but - assuming the authors of the study knew what they did - with body fat calipers (I calculated the more meaningful absolute body fat and lean mass values based on the body fat % from the study). A 26% body fat loss and a 7% improvement in body fat percentage - without dieting - that's quite huge... isn't it?

Figure 2: Total changes (kg) in body fat and total lean mass and corresponding relative changes (in %) above the bars.

Yes, it is, but the way these beneficial effects on the women's body composition relates to their SIRT-1 and PGC-1alpha level is a putative one. Yes, the levels increased significantly in both the HIIT and the HIIT+G group, but the study design does not allow for statements about a causal link between the two: body fat and SIRT-1 and PGC-1a expression. In the end, I guess most women will say that it doesn't really matter, the fact that the PGC-1A expression was another 31% higher in the green tea group (HIIT+G) and went hand in hand with an exclusively significant increase in VO2-max (for the other treatments, the changes were non-significant) would yet argue in favor of an independent or interactive effect of green tea on the expression of these regulatory proteins that could have triggered the additional benefits.

Figure 3: Relative changes in SIRT1, PGC-1A activity and physical fitness as measured by the women's VO2-max.

What does matter, however, is the potential hepatoxicity (see red box), especially green tea products with a high EGCG content appear to have for some, but not all individuals. Against that background it is very unfortunate that (a) the product in the study at hand was either not standardized or the standardization was not reported, and that (b) any effect would have gone unobserved, in the study at hand, simply because no relevant parameters were measured... reason enough to re-address the issue in (a) the red box (general discussion) and the bottom line (weight loss adjuvant specific discussion).

Don't get me wrong: There are a lot of studies showing beneficial effects of green tea extracts, including the recently discussed study showing that "Green Tea Extract Reduces the Amount of Insulin You Need to Store Your PWO Carbs by ~20%". Unfor-tunately, its probably individual liver-damaging effects are being observed in more and more studies, too. 

What do I have to know: The concomitant use of 3x500 mg green tea supplements ingested with all three main meals accelerates the already impressive body fat loss a 10-week HIIT (3x per week) regimen produces in otherwise healthy overweight young women.

Now, the question remains: Is it worth taking the (probably small, but existing) risk of putting your liver health in jeopardy? You got to answer this question for yourself, but if you're having liver problems already, high dose EGCG supplements should IMHO be a no-go... the good news is: since the authors didn't report any EGCG standardization for their supplement, it is very likely that they are also not necessary and drinking green tea, which is a way of preparing your own hot water extract from tea, alone, with every meal could boost your fat loss and is associated w/ a reduced risk of liver cancer (Ni. 2017) |  Comment!

References:

• Afzalpour, M. E., E. Ghasemi, and A. Zarban. "Effects of 10 weeks of high intensity interval training and green tea supplementation on serum levels of Sirtuin-1 and peroxisome proliferator-activated receptor gamma co-activator 1-alpha in overweight women." Science & Sports (2017).
• Galati, Giuseppe, et al. "Cellular and in vivo hepatotoxicity caused by green tea phenolic acids and catechins." Free Radical Biology and Medicine 40.4 (2006): 570-580.
• James, Karma. Effect of dietary pretreatment and obesity on (-)-epigallocatechin-3-gallate (EGCG) mediated hepatotoxicity and the underlying mechanism. Diss. The Pennsylvania State University, 2016.
• Mazzanti, Gabriela, et al. "Hepatotoxicity from green tea: a review of the literature and two unpublished cases." European journal of clinical pharmacology 65.4 (2009): 331-341.
• Molinari, Michele, et al. "Acute liver failure induced by green tea extracts: case report and review of the literature." Liver transplantation 12.12 (2006): 1892-1895.
• Ni, Chen-Xu, et al. "Green Tea Consumption and the Risk of Liver Cancer: A Meta-Analysis." Nutrition and Cancer (2017): 1-10.