Wednesday, November 28, 2012

Probiotics + Green Tea - Synergistic Superstack or Sciency Non-Sense? Green Tea Alone Totally Blunts HFD Induced Weight Gain, L. Plantarum Does Not Add to Its Effects

L. plantarum may metabolize green tea phenols, but don't add to their anti-diabesity effects 
Green tea has actually never seized being all the rage and probiotics are the sexy new kid on the block right around the corner of the supplement shops and and science laboratories of the western hemisphere. Against that background I guess that the title of a paper that's been published ahead of print on Monday will probably suffice to catch your interest: "Green tea powder and Lactobacillus plantarum affect gut microbiota, lipid metabolism and inflammation in high-fat fed C57BL/6J mice." (Axling. 2012) - and that despite the fact that "mice are no little men" ;-)

'1 + 1 =4' the synergism of green tea and probiotics could make it possible

I guess, the idea sounds logic: Take one thing that has been proven to ameliorate diet induced obesity, namely green tea, and combine that with another one, of which it appears as if it would also exhibit beneficial effects into an even more potent stack. In fact, the scientists' rationale was yet slightly different:
"The species Lactobacillus plantarum (L. plantarum) has the ability to metabolize phenolic acids  and to split up tannins. The metabolites are presumably more easily absorbed and distributed into the tissues where they can act as antioxidants and electron scavengers. Phenolic compounds can also have antimicrobial effects that may affect the composition of the gut microbiota, in favour of polyphenol-metabolizing components of the microbiota. Also, green tea extracts have been shown to selectively inhibit the growth of pathogenic bacteria while either enhancing or not affecting the growth of beneficial bacteria like lactic acid bacteria. To the best of our knowledge, the impact of green tea powder as a prebiotic compound to promote lactobacilli or other health promoting components of the microbiota has not previously been evaluated."
In other words, the expected benefits of providing both green tea and probiotics in conjunction were (1) an increased bioavailability of the phenols and tannins from the green tea that would be induced by the probiotics and (2) an increase in the probiotics' survival and ability to modify the gut microbiome that would be brought about by the addition of the green tea.

What looks good on paper does not necessarily work out in a complex organism

Figure 1: Ingredient total amount of Flavan-3-ol, Phenolic acid and Flavenol in water and methanol extracts from the green tea leaves that have been used in the study (Axling. 2012); as you can see the total quantity and the ratios of the bioactive ingredients of the extract actually depend on the extraction method.
Apropos green tea, you can see the exact ingredient profile of the green tea supplement that has been used in the study at hand in figure 1. In view of the fact that the C57BL/6J mice received no extract, but simply powdered green tea leaves, it may not be important in this context, but could be relevant for your future purchases that methanol and water extracts differ not only in terms of the total amount of Flavan-3-ol, Phenolic acid and Flavenol they contain, but also with respect to the ratio of the respective phytochemicals. I guess, those of you who have been around in September 2011, already, will remember that I have discussed the impact these ostensibly negligible differences can have more than a year ago in "-20% Reduction in Serum Testosterone by 5 Cups of Green Tea. Endocrine Effects Depend on Catechin Composition". In case you are one of the many newcomers or have simply forgotten (let alone missed ;-) this post, I suggest you go back and read that up, as it may help you get a better understanding of the underlying reasons due to which quality and quantity of the health effects of green tea (supplements) wary from study to study... but let's now get back to the experimental setup of the Axling study.

Green tea alone already blunts HFD induced weight gain

As mentioned before the extracts were simply mixed with the high fat diet, the mice were consuming in the course of the 22 week study period. With the probiotic supplement that was administered with the drinking water (L. plantarum at 1.5% (v/v) or roughly 3 × 10^9 cfu/ml) we are thus dealing with four different groups:
  • Control: High fat chow + no supplement
  • LP: High fat chow + L. plantarum
  • GT: High fat chow + green tea
  • GT + LP: High fat chow + green tea + L. plantarum
If you focus solely on the initially quoted hypothesis about the synergistic effects of green tea + L. plantarum, the actual study outcomes - at least as far as the blood markers in figure 2 are concerned  - are certainly disappointing.
Figure 2: Glucose insulin, fructosamine, cholesterol, triacylglycerol, non-esterified fatty acids and adiponectin levels in the blood of the mice in week 11 and week 22 of the study (Axling. 2012)
It's not like '1+1 would equal 4', but rather like '1 + 1' would just be sufficient to yield '1' not just '0.9' or even less. The in fact, the addition of the probiotics, alone, did very little within the first 11 weeks as far as it's ability to th reduce the diet-induced insulin resistance is concerned and it's addition to the green tea supplement did not improve blood glucose and lipid management, but did in fact diminish the impressive effects the green tea supplement brought about.
Figure 3: Relative change (compared to control) in bacterial diversity and lactobacilli count in response to the supplement regimen (Axling. 2012)
That the probiotic was basically useless, is actually no wonder if you take a closer look at the changes of gut microbiome in figure 3. Aside from an intermediate increase in lactobacilli, it could not boost the amount of these supposedly healthy bacteria in the long term. Rather than that it did induce an allegedly statistically non-significant decrease in the overall diversity (figure 3, left).

Minor differences with quasi-nonexistent real-world effects

At the mRNA level, the addition of L. planatrum counter-acted the anti-obesity effects of green tea, as evidenced by
    Figure 4: Body weight and fat levels of the mice (Axling. 2012)
  • 20% higher fatty acid synthase levels, an enzyme that's responsible for the synthesis of fatty acid
  • the reversal of the statistically significant reduction in acetyl-CoA caroxylase (ACC), an enzyme that's one step ahead of FAS in the cascade of which you could say that it supplies the raw material for fatty acid synthesis, and
  • minimally higher PPAR-gamma levels (responsible for fat storage) 
in the LP + GT vs. GT group, respectively. The net effects on body weight and fat mass, on the other hand were negligible. In essence the bulk of the beneficial effects of the green tea extract remained intact. Moreover, the addition of L. plantarum did have two distinct effects, that were not observed in the GT only group:
    Figure 5: Liver cholesterol and HMG-CoA-R after 11 (top) and 12 (bottom) weeks (Axling. 2012)
  1. a statistically non-significant -20% reduction in the mRNA expression of the inflammatory marker TNF-alpha, and
  2. a whopping and surprising increase in HMG-CoA reductase of +50% and +70% increase in HMG-CoA reductase mRNA compared to the green tee only and the control group, respectively
And while there is nothing in the study that would suggest that there were any beneficial effects from the TNF-alpha reduction, the increase in HMG-CoA reductase is in fact an oddity. After all, despite statistically significant increases in the enzyme that's responsible for the synthesis of cholesterol and the main target of statin drugs (Stancu. 2001), the cholesterol levels dropped by 64% and 39% compared to the control group, in weeks 11 and 22, respectively.

What do these Jerusalem artichokes, agave, bananas, burdock, camas, chicory, coneflower, costus, dandelion, elecampane, garlic,jicama, Leopard's-bane, mugwort, onion, wild yams, yacon and a whole host of other foods have in common? Right! They contain inulin. which has only recently been shown to have the ability to ameliorate body weight gains by up to 50%! Intriguing? Go back to my previous post and learn more about inulin, beta-glucans and their anti-diabesity effects.
Bottom line: A non-statistically significant reduction in TNF-alpha and an elevation of cholesterol synthesis in the presence of lower liver cholesterol levels, which would be suggestive of an increased excretion of cholesterol (thus the increased synthesis to come up for the loss), are in my humble opinion nothing that would render the combination of green tea + L. plantarum superior to the provision of green tea alone. The latter on the other hand, appears to be a great tool to keep the damage of the energy-dense Western diet in check - with no added, let alone synergistic benefit of these particular probiotic.

Maybe the provision of another probiotic or even another strain of L. plantaris would yield at least '1 + 1' results. This would yet be a research question for another study (one I would by the way not be willing to finance ;-) and does not change the fact that the original research hypothesis that there would be a potentiating effect due to the synergism of the two supplements is - even if the scientists don't openly acknowledge that - debunked for L. plantaris DSM 15313 and green tea.

  • Axling U, Olsson C, Xu J, Fernandez C, Larsson S, Ström K, Ahrné S, Holm C, Molin G, Berger K. Green tea powder and Lactobacillus plantarum affect gut microbiota, lipid metabolism and inflammation in high-fat fed C57BL/6J mice. Nutr Metab (Lond). 2012 Nov 26;9(1):105.
  • Stancu C, Sima A. Statins: mechanism of action and effects. J Cell Mol Med. 2001 Oct-Dec;5(4):378-87.