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| Image 1: I wonder whether the silk worms, themselves, aren't a "highly anabolic" source of dietary protein as well... for the time being, BPI (and I assume a handful of soon to follow copy cats) rely on their produce, though. |
If you have been following the protein supplement market over the last couple of years, you will certainly have noticed that, flavoring and packaging aside, most products are as alike as two peas in a pod... a pros pos, peas. About 2 years ago,
LG Sciences tried to establish a pea-protein concentrate as a "fat-burning" (that was what LG said ;-) alternative to Whey and failed equally miserably as their competition whose initially omnipresent advertisements for their "revolutionary" beef protein product have disappeared from most of the pertinent websites as of late. Now, January 2012, it appears as if
BPI Sports, who have hitherto not exactly been known for their "innovative" products, are about to launch another assault against the ever-increasing predominance of milk proteins: BLOX is the name of the breakthrough BPI obviously thinks I have been waiting for... and guess what, they are right!
A silky ergogenic from the domesticated silk moth?!In fact, my interest in the silk proteins, which are the major (as far as the hitherto available information is concerned, even the "only") ingredient of BPI's new product, dates back to 2010, when Shin et al. published the results of a rodent study, which found that supplementation with 500mg/kg (
HED ~40mg/kg) silk amino acids for 42 days increased the maximal (loaded) swimming time in mice by more than +100% while concomittantly increasing the gain in total lean body mass by ~15% over the unsupplemented, yet exercised control (
Shin. 2010).
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| Figure 1: Blood glucose, liver glycogen, muscle glycogen, plasma protein, corticosteroid and testosterone levels in mice after 42days of 30min daily swimming exercise; data expressed relative to sedentary control (data calculated based on Shin. 2010) |
In view of the fact that this regimen also
reduced the exercise induced depletion of liver and muscle glycogen, and
kept the cortisol levels in check, and
boosted the total testosterone levels to levels which make me doubt whether those increases were not due to some sort of methodological error (cf.
figure 1), I was actually quite surprised that it took so long for someone to find an affordable source (probably in China) for the, in the case of the Shin study, hydrolyzed proteins that are produced by
Bombyx mori, the worm of the domesticated silk moth.
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| Figure 2: Amino acid composition of the silk protein hydrosolate from Worldway Co., Ltd. (Jeoneui, Korea) that was used in the exercise study (data adapted from Shin. 2010) |
Now, the interesting thing about these proteins (remember: a protein is a complex that consists of several amino acids) is that despite their nondescript amino acid composition (cf.
figure 2) their specific structure within the proteins gives them an unexpected biological activity, of which its anti-diabetic and anti-hyperlipidemic effects have received the greatest interest among researchers (I mean, who would be interested in getting jacked and horny, anyways *rofl*). The underlying mechanisms are yet still not fully understood.
So, how does that stuff work? I mean, it does work, right?A recently published study by scientists from the
Korea University in Seoul does yet shed
some light at least onto the not immediately ergogenic effects of silk protein hydrosolates. In an in-vitro experiment with 3T3-L1 fibroblasts (stem cells that would usually form connective tissue), Hyun-Sun Lee, Hyun Jung Lee, Hyung Joo Suh were able to show that the fundamental physiological processes that are responsible for the improvements in glucose and lipid metabolism reported in previous studies (
Gao. 2000;
Hyun. 2004;
Lee. 2007) are in fact attributable to two of our old acquaintances:
Increases in GLUT-4, the glucose transporter on the cell surface of eg. muscle tissue,
and leptin, the adipokine that tells your body that there is more than enough fat to burn (
Lee. 2011).
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| Figure 3: Glucose uptake in fibroblasts incubated with different amounts of silk protein with and without insulin and insulin and piogliazone controls; data expressed relative to untreated control (data adapted from Lee. 2011) |
As the data in
figure 3 goes to show, the effect size of the transporter specific (the scientists found no statistically significant increase in GLUT-1 expression) increase in glucose uptake is comparatively small
and depends, contrary to the diabetes drug
pioglitazone, the silk protein hydrosolate increased GLUT-4 expression and subsequent glucose uptake only in the presence of
albeit low amounts insulin.
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| Figure 4: Relative mRNA expression of selected transcription factors in adipogenesis pathway after incubation of fibroblasts with either 1mg/mL silk protein hydrosolate or 50nM pioglitazone (data adapted from Lee. 2011) |
What is interesting, however, is that the silk protein hydrosolate did not only produce a significantly more pronounced increase in leptin expression (175.9% ± 11.1%) that the thiazolidinedione class anti-diabetes drug,
pioglitazone, it also left the fatty acid synthase (FAS) activity, which is partly responsible for the obesogenic side-effects of many of
pioglitazone untouched.
BPI is right, I have been waiting for this, but I am still waiting for more studies, as well ;-) |
| Image 2: Even if it turns out to be another supplement non-starter, the BLOX box looks nice, doesn't it? |
These latest results are yet unsuitable to explain the way more exciting findings from the initially discussed study by Shin et al. who invoke the activity of
PGC-alpha, the transcription factor that is responsible for the release of
irisin, and subsequent increases in the capacity to oxidize fatty acids as a possible, yet hitherto not established mechanism behind the perseverance of muscle and liver glycogen. The non-existent increase in PPAR-gamma activity in the Lee study would however go against this hypothesis, if... well, if we even knew if the composition of the silk proteins the two groups used were similar, let alone identical
and, of course, whether they survive the passage through the
human digestive tract and exhibit similarly beneficial effects, when they hit
your bloodstream... after all, I may assume you are neither a rat, nor a mouse, right?
So, even if the currently available research does suggest that "silk proteins" hold some promise, these products are fundamentally different from your usual amino acid supplements, because
their biological activity is a function of both their amino acid composition, as well as the structural arrangement of those aminos within individual proteins and peptides. The source, the way the product is processed and God knows what else will thusly decide whether
BPI's BLOX will become a valid addition (I am sure it won't replace whey proteins) to the established supplemental protein sources, or whether it will end up in one of those niches of the supplement stores right next to pea and other exotic protein sources.
