10g/d BCAA Sign. Affect Gut Tenants & Metabolites - Is This the Reason for Good or Bad Effects of BCAA Supplements?

One major problem with all the "gut microbiome"-research is that we're still having a hard time predicting the health outcomes of specific changes in the total and relative numbers of bacteria.

I have to admit that the last posts about BCAAs, here at SuppVersity.com, were mostly "bad news" for BCAA guzzlers, not because I am biased or like to rant, but simply due to the fact that the studies that have been done lately had negative or no results.

With the publication of the latest study from the Institute of Disease Control and Prevention at the Academy of Military Medical Sciences in Beijing this changed - even if the title, "Metabolic shifts and structural changes in the gut microbiota upon branched‑chain amino acid supplementation in middle‑aged mice" (Yang. 2016) doesn't say anything positive.
I guess, I don't have to tell you about the importance of gut microbiota to human health. After all, the 'gut bugs' have gained extensive attention not just in the medical community, but also in the media lately. I myself have written repeatedly about the human microbiome and its contribution to our health.

It's likewise no news for you that the composition of your gut microbiome is heavily influenced by environmental facturs - including and first and foremost your diet - including your supplements like BCAAs. In their latest study, the Chinese researchers wanted to get to the bottom of previously reported beneficial and ill effects of BCAA supplements and planned a study. A study in which male BALB/C mice were housed identically, received identical diets and exercise, but different drinking water. In that, the mice were randomly assigned to two groups: (1) unsupplemented (control, n = 9) and (2) supplemented with BCAAem (in drinking water; 1.5 mg/g body weight per day) beginning at 11 months of age (n = 9).

Figure 1: The BCAAem supplement contained (in %): leucine 31.3; lysine 16.2; isoleucine 15.6; valine 15.6; threonine 8.8; cysteine 3.8; histidine 3.8; phenylalanine 2.5; methionine 1.3; tyrosine 0.7; and tryptophan 0.5 (Yang. 2016).

If you scrutinize the data in Figure 1 you will notice that the supplement was not a simple BCAA supplement, but rather an EAA supplement with a focus on BCAAs - with respect to the potential anti-depressant effects I've written about in previous articles this could  be a practically relevant difference. One you should think of before you start guzzling the human equivalent, i.e. 0.122 g/kg of BCAAs (e.g. if you weigh 80 kg that's ~10g) per day, of the amino acid dosage that was used in the study at hand.
To get to the bottom of effects, the gut microbiomes of the mice were analysed by 16S rDNA sequencing. Quantitative polymerase chain reaction was performed to identify Bifdobacterium spp. in the gut, and gas chromatography–mass spectrometry was conducted for faecal-metabolite detection - all to find out whether a BCAA-rich EAA mix would work any "magic" on the mouse gut - magic that could explain the metabolic effects scientists observed in previous studies.

Figure 2: OUT numbers for specifc bacterial groups (Yang. 2016).

It took ages (that's what 15 months are - in rodent terms, at least) until it became significant, but eventually, the BCAA supplement facilitated a statistically significant increase in the  OUT numbers for the specifc bacterial groups the scientists tested (Figure 2).
How's that? Well, it was not completely surprising that the results showed that "the structure of the gut microbiota changed, and BCAAem-supplementation in mice slowed the change speed of gut microbiota which is due to age" (Yang. 2016): a result that is in line with the age-specificity of many of the benefits of BCAAs scientists have observed in both human and rodent studies, where similar high BCAA amino acid products have been shown to help conserve lean mass and/or even extend the life of smaller animals - in a similar way as caloric restriction does. This doesn't mean that the other changes Yang et al. recorded were irrelevant, though: "

"In addition, the abundance of the Akkermansia and Bifdobacterium increased in BCAAem-supplemented mice, while the ratio of Enterobacteriaceae decreased in BCAAem-supplemented mice" (Yang. 2016).

These changes in the bacterial make-up of the lab animals, namely increases in the numbers of bacteria which are generally considered "healthy" and decreases in the numbers "unhealthy" enterobacteriaceae, could just as well (or even more likely) be responsible for the differences in a literal dozen of metabolites, representing sugar and lipid metabolism, the scientists observed when they compared the metabolome in the guts of the supplement to the control group.

Figure 3: Serum LBP concentrations in the two groups at 11 and 15 months (Yang. 2016).

Furthermore, the visibly significant difference in LPB (see Figure 3), the acute phase cousin of the pro-inflammatory LPS, i.e. lipopolysaccharides, that migrate from the gut where they are produced by "bad" bacteria through the gut wall to start their inflammatory and potentially auto-immunity triggering assaults in your body alone could make BCAA supplements interest for the elderly - and only for them! After all, the difference resurfaced only in the last months of the normal life expectancy of the lab animals in the study at hand.
References:

• Pitout, Johann DD, and Kevin B. Laupland. "Extended-spectrum β-lactamase-producing Enterobacteriaceae: an emerging public-health concern." The Lancet infectious diseases 8.3 (2008): 159-166.
• Yang, Zhan, et al. "Metabolic shifts and structural changes in the gut microbiota upon branched-chain amino acid supplementation in middle-aged mice." Amino Acids (2016): 1-15.