How Gut Bacteria Influence Protein Bioavailability

You may have heard statements before, something like egg protein or animal protein is more bioavailable to the body than, say, peanut protein. And this is actually true and can be quantified with things like a DIAAS score or a PDC-ASS score. So sorry, peanut protein chewy bar, you are not a good source of protein, albeit for other reasons as well. But for the purposes of this video, you don't really need to know what those scores are. In fact, that's kindergarten level stuff compared to what I want to talk to you about. I want to share with you brand new research that even your local creatine-loaded PhD science Gym Bro won't know. It's about how microbes, microbes in our gut, impact protein amino acid bioavailability to the body, and also consequently how they can affect things like sugar metabolism in the body. So sit back, relax, but don't really engage because this is going to be exciting. We're going to talk about some cool new science and you're going to learn something. Welcome to my channel, stay curious. The paper is entitled Microbiota Metabolism of Intestinal Amino Acids Impacts Host Nutrient Homeostasis and Physiology. And the core hypothesis driving this research is pretty straightforward. Your gut bugs, your gut bacteria, get first pass at everything you eat. You eat, right? It goes into the donut hole that is the lumen of your gastrointestinal tract, and the gut bugs get to gobble up what they want before it gets passed on to your body. So variations in these gut microbiota will lead to potentially variations in how much amino acid protein building blocks get gobbled up before they get past your body. So to begin to explore whether or not this is true, they started in mice. And you do need to start in mice because they're easier to manipulate. What they found was that particular gut bacteria present in the mice depleted levels of amino acids, as shown in A, leading to less bioavailable amino acids and lower levels of amino acids in the serum, in the blood of the mice. So you see that here in A and B respectively, where in A you're looking at the amino acids in the intestines Each panel is a different amino acid. So ASN is asparagine, GLN is glutamine, so on, so on, so on. And the green bars represent the presence of these microbiota, and the gray bars are controls. And you can see in the green bars, the green state, there's lower levels of these amino acids. And then correspondingly in B, the serum levels are also lower. So again, showing that variations, presence of certain gut bacteria depletes amino acids in the intestines and also leads to correspondingly lower levels of bioavailable amino acids circulating in the serum, which is really interesting. But here's something you might not know about microorganisms. Those funky Latin names that scientists and researchers throw out left and right when they're trying to characterize the microbiome or microbiota only very loosely predict functionality of the strains because there's so much variation in the gut microbiome. So what you really wanna know is not what is the Latin name of a given gut bug, but what is the functionality of the specific gut bug? What genes harbored by particular microbes are exerting the effect and responsible for coding for proteins that deplete amino acids. What we care about is the genes within the microbes and the proteins they produce that deplete the amino acids, just to really hammer that home. So by way of kind of goofy analogy, like if you had two Nicks that are both Nicks, but one Nick was armed with a gene that is a bazooka and the other Nick is armed with a gene that is a slingshot, they're both Nick, but they constitute different threats, so to speak. So what they did next was really cool. They systematically went through and deleted gene by gene and combinations of genes from the different microbes. To try to show that if you knock out a gene, it eliminates the amino acid depleting ability of the bacteria, suggesting that that gene is important. And then really to prove that's the case, they can then add it back. It's called complementation, the gene they deleted. So they can take a knockout for a gene, then show that the ability to deplete amino acid goes away, and then do complementation, add back the gene and show that it is returned, showing that particular gene is what's important in depleting levels of a particular amino acid. So that's how they do it really systematically. It's a Herculean effort, but they indeed did it, and they were able to confirm that at on a single gene level, they could alter the intestinal and serum amino acid profile in mice, which is super cool. But that's not the end of the story, not nearly. Yes, it's true that amino acids are precursors to protein, therefore decreasing amino acid bioavailability could affect things like muscle protein synthesis, hypothetically. But amino acids are also precursors to signaling molecules and certain hormones. So for example, the large neutral amino acid tryptophan is a precursor to serotonin, a hormone. And serotonin produced by the gut, which is different than the pool produced in the brain, can affect large elements elements of host human physiology, or mice in this case. And so what they asked was, if we deplete certain amino acid gobbling bacteria in the gut, can it affect things like serotonin levels and then have effects on things like glucose homeostasis? And in fact, they found that was the case. So if they took mice and knocked out the tryptophan gobbling microorganisms, tryptophan levels went up, serotonin levels went up, and that had effects on glucose homeostasis on oral glucose tolerance tests, such that if you wiped out the tryptophan gobbling microorganisms, there was worse performance on glucose tolerance tests. And conversely, if you knocked out levels of other amino acid gobbling bacteria or amino acid class gobbling bacteria, so for example knocked out levels of branched-chain amino acid gobbling bacteria, then there might be better performance on oral glucose tolerance tests. So from this, I don't want you to overreach and say that tryptophan or branched-chain amino acids or serotonin are, say, good or bad per se. I think that would be overreaching, but the point is that by impacting amino acid bioavailability Far more can be changed than just the amount of substrate available for muscle building. You can affect large, broad swath of host physiology, and that is a big takeaway from this paper, which I think is super cool. And I'd also like to note, while you do have to do these particular experiments in mice, there is a high degree of probability that this is relevant to humans as well. So for example, metagenomic analysis of patients with type 2 diabetes who obviously have glucose intolerance versus healthy controls show differences and say the networks of genes in the microbiome controlling branched-chain amino acid metabolism. Again, you just can't do these fine-tune manipulations in human subjects. So that's that. Now, in closing, I want to boil this down to big picture elements and leave you with some practicals. So first, it's not just about the grams of protein you eat, but how your body handles that protein. There are many elements, many variables that impact protein handling, and the composition of your microbiome may be one of those elements. And microbiome-mediated protein availability affects other aspects of metabolism beyond just protein building. It affects things like glucose tolerance and probably lots of other elements of physiology that have yet to be discovered. Now I know you probably want me to give you a precise protocol to help you optimize your microbiome for the best possible protein bioavailability. Unfortunately, that would be going way beyond the data, so I can't do that. But at a very high level, I think one takeaway from this paper could be that it's important to mind your gut bugs because they really influence lots of elements of your metabolism. And this could mean avoiding the large group of foods kind of fluffily labeled as ultra-processed foods. So for me personally, that means things like preferencing eggs and steak and fish over, say, a Quest Bar or a NYX bar, which I just discovered was a thing, and I'm kind of ticked off that they stole my name. That doesn't seem fair. That's my name. Anyway, sorry I can't offer you more, but hopefully knowledge is also its own reward. Now, for kicks and giggles, tell me in the comments what your favorite protein is and how you plan on minding your gut bugs going forward. Peace, have a good day, and enjoy some protein.