 I've seen this methionine to glycine ratio being brought up a lot lately in the context of the carnivore diet and if I see another person sprinkle collagen powder on their steak and call it nose to tail eating, I'm actually going to have a stroke. Methionine and glycine are amino acids found in animal foods in pretty much ideal ratios as long as it's not super lean muscle meat. When we look at foods like oysters, liver, fatty steak, there doesn't seem to be any reason to consume excess glycine based on the ratios of methionine to glycine as well as the presence of serine, another amino acid, which is converted into glycine. Overall this relates back to my bone broth video. Your body synthesizes collagen from certain nutrients, vitamins, amino acids. When you consume collagen itself, it's broken down into amino acids. So from a mechanistic standpoint, if you want to increase collagen production, your best bet is to actually consume high vitamin animal foods like liver, not the collagen itself. You don't see people eating pork rinds or bacon for collagen, but that's essentially what a collagen supplement is akin to. To my understanding, the reason to supplement glycine is because of its involvement in the metabolism of methionine. If methionine is too high, it can be converted into homocysteine, and from my stroke video on Monday, we know that this can lead to high blood levels of homocysteine, especially if you're deficient in certain nutrients like vitamin B9, folate, as well as vitamin B12. These are contained inherently in animal products, more so in organs like liver. It's why we see vegans and vegetarians having higher blood levels of homocysteine. These high blood levels lead to oxidative stress, but why would we look at glycine to prevent oxidative stress as opposed to other vitamins that play a much larger role in the metabolism? High homocysteine is prevented through metabolism of homocysteine back into methionine through the methylation cycle, and this methylation cycle is also the metabolism of homocysteine into glutathione, an antioxidant. Now those vitamins we just mentioned, folate, B12, in addition to vitamin B6, are the most important in this cycle. Glycine plays a much smaller role. The body needs vitamin B6 for both the methionine cycle and the folate cycle, the folate cycle being required for methylation. In methylation, vitamin B6 is required for the conversion of homocysteine into ultimately glutathione, one of the chief antioxidants in the body. In the folate cycle, vitamin B6 is required for the conversion of the amino acid serine into glycine. In this study, it was shown that serine is about 20% more effective than glycine in methionine production, but when glycine is added to serine, it's about 20% more effective than serine on its own. So this study shows that both serine and glycine together are important, but there's nothing indicating that taking extra glycine is something required for this metabolic process. I think this idea was originally based off of a rat study where glycine was implemented into rodent diets and they saw benefits, but the rats likely did not have glycine present in the diet before, therefore they were deficient. What has to be shown is that ingesting extra glycine in the context of a diet containing adequate amounts is beneficial because we already obtained plenty of amino acids on a carnivore diet, not to mention a comparison between vitamin B6, B9, and B12 seem much more relevant here. So consuming glycine clearly doesn't make sense after looking at the metabolism, but technically glycine is not what people are using. They're using collagen. Collagen contains another amino acid, hydroxyproline. Only metabolism and turnover of collagen is normally the main source of hydroxyproline in the body, so when you consume collagen from foods, it's almost an unnatural amount. The majority of hydroxyproline is metabolized in the liver into glycine. The remainder of this hydroxyproline is converted into oxalic acid, aka oxalates, as well as glycolate, and these are excreted by the kidneys. This metabolism of hydroxyproline also requires vitamin B6. The pattern that we see here is that the body needs vitamin B6 to convert amino acids. The dosage doesn't seem to matter here. Low doses of gelatin also increased oxalate and urine. Oxalates combined to calcium greatly increasing risk for kidney stones. Now, you might be thinking, what about taking glycine on its own? It was actually shown in a study to significantly increase urinary oxalate above baseline. I am surprised though why no one was suggesting to take a magnesium glycanate supplement. It would have been a very effective way to get both magnesium and glycine on a diet that is apparently lacking in both, but reality is a lot of people on the carnivore diet have been doing well for very long periods of time without either of these supplements. So overall, sprinkling collagen powder on your meal would put stress on your body's vitamin B6 stores and increase urinary oxalate excretion. The reason I had to bring this up is because Paul Saladino commonly mentions that he supplements bone meal for calcium in addition to this collagen. And seeing as oxalates bind to calcium, this combination made me a little bit concerned if people are going to be at risk for kidney stones if they're using collagen and bone meal on a daily basis. And you can test this. If you're taking collagen and bone meal, you can actually get a urinary analysis for kidney stones and know if your diet is increasing the calcium oxalate crystals in your urine. This is why I don't really use studies without applying the native or indigenous context. There are many groups of hunter-gatherers that didn't consume collagen and certainly not calcium from bones. To say that they are necessary, let alone ideal, doesn't make sense in this native context. Every indigenous group consumed approximately 80% of their calories from energy sources, be it fat or carbohydrates. Sprinkling collagen powder on your steak is not making it an energy source, nor is it a solution to a high methionine content. It's just increasing the amount of glycine, whereas you would actually want to reduce the amount of methionine in your diet if you want to improve your ratios. The real solution here is to consume animal fat products for energy, whether it be actual raw animal fat, butter, cheese, bone marrow, egg yolks. These foods contain large amounts of vitamins that are directly involved in these important metabolic processes from a mechanistic standpoint. You can find studies associated with every single one of these vitamins having a significantly higher impact than glycine. Overall, I don't think consuming bone broth or a bit of collagen in a recipe for something is a bad idea. I actually think it's a good thing because most of the time you consume collagen, it comes inherently with vitamins. Bone broth is nutritious, stews and soups that have a high collagen content are inherently nutritious because the only parts of the animal we could have gotten collagen from in nature would have had a fairly significant fat-soluble vitamin content. I haven't seen any significant evidence that incorporating a collagen supplement into your diet is going to have a significant impact unless you are deficient in these amino acids. So thank you guys for watching. Please like, subscribe, hit that bell icon and share the video. If you would like to support the channel, guys, just check out a couple of the videos that I'm going to link at the end here. Do one on bone broth and a couple of other videos related to the carnivore diet. You guys enjoy the rest of your week.