Our mitochondria make half a liter to a liter of deuterium-free water per day; hooray! We make low-deuterium fat only from mitochondrial citrate
Cameron Borg: "At complex IV [in mitochondria], oxygen meets with protons and electrons to make metabolic water. I don't think many people would think that we make our own water, but we absolutely do. And more than that, it's deuterium depleted, as you say, because there are these complex gating properties of these proteins that make sure that deuterium is excluded to a certain extent. And I want to know from your perspective, I don't know if we know this, but to what extent is that gating optimized? Is metabolic water ideally zero deuterium, like we could imagine the matrix of a mitochondria with absolutely no deuterium? Or is there a small amount that gets through that's sort of permissible for optimal function still?
László Boros, MD: "Yeah. So we only make about, like, half a liter to a liter of new water each day, and that has to be in the complex IV in mitochondria. We make water in some other ways, but it's not as significant to the amount as what we turn over, meaning that really practically, you're adding a little bit of deuterium-free water on top of what you circulate or exchange every day. That's about just like calculating in a very reserved kind of a view, we are turning over about 7 m³ – 7.5 m³ water a day. And it's easy to calculate because that's how blood you rotate through your heart. It's several cubic meters, meaning that really it's a very dynamic system. Now new water is added, and that new water is deuterium free, and it actually dilutes into the water that we drink, and the water that we produce through glycolysis, and so on, because there are other processes. So in fact those are very important regulatory mechanisms to gate out deuterium and add some water to the water amount that we circulate and recycle.
"But more importantly, the water that we add through our mitochondria, through fumarate hydratase and so on, fumaric acid and other intermediates of the TCA cycle, especially citrate through shuttling, will become part of your fat pool, meaning that's how you synthesize your fat. You shuttle citrate out, which is already using matrix water, deuterium-free water, for fat synthesis. So you can actually produce a low-deuterium substrate source, which are fat or hydrocarbons that you can use in your mitochondria very efficiently for energy source.
"As an energy source, if you eat a ketogenic, animal-based, highly saturated fat, long-chain saturated fat-based diet, that has to be low in deuterium simply because you synthesize those from mitochondrial citrate. And there's no substitute for that process either. You cannot produce fat from any other source other than mitochondrial citrate, so that seems like that's by design as well.
"So it seems that mitochondria discriminates and gates deuterium not only simply for deuterium-free water synthesis, but also for low-deuterium fat synthesis or adipose fat like ketone synthesis that preserve mitochondrial ATP synthase in another species that consumes that low-deuterium fat. So it seems like it doesn't start with mitochondria and it actually goes in the very bottom of the food chain that we eat that this deuterium discrimination or regulation or regulatory processes. So for that matter this is a more complex issue, but the bottom line is that practically as long as you produce matrix or mitochondrial water from low-deuterium animal fat, then your mitochondria has a much easier time if you live in latitudes or longitudes that actually have lower deuterium in the environment."
László Boros, MD with Cameron Borg @ 54:36–59:26 (posted 2025-09-23) https://youtu.be/DmuO5uFuAcE&t=3276