What if the declines of aging are just the declines of taurine?

Note: I originally wrote this as an intro to a research proposal on taurine and glycine, as I discussed in my last post, but gave up on the research proposal. Decided to just put it out there instead.

You gain certain things as you age: ear hair, back aches, wisdom (maybe). You lose even more: head hair, muscle mass, fluid intelligence. This is known, as the Dothraki might say.

What’s not generally known is that you also lose taurine in your blood serum ¹ as you age. You will, on average, lose about 80% of your circulating serum taurine from age 0 to 60. You share this loss of serum taurine with age with mice and monkeys.

This loss is probably not alarming to you, compared to say, your loss of hair or memory. If you know what taurine is, you likely know of it as a nonessential amino acid. You may also recognize it as one of the random, mysterious non-caffeine ingredients of Red Bull, and, if you were a teenage boy around the early 2000s like myself, may remember it as the source of the rumor that Red Bull is bull urine.

Note: the taurine amount in Red Bull is way lower than the taurine amount used in longevity studies. It’s unclear if the taurine amount in Red Bull has any health effects. Also, supposedly, Red Bull just put taurine in their drink because the word “taurine” comes from “taurus”, meaning bull, and any actual health benefits are accdiental.

I think you should be more concerned about this loss, though. Taurine is nonessential as an amino acid in terms of not essential for humans to supplement, because we produce it endogenously. But it’s not nonessential in terms of humans not needing it. After all, there’s a reason we produce it endogenously. In animals that don’t produce it endogenously, like cats, taurine deficiency eventually leads to blindness and cardiomyopathy.

Nothing quite so dramatic as blindness can be conclusively linked to the decline in circulating taurine in mice or monkeys as they age. But, there are clues there are serious consequences to that decline, too. The same 2023 study in Science that showed the loss in taurine in aging animals also showed a significant increase in lifespan for taurine supplemented worms, zebrafish, and mice, and in the bone, glucose, liver, and immune systems of middle-aged monkeys.

This joined a host of smaller recent studies showing beneficial effects of taurine supplementation in humans, such as:

1. Taurine supplementation for prevention of stroke-like episodes

2. Taurine supplementation for reducing the risk for metabolic syndrome

3. Taurine supplementation for improving insulin response in patients with diabetes mellitus

What I find particularly interesting about this is that this isn’t a drug in the normal sense. It’s not even really a traditional supplement, like iron or vitamin D, which we’d normally get from our diet. It’s a partial restoration of our endogenous taurine to the levels of our youth.

I think this is an important distinction. Taurine, unlike most drugs or supplements, is basically impossible to overdose on for any species. Our body can support a wide range of levels of circulating taurine for an extended period of time, as the decline with aging shows. This makes taurine unique compared to what we’d normally consider as an anti-aging treatment.

Given all this evidence of the beneficial effects of taurine and its lack of side effects, you might be surprised that it’s taken so long for taurine to be tested in these diseases. After all, we’ve known about taurine since the 1820s, while these studies are all from the 2020s. What’s the cause of the 200 year gap?

There are a few factors that I think go into it. First is that even now it’s hard to tell what exactly taurine does. We know it’s widely distributed in the body and essential for life for a very wide range of organisms, but most of what it does is a mystery. The few functions that we are somewhat confident about are its role in ionic balance, especially in the retinal cells (hence why the deficiency leads to blindness), and its role in increasing the efficacy of bile acids through bile acid conjugation².

This bile acid conjugation brings us squarely to the second factor, which is that the fact that taurine is best known for bile acid conjugation has placed it squarely in the lineage of traditional Chinese medicine. Traditional Chinese medicine has used bear bile acid for centuries as a treatment for a host of ailments. Bear bile acid is high in TUDCA, which is taurine-conjugated bile acid.

The plus side of this is that this means there’s a lot of literature, both traditional and scientific, on the benefits of taurine in the context of bear bile acid. The negative side is that this literature is heavily motivated by the Chinese government’s aggressive pushing of traditional Chinese medicine for the past 70 years, making it hard to tell which papers are scientifically motivated and which are political. It’s easiest to just assume all these papers are political, leaving them in the ghetto of other politically motivated supplement papers along with the curcumin and ginkgo biloba papers.

Then the final factor is that taurine is a commonly available, cheap supplement. Nobody has a patent on it or even can patent it, given that it’s a natural substance. This is great for its availability, but bad for the commercial incentives to run expensive trials on it. There are a few nonprofit efforts (e.g. Vijay Yanav, the author of the article in Science, is running a 6 month trial in aged, healthy humans), but not enough.

I think there needs to be more research done on taurine. It’s a safe, cheap supplement. Any of the numerous, well-funded longevity companies should try verifying it themselves and see if it can have a synergistic effect with the interventions they’re already trying. Lord knows American academia shouldn’t have to shoulder this alone, given its current state.

1. Blood serum being blood minus blood cells and clotting factors. Basically, it’s everything in your blood except the stuff that makes it “blood”.

2. Bile acids help breakup and digest lipids going through your stomach. In order to do so, they need to be well mixed in solution with the food in your intestine. Taurine conjugation, or chemically attaching a taurine to bile acid molecules, makes the bile acids more soluble. Interestingly, a different amino acid, glycine, can also be conjugated with bile acids, although it’s less effective than glycine at keeping bile acids in solution.

Even more interestingly, the proportion of glycine vs. taurine bile acid conjugation varies between species, with humans having majority glycine-conjugated bile acids and cats having almost solely taurine-conjugated bile acids. I wrote about this in my last blog post.