Today, we’re taking a deep dive into one of the lesser known ingredients of mainstream supplements and energy drinks: glucuronolactone, and its sibling glucuronic acid.
We’ll begin by taking a look at glucuronic acid and what it does in the human body, and then we’ll pick apart its close relationship to glucuronolactone.
Finally, we’ll examine the theory around glucuronolactone as a dietary supplement and investigate whether or not it lives up to the hype.
What Is Glucuronic Acid?
Let’s break the term apart. We’ll start with the prefix ‘gluc-’, as in glucose (sugar). As for the ‘-uron-’ in the middle of the word ‘glucuronic’, yes, it’s a reference to urine. Glucuronic acid was first isolated from the urine of dogs, and urine is where this specialized sugar does its most important job.
You see, glucuronic acid is a part of the excretory process of human metabolism. The work begins in the liver: this is the organ responsible for processing everything we put into our bodies - byproducts and metabolites of processed foods, pharmaceutical drugs, and so on - that can’t be put to good use. Glucuronic acid binds to these waste products in the liver (a process called glucuronidation) to make them more water soluble, so that they can then be excreted from the body via the urine.
That’s a bit technical, so let’s put this in simpler terms. Imagine you’re washing the dishes. If your liver is the dirty dishes, then the waste products in the liver are the food gunk that’s left over on those dishes. Running hot water over these dirty cups and plates isn’t enough to get them clean. You need to remove the gunk from the dishes with a soapy sponge, and you need to remove the gunk from your liver with glucuronic acid. So glucuronic acid is part of how your body cleans itself out. For this reason, glucuronolactone supplements have been advertised as detoxification agents.
Wait, glucuronolactone? Weren’t we talking about glucuronic acid just a second ago?
Yes, we were. The two are very closely related. Of the two, glucuronolactone is the one sold as a nutritional supplement and more likely to be found in the ingredient list of an energy drink. This is because the human body doesn’t know what to do with glucuronic acid taken by mouth. Glucuronolactone is used in supplements because it is much more readily absorbed in the digestive tract than glucuronic acid. Once the glucuronolactone is consumed, the body transforms it into glucuronic acid. As it turns out, your body would rather take the extra step of processing the glucuronolactone than make use of orally ingested glucuronic acid.
Are Glucuronolactone Supplements Genuinely Effective In Improving Human Health?
The honest answer is that we don’t know. There simply hasn’t been enough research on the efficacy of glucuronolactone supplementation on the human body. So, here’s what we do know:
First of all, gluconic acid is intrinsic to the human body. It is manufactured endogenously - meaning that the human body produces it on its own - and a genuine deficiency is unusual.
Second, glucuronolactone occurs naturally in the human diet, but only at around 2 mg per day - a very small amount (the notable exception here being wine, which contains 20 mg/L of glucuronolactone). By comparison, the quantities of glucuronolactone in energy drinks and nutritional supplements are in the vicinity of 1200 mg per day, some six hundred times the amount consumed through normal meals.
That’s a huge increase! Is that… is that safe?
Well, maybe it is and maybe it isn’t. Again, there has been very little research exploring the possible side effects of large doses of exogenous glucuronolactone on the human body (or on any bodies, for that matter). Furthermore, most of the research that has been done used energy drinks with glucuronolactone alongside a host of other ingredients, as opposed to research using glucuronolactone in isolation.
So, who knows. Maybe it’s a very effective nutritional supplement. Maybe it has a whole host of toxic side effects yet to be discovered. Maybe both these things are true at once. Maybe neither of them are. Nutritional scientists will likely have all the answers we seek someday soon, but for right now, we are almost entirely in the dark.
Here’s some of the research that actually has been done. The 1968 Tamura study found that rats injected with glucuronolactone and forced to swim to the point of exhaustion had more endurance than a control group. In a much more recent study, rats with liver disease given glucuronolactone demonstrated lowered inflammation and increased levels of antioxidants in the liver. In contrast, Ahren et al found in 1987 that supplements of glucuronolactone and glucuronic acid had no impact on the lifespans of lab rats.
Those are just a few of the available rodent studies. But do rats and humans process glucuronolactone the same way? It’s a subject of debate, and some would say they do not. In which case, even if glucuronolactone is proven to be safe for rodent consumption, it will still be unclear whether or not that tells us anything about human consumption.
So, how about the studies on humans? In 1960, a study was performed on six humans given glucuronolactone and glucuronic acid, and no harmful side effects were recorded. And then we have… nothing.
As of autumn ‘22, there have been no definitive studies on the potential toxicity of glucuronolactone in humans. As it is present in small amounts in a normal human diet and easily processed and metabolized by the human body, some believe the supplement is unlikely to be dangerous.
On the other hand, the large doses contained in energy drinks far eclipse the small amounts present in food and drink. Glucuronolactone’s LD50 (lethal dose) in humans is unknown. It has not been approved by the FDA for medical use, and therefore there is no official recommended dose.
Okay, But Does Glucuronolactone Actually Increase the Potency of Energy Drinks?
Take a look at the list of ingredients on the back of an energy drink, and you’ll find six syllable textbook words and mysterious plants gathered from exotic locations. What is the purpose of this elaborate alchemical recipe? Does this delicate balance of chemical compounds unlock the previously inaccessible secret powers of the ingredients?
Probably not. Most energy drink ingredients appear to be simply window dressing. We’ve already discussed the common energy drink ingredient taurine (and why we don’t use it) in a previous entry of the Proper Wild blog. There’s no good reason to put taurine in a caffeinated drink, and there appears to be no good reason to put glucuronolactone into one either.
Which is why Proper Wild does not add glucuronolactone to our energy shots. If there were hard evidence pointing to the power of glucuronolactone supplements to improve performance and activate a sleepy nervous system, things would be different. But that evidence has yet to be discovered. Until then, Proper Wild will stick with clean ingredients backed by science, and leave the unhelpful but eye-grabbing additives like glucuronolactone, taurine, and so on for someone else.