Avocados have exploded in popularity over the past two decades. Per capita consumption of avocados has risen four fold, from 2 pounds in 2001 to nearly 8 pounds in 2018.
Why avocados have become so coveted is pretty obvious – they are super tasty! But that is clearly not the sole driver. Recent surveys suggest that around 3 out of 4 people who buy avocados do so because they are good for their health.
And avocados do indeed have a lot going for them, from that standpoint. Avocados are a good source of vitamins, minerals, and fiber. They also contain carotenoids, and have been shown enhance your ability to take up carotenoids from other foods. Adding avocado boosts absorption of lycopene and beta-carotene from salsa by 2.6-4.4 fold. Perhaps most notably, they are a rich source of monounsaturated fats and antioxidants, which seem to modulate blood lipids and keep your coronary arteries happy.
But some of the most compelling attributes of avocados can’t be found on the nutrition facts label, and remain to be fully elucidated.
For example, one study found that adults who consumed one whole avocado daily for twelve weeks showed significant improvements in a cognitive test designed to assess attentional control, compared to controls who ate isocaloric meals without avocado. But interestingly, why exactly the avocados had this effect remains unclear. The participants in the experimental group did show increases in serum lutein levels, which you would expect to be beneficial with respect to brain function. But the improvements in cognition were independent of rising lutein concentrations – suggesting that other unknown components of the avocado may have been responsible.
Researchers are continuing to untangle potential beneficial effects of avocados and avocado-derived compounds. And this goes beyond just healthy eating; it is possible that this line of investigation may eventually lead to promising medical interventions for the most common diseases of Western civilization.
Our guest for this episode is among those researchers.
On this episode of humanOS Radio, Dan speaks with Paul Spagnuolo. Dr. Spagnuolo has a PhD in Applied Health Sciences from the University of Waterloo, and is currently a Professor at the Department of Food Science at the University of Guelph in Ontario Canada.
His lab has been focused on identifying and developing nutraceuticals as novel therapeutic agents, and figuring out the molecular and cellular mechanisms through which these food-derived bioactive compounds influence cell biology. To that end, the Spagnuolo lab has created a unique, in-house nutraceutical library that is conducive for high-throughput screening. This is useful because it allows the lab to efficiently search for compounds with potent and selective toxicity against cancer cells.When screening this natural health product library for potential therapeutics, they discovered avocatin B, a mixture of polyhydroxylated fatty alcohols that is found exclusively in avocados.
Avocatin B was shown to have selective toxicity to leukemia and leukemia stem cells – meaning that it specifically reduces the viability of cancerous cells without affecting normal peripheral blood stem cells.
It is able to do this, seemingly, because it’s a potent inhibitor of fatty acid oxidation (FAO). Compared with normal cells, leukemia cells appear to depend more heavily upon FAO for survival, so it makes sense that interfering with this process would be a useful therapeutic target. But this property is especially intriguing because it could also make avocatin B a promising candidate as a drug to block or delay some of the cellular processes that lead to insulin resistance and diabetes.
Here’s why: We know that incomplete mitochondrial fatty acid oxidation is a key factor in skeletal muscle insulin resistance. In normal healthy individuals, fatty acid oxidation enables the body to burn fats. However, in the context of obesity or type 2 diabetes, this process is impaired, leading to incomplete oxidation, accumulation of free fatty acids outside of adipose tissue, and ultimately lipotoxicity and all the bad stuff that comes with that. No bueno.
Since we did all this work to tease out how Avocatin B works in leukemia…maybe targeting the same pathway in another disease state might result in some clinical utility. It was about five years ago that we embarked to answer that question: could Avocatin B inhibit fatty acid oxidation in an insulin insensitive state?
In theory, reducing FAO in skeletal muscle and in pancreatic beta cells would force cells to burn glucose instead of fatty acids. This boost in glucose oxidation would be expected to lower blood sugar levels and restore insulin sensitivity.
But of course, the only way to know whether it actually works is to put it to the test.
Paul and his team wanted to explore whether this avocado compound could indeed help with metabolic syndrome. To that end, they recently performed a series of experiments testing avocatin B in rodent models of obesity and insulin resistance, as well as a randomized controlled clinical trial in humans. To learn what they found, check out the interview below!
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Paul Spagnuolo (00:06): In two of the groups that were consuming the Avocatin B supplement, we did see a slighter reduction in their weight.
Kendall Kendrick (00:13): humanOS; learn, master, achieve.
Dan Pardi (00:28): Welcome back to humanOS Radio, everyone. Today, I am pleased to have Paul Spagnuolo on the show. Dr. Spagnuolo has a PhD in applied health sciences from the University of Waterloo, and is currently a professor at the department of food sciences at the University of Guelph in Ontario, Canada. His lab has been focused on identifying and developing nutraceuticals as novel therapeutic agents and figuring out the molecular and cellular mechanisms through which these food-derived bioactive compounds influence cell biology. Through their work conducting high-throughput screening, they discovered Avocatin B, a lipid found in avocados. Avocatin B is a potent inhibitor of fatty acid oxidation, and this property also made it a promising candidate as a drug to block or delay some of the cellular processes that lead to insulin resistance and diabetes. Paul and his team recently conducted a study testing Avocatin B in rodents and in humans to explore this possibility. And he is here to discuss his findings. Paul, welcome to humanOS Radio.
Paul Spagnuolo (01:33): Thank you for having me, Dan.
Dan Pardi (01:35): Tell us more about your background.
Paul Spagnuolo (01:37): I come from a very unique interdisciplinary background that started with an undergraduate and master's degree in food science. And that was actually at the University of Guelph where I am currently a professor. During my masters, I tried to understand from a physical chemistry perspective how the structure of these bioactive molecules imparts their function. From there, I went on to do a PhD in nutraceutical immunology, where I learned more about how these food-derived bioactive compounds, these dietary supplements or nutraceuticals as they're more commonly called impact immune function, and more specifically how these nutraceuticals are modifiers of inflammation as inflammation promotes colon cancer.
Dan Pardi (02:15): Nutraceuticals seem to be relatively overlooked as a source for health and medical therapeutics. Do you agree with that? And why do you think that is if you do?
Paul Spagnuolo (02:24): I do agree with that, but it might boil down to intellectual property, challenges of recovering the hundreds of millions of dollars that are associated with taking a drug, from idea all the way through to human use is also an issue in terms of perception, that the existing research in this area is just simply not sufficient enough to be looked at seriously. And unfortunately, there are just many examples of researchers and companies that exaggerate their research for personal profit. But I do want to point out that nutraceuticals are actually strongly linked to a history of drug development, so it becomes important for us to have a true balanced perspective that these molecules can definitely be beneficial, but they can also be detrimental. We need to be as systematic and as unbiased in our assessment of these molecules as possible. 80% of chemotherapeutics right now are naturally derived.
Dan Pardi (03:15): Did you say 80%?
Paul Spagnuolo (03:17): Correct. So they could be either derived from microbes, they could be derived from natural plants or barks of trees and that kind of thing. Very high percentage do originate from natural sources. If you look at some of the [inaudible 00:03:30] therapeutics for the treatment of several diseases, you have incretins, you have [inaudible 00:03:34], your Taxol, your cytarabines, they're all naturally derived.
Dan Pardi (03:37): Let me do a little summary here. Many of the therapeutics that we have derive from natural products. The process of drug discovery, however, is very expensive. And if you can't develop intellectual property that protects your research and allows you to capitalize on it at the end of the day, then it's hard to continue to pour money into it if it ends up just being something for the general good, which in itself is frustrating. On the flip side of that, you have an industry that will do a few studies, usually in-house, that then exaggerate the marketing claims of their product and that creates issues on that side of the equation.
So overall, you have the somewhat frustrating situation where there's a ton of potential, but there's also poor incentives on both sides of the development side, and then also on the commercialization side. I'm glad that you're taking a very rigorous approach so that we understand what's working and why. Much of your current research revolves around a compound mixture called Avocatin B, which I mentioned in the introduction. What is Avocatin B?
Paul Spagnuolo (04:37): It's a bioactive compound found in avocados. Chemically, it is very unique in that it is a 17 carbon polyhydroxylated fatty alcohol. I know it's a mouthful. And so nature likes even numbers for many reasons that we can get into, but for the process of fatty acid oxidation, it likes even numbers, so that's what makes this compound partly unique, because it's a 17 carbon molecule. It actually comprised of two molecules that differ just based on the terminal and saturation, which provides various functional properties. It's also an alcoholic, not necessarily an acid so it's different from your conventional fatty acids, and it's polyhydroxylated so it has a very unique structure to it as a whole. And so it's in part because of all of these unique features that provide its bioactivity.
Dan Pardi (05:22): So it's found in an avocado, and how much Avocatin is found in a single avocado, and does that amount vary? And if so, what are the factors that will determine how much of this is in one avocado to the next?
Paul Spagnuolo (05:35): We worked with the Hass Avocado Board because they were also interested in this. And in order to do this, we had to develop enough at first. And so we went off, we set off to do method development to be able to detect this molecule because we needed to quantify it quite sensitively. We actually tested just Hass avocados and the part that we eat. And we were actually surprised to find that an average avocado can contain anywhere between 50 to 100 milligrams of this molecule, which is quite a substantial amount.
The thing that we always want to stress though, is that what we have learned through our years of research, particularly this project, is that how this molecule is found inside the avocado means that it's not necessarily that if you consume one avocado, you will get 100% of the Avocatin B inside it, but it has to do with how the human body digests these types of products and how it's found in its native form. Fast forwarding into our clinical trial work, when we developed a supplement based on this molecule, we really needed to understand those nuances in order to create something that would in essence, translate some of this impressive benchtop work into our clinical work.
Dan Pardi (06:44): The Avocatin B is found in the parts of the avocado that we eat, but it's also found in the seed and in the shell as well.
Paul Spagnuolo (06:52): Correct. So the initial discovery of this molecule back in the 1960s was actually identifying it in the pit or the seed of the avocado. And it wasn't until we quantified this molecule directly in the compartment that we eat, which is the flesh of the avocado.
Dan Pardi (07:10): Originally, Avocatin B came across as a potential treatment for leukemia. Tell me what the process was there for you to discover this and start to investigate it further.
Paul Spagnuolo (07:19): Utilizing that pharmaceutical drug discovery platform is really important because it's truly an unbiased assessment. So my lab possesses a unique chemical library we have in our hands, a thousand different types of nutraceuticals, food-derived bioactive molecules. And we use this drug discovery platform to systematically screen these molecules. And by asking ourselves a very simple question at the beginning, which is the most active of these nutraceuticals, we then set up our experiment, ensure the proper controls, and then we let our analysis decide what the best molecule is. So we didn't at the onset say, "What's the best avocado molecule out there?" We said, "Of these thousands of molecules that we have in our hands, which one is the best?" It just so happens that through that scientific process, we discovered Avocatin B. That was in a context of which molecule is the best at killing these leukemia cells.
We spent five years trying to understand at a cell and molecular level, how does Avocatin B impart this very potent antileukemic activity? What we determined was is that it inhibits the cellular process [inaudible 00:08:28] fatty oxidation. Leukemia, the cells' metabolism is rewired such that it depends on fatty acid oxidation for survival. So if you inhibit it, the leukemia cells die. If you inhibit it in a normal cell, the cell can adapt and survive. This becomes a mechanism by which I have Avocatin B imparts this unique antileukemic activity, through which we then translated that work into insulin resistance because our knowledge of the cancer, the altered fatty acid oxidation can be inhibited in leukemia cells, we thought, "Are there any other disease states that are mediated by the same cellular process?"
Since we did all this work to tease out Avocatin B works in leukemia, maybe targeting the same pathway in another disease state might result in some clinical utility. It was about five years ago that we embarked to answer that question, could Avocatin B inhibit fatty acid oxidation in an insulin insensitive state?
Dan Pardi (09:27): So skeletal muscle insulin resistance is in part due to incomplete mitochondrial fatty acid oxidation, or at least that's a key factor there. If Avocatin B is then suppressing fatty acid oxidation, how does that change the fuel source that the cell is using? And then ultimately what's the hypothesis for then how that would be improving insulin sensitivity and hyperinsulinemia?
Paul Spagnuolo (09:50): Right. So in terms of the mechanism, and it's obviously controversial, as most things are in academic literature about the real mechanism behind insulin insensitivity. But I share your view in that incomplete mitochondrial fatty acid oxidation is a key contributor. And what can happen in periods of lipotoxicity, That's when you're consuming high amounts of fat, you have incredibly large amount of circulating free fatty acids that the body needs to process because they can in turn become toxic. As the mitochondria are attempting to, with an influx of these massive amounts of fatty acids, incomplete fatty acid oxidation can have significant downstream detrimental effects to the host. One of the features is you might get locked in this metabolic inflexibility whereby the cell is constantly trying to burn and burning efficiently fatty acids. That creates lipotoxic intermediates that could have significant detrimental effects in the mitochondria.
What we have been able to show with Avocatin B, being able to inhibit fatty acid oxidation, you're essentially able to switch the way in which the cell burns fuel. Instead of trying to force it to burn fatty acids, you shut it off with this inhibitor, forcing the cell to burn glucose instead. And that itself results in more glucose utilization then restoring insulin sensitivity.
Dan Pardi (11:14): You did a mouse study to test this. Tell us about that. And what did the structure of that study look like?
Paul Spagnuolo (11:19): We did a lot of cell culture work to define this mechanism as well and that provided us with a strong platform to then explore this in animals. And so we had 30 mice divided into three groups, and the first group were given a regular standard diet. For 13 weeks, they consumed typical diet whereby over the course of the experiment and in the course of even their lifespan, they will under normal circumstances not develop any metabolic disease. So insulin sensitivity is normal, glucose tolerance is normal, blood lipid profiles are normal. They don't overeat cetera. We then took second and third group of mice and we fed them high fat diets. This is actually quite standard in literature, and you find this routinely, where you give them a diet that's about 60% fat in comparison to the 5% fact that the control group gets. So you see that we're giving them a high, high, high amount of fat here.
And what ends up happening over the course of a few weeks is that they started to gain a lot of weight. And over the course of eight weeks, we used as a good marker, we saw that they became incredibly big, very obese, and they were insulin resistant and glucose intolerant. So it was that this eight week mark then took these two groups, we gave one group a placebo and another group the Avocatin B. So twice a week for five weeks. And so at end point, what we found was that in the mice that were getting the Avocatin B, they had lower body weights compared to the group that was getting the placebo. They were much more insulin sensitive and glucose tolerant. And so if you compare the Avocatin B treated group to the placebo, we saw that they had significant improvements in all of their pathophysiological markers.
Dan Pardi (12:55): Body weight, fat pads, improve glucose tolerance, there definitely seem to be a clear effect here. And why twice a week versus daily?
Paul Spagnuolo (13:03): It just so happened to be the schedule in which we put together. The ideal scenario would be a diet fortified with this or then giving it as a supplement. But in this case, we injected it directly into their stomachs.
Dan Pardi (13:17): Were there thoughts and considerations around there possibly being too much of an effect if it was injected daily, or that wasn't the consideration for the twice a week injections?
Paul Spagnuolo (13:26): So we've obviously, since we've been running experiments where we've created diets where mice will get this every day, and this particular experiment came a little bit from our knowledge of how the gastrointestinal system will break it down and the longevity of the molecule and circulation based on its accumulation in certain key tissues. And so based on some of that knowledge, we decided to go twice a week for five weeks.
Dan Pardi (13:51): You also performed a pilot clinical study of humans to assess the effects of consuming of Avocatin B. Tell us about the structure of the study.
Paul Spagnuolo (13:58): In this case, we had three groups, a placebo group, and then two different groups receiving two separate doses. Healthy human participants were given a powder, imagine a big whey protein tub filled with a formulation that we created to contain standardized doses of Avocatin B. So the placebo obviously had zero [inaudible 00:14:18] and then two doses, one at 50 milligrams and another one at 200. And so the participants in this case were asked to consume a smoothie containing a fixed amount of the powder every day for 60 days.
Dan Pardi (14:31): About how much is 50 milligrams in terms of amount of avocado and how much is 200 milligrams?
Paul Spagnuolo (14:37): Based on just pure numbers, not taking into consideration some of the bio availability factors associated with the consumption of an avocado, the 50 milligrams would be equivalent to half an avocado a day, whereas the 200 milligrams would be equivalent to two avocados.
Dan Pardi (14:54): Now you did some work on safety first, what did you find?
Paul Spagnuolo (14:58): We wanted to take all of the work that we had done and our knowledge of Avocatin B to create a product that we received Health Canada approval for. The Health Canada is the FDA equivalent. And so in Canada, to get these products approved, we require special approval, much like you would a drug in the U.S., and we would need it here for this natural product. And it was important for us to be able to translate some of this benchtop work that we could translate into some human results.
And so really, that's the first step of the scientific process in terms of understanding how this product was formulated, can it get into the bloodstream of these individuals? Is it well tolerated? So do they like it? Is it absorbed in the body? And so we answered all those questions. It didn't result in any detrimental side effect in terms of its accumulation in the blood. It had no dose limiting toxicity, that's the pharma talk in that there was no marker that we measured that was altered as a result of people consuming this. And that the way we formulated it was we were able to detect it in the blood at concentrations that we wanted to see it at.
Dan Pardi (15:58): Talk about some of the body weight changes that you measured.
Paul Spagnuolo (16:01): We saw the participants regularly and were interested in tracking their body weight throughout the course of the study. It was in part as just part of the protocol, and it was actually interesting that we did notice that in two of the groups that were consuming the avocado based supplement, we did see a slight reduction in their weight. It wasn't a statistically significant value, but again, we didn't power the study in order to see this effect, because the primary mandate of this study was to ensure that how we formulate the molecule, we could get the bioactive in the blood and not see any negative effect on any blood markers. So it was powered for that and that purpose. But of course, we were all curious about whether or not this molecule could have an effect on that and we did see a slight reduction. It provided us with a very solid foundation moving forward about how and what we want to look at for our next studies.
Dan Pardi (16:57): Speaking about what's next, what is on the horizon? What's next for your lab? And are there plans to commercialize Avocatin B?
Paul Spagnuolo (17:04): I don't know if I had mentioned this, but my lab has been working on Avocatin B now since 2012. So this has been a culmination of eight plus years of blood, sweat, and tears to understand the bioactivity of this molecule. Its physical chemical properties, how the human body processes it, and now we see the biological activity and then the potential of this bioactive molecule, we're being able to restore cellular metabolism in diseased states. Based on all of this, we are launching a product for consumers to be able to have the access to these benefits that we've discovered. But research continues and so we are very much interested and driving forward to look at the real world impact of the product and ensure that it continues to the normal process of scientific rigor.
And of course, as a researcher, who's driven by discovery-based research, I'm very much curious in understanding its potential more in diseased states and how we might be able to develop this molecule as a therapeutic for some diseases that desperately need new therapeutics. And so taking it through that scientific process is something that I continue to write grants for and chase funding for. And so that's definitely something that's on the horizon.
Dan Pardi (18:14): Are there other compounds, like for example, mannoheptulose in avocados that also might be contributing to a positive effect on blood sugar regulation, weight control? Or do you have an opinion about whether or not Avocatin B is a substance that is contributing to the majority of the effects with avocados, if they exist?
Paul Spagnuolo (18:36): The avocado is a very good source of multiple different nutrients and the Avocatin B is by no means the only bioactive found in avocados. But the link between avocados and weight management is something that is not new. Certain groups have done some eloquent studies that have looked at avocado consumption and weight management. For us it becomes important to separate ourselves from that because what we are really talking about here is not weight management as a primary driver of this metabolic activity. The benefit is from restoring altered metabolism, secondary outcome to that might be an improvement in weight. That becomes something that is really important for us to distinguish because the science of what we are doing is really trying to correct altered cellular metabolism that is central to various different diseased states. So whether there are other molecules in avocados that might have an effect on that metabolism, we don't know. And whether or not there are other molecules in avocados that have a great impact on weight management, we're not sure.
Dan Pardi (19:42): And if you're dealing with a clinical condition and you have the ability to test a very specific element of a food product and show metabolic benefits that could improve the situation, in that clinical situation, you're able to be more prescriptive and say, "With our standardized pill, we see these results. The higher dose of Avocatin B had more dropouts at the 30-day mark and the 60-day mark." Do you think that that was due to a side effect or was it random chance?
Paul Spagnuolo (20:10): One thing that we did notice in the very high dose, 200 milligrams, three participants developed a skin rash shortly after starting their trial. After a week of terminating the supplement use, the rash went away. One participant continued on the trial, I believe for a month and then without any issues and dropped out. And the other ones just said they're not interested which we understood. The higher the dose didn't taste very well, so there was an issue there.
So that's why reformulation took place immediately thereafter to improve the palatability of the molecule. There was also some solubility issues at the high doses. You were getting chunks of powder in your palate, which was pretty disgusting. And so once we got away from, "Wow, we were just interested in dosing people and getting the bioactive in and people can just plug their nose and swallow it." That was cool. From a commercialization perspective, they thought, "No." So we went to a lower dose that was very well tolerated from a palatability perspective, and then just improved the formulation for tastes. So that's all been removed as the trial and error process happens.
Dan Pardi (21:12): You don't have the perfect product from day one oftentimes. A lot of those commercialization issues are solvable problems once you get enough budget behind the product. Where in the United States, the audience for the show is global, when do you think that this'll be available to people?
Paul Spagnuolo (21:27): As we sit here in the middle of a global pandemic, the timelines are obviously significantly affected. We're really hopeful that it was going to be already happening, but with some of the delays, we're hoping that it will be out and available in the summer of 2020, but it will be available online right away. And then I guess for anyone who's interested in learning more about the product, where we're going with it, and we do have a website where they can go and that's www.metavo.com. So it's Metavo for the Avocatin Be in the metabolic effects. People are interested in learning more about what we've done and what we're going to do, and about the product itself, that website will provide some information for people to keep them up-to-date.
Dan Pardi (22:12): Paul, thank you for coming and talking about your work, Avocatin B, and this possibility of it being important therapeutic and the state of where it is today. So we appreciate your time in coming on to the show.
Paul Spagnuolo (22:27): Thank you for having me, Dan.
Kendall Kendrick (22:50): Thanks for listening, and come visit us soon at humanOS.me.