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The Analytical Zen Podcast
Biography and Research: See Orcid.org/0000-0001-8344-6582 (presenting 100+ academic works)
Dr. Geraldine M. Dowling SFHEA has over 20 years of experience in forensic and analytical toxicology, food safety, drug residue testing, method validation and ISO 17025 laboratory accreditation. She also has more than 10 years in academia as a university educator. She was past elected member of Academic Council at Atlantic Technological University and member of the Universal Design for Learning (UDL) Working Group. Her research spans forensic and clinical toxicology, with a focus on forensic medicine, clinical practice, drug testing, harm reduction and laboratory accreditation.
Dr. Dowling is an internationally recognized researcher and Senior Fellow of the Higher Education Academy (SFHEA), awarded for excellence in teaching, research, and leadership. She is the creator and host of The Analytical Zen Podcast, designed to make complex scientific concepts accessible to students and the public (available on platforms like Spotify, Apple Podcasts).
She serves as Vice Chair (formerly Treasurer) of the United Kingdom and Ireland Association of Forensic Toxicologists, representing forensic practitioners across England, Ireland, Wales, Northern Ireland, Scotland and the Channel Islands. She is also the elected regional representative for Ireland with the International Association of Forensic Toxicologists, a member of the Society of Forensic Toxicologists (USA), and an elected member of the London Toxicology Group Committee.
Dr. Dowling has trained professional staff and students in ISO 17025-accredited national government laboratories in Ireland, including The State Laboratory, Teagasc, and the Marine Institute. She is a Principal Investigator, supervising postgraduate students (PhD/MSc), with research interests in analytical chemistry, forensic science, clinical/medical toxicology, metabolomics, medicine, food safety and education.
Dr. Dowling contributed her expertise to the Irish Government's "Emerging Drug Trends and Drug Checking Working Group", which aims to introduce safer, harm-reduction strategies for drug use.
She is a contributing author, reviewer and editor for international journals, including Drug Testing and Analysis, Journal of Analytical Toxicology and Forensic Science Review. She has written, edited, and co-authored four books.
Dr. Dowling is Editor-in-Chief of the IACFT Journal and the Science Undergraduate Research Experience Journal.
She is nominated as a Honorary Professor at Kingston University, holds a Visiting Senior Lecturer appointment at King’s College London, UK and holds a Honorary Senior Lecturer appointment at Barts and The London School of Medicine & Dentistry, Queen Mary University of London, UK. She previously served as an Adjunct Assistant Professor at Trinity College Dublin and as a past Visiting Professor at the National University of La Plata, Argentina.
Dr. Dowling’s work has had a lasting impact, with Ireland’s Marine Institute using her methods in aquaculture monitoring since 2006 and the U.S. FDA adopting her research for drug monitoring since 2011.
www.linkedin.com/in/geraldine-dowling-msc-pgdip-phd-sfhea-2b66b835
The Analytical Zen Podcast
The Zinc Connection: The Pancreas, Diabetes and Beyond
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In this episode, we explore the connection between zinc and diabetes, focusing on functions of zinc in the pancreas and for blood glucose control. Using animal models of obesity and prediabetes, researchers investigated how mild zinc deficiency—similar to levels potentially seen in humans—affects the pancreas and regulation of blood glucose. The study found that a 30% reduction in pancreatic zinc led to enlarged pancreatic islets and poorer blood glucose control, especially during glucose tolerance tests. These findings highlight the significant impact even marginal zinc deficiency can have on the development and progression of type 2 diabetes. However, zinc supplements are not warranted unless someone is deficient in zinc.
Introduction to Dr. Carla Taylor
Speaker 1Welcome to the Analytical Zen Podcast, where we delve into the minds of leading scientists and professionals exploring forensics, toxicology, medicine and health in terms of mind, body and spirit. I'm your host, Geraldine M Dowling. What should you expect in the Analytical Zen podcast? Well, we dive into cutting edge research and topics that inspire curiosity, the latest in forensic and clinical toxicology pursuits, and engage in conversations and perspectives from disciplines outside of these fields. We're thrilled to have Professor Carla Taylor as our guest on the Analytical Zen podcast.
Speaker 1Dr Taylor is a professor in the Department of Food and Human Nutritional Sciences at the University of Manitoba and Principal Investigator of the Metabolic Nutrition Laboratory at the Canadian Centre for Agri-Food Research in Health and Medicine, or CCARM. She was Team Leader at CCARM from 2016 to 2022. Dr Taylor competed her Bachelor's Degree in Food and Nutrition at the University of Manitoba and her PhD in nutritional sciences at the University of Guelph. She had postdoctoral experiences at the University of Michigan and Arbor and the University of Washington, Seattle, before returning to the University of Manitoba in a faculty position. Her research programme investigates how dietary components such as lipids, proteins and bioactive compounds from plant, marine and animal sources may be beneficial for the prevention and management of metabolic diseases, particularly obesity, fatty liver disease and cardiovascular disease. Her research investigates potential mechanisms linking cellular, inter-organ and whole body metabolism, as well as application of findings to human health via clinical trials. Her research has been funded by multiple agencies such as NSERC, CIHR and several food and agriculture organisations and initiatives. Welcome Carla to the Analytical Zen podcast.
Speaker 2Thank you, Geraldine. It's certainly a pleasure to be here.
Speaker 1So, carla, having you this week on the Analytical Zen podcast is an absolute joy for me. Carla, how did you become interested in nutrition and nutrition research?
Speaker 2From a very young age, I was interested in what keeps our bodies healthy. I grew up on a farm and I was connected to food production. I participated in various sports and I was interested in physical activity and health. When I started university, I was not entirely sure what I wanted to do, but I knew that I like science, and it turned out that the science I really like is nutrition and understanding how our bodies function. When I was in undergraduate program and considering what I wanted to do next, I wanted to be able to understand nutrition research and to be able to translate research to the public. And years later it turns out my career is being a nutrition researcher.
Speaker 1Ah, wonderful. And how did you get interested in zinc research?
Speaker 2When I was exploring where I might do my master's degree and who I might work with, I soon found out that research that gets done is the research that gets funded. I was very fortunate to meet a potential supervisor, Dr Tammy Bray, who was very passionate about what she was doing, so I figured this was a great opportunity for me to learn about nutrition research. It just so happened that the topic was zinc. This was during the early days of research on nutrition, free radicals and antioxidant defense, so in retrospect I would say that zinc found me.
Speaker 1Ah, Carla, I love that. And what were the key findings from your dissertation then?
Speaker 2As I mentioned, we were investigating whether dietary zinc can provide antioxidant protection. We showed that zinc deficiency has to be present to detect free radical damage and that adequate zinc status protects against free radical damage. We also found that zinc supplementation does not provide any additional protection if the body already has an adequate zinc status.
Speaker 1It's a very fascinating topic, Carla. What are some of the other functions of zinc for our listeners?
Zinc Functions and Insulin Connection
Speaker 2Zinc is a component of over 200 metalloproteins. Zinc can be found at the active site of an enzyme or it can have a structural role in a protein. For example, zinc can bind to the sulfhydryl groups of certain amino acids, creating finger-like loops in proteins. We call these zinc finger proteins. Transcription factors can have these zinc finger loops and this allows them to bind to DNA. Another interesting aspect of zinc is that it binds to insulin. It's actually a component of the crystal structure of insulin, and insulin is the hormone that controls our blood sugars, or what more formally I will say, is blood glucose.
Speaker 1Wow, Carla, and how recent is that discovery?
Speaker 2Wow, carla, and how recent is that discovery? That discovery goes back quite a ways. The discovery of insulin was in the 1920s, and insulin was identified as being critical for understanding diabetes and its management, and subsequently, the scientists who studied the crystalline structure of proteins were interested in characterizing the structure of insulin, and this was accomplished in 1969.
Speaker 1So then, this is all related to zinc having a role in the management of blood sugars.
Speaker 2That is correct. As the science evolved, it was determined that zinc is required for the synthesis of insulin in the pancreas. Zinc is also associated with insulin when it is stored in the pancreas. When we consume food and our blood glucose increases, the pancreas secretes insulin into the blood, and this process involves zinc as well. At the same time, zinc is promoting insulin secretion. It is also inhibiting glucagon, the reverse hormone. Zinc is also involved in modulating various signaling pathways for glucose and lipid metabolism. These pathways and metabolic steps are comprised of various zinc-containing metalloproteins and metalloenzymes. Thus, there are many different ways in which zinc contributes to the management of blood glucose and how the glucose is metabolized by different organs and by various pathways.
Speaker 1So zinc is quite fascinating. Does this mean that there could be a connection between zinc and diabetes?
Speaker 2Yes, it does. There are reports in the literature of lower zinc concentrations in the blood of individuals who have diabetes. Other researchers have examined connections between the amount of zinc consumed in the diet and the risk of developing diabetes. For example, it has been reported that women who were in the highest quintile for dietary zinc intake had a 20% lower risk of developing type 2 diabetes. So this indicated that a higher dietary zinc intake lowers the risk for type 2 diabetes. Some meta-analyses suggest that zinc supplementation may be linked to improve management of blood glucose as well.
Zinc's Role in Diabetes
Speaker 2Research on zinc and diabetes in humans is limited to studying blood glucose control. To investigate the relationship between zinc in the pancreas and blood glucose, animal models of diabetes have been valuable, so the degree of zinc deficiency can be defined. We have been most interested in mild zinc deficiency, as this is more relevant to what humans might experience. In a study that I've conducted with my graduate students, we have shown that a marginal zinc deficiency in a rat model can reduce the zinc concentrations in the pancreas by 30%. This resulted in an enlargement of the pancreatic islets because they respond to producing more insulin to manage the blood glucose. And if we challenge these animals with a glucose load, so also called an oral glucose tolerance test, the rats have higher blood glucose concentrations than the rats without zinc deficiency. Thus mild zinc deficiency, characterized by a lower amount of zinc in the pancreas, worsens the blood glucose control.
Speaker 1And Carla. What happens then with zinc supplementation in the body, in animal models or in human studies?
Speaker 2Well, we have investigated the effects of zinc supplementation in a couple of different animal models of diabetes, of zinc supplementation in a couple of different animal models of diabetes. Putting more zinc into the diet elevates serum zinc and pancreatic zinc concentrations. During an oral glucose tolerance test there is somewhat better insulin sensitivity related to the function of the pancreas and the release of insulin. However, generally speaking, other diabetes-related parameters are not changed by zinc supplementation. There has been lots of interest in zinc supplementation in human studies. When I look at the results from these studies, it appears that zinc supplementation might be having a positive effect in individuals who have a mild zinc deficiency before they started the supplementation. But if someone has an adequate zinc status, there will not likely be any improvements. Interestingly, one of our challenges with zinc research in humans is that it's difficult to assess when there is a zinc deficiency.
Speaker 2Zinc is not like most other nutrients when there is a deficiency. Let's take iron deficiency as an example. There are many parameters based on the analysis of the blood and red blood cells to diagnose iron deficiency and specifically iron deficiency anemia. With zinc, it has to be a severe zinc deficiency to see a decrease in the plasma zinc concentrations. With mild zinc deficiency. Plasma zinc concentrations are maintained and it is the release of zinc from tissues such as the bones that are helping to maintain the plasma zinc concentrations In human studies. We do not have a way to non-invasively monitor zinc in bone or the pancreas. Thus we do not have a good way of knowing when there truly is a mild zinc deficiency in humans. And, given the name of your podcast, I should mention that atomic absorption spectrometry is how the analysis of zinc is done in plasma and various tissues.
Speaker 1There's a lot of talk in the media, Carla, about online supplements. Are there any risks with taking zinc supplements?
Speaker 2This is a very important question to ask and definitely there are risks, and this is a case where more is not better. In fact, taking high levels of zinc supplements for a period of time could create other imbalances and or deficiencies in the body, particularly with copper and likely with some other minerals. For example, in animal studies, when we supplement zinc at 10 times the normal amount in the diet, there is a substantial elevation of zinc in the blood and in the bones and in the pancreas. However, at the same time, it is reducing liver copper concentrations and in one particular study, zinc supplementation reduced the liver copper concentrations by 30% over eight weeks. That is going to have some significant effects on the functions of copper and if continued long term it will result in copper deficiency and the negative effects of copper deficiency. In humans. High intakes of zinc reduce copper status, alter iron metabolism and suppress immune responses. Thus, if zinc supplementation is being considered, the dose and the length of time it is taken are important factors. Zinc supplementation should be used by individuals who have suboptimal or deficient zinc status and they need to be monitored over the long term for the potential adverse effects.
Speaker 2Humans have a relatively small range of safety for zinc intakes In North America. We have the dietary reference intakes for nutrients. We have the dietary reference intakes for nutrients. The recommended daily allowance, or RDA, for zinc is 11 milligrams per day for men and 8 milligrams per day for women. The upper limit of intake for zinc is only 40 milligrams per day. Thus the upper limit is only about four times higher than the recommended intake. Compared to other nutrients, the adequate intake level and the upper limit for zinc is within a really small range.
Speaker 1And Carla for our listeners. How do high levels of dietary or oral zinc intake impact copper and iron in the body? Could you give us an analogy?
Speaker 2Yeah, here's an analogy. Let's say that there's a large crowd of individuals or molecules wanting to get into a stadium, and we'll pretend the stadium is a cell in our gut and that there are a limited number of entrances or doors into the stadium. The same as a cell has a limited number of transporters to move molecules in and out of the cell. One type of transporters on the cells in the small intestine prefers to let zinc enter the cell, but it will also let other divalent metals such as copper and iron to enter the cell as well. Let's say that someone is taking a zinc supplement and there are 100 molecules of zinc to only one molecule of copper and one molecule of iron waiting to get into the cell through the transporter. When those doors open or the transporters open, it's so much easier for all of those zinc molecules to flood in, and it's going to take time for one copper molecule and one iron molecule to get in through that same doorway or that same transporter, and thus there is a greater risk for developing copper and or iron deficiency.
Speaker 1Carla is food in the diet then a safe way to consume zinc?
Speaker 2Yes, food is our best bet. Consuming a healthy, balanced diet provides the nutrients we need, including zinc, because zinc is the constituent of all cells, both plant and animal cells. Whole grains and red meats are examples of foods that have higher amounts of zinc. Interestingly, oysters are a very concentrated, high source of zinc, and this reflects how oysters are able to accumulate zinc. However, that's probably more of a trivia fact, as oysters are not widely consumed.
Diverse Nutrition Research Areas
Speaker 1So, carla, what is it that excites you, then, about the types of research that you do?
Speaker 2Being curious and making new discoveries and new connections is what keeps me excited about research. I've been particularly interested in linking what happens at a molecular and cellular level with what happens at an organ level the communication between organs, and how that affects whole body metabolism. In the context of what we've been talking about today, I indicated how zinc impacts at the level of our genes and DNA that was the role of the zinc finger proteins how zinc is involved in insulin synthesis, storage and secretion from the pancreas, and then how zinc and insulin affect glucose metabolism in different organs and, ultimately, the whole body. I like to understand what is required for a healthy state, as well as the implications for development of diabetes, as an example, and the management of diabetes and other chronic diseases. I'm the type of researcher who likes linking all of these different levels together as opposed to being focused on a particular protein or a particular pathway. Maybe that's a consequence of being interested in nutrition. Nutrients affect our body at all these various levels.
Speaker 1It's certainly fascinating. It's like solving a crime and in a way, Carla, you're like the Sherlock Holmes of nutrition. What other topics do you work on, Carla?
Speaker 2There's been quite a few topics over my career. Today we chose to talk about zinc, and that's where my career as a nutrition researcher started. My research has expanded to different types of lipids, particularly the omega-3 fatty acids, and both plant-based and marine-based sources. More recently, we have been investigating high-protein diets and different sources of protein in high-protein diets for the management of metabolic fatty liver disease. We've done some research on different bioactive compounds. These are compounds that are not nutrients but have beneficial effects in the body. Our research on pulses, specifically different types of beans and lentils, which contain many bioactive compounds, has shown some positive effects for reducing cardiovascular disease.
Speaker 2Nutrition is multidisciplinary, and so is my research. I've been very fortunate to have collaborated with many people. Peter Zeraka and I have collaborated for many years. His expertise is biochemistry and molecular biology, and together our research covers the continuum of investigating nutrients and bioactive compounds from a molecular biochemistry and cell biology point of view, to effects on specific cell types and organs, to interorgan and whole body metabolism. This multidisciplinary approach, working with many different people whether it be students, trainees or collaborators who bring different knowledge, whether it be students, trainees or collaborators who bring different knowledge, ideas, concepts and skills to research makes research and science really interesting and fun, and our goal is to reveal information that's going to help people live better and live healthier.
Speaker 1Absolutely. It's wonderful to work with groups of people, carla, not just at the same institute, but globally, across different institutes, and I agree it makes it so rewarding and fun. So, carla, what are the biggest changes you've observed in nutrition research in your career to date?
Speaker 2There have certainly been advances in our understanding of how nutrients and dietary compounds operate at the molecular and cellular level in the body. What we eat affects the response of our genes and we all differ in our genetics. We still need to appreciate how much various lifestyle factors affect our health. I'm definitely interested in diet, but there are important roles for physical activity how our mindset and outlook on life having positive attitudes, being in positive environments affects our overall health as well.
Pulses and Bioactive Compounds
Speaker 2I think these days, nutrition goes beyond all the nutrients and research is being done on many other dietary constituents, including the bioactive compounds. Certainly, the analytical tools and equipment have evolved over the years, making it possible to identify and measure various bioactive compounds and metabolites in our blood and in our tissues. I'm glad to see that our focus has come back to whole foods and dietary patterns. Instead of the reductionist approach of thinking of a food or a diet in terms of its smallest individual components, we are appreciating that it's the package of nutrients and all the beneficial components that are in whole foods and in dietary patterns that are needed for promoting health. All this nutrition research is important. We are all making choices on a daily basis about the food we consume and how we are nourishing our bodies.
Speaker 1Carla, one thing that fascinates me when I travel is looking at local produce. Are there any interesting local produce foods that you're very excited about working on in the area of bioactive compound research?
Speaker 2Yes, the research that we have been doing on pulses and bioactive compounds. We have been very interested in the effects of different beans, for example, black beans, navy beans, pinto. The effects of different beans, for example, black beans, navy beans, pinto beans, red kidney beans. The different colors of the sea coats reflect the different complements of bioactive compounds in the different beans. We've been comparing different colored beans as well as green and red lentils. Colored beans as well as green and red lentils. What is interesting is that each of the colors may be linked to different beneficial outcomes. People like to ask me which one is best and which one would you choose. However, I think we need to incorporate all of the varieties and all of the colors, because they each provide slightly different benefits.
Speaker 1And so I guess that's why it comes back to having a variety in your diets is so important, Carla. Before we conclude, is there anything else you'd like to share with our listeners?
Speaker 2This has been a great conversation today, Geraldine, and it's been a pleasure to be on your podcast.
Speaker 1Thank you so much for your very valuable time and it's been great for our listeners to hear about this topic. Thank you so much for your very valuable time and it's been great for our listeners to hear about this topic thank you very much and to our listeners. Thank you for tuning in to another episode of the analytical zen podcast. Be sure to join us next time and stay curious.