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REPLAY: The Zeitgeist of Zinc with Emma Sutherland and Rachel Arthur

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REPLAY: The Zeitgeist of Zinc with Emma Sutherland and Rachel Arthur

fx Medicine ambassador Emma Sutherland talks with one of our professions most respected naturopath and nutritionist Rachel Arthur.   

In the first part of this candid conversation, Rachel shares the origins of her passion for natural health and the series of opportunities that lead her from new practitioner to industry leader. Rachel’s advice for new practitioners - say yes to everything early in your career. She also discusses an industry weakness - one that might surprise you! 

Emma and Rachel then shift gear and get into the intricacies of zinc prescribing. Together they unpack the origins of zinc, highlighting that despite the wealth of research about this nutrient, we are still in our infancy in our understanding of its myriad of functions in the body. Rachel also shares the key systems that clinically benefit from zinc supplementation, as well as a scaffolding to best determine what form to use and when. The discussion culminates in the challenges around the validity of upper tolerable limits, and best practices for dosaging that is in line with recommendations in the research. 

This episode is packed with clinical pearls, a must listen for all practitioners regardless of your understanding of this commonly prescribed nutrient.  

Covered in this episode

[00:32] Welcoming Rachel Arthur
[01:54] Rachel’s journey as a practitioner
[04:37] Saying yes to opportunities 
[08:41] Filling gaps and needs in the industry
[10:18] Splitting time between a multitude of interests
[13:41] Knowing our self worth as practitioners
[17:59] Exploring the story of zinc
[24:42] Areas zinc shines as a treatment
[27:55] Prescribing: Form follows function
[33:39] Prescribing: Dose follows form
[35:56] The evidence regarding upper tolerable limits and copper deficiency
[41:54] Timing and techniques of dosage for optimal absorption
[49:50] Excess zinc in the lumen affects gut microbiota
[55:45] Rachel’s Nutrient Prescribers Program
[59:10] Thanking Rachel and final remarks

Key takeaways

  • Rachel’s advice for practitioners: 
    • Say “yes” to as many opportunities as you can early in your career. It will lead you places you never considered. 
    • Know your self-worth. Australian naturopaths and nutritionists are being recognised as leaders on the world stage and our confidence in our prescriptions and ourselves should reflect this.  
  • In addition to being required for over 300 enzymatic reactions in the body, it has recently been discovered that zinc stabilises cellular components such as plasma membranes, and acts as a secondary messenger. We are still in our infancy in learning the extent of functions of zinc in the body.  
  • Consider using zinc clinically in these three ways: 
    • Periods of growth, particularly in pregnancy and children. Also in poor hair and nail growth, and poor wound healing. 
    • Immunity – every possible aspect of immunity. 
    • Gastrointestinal health – zinc is critical for eubiosis and the health of our gut microbiome. It also assists in reducing intestinal permeability and helps repair gastric lining. 
  • Form of zinc changes function and dosage. To determine what form to use, be clear about your therapeutic treatment objective and then follow the recommended form and dose put forth in the literature. 
  • The upper tolerance limit (UTL) of zinc has been debated by researchers and the evidence that too much zinc causes copper deficiency is patchy. 
  • Like iron, long term high doses of zinc can have a negative impact on the gastrointestinal microbiota composition. 
  • For optimal absorption of zinc without giving your patient nausea and vomiting: 
    • Mimic the low pH of the stomach acid. Zinc requires a low pH to become soluble. This can be done by using lemon juice or apple cider vinegar. 
    • Avoid taking zinc with high fibre and high phosphate foods. 
    • Do take zinc with protein such as a protein shake without milk, or with a meal that includes animal protein. Zinc binding to the amino acids histidine, cysteine, and  lysine improves absorption. 

Resources discussed and further reading

Rachel's website
Rachel's Nutrient Prescriber's Program
Research: 'Impact of the discovery of human zinc deficiency on health.' (Journal of the American College of Nutrition, 2009)
Research: 'The accuracy of the Zinc Taste Test method.' (Journal of alternative and complementary medicine, 2012)
Article: Your Burning Zinc Questions Answered (Rachel Arthur Nutrition)
Article: Zinc's Dark Side (Rachel Arthur Nutrition)


Emma: Hi, and welcome to fx Medicine, where we bring you the latest in evidence-based integrative, functional, and complementary medicine. 

fx Medicine acknowledges the traditional custodians of country throughout Australia where we live and work, and their connections to land, sea, and community. We pay our respect to the elders past and present and extend that respect to all Aboriginal and Torres Strait Islander peoples today.

With us today is Rachel Arthur, a widely published naturopath and nutritionist with a special interest in diagnostics. With over 30 years' experience in both the clinic and the classroom, she is considered a leading nutritional educator, delivering post-graduate training and mentoring to doctors, pharmacists, dieticians, naturopaths, and other health professionals.

Rachel shares her wealth of knowledge, generated from thorough research and ongoing clinical experience via a multitude of platforms, including podcasts, mentoring programs, live appearances, and her extensive online digital resource library. As you will discover, she is a truth seeker who does things differently. 

Welcome to fx Medicine, Rachel. Thank you so much for being with us today.

Rachel: Oh, thanks, Emma. Great to be here.

Emma: Now, today, we're going to explore your time in the industry over the last 30 years, and we're going to learn from your extensive experience and then we're going to pick your clinical and research brain by taking a deep dive into one of the most commonly prescribed nutrients in clinical practice, which is zinc.

Rachel: I'm excited. I’m very excited

Emma: Me, too. But to, sort of, kick things off, can you share with us how you first decided to become a naturopath? What influenced that decision and where did your passion for natural health come from?

Rachel: Well, like you, I love hearing people's versions of how this started for them because they're all so different, aren't they? I wasn't somebody who visited a naturopath first, I have to say. I didn't know it was a job or a career. I was sort of heading towards science, generally, when I was in high school and leaving high school.

When I look back though, I can see that the influences were there. Like my mum, far from being a hippie, but she was very health conscious. I remember the bottles of pills on the kitchen table, everything was handmade, all the food. She was very attentive to health and nutrition. So, when I looked back, the influence was definitely there.

I was more the hippie than she was, left home, hitchhiked up the East Coast - this is a true story. So, I end up in Byron Bay in my gap year, and I end up not just discovering that you could be a naturopath but sharing a house with someone who was a naturopath.

So, it was like, "Oh, that's a thing? Oh, okay. Well, I love science. I'm kind of interested in health. You know, maybe when I'm done gallivanting around northern New South Wales, I might come back and study this thing called naturopathy," which is what I did.

There's lots of, sort of, twists and turns in there. I do love that, at first, my application to study at SSNT was rejected, which I love to remind them of all the time. I always say, "What was it about me that you thought I wasn't going to be a good student or a good naturopath?" But, anyway, that’s the short version of that story of how I ended up studying naturopathy.

Emma: Really interesting. I always eally enjoy hearing those, sort of, preliminary pathways and how they form. 

But can you talk us through how did you build your brand within the healthcare sector? And can you give us a couple of examples of some opportunities that presented?

Rachel: Well, I mean, like you said, 30 years, so you fit a lot into 30 years. And I won't bore us with all the detail, but I think you've hit something right there in terms of using that term "opportunities" because I certainly didn't start out with a vision about where I was going to end up.

Like everyone else, I was so passionate about what I was learning, and I was so thrilled about private practice, because it is such an exhilarating part of what we are trained to do. So, I was working in a health food store towards the latter part of my training, and I continued to do that when I graduated and then they opened up a consulting room, so I started to practice from there. 

I ended up going back to study because I was actually looking to qualify to get into medicine. The arrival of two babies, sort of changed that plan. So, once I had my kids, I'm in my early 20s. I'm still in private practice. I worked for a year for a pharmaceutical company. I then move across into a supplement company where I'm working in field technical support. And then probably when I move into my 30s is when I start picking up casual lecturing and I also started tutoring at Monash Uni in the medical degree. They were all, kind of, just opportunities that arise. Again, I didn't have that idea. They sort of popped up and I seized them.

Probably the biggest turning point for me was when someone that a lot of your listeners will know, Liza Oates, approached me, and she was already helping Lesley Braun with the first edition of Braun and Cohen. And Liza said “We need more researchers. We need more writers. And I've mentioned your name to Lesley.” So, obviously that started a really big new chapter of being a writer, being a researcher, and opened up a lot of doors from there.

So, I spent the first few years while I'm doing my thesis, actually working extensively in the corporate health field. Picked up work at the university as a research assistant as well, doing lots of research and writing, not only for Braun and Cohen but also there was a journal around at that time called Journal of Complementary Medicine.

Emma: Oh, yeah.

Rachel: A lot of people might know. Yeah, I was one of the frequent contributors to that. 

It goes on and on. Eventually, Southern Cross University went, "All right, you're not bad. Yeah, you can teach." And so I end up teaching and supervising there at Southern Cross until about 2012 when I finally went, "That's it. I'm done. I'm done working for other tertiary institutions." And, again, it wasn't my vision to create my own brand of education or to step out independently. It always comes from other wiser women, I've got to say.

So, it was someone else who was watching me often doing the corporate circuit where I was speaking on behalf of other companies, supplement, or service provider companies. And she said to me, "You know what? You should record these.” Famous last words. And so that was around about that time, about 2012. And so basically, I did start recording things. I launched the Update in Under 30 series and started delivering my own mentoring program. And basically, I've been doing the same thing ever since.

Emma: Yeah, and I feel that you have a good eye for picking a market need and filling gaps that are there.

Rachel: I hope so. I mean, I think it comes from being fortunate enough to have lots of conversations, lots of touch points with people in our profession. So, if I'm group mentoring, I'm constantly paying attention to what's going on for people. What are their strengths? What are their challenges? What are the gaps? What are the needs that aren't being met?

And so I'm just really paying attention to that and then thinking, "Well, is that something I can do something about?" And Emma, there are a lot of conversations I have, you’d probably be surprised how much of my time is taken up with me contacting other people and saying, "You know, there's a need here.  I'm not the person who can meet this need, but I might reach out to variety of my contacts who I think are better positioned to help our profession." It's a real privilege, but it is something that I feel obviously passionate about. I think that, as a professional group, we do need ongoing support in a variety of ways. We have more than we've ever had. But, yeah, I'm always sort of chipping away, trying to bring other people in and see if we can bolster that even further.

Emma: Which is brilliant because we do need more support. I mean, there's various ways to get it, but we could always do with more. 

One thing I think about, as such a busy person or doing lots of different things, how do you split your time? And how do you find a sense of balance between all your projects? Because I know a lot of practitioners wear more than one hat, and it would be great to get a couple of tips from you on this.

Rachel: I think I probably am of course very still diverse and divided in how I spend my time now. But when I look back, it was really my 30s and my 40s when I was bringing up my kids single handedly and I was doing all those things that I mentioned before like working as a research assistant, writing for the Journal of Complementary Medicine, writing for Braun and Cohen.

I always say that there was a period in my career where I just had to say yes to everything. And I do say that to upcoming practitioners and graduates. If you can, just saying yes to whatever opportunities come your way is a good thing early in your career. And it is dizzying because of course, that's a lot of different roles like you just said. And I think it's appropriate that I say that that was a period that's a bit of a blur or all of those things. Extremely busy. 

I think now I feel that a little bit later in my career, I now have the privilege of saying no. So, I don't need to say yes, and I choose not to say yes to everything, and I have that opportunity for a little bit more discernment. So I can be a little bit more focused and not split my attention quite so much.

I think there is a question now for me whenever the opportunities do come up where I think, "Well, in how many ways does this give back?" So, either does it give back to the profession, yes, but in how many ways does it deliver to my business or something like that?” So, that probably sounds quite strategic, but I think you have to be. You get to a certain point that you have to be very strategic about the finite amount of time, and energy, and resources you have. When you're done saying yes to every opportunity and you're on that other side where you're trying to really, I guess, streamline things and work in a way that's not working harder all the time but working more effectively.

Emma: Mm, and I love that piece of advice of saying yes to every opportunity in the early stages because my thing was always “Say yes and then work out the how later.” And it's amazing how your skillset gets stretched like a rubber band because you have to learn new skills in order to deliver what you've said yes to. So, I completely concur with that. It's scary but it is such a growth opportunity.

Rachel: It is. And I think that stretching like a rubber band is such a good metaphor because there's a number of situations I found myself in thinking, "Oh, well, I guess I'll work this out." That did, as you say, really stimulate growth. And I could then add more skills to my skill list. I go, "Okay, I can do that” 

Emma: I love that. Now, what I think is that you have a unique lens on the industry. And I'd love to do a bit of a zoom out and ask your opinion on how do you feel our industry is tracking as a whole. What are our collective strengths and our collective weaknesses?

Rachel: I think maybe I have one sort of set of responses to us as a profession and then a separate set of responses to the industry side. So, I would, kind of, put that line between them being in the related industry like products and service providers and things like that.

If I'm looking at us as a profession, I think that there's this one big, persisting challenge. And it was there when I graduated, and I think it's diminished a little bit, but it's still certainly present with recent graduates. And that is, I think, a challenge of knowing our own worth. And, I mean, we've got this extraordinary paradox going on. If you think about what is involved in our training, many of us can itemise that it's effectively the first couple of years of a medical degree and then some. Then it's all the modality-specific knowledge, then it's supervised clinic and what have you.

And I think that we know that at a micro level and even at a macro level, if you look particularly at Australia and New Zealand, the quality of our training, the quality of our graduates and where we sit on the global stage, we are right up there. We are right up near the apex. We are considered leaders, that we are really progressive in our approach to naturopathic medicine, all of those sorts of things. And that has been really showcased, particularly, I've noticed this year, at some of those big international conferences where we've got this incredible almost overrepresentation of Australian researchers, and educators, and clinicians.

And so I think, if we can remind ourselves, because I don't think we all are born with innate self-worth, and I think that naturopathy has had this kind of underdog identity lurking around it for a long time, where people go, "Oh, yes, but it's on the edge. It's still being considered fringe by some." But I think that, when I look around and I look at a lot of my peers who I regard as being highly successful and these are in really different or divergent fields.

So, whether that's private practice or academia, creating their own products, or working in the corporate space, I look at these people and I think “They know their self-worth, or it isn't apparent that they question the quality of their qualifications." And I think that that confidence that they've had, not only in our medicines but also in themselves, is what's really probably contributed substantially to their success.

Certainly some people have more confidence than others, but I think we have to actively work on fostering it within the profession and within ourselves. We really need to keep giving ourselves a little slap on the face and going, "Hang on, I've done the training. I've done x number of years of this number of medical units. I am incredibly well-versed and well-equipped." I think probably that is the biggest thing that I think we're still tackling.

Emma: Yeah. And that's also where mentoring can be very helpful to remind ourselves of what an incredible dynamic profession we are.

Now, I know you have a very big interest in diagnostics, and you're really skilled at interpreting pathology. When you did your honours at Southern Cross Uni, which congrats, you got first class honours. That's very amazing. Your thesis was titled, "Zinc Assessment in Australian Naturopathic Practice: Its influences, methodology and perceived validity."

So, I want to deep dive into this very commonly prescribed nutrient, and I have to say, in researching this episode, I found myself in such a rabbit hole of zinc literature. There was so much more out there than I even realised. 

Now it is one of the most widely prescribed supplements in clinical practice due to its very diverse range of indications. And after iron, it is the second-most abundant micronutrient in the human body. It's estimated that up to around 17% of the global population is at risk for inadequate zinc intake. So, it's something that comes in front of us all the time. And we know that zinc is ubiquitous. It's utilised in more than 300 enzyme pathways. 

So, I guess my question, Rachel, is where do we start this zinc story? I know you love using caricatures and stories to help ground what can sometimes be seen as tricky science. So, maybe you can reacquaint us with this mineral from a different perspective.

Rachel: Well, I mean, like you said, I wrote a thesis on it. We were just working out how long ago that was. That's scary. And I was mentioning to you just before that writing that thesis meant that I literally was reading zinc research every day for about 18 months. So, it is extraordinary, like you say, to...you said you've learnt so much and I'm sure you knew a lot already, but just by doing a quick refresh where you're like, "Oh, gosh, that's new."

And I guess one thing that helps us to not become frustrated by the dynamism of zinc but recognise that it is a fait accompli, something that has to happen, is how recently it was discovered. So, not the element but the discovery that it was essential for humans only occurred in 1964. So, I think about zinc as really being the newish kid on the block. The only micronutrient that was discovered subsequent to zinc as being essential was selenium in the 1970s. That means that we are genuinely in our infancy of really understanding zinc, who zinc is, how they operate.

And the way that I think about zinc is I talk about zinc, the zeitgeist. If you go back to the original definition of zeitgeist, which is not really the way we tend to use it now, it was an invisible agent or force that dominates the characteristics of something. And I feel like that term really encapsulates so much about zinc, because as you said, it’s everywhere. That often cited quote of being a component of more than 300 enzymes, that's actually the tip of the iceberg, because zinc, in addition to that, is a key stability factor in structures. So, it stabilises other cellular components like our plasma membranes. 

We have come to discover that zinc is also a very recently discovered second messenger. So, some of us know second messengers like calcium, for example, and how its engagement with receptors on cell surfaces trigger mechanisms inside the cell that then basically convey the messages that neurotransmitters or hormones are trying to send. Zinc is one of those.

So, we just go, "Oh, the 300 enzymes? That's just the beginning.” When we say ubiquitous, we really mean ubiquitous. It is everywhere. It has a finger in every single pie. And that's why its disease associations are so insanely long, and the signs and symptoms associated with a deficiency of it are so broad but also ambiguous at times.

So, to speak to the other element of zeitgeist, which is this invisibility, right? A zeitgeist is an invisible agent. Zinc is, to quote that old ad, a slippery little sucker. It's really hard to track and trace. And you can think about that in really literal terms like trying to measure it. That's what my thesis is on. That's what people have been trying to refine since the 1980s, and we're not there yet. We still find it impossible to measure, impossible to find a reliable marker of it.
And this is because we have such tight control of zinc in a way, and it's such tight regulatory control at a cellular level. But also this invisibility, I always think about zinc as kind of being here today and gone not quite tomorrow, but unlike iron, which it's constantly compared with, for good reason as you've mentioned, we don't have stores. We do not have active stores of zinc. So, while we've said the whole body, not just anatomically but physiologically, relies on this micromineral, this trace element. We don't have active stores of that. So, it, kind of, gives us that sense of vulnerability and fragility of status in a way.

Emma: It is just so complex. It really is related to everything from gut to immune to mood to... I mean, literally everything. 

Can you let us know where you see zinc having particular benefits and in what conditions do you see it as a bit of a go-to or where it particularly shines, I guess, is what I'm trying to work out.

Rachel: Yeah, and I think that probably is the way - where it shines. I think if we go back one, I think you said, "Where does it make sense or where would it be your go-to?" I think there are three key tenants. 

The first is growth because let's never forget that that's how we discovered zinc was essential to humans. It was a medical graduate traveling in Iran, Prasad, who was aware of stunting, and he was like, "Look at all these people that are really abnormally short." That's how we discovered zinc's essentiality for humans.

Now, we go, "Well, we're not seeing stunting, because we know we're not as a population in Australia generally." But how do we recognise impaired growth? It's really easy at the pointy ends, so think about it. Intrauterine growth retardation. We know zinc deficiency is a major issue behind that. We know that zinc deficiency is a major influence in kids that have failure to thrive, that just aren't quite meeting their growth landmarks. They're the easy ones to spot. In the rest of us, kind of, middle-ground dwellers that aren't at a pointy end of growth, it's poor hair growth, poor nails, poor wound healing. That's what we have to look for.

The second kind of landmark feature I would say is immunity, and that is every possible aspect of immunity. So, obviously this is zinc's largest claim to fame outside of stunting because we know from zinc interventions all over the world, particularly in developing countries, that just ensuring people are zinc-adequate is on par with clean water in terms of preventing infection, and surviving infection, and things like that.

And the third key area would be gut. And this is becoming, as the gut is, so complex. This is a big area for zinc that is very multilayered and multifaceted. So, we know zinc adequacy is critical for eubiosis, but we know that it offers so much more. It reduces increased gut permeability. It helps repair stomach lining in terms of gastritis and ulcers and so on and so forth. 

I think where it shines, maybe I'd throw in mental health in there. In addition to what we've talked about, I'd probably put that in as an extra.

Emma: It's hard to know where to stop, isn't it? It really is but I think the gross immunity, and gut primarily, and then mental health. It's nice to, sort of, set some parameters around where it should particularly pop up in our brains when we're working with patients. 

In my time in clinical practice, it has been so confusing to know exactly what form to use and then what dose to prescribe. Can you talk us through the various forms and then highlight which ones you think are the best to use and why? Because honestly, the forms, the types, more and more keep coming across my knowledge base, and it is confusing.

Rachel: Yeah. I think this is a really common source of confusion, and I think this is one of the big things that I've been trying to address in creating this Nutrient Prescriber's Program that we're just building for 2024, which is the way we've been taught nutrition is we get taught about zinc like as a entity that exists on its own. But what we have to remember is that the form changes the function. And the dose obviously, there's that wonderful quote, which I'm going to butcher, which is something, whether something's a medicine or a poison is all about the dose, that Paracelsus said. Form and dose change everything.

So, in this Nutrient Prescriber's Program, we're trying to give people a method for formulating nutritional prescriptions, because I think that's where people just feel like they're falling off a cliff. They go, "Well, I know zinc is needed." And they're right. And then they go, "But what form and what dose and at what time of the day would you administer that?" 

So, the place that we start with the framework that we're using in NPP is we start with application. So, the question is, "What's your treatment objective?" And really getting people to be crystal clear because sometimes we do a lot of hand waving about therapeutic objectives. “We'd like them to have more zinc.” No, no, no. So, what are you actually saying? Are you saying that you need to meet a shortfall that is there in their diet, that they're unable to redress with their food choices, or do you have something more explicit? Is it about immunity or is it about gut? What is your treatment objective or objectives?

So, we have to start with that because that is the strongest first indication of form, what form you're going to use. I mean you think about it. You know this, I know this. Lots of our listeners will know this. If I want to work on somebody's stomach lining, I'm going to use zinc carnosine. And zinc carnosine will be medicinal but lots of other zinc forms would actually be meddlesome. They would be problematic in that stomach. So, that is such a great example. 

Or, if I want to reduce the severity and duration of an upper respiratory tract infection, I'm going to use zinc gluconate as a lozenge very specifically because I know that that will directly release the zinc ions in the nasopharyngeal area and have a direct antiviral action. But do I use zinc gluconate when I want to treat hyperbilirubinemia? No. Do I use it when I want to treat gastritis? No. So, I think that we have to start using a framework that helps us to methodically answer these questions.

So, we start with application. What's your treatment objective? And then we look to the literature for guidance about what form of zinc is best indicated in that. The most common application, of course, and the burning question for a lot of people is what about when it is just a shortfall? What about when it's not a specific indication like that? 

Well, this is the great source of frustration, right? Because we're all using zinc salts, just a variety of different zinc salts. So, whether we're using zinc sulfate, or we're using a zinc chelate like a citrate, or a picolinate, they're all much of a muchness. They've all got their strengths and limitations, and there are certain areas where they shine, and there's certain areas where you go, "Oh, I probably..." If someone's prone to nausea, we're not going to give them zinc sulfate, right, because it's the strongest emetic form of all zincs.

So, I think we're really desperate for innovation in the area of mineral supplements. There's a lot of research going on. There's a lot of research that has the runs on the board where zinc and other minerals, are being presented as diene tripeptides. That shows superiority. And there's some really easy ways to understand why that would be so much more effective, so much more bioavailable than a zinc salt or a chelate. So, I think hopefully we're going to see them come onto the market.

Emma: Yeah, and, look, for now, the framework of first of all, focusing on what is your treatment objective and then matching the objective to the form with the knowledge that the form changes function. I think that's something that, if we can all keep that in mind, we're going to be steps ahead. 

Rachel: Absolutely.

But when it comes to dose, I mean, looking at labels, it is confusing. Can we just, kind of, get on the same page with that first? Because when we're talking about elemental zinc, each of the various forms of zinc contain different amounts of elemental zinc, which refers to the weight of the zinc molecule itself. So, a label might state zinc citrate 95.8 milligrams, but that's equivalent to 30 milligrams of elemental zinc. Now, when it comes to therapeutic doses, what do you recommend?

Rachel: So, it follows the same principle, which is I'm getting people to refine their thinking and be really explicit about what their therapeutic objective is. And then we see that form follows, because it dictates function, and then that will also dictate dose. Because if we go back to what we were talking about before, if we were using zinc carnosine for gastritis, you and I might use 15 milligrams of elemental zinc. And we might use that twice a day. We might use it three times a day, but really it's quite a low dose compared to some other applications and different forms. 

Because if you follow the, the evidence-based protocol for upper respiratory tract infection, where you use those zinc lozenges, you're getting up around 100 milligrams a day, and that's effective. That works a treat. And no one is suggesting for a second that that's excessive. I know you and I might talk about excess zinc a little bit later, but it is about what you're trying to achieve. So, I think that we just have to go back, and we have to follow those steps. What's the therapeutic objective? Therefore, what's the application? Therefore, what's the form? What does the evidence support? You're basically being led to dose very clearly if you take that path.

Emma: Yeah, which is very reassuring. And looking at the literature for this episode, it's very clear what doses do get the outcomes that you want to replicate in your patients. 

Now, one thing that worries me, zinc is in a lot of supplements, and many practitioners and people that self-prescribe often don't recognise that cumulative dose when taking multiple supplements. And zinc has an upper tolerable limit set by the NHMRC with specific reference to the potential that high-dose zinc may induce a copper deficiency. So, can you just speak to that? And then how can we identify when zinc is too high? I mean, what would we see as clinicians?

Rachel: It's such a good aspect to cover I think. Look, the upper tolerable limit is hotly debated, and this is hotly debated internationally by very highly respected researchers, leaders in zinc, kind of, thought. The upper tolerable limit in Australia, as you mentioned, is set at 40 milligrams for adults. And depending on the age of the child anywhere from 5 milligrams for under one-year-olds but often around 10 to 20 milligrams for primary school children.

So, the hot debate that's going on on an international level is that the evidence that too much zinc produces copper deficiency is really patchy. It certainly has been demonstrated, but there are many instances where it hasn't. And so that's the thing that continues to further discussion or prompt this kind of reflection. I think one big misunderstanding is that in the studies where excess zinc supplementation did appear to have a negative effect on copper status, it wasn't that it lowered copper levels in the blood. It was that it produced, if you like, change in functional markers consistent with copper impairment. 

So, that's things like your neutrophil count dropping, your platelet count dropping. Potentially your HDL is dropping because copper is quite a tricky beast itself, and it can have quite a Machiavellian or, kind of, really hard to pin deficiency picture that tends to emerge differently in different people. And certainly those serum copper and plasma copper levels are not the be all and end all of reflecting copper status.

So, that's the first thing to say. We do need to be on the watch for that. I have seen it. So, I have actually, unfortunately, had a few paediatric patients who were treated by someone else or DIY-dosed by mum or dad, and they were given excessive amounts of zinc over a period of time. And I've seen the neutropenia and the thrombocytopenia. And actually in a couple of kids, I've actually seen the serum copper drop very low because copper should be really high in kids. It's incredibly important for kids as part of their neurological development to have very high copper. So, we should be on the lookout for it. We shouldn't put all our eggs in the basket of just monitoring serum copper. We should be watching those kind of white cell counts and platelets, etc. 

But the debate is that zinc in excess doesn't reliably do this. It just doesn't. So, it's like we've always got to be watchful, and this probably just supports people's empirical experience, which is but it often doesn't happen. And the researchers have, sort of, refined their way of talking about zinc toxicity. They say things like, "Look, let's be clear,” the only time where this was demonstrated, because they've tried to induce zinc toxicity through diet drastically high dietary zinc intake levels, and they can't do it. The patient never gets there. The only time that there has been this negative effect on copper has been in adults taking 50 milligrams of elemental zinc for weeks. So, the research is saying, "Well, let's just be watchful. Let's be mindful, but let's perhaps not be hysterical."

And the other thing that the researchers are arguing for is to lift the UL in kids. Now, they have a very strong argument to do this because the RCTs that have been done in paediatric populations using zinc at higher doses than the upper tolerable limit have generally proven to be safe and proven to be successful. So, I know I'm kind of speaking in riddles because I am saying watch those kids really carefully. I've seen a few that have absolutely been over treated, and copper needs to stay high in kids. And these researchers are not saying give them the sky is the limit, but what they are arguing is there has never been evidence in a paediatric population at a scientific level that zinc will reliably have a negative effect on copper. 

So, they're just saying, yeah, those ULs, they sound like they're written in stone, but maybe they need to be a little bit higher than where they are and we need to be clear about the level of evidence."

Emma: Really interesting. And once again, it does present more complexity than simplicity, which makes it challenging. But I do think that we need to look at that cumulative dosing, the length of the treatment. For me, I'm very mindful in clinical practice about how long somebody has been on these higher doses and that sometimes it's good to take a break from that. 

But I want to talk about the timing of the zinc dose, because when you read about it, so we need to be away from phytates. It's great given with meat, or fish, or proteins, and take it away from oxalates. I mean, sometimes it just gets really confusing on that front. Can you simplify the timing of the dose for us?

Rachel: Oh, gee. I've worked hard to try and simplify it, Emma. I'm not sure I get there because like you, I know too much. And I go, "This is difficult." 

So, in some ways, the answer's easy, right? The answer is really easy. You're going to laugh. Because if you look at all the evidence, the evidence says for optimal fractional zinc absorptions, that means your highest bioavailability factor, your highest uptake rate, you should just have zinc as a supplement, as a liquid in particular, on an empty stomach. And you and I go, "Someone's going to get punched, and it's going to be the practitioner that recommended that," because we know that all forms of zinc are gastric irritants and that gastric irritation can quickly progress to nausea and vomiting. And we know that that's a surefire recipe to bring that on in susceptible patients. 

So, we go, "Oh, okay." So, probably not going to recommend that to my patient even though, on paper, that is the ultimate way to maximise uptake and use least dose, best dose and all that sort of stuff. So, really what we need to do is break down the elements of why that scenario is ideal and think about how do we get close to that. 

Emma: Yeah.

Rachel: So, the reason why that scenario is ideal is because the first step of digestion of a zinc supplement in terms of all the forms we use at the moment, chelates and salts, is solubilisation. And solubilisation requires a really high stomach acid, or a very low pH. So, we know that our stomach acids is at its highest when our stomach is empty. We can approach that perhaps in patients. We know that we have certain things we can use like lemon juice and apple cider vinegar and things like that that mimic or approach that very low pH. So, maybe we employ those sort of things around the time of zinc dosing.

We know that the reason why zinc ideally should be taken on an empty stomach is because zinc is always finding Mr. Wrong. Zinc once it becomes solubilised, which means it becomes a free ion, just zinc hanging out on its own, it will very quickly hook up with other entities like the phosphorus in phytates that you mentioned. That's in nuts and seeds and fibre and whatever. Or it'll hook up with calcium, or it will hook up with an oxalate, or, or, or.

So, again, we go, "Okay, all right, not going to recommend my patient does this on an empty stomach but certainly will not be encouraging them to have zinc around these kinds of fibrous, high phosphorus sort of foods." We can try and get zinc to hook up with Mr. Right rather than Mr. Wrong, which follows your idea, which is provide it with amino acids. So, favourable amino acids. 

So, there is something in both zinc and iron literature that has been such a fascinating preoccupation for lots of clinicians and researchers, which is how these minerals are so radically more bioavailable when consumed in animal food. And it's not just the absence of phytates. It's something that we call the “meat factor.” But what we think that meat factor really is, is very particular amino acids. And those are histidine and cysteine, especially. To a lesser extent lysine, that zinc likes to bind with. And funnily enough, these amino acids, zinc is bound to, in most of its moieties in the body, so the zinc finger protein motif which is how zinc is expressed over and over again. It's just bound to these amino acids.

So, this is its kind of natural mate. If we could consume zinc with these amino acids, so perhaps we're using a formula that has those in it or perhaps we're compounding or perhaps we say to our patient, "Look, have this first thing in the morning with a protein shake that is non-milk-based." So, you're using a protein that's a really good quality protein. You're not mixing it with any milk or milk substitute. You're actually mixing it with water or coconut water or something like that. Maybe then we're going to get closer to a situation that isn't ideal because people would just be taking it on an empty stomach. But because it's emetic, it's just unreal. So, we have to, kind of, fashion these other ways.

The other alternative is saying to people, like I often say with iron, take your iron with a meat meal. And so that's another thing that you can use, is you can say to people “Take your zinc with a meat meal.” Now, a meat meal doesn't mean you ate a leg of cow. A meat meal means there was just some small quantity of animal product in it, particularly muscle. But because I've often got—and I'm sure you have the same kind of patients—patients who need zinc often need iron.

So, if they're doing their iron with the meat meal, that spot's already taken, and we don't actually like to use the two supplements together because there is plenty of research. It's been, kind of, modified over time, but we do know that iron and zinc don't compete when they're in food, right? When we eat meat, we get both of them. We absorb them beautifully. But when you're having them as supplements and the gut is being presented with larger quantities and potentially in an imbalanced ratio, more of one than the other, that's when you start to see the competition and antagonism and the impaired uptake.

If I had a patient who wasn't doing any iron, I might say, "Take your zinc with a meat meal. No grains, no legumes, no nothing. Just vegetables and meat." But for a lot of patients, that spot in their day is already occupied by iron. So, I move zinc towards the top of the day, and I talk about that kind of protein or amino acid combination.

Emma: Okay, so essentially you're looking at the zinc in the morning with a protein and then the iron, if they need iron, at nighttime.

Rachel: Yep. But, I mean, it depends on the patient. There can be other things that you're trying to include in there that might change that sort of pattern, but that's a reasonable place to start with a lot of people.

Emma: Okay, perfect. So, we know that the world of nutrition is constantly shifting, and there's some future perspectives around zinc and microbiota, some new understandings around the absorption. And that might inform whether we should dose daily. Can you just give us some very high-level information around this and what practitioners need to be across as our understanding does start to shift?

Rachel: I think this is where my reading recently in preparation for The Nutrient Prescriber's Program on zinc has really, you know, this is the area where I was like, "Wow," because we all know the whole world has gone microbiota mad, and zinc it would seem has not escaped that sensation.

So, I guess a couple of things about that. I mean, I said at the very beginning, we need adequate zinc for eubiosis. We absolutely know one of the most consistent findings is if you are zinc deficient, you will have a lack of diversity in your microbiome. You will have a deficiency and an imbalanced, kind of, dysbiosis. So, we know because microbes all need the minerals, like we do, all microbes use what we call the first-row transition metals, just like we do. So, that's iron, zinc, manganese, cobalt, etc. So, it makes sense that it's going to have this powerful interface with our microflora.

However, something that a lot of practitioners have become alert to in the last few years is that appreciation for no nutrients...well, iodine maybe is the exception, but every other nutrient demonstrates less than 100% bioavailability. And something like iron has shockingly low bioavailability, a non-heme form is under 10%. Something like zinc, if you're using supplements, probably not far off that. Probably 10% something like that bioavailability, depending on the dose principally.

So, this awareness has crept in for practitioners about what happens to what is left behind, because we know that that is a large quantity, much larger than you could ever get dietary-wise or anything like that, that is then awash amongst your microflora. I said microbes demands, needs have an essential requirement for the first-rate transition metals. They are incredibly important for their survival, etc. So, you go, "Mm, okay.” This has been particularly showcased around iron where we, as a profession, are increasingly aware that what happens to what's left behind, in terms of somebody who's taking iron long-term, particularly high dose, is that it starts to change the populations of microbiota. And it doesn't necessarily change them for the better. So, we are starting to see the same emerge for zinc. 

Now probably the most clear case of this, which I think is worth mentioning because I think it really illustrates how much levelling up we need to do with zinc, how much things have changed, probably in the way you and I, and a lot of the other practitioners were taught zinc, is that if you have someone with IBD, we would often think and know because the literature absolutely speaks to this, that they have compromised zinc uptake as part of that inflammatory bowel disease. So, a lot of us would put them on zinc, and we might in fact be inclined to put them on more zinc because we know that their uptake is impaired. We'd say, "Well, we've got to, kind of, compensate for that."

The research now says that, when we do that, if that patient with IBD happens to have clostridia present or needs to go on antibiotics and then clostridia becomes the opportunistic infection, it is the zinc excess in the lumen that actually will make that clostridia bloom. So, this is where I'm like, "Oh, yeah, we really need to level up. We really need to get on board with these big changes in our understanding about zinc kinetics, because it really will change how we dose."

Emma: Now, some key clinical pearls I have learned today is that zinc is actually in its infancy. We still have so much to learn. It does shine particularly in the areas of growth, immunity, and gut health. And when looking at forms and dose, first consider what is your treatment objective. Match the objective to the form. Example, zinc carnosine for gut lining repair or gluconate as a lozenge for respiratory viral infections. Remember that form changes function, and dose changes function. And lastly, timing ideally is with animal protein and away from phytates.

Now, before we finish, Rachel, I know you have your Nutrient Prescriber's Program kicking off soon. So, what led you to actually write that program?

Rachel: I think it was going back to where we started. It was listening to practitioners and just recognising that they didn't have a method, that there was this, "I know this person needs B3. I believe they need B6. I think there's a zinc deficiency. I think they need magnesium." And then this, kind of, jumping off the cliff with all confidence and fingers crossed going, "Yeah, but I don't really know how to formulate from there." I would say to practitioners, “How long will this...you've given me a form and you've given me a dose. Quite frankly, I'm not quite sure where you've come at that from, or maybe I am.” And then I would say, “And how long? How will you know when you're there?” And that would just get crickets.

And I would think this is not a weakness of this person. This is a weakness of our training. And I think, to be honest, we have been given in our training a stronger methodology for herbal prescription than we have for nutritional prescription. Because as I said, we were just taught nutrients in isolation. We're like, "Well, they need magnesium. Here are some so-called therapeutic dose ranges,” which by the way highly debatable.

And then we then try to cobble these things together, and we don't have immediate clarity about form and timing and how those need to change based on the treatment objective and the host. So, again, that framework that we're teaching in the NPP includes these steps that they go through. So, they start with the pharmacokinetic model of micronutrients, so top three LADME, which is thinking about liberation, absorption, distribution, metabolism, elimination. Sounds boring. It’s anything but. Because once you have all those nuts and bolts in place, then you know your nutrient that you're working with, and then you move in to answering the questions about application, form, dose, host. And you, kind of, get yourself to that answer.

I think, in short, I know that nutrition is just such a powerful modality, but I know that it is, like you said, really nuanced actually. And so sometimes when I see myself writing prescriptions, I feel like I'm not getting the best out of my tools because I'm, kind of, going up and up in dose, and I think that's a surefire sign that you've got something wrong. When I hear about the kind of magnesium doses that are being used out there, the kind of zinc doses, I'm like, "Oh, no, no, no. Back up. Back up." It's more nuanced than that. We've got something wrong here, and we need to refine our thinking, follow a framework, and therefore sharpen our tools so that we really get the most out of those nutritional prescriptions."

Emma: Mm, and I love the sound of a framework. It also builds really good levels of confidence in prescribing as well. So, a link to your programme can be found in the show notes, so make sure you head over there for more information. Thank you so much for joining us today, Rachel.

Rachel: Thank you so much, Emma. You've been an absolutely gem.

Emma: Thank you, and thank you, everyone, for listening today. Don't forget that you can find all the show notes, transcripts, and other resources from today's episode on the fx Medicine website. I'm Emma Sutherland. Thanks for joining us and we'll see you next time.


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