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#601: Gallstones & Gallbladder Conditions: Impact of Diet – Angela Madden, PhD RD
00:53:26
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- [00:00]
A
Hello and welcome to Sigma Nutrition Radio. My name is Danny Lennon. You are listening to episode 601 of the podcast. You are very welcome and a very special thank you to everyone who listened into our milestone episode 600 of the podcast last week and had very pleasant things to say about it. Thank you for that and thank you for being a listener for however long it's been for you, whether that's for many years and for the 12 years that this podcast has been going, or maybe you're a relatively new listener. Regardless, thank you so much for listening in and hopefully you enjoy another evidence based discussion here today. We're going to be getting into some clinical nutrition and dietetics today and specifically taking a look at gallstone formation related to other gallbladder conditions and some of the dietary management around that for people who are symptomatic and suffering from with gallstones or the related consequences of that. And then also we maybe touch on situations post gallbladder removal as well. And this actually comes off the back of a question that I got quite a while back from one of our premium subscribers, Katarina. And so thank you so much, Katerina, for the suggestion for this as a topic and some of the questions around this. And indeed one of the things we do inside of Sigma Nutrition Premium is, is have a place where our premium subscribers can suggest either questions or topics like this that they would like to see covered at some point on the podcast and those are used to generate some of the podcast episodes. Some of those are premium exclusive episodes. Others like this are conversations with experts. And so some of the discussion that comes up around dietary fat intake in particular and how that relates to either someone that is symptomatic with a gallbladder condition or post surgery and has had their gallbladder removed. Some of the recommendations there was a question that Katarina had put forward on the basis that it's a commonly discussed issue, this kind of connection with dietary fat intake and maybe the use of a low fat diet, but do we actually have good evidence for such interventions? And so to discuss this topic, I'm very lucky and honored to be talking to Dr. Angela Madden about this, who is a clinical researcher in nutrition and dietetics, currently based at the University of Hertfordshire in the uk and she's been embedded within nutrition and dietetics research for decades now across a range of different issues. One of which that she has looked at in detail and indeed was the lead author of a Cochrane review on the topic, relates to the very thing we want to investigate today and that is dietary fat and gallstones. And so this is what we're going to hopefully work our way through. Take a look at what evidence there is, why this even comes up as a question, some of the plausibility behind it, and then all importantly, based on the excellent work that Dr. Madden has done along with her colleagues, see what we can tell from the current evidence. And then where does that leave us in actual practice? For those of you who are dietitians or maybe you are patients or are a family member of someone who may be suffering with this, where does that leave us in terms of practical things that we can actually do? And so that's our aim for today. If you are a Sigma Nutrition Premium subscriber, in addition to be able to make recommendations for topics like this, remember you also get your detailed study notes that are linked in the description box here or over on Sigma Nutrition.com if you're listening on the free public feed of the podcast and you're interested in getting these extra materials like our study notes for each episode or, or our edited transcripts or indeed the key idea segment that will play after the interview is over, then check all that out in the description box where you're currently listening to right now, or all of that information is again on Sigma Nutrition.com see if it's something that might be useful to you and maybe give it a try. See if it actually helps you get more out of your podcast listening, retain more of the information and to understand it more deeply. That is certainly our goal and all of that is what keeps this podcast running. So thank you very much for your support, those of you who are premium subscribers or maybe who are considering doing so. So with that out of the way, let's dive into this discussion between myself and Dr. Angela Madden. A very big welcome to the podcast to Dr. Angela Madden. Thank you so much for taking the time to join me on the show.
- [04:35]
B
Thank you, Danny. Thanks for the opportunity to talk.
- [04:37]
A
I'm really looking forward to this. There's going to be a topic that I don't think we've really got into in depth and actually has been asked by a few of our regular listeners who are looking for more guidance in this area. And so given your background, as I'm sure we'll discuss in a moment, and some of the reading I've done based on things that you've put out, I think you're in an excellent place to hopefully provide some nuance and some understanding of what evidence we have in this area. But before getting into any of the details, maybe just to open us up and start into the conversation, can you maybe give people an idea of a bit about your background, your work and your interests and anything that might relate to the topic we'll discuss today?
- [05:18]
B
Yes, of course. So I'm a dietitian. I qualified from the University of Surrey over 40 years ago, so quite a long time, working in the NHS in the UK for the first 10 years of my work. During that time I started working clinically in liver disease. So not specifically gallbladders, but I did cover a ward where gallbladder surgery was undertaken and I carried on working in liver disease, went into research and did my PhD there. But it was actually the gallbladder that got me started in research in the first place because I became aware that I wasn't able to base my advice on any useful information. So after doing my PhD in liver, I then did a bit of research as a postdoc and then I started working as an academic, lecturing, finishing off my most recent job and where I still am based, University of Hertfordshire, where I led the dietetic undergraduate program. Five years ago, I stood down from my full time job and continued to work part time in research. And all during that, during, well, that time, the gallbladder keeps coming back to haunt me every now and again. We've completed a Cochrane review which was published in 2024, so that was the most recent piece of work on it.
- [06:33]
A
And it's of course one of the things that has caught my attention trying to look for some of the evidence in this area and try to see what evidence base we do have. And so your work has been very instructive in the area and I'm sure we'll walk through some of that before getting to some of the details and some of those, the specific issues that can crop up here. Maybe the most simple question to help us set the scene is what exactly does the gallbladder do for those who are unaware?
- [07:01]
B
Yes. So it plays a role in the digestion of our food. So just to briefly outline its structure, it's a small sack, it has muscular walls, it's about somewhere between 6 and 12 centimeters long in the abdomen and tucked under the liver. And it's connected to the liver through the bile ducts and also connected to the gastrointestinal tract through the bile ducts. And that sort of location is really key to its function. So its really unknown function is to store bile that's been produced in the liver and then to reduce release the bile into the GI tract. When it's required to act as an emulsifier for dietary fat. So that's food that's already come through the stomach and is in the lumen of the GI tract. So it's playing an important role in digestion, but it's not actually part of the GI tract itself. It's connected to.
- [07:56]
A
Of course, one of our goals today is to give people a better understanding of generally gallbladder disorders or issues that can crop up and then some of the specific things you've written about in relation to nutrition. But if we think of that kind of phrasing, I've just used of a gallbladder issue or a gallbladder disorder, this is obviously quite a vague umbrella term that can encapsulate a number of different things. What is maybe a good way to start categorizing the different things that can arise clinically that are related to the gallbladder, what kind of buckets we can come into, come up with and then what are some examples to give people an idea about?
- [08:33]
B
Yes, the main conditions affecting the gallbladder, particularly in western type diets and lifestyle, are gallstones. It's a worldwide problem, so it does exist even where people are not having western type diets and lifestyles. But by far the biggest prevalence of disease relates to two gallstones. The gallstones themselves can be divided into two types. The ones that we more commonly see is in countries like the UK and Ireland are gallstones made of cholesterol. So deposits of cholesterol become hardened and calcified. The other type, which we occasionally see but are much less common here, are stones that are predominantly made of pigment. So most of the conversation today is going to focus around cholesterol type gallstones, but some of the conversation is applicable to bile pigment stones as well. I'll try and differentiate between the two, but those are by far the most common conditions. Do you want me to mention perhaps some of how that affects people or what it, how it presents, or do you want me to perhaps mention some of the less common conditions?
- [09:47]
A
Yeah, I think maybe a good starting point is if we stick with those gallstones that you've outlined some of that kind of clinical presentation. So people might have an idea.
- [09:57]
B
Gallstones are very, very common and in a lot of people they are asymptomatic, so often called silent gallstones, where people may not know they have them and they're only identified if someone has a scan for another purpose or perhaps a post mortem after death, but they've never caused any trouble. People with gallstones A small proportion of them do start to develop symptoms and some of those then develop complications and the symptoms tend to be abdominal pain. People call it biliary colic at times, and this can be relatively mild in some people, but it can also be extremely severe and incapacitating. Nausea and vomiting are often associated with that as well. The complications that arise, as well as the pain is more related to the pain, is that the gallbladder itself becomes very inflamed and infection may set in. And that's referred to as cholecystitis. And the condition itself can be acute or chronic. So acute cholecystitis, coming on very rapidly, being extremely severe, may need hospitalization. Whereas for people with chronic cholecystitis, it may be something that rumbles on for a period of time, flares up, but then settles down again.
- [11:10]
A
You've already mentioned a bit around the prevalence and given that we can have a whole range here from something that may be asymptomatic and not causing people any problems, all the way up to things that can end up, if not treated, becoming quite severe within that range. What do we know about how common this is within the general population and what kind of way that distributes among mild, severe and so on? Do we have any data that gives us any idea about that?
- [11:36]
B
Yes, we do. It is quite hard to get good figures. There was a paper that came out last year that looked at global studies and I think they identified approximately 6% of the population overall have stones that was looking at a variety of publications and pulling out the data. It varies hugely. I think most populations would probably be somewhere between, say 3 and 15%. But there are some sections of the world's populations where it's even much higher than that. I think the most common, highest prevalence is in the Pima Indians in North America, where maybe as high as 60% of women have gallstones. But just to sort of caveat, those prevalence figures, it really does depend on how you're assessing it, because as I say, if they're silent, asymptomatic, they're only identifiable either on scans or post mortem. And if you're looking at identifying through symptoms, that's a much smaller proportion. I think the thing to be aware of is prevalence is changing. It's actually increasing with the obesity problem that we have worldwide. It's not just obesity, but it's populations that are taking, becoming a more taking on eating a more Western style diet. And I'm meaning they're tending to be higher in fat and refined sugars. Lower fibre, less fruit and vegetables, and also a more sedentary lifestyle. Finally, the last thing. Gallstones, when I was working clinically decades ago, were almost unheard of in children. But now gallstones and cholecystectomy surgery to remove gallstones is becoming quite a regular thing that is seen in children.
- [13:17]
A
I think you've already alluded to a couple of these things, so I think it's worth expanding on that. You've already suggested that we're seeing this increasing prevalence that may be tied to things like increasing obesity rates, but also the general dietary pattern we have. Of course, we'll talk a bit more about diet later on, but yeah, if you could get into some of those other related risk factors that seem to be main things that are contributing to these.
- [13:42]
B
Yes. So I think in all populations, the prevalence is higher in women than in men and prevalence tends to increase as people get older. It's also more prevalent in people who are overweight, in people who are more sedentary, and then the dietary factors that come into it as well. There's something I haven't touched on at the moment when we talk about function. I was saying about the gallbladder releases bile into the GI tract and it does that by contracting the muscles of the wall of the gallbladder, squeezing the bile out. And there's a much higher prevalence of gallstones in people where that emptying doesn't happen either because they've got a gallbladder that's not functioning well, maybe the structure is slightly abnormal, or it may be that they are not eating normally. And I'm thinking here of people who perhaps are having total parenteral nutrition, so completely IV feeding, where they're not eating nothing or very little is going into the GI tract. So bile isn't really needed to do the digestion that it would in healthy people, and therefore the bile remains in the gallbladder and it's allowed to stay there without coming out as often as it normally would do in someone who's eating normally. And I'm hoping I'm triggering some thoughts here. These are actually very unusual situations, but I'm just picking out some unusual places because I think it does help us a little bit with the understanding of perhaps how things work, but also how we can optimise through what we're eating.
- [15:17]
A
Absolutely. And it's something that I do want to get into detail and have a lot of questions that relate to. For example, one of the big topics that's discussed often, I think, within dietetics is around things like dietary fat intake, which I'll get to in a moment, you've already alluded to that overall dietary patterns contribute to risk here. But we also have these other factors like you mentioned, sex, age, level of physical activity, level of adiposity and so on that may contribute to risk. And you've just talked a bit about some of that pathophysio physiology and that development of gallstones. And so maybe just to reiterate some of that, to make it clear for people, what is it that is happening during, let's say, the formation of those gallstones or the development of that condition and it getting worse, that connects to these different risk factors we've said. Why are they, why is there a connection between some of these things we've mentioned and the actual development of gallstones?
- [16:13]
B
Yes. So the stones arise through the precipitation of substances that can harden and form into first of all, crystals or sludge in the gallbladder. And then they can actually form together into a stone. Stones vary a little bit. Sometimes they're little round stones, sometimes they're, they have more shape, not quite like a dice, but you know, they slightly may have edges to them. The size varies. Sometimes they're huge, but much more often they're much smaller than that. And the smaller ones can pass out through the bile duct if they're small enough, but they can get stuck if they, their size is not able to flow through the bile duct. So basically it's when the bile has something in solution that reaches a concentration where it precipitates out. So the two main groups I've mentioned are cholesterol and the pigment, bile pigments. And both of those are capable, if the concentration is high enough, of precipitating out to form the small crystals. And did you ever grow crystals as a child at little science experiments at school or something? Well, it's great to see them form into shapes, but if you stir the water or keep moving the water, the solution rather, they don't have time to settle, they can't make the crystals. And it's the same with the bile. If the bile is continually moving through the gallbladder, then it's much more difficult for precipitation to happen. I mentioned about the concentration rising in the bile and we really then have to think where that comes from. And I'm going to focus only on cholesterol now. So if the cholesterol levels in the bile are high, they're usually high because they're reflecting the cholesterol levels in blood. And I think one of the, one of the Things that triggered a lot of interest in the last century. So I'm thinking 70s, 80s, where quite sophisticated research was done, but nothing on the level that we are able to do today. They're very interested in cholesterol intake, dietary cholesterol intake, and the impact on bile and on what was going on in the gallbladder. So that's the logic to it. But problem with that, we know now, is not really, really relevant thing is that our dietary cholesterol doesn't have as much control or influence on blood cholesterol levels as saturated fat and some other dietary components. Okay. Because we basically make cholesterol, the liver makes cholesterol. So we have a lot of endogenous cholesterol and don't need to be that focused on the pure cholesterol content of food. So there is this relationship between the blood cholesterol and bile cholesterol and therefore risk of precipitation. It's not specifically relating to cholesterol in food, but there are other components of the diet that may have an impact on blood lipids. And looking more holistically then at aspects of the diet may be more helpful in trying to reduce the risk of gallstone formation in the first place and then managing it when they've actually been formed. And I suppose that's another thing that I just want to separate out is we've got these two things going on. We've got the formation of the gallstones, and then we've got the management of the symptoms in people who already have gallstones.
- [19:30]
A
So if we take that first part, and again, if I try and recap some of the things you've just mentioned, and feel free to correct me if any of this is incorrect, but you've alluded to this importance of during that formation of that role of cholesterol. And you said how that connects most directly to blood levels of cholesterol. And so from there, when we start thinking about, well, what are some of the factors, at least from a dietary perspective, that could be playing a role here rather than necessarily it being dietary cholesterol, although we can maybe talk about about that later on, and some of the impact. But more so, we're thinking about what can be driving blood levels of cholesterol. And so therefore we. We look at the evidence around things like the total amount of saturated fat, perhaps in the diet. There's other components that we know then can be related to lipids either going up or down from a diet that we might discuss. But we're seeing that really one of the key things here Is what is someone's blood level of cholesterol as maybe even more specifically, I don't know if we then can narrow that down to LDL cholesterol as opposed to total cholesterol and what kind of relationships we see here. But we're starting to see this picture form of the blood levels of cholesterol are something that is going to be relating to this risk. And so can we modify that risk by changing blood levels of cholesterol? And one way to potentially do that is through dietary changes. Is that a relatively accurate picture or is there anything you want to clear up with that?
- [20:58]
B
No, it's a. It's a good summary. I don't think we've got the answer to all of it. And interest in blood cholesterol is good because it's much easier to take a blood sample. It's quite bothersome and hard for the person involved to take a sample of bile. You can imagine how the complexities of going down into the beyond the stomach to retrieve bile is just not something that can be done easily unlike blood cholesterol. And also you touched on it there thinking about the different types of blood cholesterol. Cholesterol. Now I may be wrong and have missed this, but I'm not aware that a lot of work has been done in tracking blood with bile. In fact, when I was writing something, you have to look quite hard to find where there is where people report evidence of a connection between the two. But I haven't actually seen it broken down into the different sub fractions of cholesterol. And I think that's perhaps what needs to be done.
- [21:52]
A
This is maybe one of the things that at least originally there was this interest firstly noted in people looking at dietary cholesterol. Over time that's now been more refined to understand what are some of these factors impacting blood cholesterol. And then there's historically also been an interest in low fat diets for that. For that reason as well potentially that if we have less dietary fat, maybe that is contributing here when it comes to that. Can you give us a picture of not only the. What we currently know from a general overview level of the relationship with that total level of dietary fat influencing some of this potential stone formation. But then also the. Let's see types of dietary fats and then what. How that is relating to some of these risks that we just discussed.
- [22:38]
B
Maybe if I can just perhaps suggest why I think it has become concern about fat intake related to gallstones. I think there's two aspects. There is one because of the role that the gallbladder has in fat digestion. And it makes obvious sense there, if you are having a problem with your gallbladder that if its role is in fat digestion, if you reduce your fat intake, then that might help the problem. I'm not sure that that's been very clearly articulated, but that's had become in practice what has been advocated for a long time, restricting fat. Because if you've got gallstones or gallbladder problem, that's a problem, I think also because the dietary fat provokes the a gallbladder response. So dietary fat provokes the release of cholecystokinin, gut hormones that then trigger gallbladder contraction. It's thought the gallbladder contraction, the muscle contraction, is related to the pain that people experience when they've got cholecystitis. And as I said, that can be very severe and very traumatizing for them. Not everybody, but in those that are affected. So if there's a suggestion that what you eaten, what you've eaten, if there's fat in it is going to provoke your pain, then that's quite a good stimulant for not eating those particular foods. So that's my thoughts of the reasons why, apart from we've already talked about the cholesterol in terms of the formation of. But I think that's also been part of the concept of why dietary fat should be avoided. And thinking back, nutrition and dietetics is a science. It's actually quite young and a lot of the practice that has been undertaken for quite a long period of time is based on custom and practice. And a lot of it has not been evaluated to really scrutinise is this beneficial. So I'm sure you're all aware of things like diets for ulcers. That's always quoted as something, you know, people had to keep off fruit and vegetable. Anything was sharp and acidic because that would make a gastric stomach ulcer worse. And that's been identified for a long time. That's really not helpful because the stomach acid is much more acidic than fruit and vegetables. And you need your vitamin C and all your other micronutrients from fruit and veg to help healing anyway. But that's, I think, an example why the logic of thinking we should do something and then if you don't actually explore it, test it out, it doesn't necessarily lead to the optimum, optimum management. I think the other thing a lot and Danny, pull me back if I'm going off in the Wrong direction. I think another reason why there hasn't been a lot of interest in investigation into the dietary effects is because we have some very effective ways of managing cholecystitis. Surgical removal of the gallbladder is very efficient, has a very low mortality rate and most of the ones were certainly undertaken in the uk. I would guess probably Ireland is very similar. For the United States it's through keyhole surgery, so not an open abdominal incision. And people recover very quickly from it. And this process, I think there's about, I don't know about Ireland, but I think it's about 70,000. Cholecystectomy is done in the UK each year. There's over a million of them done each year in the usa. So it's. The more you do something, the better you get at doing it. So it's a really good treatment, but it doesn't necessarily. Excuse me, look at the. What other potential inputs could be there in terms of perhaps dietary advice either to prevent or to manage, either before surgery or while someone is waiting for surgery.
- [26:21]
A
There's quite a lot that I think is really useful there that I'd love us to, to walk through first to maybe fine tune. Something that I said earlier based on what you just said is that really we can think of this in a couple of ways. And the point you made earlier about one is thinking about maybe some of these dietary aspects that could relate to risk over time. And so that would fall into this category of if we're pushing up blood levels of cholesterol, that could relate to risk. But then the other aspect that you've highlighted is in the situation where someone does have gallstones and let's say that we have symptoms and there's being diagnosis, there's some degree of dietary management that comes in and some ideas that have been around within dietetics for periods of time have related to some of these hypotheses that mechanistically might make some sense. For example, we know the gallbladder's role here in fat digestion and so maybe having a lower dietary fat intake could be hypothesized to, to be useful or we don't want to cause any degree of aggravation, so we might change some of these dietary factors, including dietary fat. And as is often the case, sometimes we have to have hypotheses based on those mechanisms and practice that comes before we maybe have some of the best evidence, which is where some of your work that we're going to discuss comes in to hopefully try and get These answers. But the point being for people is that we've had certain hypotheses put forward as to why maybe moderating fat intake in situations where people do have gallstones could have been useful or why it was maybe used in practice. But again, that is maybe distinct from the question of what is the quality of the evidence we have for some of these interventions, which we'll discuss now in a moment. And so with that, and knowing that we have these ideas and maybe they're being used as, you know, that there's maybe this next step of going and seeing can we get some good quality evidence or can we kind of scrutinize some of these ideas? And you were part of the group that were doing that. And is the publication that you mentioned earlier, the Cochrane Review was one of those publications can maybe start talking about that movement from those hypotheses that you just mentioned earlier into trying getting better quality answers around this dietary management for those with gallstones?
- [28:37]
B
Yes, of course. Okay, well, just a little caveat here. It's a big disappointment because basically we looked for the evidence and didn't find it. So we were very. I'm sure people know what a Cochrane Review is. Ours was set up so we were only going to look at randomised control trials. We wanted to make sure that it was the best quality intervention studies that were included. And it had to be in people who had a confirmed diagnosis of Gould Stones, not just clinically on a scan or other visual presentation. And we were looking at outcomes that related to the person's wellbeing. So important things like mortality, hospital readmissions, quality of life, pain, bleeding, infection, things like that. And I think we actually identified just over 500 papers and of going through them there were five papers that could be included. All but one came from the last century and I'm talking from the 70s and 80s. So there was one from published in the last 15 years and only one of them had looked at the outcomes that we were interested in, but nothing was reported in a way where we could say there was good quality evidence. So then to recap. So this was looking at, to see whether modifying fat intake, originally I was interested in the low fat diet, but this was modifying dietary fat intake in any way, whether that was the different type of fat, saturated fat, monopoly, poly, et cetera. And there was nothing. There was nothing there. Now maybe if we had a broader protocol, looking at other types of studies. So rather than including only randomised controlled trials, we may have been able to identify some kind of evidence. But the Difficulty is that the quality of that evidence is not good. And I think what we really need to be aware of is that if people are changing their fat intake on the basis that it's going to be helpful, then I think we need to be a little bit more confident that it actually is helpful. And I just want to suggest a couple of things where not only do we know that it's not helpful, but there may be some evidence that perhaps it isn't helpful. Can I go off in that direction?
- [30:50]
A
Please do.
- [30:51]
B
Thank you. I mentioned a few minutes ago that fat is a potent stimulator of the gallbladder. So through cholecystokine in the gut hormone, it, it causes the gallbladder to contract. But we also know the gallbladder contracts in response to other things. A Dutch team, late 80s, early 90s, did quite a lot of work looking at lots of different things. It looked at protein, it looked at medium chain triglycerides, a type of fat that's commonly found in coconut oil, but it's used therapeutically, but it's not actually the most common part of the diet. But they looked at different elements and they found that the gallbladder contracted in response to a whole range of different dietary components. They also identified that if a sham feeding procedure was undertaken. So by that I mean, you get someone to eat something but they don't swallow it. So you're not getting the stimulation from inside the gut, you're getting just the cathonic, the. Just the brain stimulation from the pleasure of what's in the mouth, et cetera. And they also found that the gallbladder contracted in response to that sort of, I suppose, a bit like a Pavlovian response, but rather than just salivation, this is the gallbladder contracting in response. So if we've got these contractions happening in relation to other parts of the diet, and I can't tell you the sort of the degree of contraction, but there is contraction going on in relation to all of these. It seems not logical to cut back on one aspect if all of these others may be problematic. Now, if I can put that to the side for a moment and think, well, actually, maybe there's something positive about contractions in that we do want the gallbladder to empty, because if we think about how the mechanism of how the gallstones develop, it's bile that's sitting in the gallbladder for a long time between contractions before between the bile being released. Stagnant is not a very nice word to think about in Your in your gut. But you know, if the bile is stagnant, it's much more likely to have gallstones develop. So if we can help by having the gallbladder emptying on a regular basis, it may then be actually helpful both in terms of preventing formation of gallstones at all or further formation. And bearing in mind once you've got them, they can become larger. That might be useful. And there have been just a few papers that have looked at this, some from lab tests where they'd done actual observations of bile. And they suggest that you should have at least 10 grams of fat per day to ensure that the bile there is some contractions there that, that help. You'd get some contractions from eating anything. But I think that's almost like the other side of the coin. So we want to cause some contractions and if we cut out fat completely then that might be problematic. Can I just say a 10 gram fat diet is very, very low. So even someone who's having a nice healthy diet would be probably having considerably more than 10 grams of fat per day. But it's this idea that cutting out all fat is just not the right thing to do. It's not, it's not optimum for health. So I'm certainly not advocating a high fat diet, but thinking about having some fat, thinking about other aspects of the food as well. One of the difficulties, I'm sure from a nutritional perspective you feel the same is that when we start looking at one component of the diet we can forget all the other bits that are going on. And if you tend to reduce your fat intake, low fat intake, people usually increase their carbohydrate and or protein, but mainly carbohydrates to maintain calorie intake. We know that unrefined carbohydrate is not associated with risk, increased risk of gallstones, but a high refined carbohydrate intake. So including sucrose and fructose, we know that increases risk as well. In fact that evidence is stronger than looking at the fat intake. This might be mediated via a cholesterol route. So we might be thinking of the effect of high sugars on triglycerides, but that's a clearer prognostic risk factor than fats. Have I been very muddly there? Because I originally.
- [35:08]
A
Not at all fascinating and really interesting. It's triggered off a number of things I'm thinking about and certainly when we think of that typical recommendation, let's say to use a low fat diet, as has become a kind of a conventional thing to have been done for some of the hypotheses that we mentioned earlier. But as you've noted, this real lack of good quality evidence that just isn't existing when we're going to look for good quality evidence for this intervention leaves us almost with, at least the way I'm seeing it from what you said, almost these three different layers we can think of. First, if someone is going to use that intervention, what we need to accept is that that is not based on good quality evidence. But we can't point to good quality evidence showing that this intervention is doing what we hope that it's doing. So that's one thing. But we can take it then a couple of steps further. One is that in a pragmatic sense, given that's the case, it could actually be unnecessary to do that at all. And if that is the case, that it is unnecessary to have this fat restriction, those particular circumstances that could lead to some unintended consequences, some of which are just pragmatic and some actually could actually be physiologically, as you've outlined, could be having a problem. Again, we don't know if that's the case. But as you've put forward, if we are thinking about the stimulation of the gallbladder and having some degree of dietary fat can be useful to do that, maybe we're having this unintended negative consequence by having a complete restriction. And even beyond that, from a more practical level, trying to get to the levels of absolute fat restriction, someone might conclude they should be doing if they're worried about their gallbladder, that could lead them to make dietary choices that could actually be worse overall for their dietary pattern that they're leaving out certain types of foods that could be beneficial, or just trying to stick to that level of dietary fat being so low, unless you're doing something that is just like only whole plants, beyond that, you are going to run the risk for most people in the general population of trying to stick to that type of dietary pattern is not only very difficult, but might lead them to make poor food choices. Or at least we could hypothesize so we have these different layers of unintended consequences. But at the very basis we can say we don't have this strong or really any evidence to point to for such an intervention. And so just to pull back on something that you did mention around that, Angela, when it comes to why we don't have evidence to point to here, why do you think that is, is that there's been just a lack of interest in this from a research perspective given that success you mentioned of surgery for example, or is there other things going on that relate to why we don't have a robust evidence base or at least some answers to this research question that we would ideally like to have?
- [37:52]
B
It is a good question. I think there is a lack of interest perhaps in the research population. I think if we could tag this on to the whole metabolic disease. So the interest we have now with diabetes, cardiovascular disease, I see this is probably just a similar, another branch of that. There's certainly a lot of interest from a patient public perspective. The nice guidelines you're probably familiar with, the National Institute of Clinical and Health have produces guidelines in the lines in the UK. They're 2014 guidelines. They have members of the public patients on those, the guideline panels and they were saying, you know, this is what we want to know about it. But there wasn't evidence that could be included. But it just a flag up evidence is needed. So that's now 1212, nearly 12 years ago. I think it's because cholecystitis, so when there's inflammation it sits under a surgical specialty and it's one of those very quick surgical things where for the vast majority of people, they come in, they're assessed, they're diagnosed, they're prepped, they have their surgery, they might have to wait a little bit, but then hopefully they feel a lot better afterwards. And the vast majority of people do. Some people have some problems afterwards, but vast majority of people feel better afterwards. So I think it may be from a clinician's point of view there doesn't seem to be a need and I think, I think there's just so much potential here. If there's any surgeons out there and I would call to surgeons because I think they're the people who are managing this group for taking the referrals and managing them. I think they would be in a really good place to organise future trials, ideally randomised controlled trials. But I would suggest that looking more broadly at fat would be fantastic to their lunch and then reduce their need for surgery. But if it did, I think everybody would be happy patients and also resources would be, would be better served too.
- [39:48]
A
And to clarify, because earlier you mentioned that really important distinction between let's say someone that has symptomatic gallstones but maybe has yet to have any surgery and some of the potential dietary recommendations they're given and then there's a separate population for people that after let's say a gallbladder removal are also given some type of recommendations or at least they might have logically jump to things with this idea, oh, because now I don't have my gallbladder. And because of its role within fat digestion, therefore a long term or lifelong low fat diet is required. Presumably the kind of scant evidence applies to both of those situations.
- [40:28]
B
It does. I mean, from a clinical perspective, people after had their gallbladder removed surgically, typically don't need any dietary restrictions or any dietary advice. Some people take a little bit longer to get back to recovery and eating again, but they're in a small minority. I think there is evidence that people tend to have higher faecal fat output. So normally in a healthy person you wouldn't expect to find a lot of fat in the faeces, but it is higher in people after, after gallbladder removals. There's also a tendency for them to gain weight, which might be a reflection that they're feeling so much better. So perhaps their appetite increases. I don't know. But I would say from how I can interpret the evidence that's there for most people, following a typical healthy diet would not only help manage their health in relation to gallstones, even after ghost bladder removal, but also their risk of other things, of diabetes, cardiovascular disease, disease, et cetera. So I'm thinking here. So in Ireland, I believe you have the food pyramid, the five shelves of food. Does that sound familiar?
- [41:41]
A
Yes, I've certainly seen them. Yes.
- [41:43]
B
I hope I've got it right because I'm not that familiar with it myself. But basically that you, you do keep intake of refined carbohydrates and fats to a low level, but your biggest intake comes from fruit and vegetables and then from unrefined high fiber carbohydrates, breads, pastas, rice, potatoes, et cetera. And it's the same or similar. In the UK we just have the Eat well guide, which is in a circular format, but the concept is still the same. It's a healthy diet, nothing extreme. And if you'll allow me, I would also like to break out from thinking about the diet in terms of what and introduce when the diet and when people eat and also other things like health related things. Is that okay? Danny, can I move to the question?
- [42:27]
A
Yes, please do. I'd love to hear.
- [42:28]
B
Thank you. So you're really brilliant. You keep referring to evidence and that is so important. And I have to say I don't have evidence for this, but it seems to be logical and it needs to be tested. So I don't think we're in a position to say this is what people should do. But this is, I think, potentially of great interest, is if we want to encourage gallbladder emptying to reduce the chance of bile stagnating and forming gallstones, or forming more or larger gallstones, then eating regularly, rather than having very long periods of time between food intake would logically be helpful. But we need evidence to confirm that. And I'm thinking we know that bile that's produced overnight tends to have a higher cholesterol concentration, so that's just part of the normal circadian rhythms. So overnight bile is more lithogenic, more likely to form stones. So if someone has breakfast, whatever that breakfast might be, then hopefully the gallbladder would contract and that lithogenic bile would then be released into the GI tract and it's gone. I mean, this is based on the evidence of people who are not eating or people who are fasting for long periods of time having a higher risk. So that's one thing. So I'm thinking it's not just what, but it's when or how often people eat. There's some quite interesting studies that have been published in the last couple of years where they've analysed very large, either a large data set, a meta analysis or sort of large population studies where they found that people who take more physical activity have a lower risk of gallstones. And there's also recently been one related to sleep. So people who have quite a low average sleep rate, number of hours sleep over a week, have a higher risk than those who sleep more, and they think, again, that's related to what happens to cholesterol when people are sleeping. I think what it's all pointing to is healthy diet, eating regularly, exercising regularly, getting enough sleep to have really good evidence. We clearly need more studies, but I think we could pull things together to say these are the things that are definitely worth testing.
- [44:45]
A
And I mean, that's the whole issue that often comes up for dietitians and nutrition professionals, that in situations where we don't have an evidence base that we would ideally like, we're kind of left to put together recommendations that are still based in some degree of evidence, or at least we can point to some degree of reasoning and some evidence for that that makes some degree of sense. So I think everything you've said is completely reasonable. And we've before talked about some of those metabolic responses that occur, let's say, at eating during the biological night, where you do see these really exaggerated free fatty acid levels in the blood and that postprandial response is much greater than it would be at other times. And so foreseeably that is relating to some of this risk that you've just outlined here as well, given what we've talked about with blood lipids and the potential connection there. And so given that for maybe people who are in dietetic practice and are going to be coming across people that no doubt have some degree of gallstone issue from your perspective, given that we've already given that caveat that there are some clear gaps in the evidence that we would like to see answers to for right now, what do you think we can summarize some of those dietary aspects or dietary recommendations that you would consider at least to be best practice or a good starting point.
- [46:08]
B
Okay, thank you. So I would suggest people follow a healthy diet, so following either the food pyramid or the eat well guide, that they try and eat regularly, particularly eating breakfast, that they watch their weight. So if they are currently overweight or gaining weight, to try and control that, that is so hard. We know that's a real challenge for people, but I think that would be important. And then to pay attention to things like their lifestyle in terms of activity and sleep. I'd also tell them that we don't have absolutely good evidence that this is definitely going to help you, but it's worth a try and it will definitely have beneficial effects on other aspects of your wellbeing. So cardiovascular risk, et cetera. And I would also say to them if they are experiencing pain, often abdominal pain that they think might be related to their gallstones after eating something specific is just to keep a diary of it. And if they noticing a pattern to try and avoid that. And I think just to take it from there. So I think that's probably my summary. But it's really important to be honest with people. You can't say you've got to do this. That's not how we work now. It has to be much more collaborative and trying to find out what will fit in with their lifestyle as well.
- [47:29]
A
And again, a number of those things that you mentioned, even if we need some more evidence on them for this particular outcome, there's a number of those steps that someone could take that are going to have beneficial impacts on other aspects of their life anyway and other risk factors, whether that relates to their overall dietary fiber intake or the meal pattern that you mentioned, or some of these aspects related to lower levels of saturated fat and so on. There's lots of counseling that can be done, it seems, from this perspective. So, Dr. Madden, I know you've mentioned Some of the gaps we have in research, and I don't want you to necessarily rehash that over again, but maybe as a nice way to tie all this together, if there is a kind of particular research question you would love to see answered in this area in. In the coming years, what would that be?
- [48:17]
B
I guess to. To try it out and to have an even investigation that tries out. These suggestions really can then give us some indication of whether they are helpful. If they're not, they should be chucked out. But if they are helpful, then we need to know that so that we can ensure that's the practice that we are encouraging everybody to do.
- [48:37]
A
So before I get to my final question, for maybe people who are interested in learning a bit more about your group and the work you've done or any of your other publications, is there any places you would like to send their attention towards online or anything that you would suggest for them to look into?
- [48:52]
B
So my research papers are up on my university research page. So just by Googling. Googling my name, Angela Madden at the University of Hertfordshire. The publications are there and I think that we have. They should all be open access, so hopefully they can find them. If not, my email address is there. People are welcome to email me.
- [49:12]
A
Great. And I'll put links to all of that as well as any of the research that we've mentioned to today in the show. Notes for people listening. So please do go and read through all of that. With that Dr. Madden. That brings us to the final question that I always end the podcast on. And this can be to do with anything, even outside of our topic of discussion today. And it's simply if you could advise people to do one thing each day that might have a positive impact on any area of their life, what might that one thing be?
- [49:40]
B
Oh, that is a fantastic question, Danny. Okay. I think it would probably be to go outside, preferably into a garden, if you can. But even if it's a street that's got a tree on it or something like that, and just to breathe, just breathe in, outside. I'm currently living in Felixstowe on the east coast of Suffolk in England. And it's lovely to be by the sea, but I found I'm spending much more time just being outside, even briefly, going to the washing line and doing domestic things. It's just such a break from work and I think from a wellbeing perspective, I'd encourage people to do that, even if it's looking down at. Sometimes in the gutter you find these little plants that have escaped. Maybe not in January, but little plants that are growing there. So resilient and it's a great encouragement when sometimes the world and politics and whatnot is looking quite discouraging and worrying. It's just a step back from that,
- [50:34]
A
as you mentioned, it's certainly something that we need at this current time. So very much appreciate that advice. It's something I'm going to take myself. And with that, Dr. Angela Madden, thank you so much for giving up your time today, for coming and sharing this great information and more so for the work you've done that has been, as I mentioned, very instructive to me and I'm sure to other people. So thank you so much for doing this.
- [50:53]
B
Thank you for the opportunity. It's been a pleasure. And thank you for all your well informed questions as well. Thank you. Danny.
- [51:04]
A
Foreign. Thanks so much for listening in to today's episode. Before you go, I just wanted to remind you about Sigma Nutrition Premium, our subscription for those of you podcast listeners who want to significantly deepen your understanding of nutrition science and become truly confident in your knowledge. So what's the idea of this subscription? Essentially, it was created with the goal of allowing you to more deeply understand the material you're hearing on the podcast episodes themselves, to be able to retain more of that after you've finished listening or reading through the notes, and then be able to easily and efficiently revise over that so that in the future you can be able to remember that information, to be able to reuse it, to be able to create your own content or ideas using things that you have learned. And how do we go about this? Well, there's a few different ways, but at the core of the subscription is our detailed study notes that you get to each episode where you get a beautiful PDF that is full of all useful descriptions, background, context diagrams, charts, etc. To allow you to more deeply understand some of the concepts that were mentioned throughout that particular episode, as well as then linking them back to previous episodes. You also get these segments at the end of each episode called our Key Ideas segment where I recap certain key ideas. You get episode transcripts. You get then a number of premium only episodes, so you have your own premium podcast feed that appears on whatever app you already use and you get these extra premium only episodes. Some of them might be Ask Me Anything sessions where we answer your questions that you submitted directly, or they could be a variety of other episodes that you may have seen previews to in the public feed. So for full details on this then check out the link in the description box, wherever you're currently listening right now. Or just go to SigManutrition.com and you can see all the details there. And of course, your support is what keeps Sigma Nutrition going. We don't run ads, we don't sell supplements, anything like that. So your support is what allows me to continue to do this. So thank you for that. I hope you do come back for the next episode regardless. And until then, have a great week. Stay safe and take care of.