Welcome to Dr. Warrick's podcast channel. Warrick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warrick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love. Hi, today I'd like to talk a little bit about diet and nutrition and the heart. One of the most common questions I get is, what should I eat doc? And one of the most common things that people say to me is, well, I have a healthy diet. Well, what does all that mean? I've taken some notes here so that I can refer to them because there's quite a lot of detail and I don't want to miss any of it. So excuse me as I refer to them from time to time. It's important to understand that over the last four decades or thereabouts, there's been a gradual decline in the incidence of heart attack. And this is probably related to our better surveillance and our better treatment strategies. Probably, most likely, medications like aspirin, cholesterol lowering drugs, blood pressure lowering drugs, and really good treatments for heart attack, the clot busting. medications that we have, the stents that we put in the arteries. That trend of decreased rates of death from heart attack however changed in around about 2015 and started to tick up. Well the reason that people think that is the case is that we're now confronting a diabetes and obesity crisis which is undoing the good that's being done by therapy. That obesity crisis is really a concern and really drives us to be more particular about how we think about what we eat and what we do because there's no question that diet and lifestyle are implicated in our risk of heart attack. One of the difficulties with looking at the data around nutrition is that trials are very difficult to perform it's hard to randomise human beings to very particular diets and control them. And so prospectively or starting at point zero and following people over time can be difficult. But even less reliable is asking people historically what's been going on. That's called a retrospective trial. Asking people to remember. the sort of things that they eat, the sort of foods that they buy. These retrospective trials looking backwards are often associated with observations of events or occurrences of problems. So observational type trials, really not randomizing people, but just simply observing one particular factor and trying to link that to an outcome. For example, We might observe in a population the people that eat the most bananas seem to live the longest. Well of course that's an observation in isolation and doesn't tell us the whole picture. We might find that when we drill down on that observation the bananas are very very very expensive in that particular population and so that the only people who can afford to buy bananas can also afford to have the best health care in which case they're going to have the best outcomes. So observational data can be fraught with problems. I'm not drawing a conclusion on bananas, I'm simply using that as an example. But of course there's been observational data about all sorts of things such as how much sugar we have in diets, sugar replacement agents, trans fats, saturated fats, sodium in the diet, red meats, processed meats and so on. So this collection of observational data, retrospective data can be difficult to interpret and hang your hat on. So it becomes reasonably important for us to try and focus in on studies that have been done prospectively or randomized in such a way that you start at a beginning point and follow people through which is with as much rigor as possible. So for this particular piece I'd really like to focus on those most important studies which have been prospective so start at point zero and go into the future and have been randomized. These give us the best idea of really trying to get a handle on what dietary interventions may or may not be scientifically most validated. So let's have a look at those. The major outcome trials, prospective outcome trials can be divided into two main groups. Trials that are to stop people having a heart attack in the first place, stopping a first event or primary prevention. So this is taking people who haven't had a problem yet and trying to stop them having a problem. or secondary prevention. This is taking people and trying to prevent them having a second coronary event. So we are identifying people who've had a heart problem and we want to stop them having another problem. Primary and secondary prevention. Let's start with the primary prevention group. con dieter mediterranean study or the predi med study. This was run somewhere around 2013. It was a primary prevention study looking at people who had not had a heart attack. It took approximately 7,000 Spanish men and women who were at increased risk of heart attack and randomized these individuals to a low-fat diet. to a Mediterranean diet enriched with extra virgin olive oil and to a Mediterranean diet enriched with nuts. So three major randomizations. The Mediterranean style diets had more fat obviously than the low-fat diet and was more plant-based and focused towards fish consumption. PREDIMED trial strikingly demonstrated approximately a 30% reduction in cardiovascular events compared to the low fat randomization. And this is in spite of the individuals in the Mediterranean diet randomizations having higher LDL or so called bad cholesterol measurements at the end of the trial and absolutely staggering. piece of information and certainly a foundation block to our recommendation for the use of Mediterranean diet for primary and secondary prevention of heart disease. So the PREDIMED study an important piece of our randomised data set to point us in the direction of where to go. There are three main secondary prevention studies that I'd like to talk about. One is the diet re-infarction trial, referred to as the DART, D-A-R-T, trial. The other is the Leon Heart Study, and the last is the Spokane Diet and Intervention Trial. So first, the DART study. This was run somewhere around 1990 or thereabouts. It took over 2000. men who had a heart attack and these men were randomised to three different diets. One was a low fat diet with an increased ratio of polyunsaturated fats to saturated fats and this was to try and drive down LDL cholesterol. The second group was an increase in fatty fish consumption or an omega 3 enriched group and the third group was a cereal or fibre group. So low fat with more polyunsaturates, fatty fish or cereal and fibre. So over a two year period these individuals were followed. Strikingly there was a 30% relative reduction in the fatty fish group of all cause mortality which is striking. So fatty fish looks for this group. in a secondary prevention sense to be reducing all-cause mortality. Interestingly though, the close examination of those subgroups didn't demonstrate a reduction in re-infarction rate, just a reduction in all-cause mortality. So a small win for a fish-enriched diet. secondary prevention trials that I'd like to talk about is the Leon Heart Study which was run around 2,600 people post heart attack randomised to two different dietary interventions. The first was the American Heart Association low-fat diet at the time and the other randomisation was to a Mediterranean diet which was driven to be low in animal products, increased in plant based content, enriched with extra virgin olive oil and butter and cream was swapped to canola and alpha linoleic acid. When they looked at these individuals over a period of a couple of years they found little difference in the biochemistry so the so called LDL cholesterol or bad cholesterol really wasn't greatly different between the two groups. The trial, however, was stopped early because there was found to be a 70% relative risk reduction in non-fatal myocardial infarction or heart attack and cardiovascular death, a striking outcome. And that was shown in the group with the Mediterranean diet enriched with extra virgin olive oil, terrestrial omega-3 oils and reduced animal products. This is a real win for good oils. reduced animal products, plant-based eating and omega-3 oils. The last of those secondary intervention randomized trials is the Spokane trial which is smaller, included about 100 patients post heart attack who were randomized to usual care or randomized to one of two diets, a low-fat diet, or a Mediterranean diet. In the Mediterranean diet there was a decrease in saturated fats and increase in omega-3 oils and over the period of the study there was a clear 30% relative risk reduction in both the low fat and the Mediterranean dietary intervention groups compared to the usual care. What does that mean? The summary point or the take home point for me is that if I'm advising someone who's asked me about what they should or shouldn't be eating in the space of either primary or secondary prevention, I think the data is pretty clear and we would look toward a Mediterranean style diet. And what does that mean? Probably more plant-based than animal product. Probably enriched in extra virgin olive oil plus nuts if you can. plus fish if you can as well. I think local green produce without too much animal product and certainly steering away from trans fat and processed fats is a great idea. In my own practice particularly for people who are looking to reduce their weight I try and steer them away from carbohydrate. I'm not sure that there's a great benefit in breads, pastas, rice, potatoes, cereals, fruit and beer in large amounts for people who are wanting to lose weight or who may be at risk of developing diabetes. So there's a number of different components to how we consider our eating. Is it just to reduce risk of heart attack or is it to reduce weight or is it to reduce risk of progression to diabetes? And I think we can combine all these. with a Mediterranean style diet, predominantly plant-based, enriched with extra virgin olive oil, enriched with nuts, avoiding processed foods. I think eggs are acceptable in there in moderation and keeping a close eye to not consuming refined carbohydrates, sugars of course, but also minimizing complex carbohydrates if you're looking to reduce weight. I hope that makes a bit of sense for you. If you have any queries or questions, drop us a note. Take care. Bye for now. And of course, please don't die from a heart attack. Goodbye. You have been listening to another podcast from Dr Warrick. Visit his website at drWarrickbishop.com for the latest news on heart disease. If you love this podcast, feel free to leave us a review.
