Forskare från Cochrane stöder påstående att mättat fett inte täpper till kärlen

Blogg-Postare · May 26, 2017

Mättat fett är INTE boven när det gäller hjärtsjukdom

Vad orsakar egentligen hjärtsjukdom? Har mättat fett någon skuld alls? Och vad kan du göra för att minska risken för att drabbas av hjärtsjukdom?

Om du är intresserad av frågor som dessa kan du lyssna på den här podcasten med dr Aseem Malhotra. Den har sin grund i en ledare om hjärtsjukdom som han är medförfattare till. Han beskriver där de verkliga orsakerna till hjärtsjukdom (det är inte mättat fett eller kolesterol i kosten).

Vill du hellre läsa än lyssna finns en transkription på engelska av podcasten nedan, med relevanta länkar.

Här är några kommentarer om podcasten av framstående forskare:

Aseem Malhotra har ett klart budskap tillsammans med fängslande argument om varför vi behöver anpassa vårt tänkande och våra strategier för att hantera hjärtsjukdom. Mättat fett, statiner, stent, stroke och socker är de fem nyckelämnen som diskuteras övergripande tillsammans med möjliga konsekvenser för framtida forskning.
– Prof Zbys Fedorowicz PhD,MSc D.P.H, BDS, LDS RCS (Eng)
Director Cochrane BAHRAIN

Aseem Malhotra slår huvudet på spiken. Prevention och behandling av hjärtsjukdom ska vara fokuserad på livsstilsförändringar, som medelhavskost och medveten rörelse.
– Dr. Esther van Zuuren, MD, Methods Editor of Cochrane Skin Group and Recommendations Editor of DynaMed

Aseem Malhotras argument är provokativa och övertygande. Hans talande utvärdering av orsak och behandling av hjärtsjukdom indikerar klart att vi borde omvärdera våra strategier för prevention och behandling.
– Hanno Pijl, MD, PhD internist-endocrinologist, Professor of Diabetology, Leiden University Medical Center

Transkription av podcasten

Karim Khan: Welcome to this podcast for the BJSM community. I’m particularly pleased to be speaking to Dr Aseem Malhotra, a Consultant Cardiologist from London and he and two colleagues have just written a very provocative but important piece about the cause of heart disease. His colleagues are, Pascal Meier, the editor of Open Heart and Rita Redberg, a massively respected cardiologist from the U.S. who’s editor of JAMA Internal Medicine. Aseem, thanks for joining the podcast today

Dr. Aseem Malhotra: Karim, nice to be here.

Karim Khan: Tell us why you thought it’s time to bring a few important points to light in one short piece

There is a realization, more and more now, that the current approach to combating heart disease is fatally flawed.

Dr. Aseem Malhotra: I think the first thing to say, Karim, is that the reason that we wrote this piece at this time, is that the global campaign for decades to lower cholesterol through diet or drugs, has failed to curb the pandemic of heart disease. And the reason behind that, is because there is a realization, more and more now, that the current approach to combating heart disease is fatally flawed. And I think the first thing that we mentioned in the editorial to try and put to bed, essentially is this over-obsession with saturated fat and heart disease and we use the best quality evidence-we use systematic reviews both of observational studies in healthy people which showed no association between consumption of saturated fat and from measures, whether it’s all-cause mortality, cardiovascular mortality, heart attacks, strokes and type 2 diabetes., But also in secondary prevention we cited research published in BMJ Open in 2014 that showed a systematic review of randomized controlled trials showed no benefit from reduction in fat or saturated fat in any cardiovascular outcome. And what was interesting was even replacing saturated fat with polyunsaturated fats in people with established heart disease had no benefit either. So, we wanted to use up-to-date high-quality evidence, which essentially, you know, puts to bed this obsessional with saturated fat and its link to heart disease.

Karim Khan: The rates have gone down so, what if the critics say, you know, the approach has been successful, how, how do you dispute that?

Dr. Aseem Malhotra: Yes, that’s a very fair point, Karim, and people do mention that. So, I’ve also alluded to this before in an editorial in the BMJ in 2013 about saturated fat not being the major issue and we should shift our focus to sugar and it’s great. Obviously, when I first wrote that there were a lot of critics coming out saying ‘What’s this guy going on about sugar?’. Now obviously, everyone’s talking about sugar now, so I think we’ve made some progress there. The issue about cardiovascular mortality reduction in the population, which has happened in the last thirty years, is absolutely correct. But the factors are quite clear that have reduced that cardiovascular mortality through public health interventions, are reduction in smoking, that had the biggest impact, reductions in trans-fats in the diet but also better acute treatments for cardiovascular disease or for heart disease in particular, which involve emergency treatment such as stenting for heart attacks, as well as also better use of coronary care units. It’s where we have rapid defibrillation for people suffering cardiac arrest because of coronary event. So, all of those factors together are more than enough explain for the reduction in cardiovascular mortality.

Interestingly, people often also cite statins. Now, although randomized controlled trials reveal that there is a marginal effect in reduced mortality of about 1 in 83, when you look at numbers needed to treat for people with established heart disease taking a statin for five years, when you actually look at the overall population, interestingly an ecological study, again published in BMJ Open not so long ago, revealed that there was no reduction in overall mortality in the population in Western European countries in secondary prevention. Now, how can that be explained? I think one of the reasons is a separate analysis that looked at giving statins both in primary and secondary prevention, looking at industry-sponsored randomized controlled trials, which obviously have their limitations, only showed that if you look at the statistics slightly differently and take the population as a whole in those RCTs where people were adhering to statins and that’s crucial, every day for five years, the median increase in life expectancy was four and a half days! So, if you think about the fact that in community-based studies more than half of people stop their statins within a year of prescription and most of those cite side effects as the reason, it’s easy to understand why we’ve not seen any significant reduction in mortality in the population from people taking statins. So, there’s a big issue there round the drugs approach as well because of lots of different reasons, including you know, people certainly claiming to experience side effects and in my own practice I see that quite frequently, often reversible in reducing the dose of the drug. But to answer your point, I think it’s quite clear there is no evidence to suggest that reduction in saturated fat per se has had any effect in reduction in cardiovascular mortality in the population.

Karim Khan: Let’s move on to the Guardian. It’s great to get promotion of the paper in the Guardian. Two, two articles, one sharing what you found then one somewhat critical saying that there’s been a backlash to your article. Can you summarize that for us, Aseem?

Dr. Aseem Malhotra: Yeah sure. I think, I’ve looked at those critiques that were in the Guardian and it’s also good to know, Karim, that this was picked up internationally as well by CNN and Reuters as well-as well as many of the newspapers including The Telegraph and The Mail and The Express. But it’s interesting, yes, the Guardian is the one that seemed to report quite extensively the-the critiques and I’ll summarize those critiques. First of all; as a combination of, in my view, sheer ignorance, there are clearly people that haven’t read the editorial and a combination of both intellectual and financial conflicts of interest behind some of the views expressed in that Guardian article. Others pick a few of the issues that were mentioned. I think one originally was by the British Heart Foundation [BHF] in their press release where they made a factually incorrect statement regards to heart stents suggesting that they save lives. That is true if you are having a heart attack, but it’s very clear and most cardiologists would agree, that it’s very clear from randomized controlled trials that stenting stable lesions in coronary arteries do not prevent heart attacks or prolong life. So, my guess is that BHF, I think at best, this made a mistake.

The other thing that was mentioned by a few people is that there was this mention that we cherry picked evidence. Well, if you go and read the editorial specifically on the saturated fat bit, I don’t think is any cherry picking there, both of the citations there were systematic reviews. So, they need to provide better evidence than that to the contrary to suggest why we are cherry picked and I can’t see any reason for that so, as far as I’m concerned, that was complete nonsense.

The third thing to mention is they-, what has been brought up a few times is a Cochrane Review, which we didn’t include in the editorial, which was done in 2015 which suggested there was a reduction in cardiovascular events from replacing saturated fat with polyunsaturated fatty acids. But the reality is, actually, that Cochrane Review was fatally flawed. It did not show any evidence of reduction in all-cause mortality, cardiovascular mortality or heart attacks. And the event rate reduction that was mentioned actually was a very specific, small group of studies that were included and in fact one of the best criticisms, if people want to read in more detail is- I don’t go into a lot of detail on it, as it has been done and reported and posted in a blog by Professor Grant Schofield from New Zealand, who is an epidemiologist and George Henderson and his actual ‘in quotes’ in reference to people mentioning the Cochrane Review as being “reliable evidence”, his quotes were “nonsense”. So, I think people can look at that and read into that in a bit more detail. But actually, you know, what we were saying, interestingly, in some ways, does support some of what the Cochrane review was saying and that is, that we’re not saying that people should consume a diet high in saturated fat, what we were saying is that saturated fat has been – the focus has been misplaced. But actually, what we should be doing is looking at the evidence where there really is outcome benefit, Karim, from randomized controlled trials with dietary interventions.

And that comes from the two citations, the two studies that we cite, with a PREDIMED study in primary prevention (and the Lyon Heart study) where they showed there was a significant reduction in strokes. In the PREDIMED study, which was basically a randomized controlled trial which was Spanish government sponsored, that looked at several thousand people at high risk of cardiovascular disease and they showed an NNT of 61, numbers needed to treat and in stroke reduction in people adopting what was a higher fat Mediterranean diet which is 41 percent fat as opposed to an advice to follow a low fat diet which was only a very small difference in fat consumption, 37 percent in the control diet, which interestingly and we mentioned this in the editorial, was still a relatively healthy diet they were still advised to have less sugar for example. Interestingly, the saturated fat content in both those groups, both the intervention and the control group, in PREDIMED was less than 10 percent. But you see, at the time of that study when it was conducted, the global advice across western European countries, if you like, around saturated fat was to consume less than 10 percent of fat from saturated fat. They wouldn’t have got ethical approval at that time if they had said people should consume more saturated fat. But what’s interesting is a saturated fat consumption in both groups are similar.

All the dietary interventions which have lowered cholesterol for the purpose of low cholesterol, have never shown any outcome benefit.

When the results were published the interesting aspect both in the Lyon Heart study and secondary prevention which is much more powerful in reducing cardiovascular event rates, reduction in all-cause mortality, reduction in cardiovascular mortality, even reduction in cancer. There was no difference in cholesterol between the two groups which suggests that the mechanism of dietary benefit from-in these trials, has nothing to do with lowering cholesterol. Which brings me to another point which is all the dietary interventions which have lowered cholesterol for the purpose of low cholesterol, have never shown any outcome benefit. So, the whole hypothesis is-is fatally flawed and that needs to change.

Karim Khan: A lot of powerful messages for the listener there, Aseem. And if a person is thinking about their own cooking, when you say polyunsaturated fats and when you say saturated fats; what are the practical implications of what people should do from what you’ve told us so far?

Dr. Aseem Malhotra: I’m glad you’ve raised this point; we talk about polyunsaturated fats in layman’s terms. Basically, what’s happened over the last three decades with this demonization of saturated fat, the whole cholesterol is the villain is that people have replaced foods like butter with either vegetable oils or margarine and the vegetable oils are really high in polyunsaturated fats especially omega-6 fatty acids. But there’s a problem, there are two issues with this. One is there is very good research which shows that if you heat these vegetable oils to high temperatures just from simple frying, then they become unstable. In fact, they release compounds called aldehydes which have been linked to both cancer, dementia and heart disease. There is also concern regarding the omega-3 to omega-6 ratio in the population where traditional diets had ratios of around 1 to 1 or 1 to 2 of omega-3 to omega-6. But modern Western diets the ratio is much higher, around 25 to 1 of omega-6 to omega-3 which seems to be a problem. In fact, there was a very good editorial in BMJ Open Heart, which, obviously Pascal is editor of, by Artemis Simopoulos, who is a researcher in this area based in the United States. They did a very extensive editorial looking at the science and basically saying that omega-3 to omega-6 ratio is very much implicated in many diseases including cancer and is pro-inflammatory.

And that brings us back to the issue about the heart disease being more of an inflammatory condition that underlies the process of development of coronary disease and cardiovascular events. So that is the problem and then, obviously, so you are consuming too much omega-6 certainly from my perspective having looked at the evidence. You know, I think the best cooking oil certainly or the best oil, that someone should be consuming is extra virgin olive oil and that’s – and all that spans all across the Mediterranean regions. And you know, clearly showed to have benefit in the PREDIMED study where people were consuming at least four tablespoons of extra virgin olive oil per day in the – in the intervention arm. But also, it’s relatively stable when it’s heated and seems to be very beneficial in many different ways in terms of health benefits.

And then we talk about other things such as butter and coconut oil which are also very stable when you heat them., But as we’ve pointed out, obviously in the editorial, these are the typical oils that are high in – very high in saturated fatty acids.

And it’s not that I’m saying they should make it predominantly your diet but certainly, once you get the base right and we’ve mentioned that in the nice graphic that was done by the graphic artist for the editorial, where we actually mentioned that the key beneficial components in our view when you look at the evidence from the Mediterranean diet, the key things are extra virgin olive oil, handful of nuts every day, lots of vegetables, clearly fibrous vegetables, and oily fish which is high in omega-3. And just to add to that, the foods to – that are certainly are implicated in the insulin-resistance syndrome which we will come on to in a second, are excessive consumption of refined carbohydrates, described by a cardiologist in Australia, Ross Walker recently, as a “white-death diet” which includes sugar, white bread, pasta, too much potatoes. And those are the sorts of foods that we are recommending people should be avoiding. And then, obviously we combine in – we’ll come to the lifestyle – other lifestyle aspects as well, which we believe that can have significant impact on reduced coronary disease if people institute them.

Karim Khan: There was one other criticism of the paper before we forget, from the Centre for Evidence-Based Medicine at Oxford which is a prestigious brand.

Dr. Aseem Malhotra: So, to answer that I’ll come on to this specific criticism from the Centre of Evidence-based Medicine in a second who I have a lot of respect for as an organization, they’ve done a lot of great work but they are not immune to errors or bias and I’ll elaborate that in a second. I think one of the important issues to mention, which we again focus on in the editorial, is that traditionally people take cholesterol and they know about the good cholesterol, HDL and the so-called bad cholesterol, LDL.

So, what actually tends to happen is when people eat saturated fat from foods like butter and cheese etcetera traditionally, yes it may well raise LDL cholesterol but it raises HDL, the other good cholesterol as well and the overall effect on cardiovascular risk is, therefore, neutral.

Now, the first thing to say is that the drug and dietary focus to saturated fat reduction has been on reducing LDL cholesterol. But when you look at cardiovascular risk calculators, something called a QRisk calculator that doctors use to calculate someone’s risk of a heart attack or stroke in the next 10 years, LDL cholesterol is nowhere to be seen. What is used is your total cholesterol divided by your HDL to give you a ratio and the lower the ratio the lower the risk. So, what actually tends to happen is when people eat saturated fat from foods like butter and cheese etcetera traditionally, yes it may well raise LDL cholesterol but it raises HDL, the other good cholesterol as well and the overall effect on cardiovascular risk is, therefore, neutral. And this is also supported as a statement that was made by very well-known respected researcher called Dariush Mozaffarian in the United States. To add further to that Karim I was involved in a systematic review that was published in BMJ Open not so long ago that looked at the so-called bad cholesterol. Everyone has been very obsessed with getting their bad cholesterol lower. And what we did was, we looked at people aged over the age of 60 and what we found was that there was no association with cardiovascular disease and there was an inverse association with all-cause mortality. In other words, the higher LDL if you’re over 60 the less likely you are to die.

And one of the mechanisms for that could well be, because cholesterol is very heavily involved in the immune system and it may protect against people getting infections, such as pneumonia and gastrointestinal illnesses, which is a problem for people, elderly people can die from these infections. So that may be a protective mechanism. But I think the point to be made – we were criticized by the Centre of Evidence-based Medicine, they’re saying that we should use obsolete or flawed methodology to do this. There’s two things I would say. One is there’s no one that’s come out with any kind of counter-analysis to suggest that our findings were incorrect. But even if they did what are we going to find? We may find a weak association but clearly that still doesn’t undermine essentially what we were saying, that this has been grossly exaggerated as a – as a risk factor in people and the elderly in particular.

But the second thing is and this is where the Centre of Evidence-Based Medicine made a mistake, one of my friends and colleagues is the director of the Cochrane Collaboration in Bahrain. His name is Professor Zbys Fedorowicz and he pointed out that, when the Centre of Evidence-based Medicine did their blog criticizing this paper, they mentioned something called the AMSTAR methodology that should have been used or implied it should have been used, in our paper was a better way of analyzing the data. But in fact, actually, that’s incorrect because this methodology has only been validated for interventions and treatments in randomized controlled trials.

This was an associational study, this is a looking at the association of LDLs so they appear to have got that wrong as well. So, and the second thing we must mention this is because I’ve kept quiet about this for some time, they also mentioned that I failed to declare conflicts of interest suggesting that I had links to the pharmaceutical and the food industry because I am advisor to the National Obesity Forum who, over the years apparently for conferences, have been linked to some financial links for funding their conferences. There’s a few things to be said here. One is that the National Obesity Forum doesn’t take any money directly from any industry. Two, I’m an unofficial voluntary advisor to them so to suggest that I’m somehow funded by the meat industry is defamatory and incorrect and I wanted to make that statement now. And they also suggested that because of my role as a founding member of the Public Health Collaboration which is also involved in a report suggesting fat was not the major issue and that there was a report that was being sold on Amazon and that, therefore, there was a financial interest for me. There was no financial interest, whatsoever, I do not make any money from this. In fact, I’m not even – I wasn’t even an author on that specific report so they’ve made a few errors there, which in my view suggests one, of lack of rigour and clearly a bias from the Centre of Evidence-based Medicine who I have a lot of respect for but I just wanted to point out they are not immune from either bias or error.

Karim Khan: So, let’s get the take home messages, a short version of what you think the key problem is with nutrition right now and what you’d advise, given the findings and the information you’ve shared about coronary artery disease.

The elephant in the room is that the root – number one risk factor for heart attacks is insulin resistance.

Dr. Aseem Malhotra: Let’s not ignore the elephant in the room. The elephant in the room is that the root – number one risk factor for heart attacks is insulin resistance. I’ll elaborate that a little bit more. Very good data in the United States from not so long ago, looking at well over 100,000 people admitted with heart attacks, has revealed that 66 percent of people admitted with heart attacks have the criteria for… criteria for metabolic syndrome which, in some ways… in many ways, in fact, is synonymous with insulin resistance. So, this is a syndrome where you have any three of the following five criteria which is; high blood pressure, impaired glucose tolerance or type 2 diabetes, increased triglycerides in the blood stream, low HDL or low good cholesterol and increased waist circumference. You have any three of those five, you have metabolic syndrome and it has an adverse prognosis. Interestingly, in the same data 75 percent of people admitted with heart attacks now have normal total cholesterol and almost 75 percent have normal LDL. So clearly, there’s some thinking missed here.

And, you know, one of the best studies to look at the risk factors was published in Diabetes Care in 2009. And that was a mathematical modelling study and what they found, looking at different risk factors, if you addressed insulin resistance in people aged between 20 and 30 you’d prevent-now obviously, these are not perfect numbers but it does put things in perspective-you’d prevent 42 percent of heart attacks. If you addressed hypertension that came next I think, if I’m not wrong, it was 31 percent. And actually, if you go down the next one after that, was low HDL cholesterol, then you had BMI and actually closer to the bottom, was LDL cholesterol. So, LDL cholesterol is implicated certainly in cardiovascular disease in terms of association if you’re under 60. But again, it’s not as strong as insulin resistance or anywhere close. And again, that doesn’t distinguish between sub-particles so there’s another interesting aspect to the whole LDL story is that LDL itself is broken into Type-A and Type-B sub-particles. And the Type-A particles are the ones that are considered what we call large and fluffy and the Type-B ones are the ones that are atherogenic which are small and dense. Interestingly, saturated fat seems to increase the Type-A particles, refined carbohydrates and sugar increase the Type-B. So there’s a lot of nuance here which is extremely important but the point is that insulin resistance seems to be the number one risk factor for heart attacks and therefore, we should target insulin resistance but it’s also responsible or associated with 50 percent of high blood pressure which is the biggest risk factor for death globally overall and is also the precursor for Type 2 diabetes.

Karim Khan: Before you discuss the treatment of insulin resistance I find it a slightly awkward concept. If you say to the man in the street ‘insulin resistance’ it doesn’t have an immediate psychic response. What’s the best way to think of insulin resistance and then how do we treat it?

Dr. Aseem Malhotra: I think – first of all, let’s explain it – insulin resistance. Essentially the body over time becomes resistant to the effects of the hormone insulin which is the hormone responsible for maintaining blood glucose levels within, you know, the correct range. And what increases insulin resistance over time which is, you know, for the layman, in a way, could be-you could say- it’s a precursor, it’s something that happens before you get Type 2 diabetes which most people understand there’s a problem with-with the glucose control is that certain foods that are responsible over, constantly if you feel like your body being hit with foods, very high glycemic index foods or added sugars, lots of added sugars that increases insulin resistance and over-so over time that can-then you can develop insulin resistance syndrome which, as we said, overlaps with metabolic syndrome and essentially that’s what insulin resistance is.

But the interesting thing is that insulin resistance is not just obviously linked, as we mentioned before, to heart disease and the precursors of Type 2 diabetes and high blood pressure. But the solutions come through dietary changes, exercise or what I’d prefer to refer to really as mindful movement. Even one night’s poor sleep, Karim, has been shown to increase insulin resistance in the blood which is also linked to stress as well. So we know that people who do at least 30 minutes walking five times a week compared to sedentary individuals over even a few months independent of weight loss or obesity, will reduce insulin resistance in their bloodstream. So actually you know we don’t oversimplify it but we’re missing the elephant in the room here that you know 80 percent of heart disease is relates poor lifestyle. And you can combat the majority of this, in our view and this is the point we are making in the editorial, by concentrating on reducing insulin resistance. And the best solution for that is not through drugs, it’s through lifestyle changes.

Karim Khan: Nice science underpinning practical implications. What’s the 30 second take home message for the listener?

Dr. Aseem Malhotra: I think the take home message Karim is that, you know, the future of our health care is going to be lifestyle medicine and adopting a high fat, low refined carbohydrate, Mediterranean diet, mindful movement or exercising regularly and reducing stress, is more powerful than any drug in both the prevention and the treatment of heart disease

Karim Khan: And that was Dr Aseem Malhotra. The links with the podcast related to his provocative editorial in the BJSM. You can find a lot of information about healthy diet, exercise on various BJSM resources, obviously and on twitter@bjsm_bmj and I do hope you get a chance to have a peaceful active day today. Thanks for listening.

Acknowledgments

We would like to extend our thanks to Anirudha Agnihotry and James Mason for their very helpful work in doing the transcription.

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Forskare från Cochrane stöder påstående att mättat fett inte täpper till kärlen

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