By George Henderson and Grant Schofield
In today’s Guardian, there’s a report on the backlash against an editorial in the British Journal of Sports Medicine entitled “Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions”.[1]
The authors are cardiologists Aseem Malhotra and Pascal Meier, well known for their support of low carb interventions (Pascal Meier is also editor of BMJ Open Heart). And, coming as a surprise to us, Rita Redberg, a cardiologist who is better known as the editor of the high-impact American journal JAMA Internal Medicine (perhaps making this the first meta-editorial). We recently had a letter published in JAMA Int Med questioning the analysis in a Harvard epidemiology paper concerning dietary fats and mortality (Wang response), so maybe this shouldn’t have been a surprise if they’re open to readers questioning the established wisdom.
The editor of BMJ British Journal of Sports Medicine has supported low carb in the past, publishing papers by Tim Noakes and Aseem Malhotra; there’s a fine tradition of the “reforming journal” which is being revived around the dietary guidelines question today, with some journals (the BMJ itself also comes to mind) not being afraid to court controversy.
The gist of the article is in the graphic above and in this press release:
Journals from BMJ Press Release:
Embargoed 23.30 hours UK time Tuesday 25 April 2017
BRITISH JOURNAL OF SPORTS MEDICINE
Popular belief that saturated fats clog up arteries “plain wrong” say experts
Best form of prevention and treatment are ‘real’ food and a brisk 22 minute daily walk
The widely held belief among doctors and the public that saturated fats clog up the arteries, and so cause coronary heart disease, is just “plain wrong,” contend experts in an editorial published online in the British Journal of Sports Medicine.
It’s time to shift the focus away from lowering blood fats and cutting out dietary saturated fat, to instead emphasising the importance of eating “real food,” taking a brisk daily walk, and minimising stress to stave off heart disease, they insist.
Coronary artery heart disease is a chronic inflammatory condition which responds to a Mediterranean style diet rich in the anti-inflammatory compounds found in nuts, extra virgin olive oil, vegetables and oily fish, they emphasise.
In support of their argument Cardiologists Dr Aseem Malhotra, of Lister Hospital, Stevenage, Professor Rita Redberg of UCSF School of Medicine, San Francisco (editor of JAMA Internal medicine) and Pascal Meier of University Hospital Geneva and University College London (editor of BMJ Open Heart) cite evidence reviews showing no association between consumption of saturated fat and heightened risk of cardiovascular disease, diabetes, and death.
And the limitations of the current ‘plumbing theory’ are writ large in a series of clinical trials showing that inserting a stent (stainless steel mesh) to widen narrowed arteries fails to reduce the risk of heart attack or death, they say.
“Decades of emphasis on the primacy of lowering plasma cholesterol, as if this was an end in itself and driving a market of ‘proven to lower cholesterol’ and ‘low fat’ foods and medications, has been misguided,” they contend.
Selective reporting of the data may account for these misconceptions, they suggest.
A high total cholesterol to high density lipoprotein (HDL) ratio is the best predictor of cardiovascular disease risk, rather than low density lipoprotein (LDL). And this ratio can be rapidly reduced with dietary changes such as replacing refined carbohydrates with healthy high fat foods (such as nuts and olive oil), they say.
A key aspect of coronary heart disease prevention is exercise, and a little goes a long way, they say. Just 30 minutes of moderate activity a day three or more times a week works wonders for reducing biological risk factors for sedentary adults, they point out.
And the impact of chronic stress should not be overlooked because it puts the body’s inflammatory response on permanent high alert, they say.
All in all, a healthy diet, regular exercise, and stress reduction will not only boost quality of life but will curb the risk of death from cardiovascular disease and all causes, they insist.
“It is time to shift the public health message in the prevention and treatment of coronary artery disease away from measuring serum lipids and reducing dietary saturated fat,” they write.
“Coronary artery disease is a chronic inflammatory disease and it can be reduced effectively by walking 22 minutes a day and eating real food.”
But, they point out: “There is no business model or market to help spread this simple yet powerful intervention.”
The push-back in the Guardian made use of the Hooper at al 2015 meta-analysis of diet-heart RCTs:[2]
Dr Amitava Banrejee, a senior clinical lecturer in clinical data science and honorary consultant cardiologist at UCL, said: “Unfortunately the authors have reported evidence simplistically and selectively. They failed to cite a rigorous Cochrane systematic review which concluded that cutting down dietary saturated fat was associated with a 17% reduction in cardiovascular events, including CHD, on the basis of 15 randomised trials.”
This is nonsense.
1) The Hooper 2015 Cochrane meta-analysis gave no information on reducing saturated fat, because the only reduction in events was seen in some studies where saturated fat was replaced with polyunsaturated fat, not with carbohydrate. Based on population epidemiology, it’s likely that replacing carbohydrate with PUFA – and keeping SFA the same – would have had as much or a greater effect, except that this was never tested in these RCTs.
2) There were no reductions in heart attacks, strokes, cardiovascular deaths, or all-cause mortality from saturated fat replacement in Hooper 2015. The only reductions were in “unblinded” event outcomes, where the LDL level is one of the diagnostic criteria.
3) Hooper 2015 included many studies in which SFA was reduced by replacing processed food (pizzas, pies, desserts) with wholefoods (nuts, whole grains, fish, fruit). This improvement in food quality should have produced some benefit independent of fats. Ramsden et al isolated those studies where PUFA cooking fats and spreads replaced more saturated cooking fats and spreads, and there was no benefit overall, with some harm from high omega-6 interventions and a suggestion of benefit from omega-3 ones.[3] In fact, the Hooper et al studies that improved food quality should have produced better results than they did, and it is possible that the focus on saturated fat reduction and on keeping total fat low hampered them.
4) Statistical modelling in Hooper et al 2015 used the random effects model, which may have exaggerated the results of the smaller, more favourable trials; had an alternative model, inverse heterogeneity analysis, been used there would have probably been no significant associations at all. Watch this space as we (led by epidemiologist Dr Simon Thornley) prepare to publish an academic paper on exactly this, with a full reanalysis of this Hooper Cochrane review using this new more modern method for the meta-analysis.
Quite a few people cited in the Guardian did support Malhotra et al.
Gaynor Bussell, a dietitian and member of the British Dietetic Association, also offered the authors qualified support. “Many of us now feel that a predominantly Med-style diet can be healthy with slightly more fats and fewer carbs, provided the fats are ‘good’ – such as in olive oil, nuts or avocados,” she said.
However, saturated fats should comprise no more than 11% of anyone’s food intake, she said – far less than the 41% fat level backed by the co-authors.
While carbohydrates should still be part of every meal, people should routinely consume high fibre or wholegrain versions, Bussell said.
Well, this is nonsense. You could easily have a 41% fat diet that was 11% saturated fat if you used some olive oil. Fancy a dietitian and member of the British Dietetic Association making that mistake. But why should saturated fats comprise no more than 11% of anyone’s food (energy) intake? What is the evidence for this cut-off? It is 14% in Scandinavia, 10% in New Zealand – irrespective of the total fat intake which it’s part of, which is surely relevant; did every country pull their figure out of a hat?
And why should carbohydrates, that is, sweet and starchy foods, be part of every meal?
We think it’s probably beneficial to be in at least mild ketosis, and have low insulin levels, for at least part of the day. Otherwise you’re always in the fed state, always packing away energy as cholesterol and fat, instead of using it up. And surely that’s where the fat that can build up in your arteries comes from – whatever puts it there, whether it’s carried there by oxidised LDL particles or by magic pixies, it’s available to go there because it wasn’t used to fuel you, which is why CHD risk due to atherosclerosis is associated with overweight and obesity and offset by exercise.
There’s one criticism that’s probably justified;
Christine Williams, professor of human nutrition at Reading University, said the cardiologists’ dietary advice was impractical, especially for poorer people. “The nature of their public health advice appears to be one of ‘let them eat nuts and olive oil’ with no consideration of how this might be successfully achieved in the UK general population and in people of different ages, socioeconomic backgrounds or dietary preferences,” she said.
Doctors’ visits and PCSK9 inhibitors aren’t cheap either. There is a need to scale healthy low-carb advice for poorer populations. Fats like olive oil are cheap per calorie compared to most healthy foods, but dearer than other oils, so would some canola oil be okay? As far as anyone knows, peanuts and sesame and sunflower seeds are as good as the more expensive nuts. High-fat yoghurts and milk are the same price as the reduced fat versions; this is one way to save money. Whole grains are much more expensive than flour and sugar, but that won’t stop the experts recommending them.
Postscript
In case you think that “inflammation” in the BMJ Sports Medicine editorial was too briefly described or explained, here’s a superb review of the “alternative hypothesis” of heart disease from 2011, which deserves to be more widely read.
Kuipers et al
References
[1] Saturated fat does not clog the arteries: coronary heart disease is a chronic inflammatory condition, the risk of which can be effectively reduced from healthy lifestyle interventions.
[2] , , , . Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews 2015, Issue 6. Art. No.: CD011737. DOI: 10.1002/14651858.CD011737.
[3] Ramsden CE , Zamora D , Majchrzak-Hong S , et al . Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota coronary experiment (1968-73). BMJ 2016;353:i1246. doi:10.1136/bmj.i1246
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