Dietary Fat. A Doctor's Review. (Short version)

Dietary Fat. A Doctor’s Review (Short version)

Dr Magda Robinson 21 November 2017

As a medical doctor specialising in the treatment of obesity, I often get asked which the best fats are.

Butter? Coconut oil? Olive oil? This article will look at saturated fat (SFA), which is found in coconut oil and animal fats such as butter, meat and cheese, and the evidence for the link to cardiovascular disease (CVD). Is there an increase in the risk of heart attacks and strokes with an increased intake of SFA? Is there any protection from CVD through the intake of polyunsaturated fats (PUFA) such as rapeseed oil and flaxseed oil, or monounsaturated fats (MUFA) such as olive oil?

There have been many confusing articles recently about the relationship between saturated fatty acids (SFA) and cardiovascular disease (CVD). These controversial articles claim that there is no evidence for a link, despite the National Institute for Clinical Excellence (NICE) guidelines stating: “Lifestyle modifications for the primary and secondary prevention of CVD. Cardioprotective diet: to eat a diet in which total fat intake is 30% or less of total energy intake, saturated fats are 7% or less of total energy intake, intake of dietary cholesterol is less than 300 mg/day and where possible saturated fats are replaced by mono-unsaturated and polyunsaturated fats.” 1 I researched the literature from the 1960’s to the present day, and now present a brief summary of the evidence. Cardiovascular disease (CVD) is the leading cause of death worldwide: 31.5% of the population dies of coronary heart disease or stroke or other CVDs. It is caused by the blocking of an artery due to a blood clot, arising from the build-up of cholesterol and fats in the artery wall (atherosclerosis). One of the well-established major risk factors is raised serum cholesterol and lowdensity lipoprotein cholesterol (LDLC) (‘bad’ cholesterol: plasma proteins which carry around cholesterol and fats to the tissues).

The link between LDLC and the risk of CVD is well known, as there is a direct correlation between levels of LDLC and the risk of CVD: GPs and cardiologists use the QRISK®2 Calculator, which includes serum cholesterol levels, to work out the risk of having a heart attack or stroke over the next ten years. Furthermore, in the genetic condition familial hypercholesterolaemia, the body is unable to remove LDLC from the blood, leading to extremely high serum cholesterol and LDLC levels. The consequences are that before the age of 50, men with the condition have a 50% chance of suffering from angina or a heart attack. The treatment is to take cholesterol-lowering drugs, which reduce the risk of CVD by up to 40%, and eat a diet reduced in saturated fat and cholesterol. The subsequent reduction in LDLC is directly correlated with a reduction in CVD. The recent controversial reports were only based on epidemiological data, which was in itself flawed because it compared diets high in SFA with diets high in unhealthy refined carbohydrates, sugars and trans fats; thus no advantage was detected with the lower SFA diets. They analysed a limited number of studies, including some erroneous data. Furthermore, their findings are contradicted by large-scale good quality epidemiological evidence from prospective cohort studies and randomised controlled trials (RCTs) which show that SFA intake is associated with an increased risk of CVD, and when replaced by PUFA the risk of CVD is reduced.2-7 In addition, the evidence for SFA inducing atherosclerosis is not based on epidemiology alone. It also stems from decades of research in pathology, biochemistry, metabolism, pharmacology, and animal and human studies. For example, saturated fat not only raises LDLC, is also has been proven to cause chronic inflammation and insulin resistance, which also increase the risk of CVD.

Saturated fat feeding studies Human feeding studies illustrate that when diets rich in butter, coconut oil and PUFA are compared, the cholesterol and LDLC are consistently raised to levels enough to cause atherosclerosis in the butter and coconut oil diets, compared to the PUFA diets, in as little as 9 days.8 For example, one randomised controlled trial (RCT) assessed diets high in SFAs (12.6%): butter or cheese; polyunsaturated fats (PUFA); monounsaturated fats (MUFA), and high carbohydrate. After 4 weeks the butter caused the greatest rise in LDLC, followed by cheese, compared to the other diets.9 Another RCT compared the consumption of 4.5% of energy from butter with olive oil. After 5 weeks, the total and LDLC were significantly higher in the butter group.10 A feeding experiment compared eating SFA-rich muffins made with palm oil to PUFA-rich muffins made with sunflower oil. After 7 weeks, the SFA group had significantly greater total fat, liver fat and visceral fat, all of which are known to be precursors to raised serum cholesterol and LDLC, insulin resistance and CVD.11 The World Health Organisation published a meta-analysis of 84 randomised controlled feeding studies examining the effects of increasing or decreasing SFA in the diet.12 Protein levels were kept constant, and the diets had an average duration of 3 to 5 weeks. The results were that replacing 1% of PUFA, MUFA or carbohydrate with SFA increased total cholesterol, LDLC, the LDLC: HDLC ratio and the Apolipoprotein B (ApoB) levels. Conversely replacing 1% of SFA with PUFA, MUFA or carbohydrate decreased the same parameters. ApoB is a type of protein made in the liver and is found in the most atherogenic lipoproteins such as LDL, VLDL and chylomicrons. It is a good predictor of CVD as it represents the total burden of the main lipoproteins involved in the atherosclerotic process. It is alarming that even small changes in SFA content of the diet over a short period of time have such dramatic effects on the atherogenicity of blood lipids. The World Health Organisation recommends that SFA are kept to below 10%.

Reliable evidence There is no doubt that SFA increases LDLC, but what about the evidence for CVD? The results of the largest ever observational study (115,782 people) with the longest duration (28 years) led to The Times printing the headline “Butter is still bad for the heart” (24.11.16): “Recent studies have questioned whether saturated fat in meat and dairy is bad for the heart but the new study, in the BMJ, found the danger had been masked by people switching to equally unhealthy sugar and refined carbohydrates... it concluded that people who eat less saturated fat do have less heart disease.”

This Harvard study, examining cohorts from the Nurses’ Health Study and the Health Professionals’ Follow-Up Study, was of excellent quality due to its size, duration and the controlling of multiple variables such as age, ethnicity, BMI, smoking, alcohol, exercise, family history, hypertension, high cholesterol and nutritional intake, and was the first to examine specific SFAs.4 There are different types of saturated fats: short, medium and long chain. Long-chain SFAs increase serum LDLC, the commonest being myristic acid (e.g. butter, meat, coconut and palm oil) and palmitic acid (e.g. butter, red meat, chicken, eggs, palm oil and chocolate). The initial findings were that the highest intake of red meat and high fat dairy increased the risk of CHD by 15% and 8% respectively. In 2016 the results were that the highest fifth intake of the SFA myristic acid led to a 13% higher risk, and the SFA palmitic acid to an 18% higher risk of CHD compared to the lowest fifth. Lauric acid (a mediumchain SFA found in coconut oil) increased risk by 7%. Combined, the SFAs lauric, myristic, palmitic and stearic acid increased risk by 18%.

If particular SFAs were replaced by certain types of macronutrients, CHD risk was reduced. For example, when replacing 1% of energy intake from SFA, CHD was reduced by 12% for PUFA, 11% for plant protein, 10% for wholegrains and 8% for MUFA.4 When replacing 5% of energy intake from SFA, CHD was reduced by 25% for PUFA, 15% for MUFA, and 9% for carbohydrates from whole grains.5 Replacement with refined starches and sugars increased risk by 1% (not significant) and replacement of 2% of SFA with trans fats increased risk by 5%.5 A further analysis of the data found that replacement of 5% of energy from SFA with PUFA also reduced total, CVD, cancer, neurodegenerative, and respiratory disease mortality13.

These results concur with meta-analyses of other studies: it has been calculated that replacing 5% of energy from SFA with PUFA is associated with a 26% lower risk of CHD death.2 In a meta-analysis of large scale RCTs there was a CHD risk reduction of 27% if 5% of SFA was replaced by PUFA over 4.25 years.6 Thus there are considerable heart health benefits by replacing as little as 5% of SFA with PUFA, plant protein, wholegrains and MUFA. The American Heart Association’s statement As a response to the controversial reports, the American Heart Association (AHA) published Dietary Fats and Cardiovascular Disease: A Presidential Advisory, in Circulation with a comprehensive review of the evidence7. It included an assessment of high quality prospective observational studies, which isolated the effects of different macronutrients (unlike the misleading reports), and also a metaanalysis of high quality RCTs. The latter were selected because the dietary intakes were controlled, of long duration, proved adherence through measurement of blood or tissue fatty acids, and did not include confounding trans fats: lowering SFA and replacing it with PUFA-rich vegetable oil lowered CHD by 29%, consistent with the effect of the experimental diets on serum cholesterol. The effects were particularly strong for patients under the age of 65, and for those with high serum cholesterol levels.

The American Heart Association states: “The scientific rationale for decreasing saturated fat in the diet has been and remains based on well-established effects of saturated fat to raise low-density lipoprotein (LDL) cholesterol, a leading cause of atherosclerosis; to cause atherosclerosis in several animal species, especially nonhuman primates; to clear the atherosclerosis when is it reduced in the diet; and likewise to reverse atherosclerosis in humans. In addition, reducing saturated fat and replacing it with polyunsaturated fat in randomised controlled trials has reduced the incidence of CVD...

“In summary, RCTs that lowered intake of dietary saturated fat and replaced it with polyunsaturated vegetable oil reduced CVD by 30%, similar to the reduction achieved by statin treatment. Prospective observational studies in many populations showed that lower intake of saturated fat coupled with higher intake of polyunsaturated and mono-unsaturated fat is associated with lower rates of CVD and of other major causes of death and all-cause mortality. In contrast, replacement of saturated fat with mostly refined carbohydrates and sugars is not associated with lower rates of CVD and did not reduce CVD in clinical trials. Replacement of saturated with unsaturated fats lowers low-density lipoprotein cholesterol (LDL), a cause of atherosclerosis... we conclude strongly that lowering intake of saturated fat and replacing is with unsaturated fats, especially with polyunsaturated fats, will lower the incidence of CVD.”7 Likewise, the European Atherosclerosis Society has issued a consensus statement summarising the evidence, entitled Low-density Lipoproteins Cause Atherosclerotic Cardiovascular Disease, based on genetic, epidemiologic and clinical studies on more than 2 million participants.14

Unreliable evidence What is wrong with the studies claiming no association between SFA and CVD? The main problem is that they only looked at changing the saturated fat intake, without considering the replacement. If a diet high in saturated fat is compared to a diet high in refined grains and sugars or trans fats (which most of the studies did), then the result is no worsening of the CVD risk with SFA.7,15 However, there is overwhelming evidence that replacing saturated fat with polyunsaturated fatty acids (PUFA) significantly reduces CVD risk.

Another criticism of the controversial reports is that they pooled together a number of studies with a huge variation in results and design, and most were of very low quality. Frequently there was inconsistent adjustment for factors such as demographic, lifestyle or macronutrients. Some of the studies only looked at all-cause mortality, not CVD mortality. Many of the studies were small or of a short duration (less than 2 years). Frequently meals were not controlled, adherence was poor (as documented by variable serum cholesterol levels) and most of the studies examined secondary prevention, using patients who already had severe heart disease and in whom a change of diet would be too late to be of any benefit.

Other faults were that the meta-analyses were incomplete, either using incorrect figures or omitting studies which found that replacing SFA with PUFA did reduce CVD. The studies were also guilty of selective reporting of original results: for example they ignored data which showed a strikingly increased incidence of heart attacks in the younger age groups on the SFA diets, and in those following the diets for 2 years or more. Furthermore, some of these studies did document (in the small print) a strong association between circulating SFA and CVD risk (records of dietary intake can be unreliable): for example a 15% higher risk of CHD with higher serum palmitic acid, but these results were ignored by the media.

The Harvard School of Public Health has criticised one of these studies16 stating that the study’s conclusions regarding types of fat were ‘seriously misleading and should be disregarded.’ Likewise a negative editorial16 was criticised by Prof Tom Sanders, Head of Diabetes and Nutritional Sciences Division in the School of Medicine at King’s College London. He said: “This article rubbishes the relationship with saturated fat and CVD, misrepresents the scientific evidence and then goes on to put the blame on sugar. It is beyond reasonable doubt that elevated LDL (low-density lipoprotein) cholesterol is a major determinant of risk factor for cardiovascular disease. The saturated fatty acids palmitic, myristic and lauric acids raise LDL cholesterol in increasing order in meta-analysis human experimental studies18. Sugar intake does not affect LDLcholesterol or blood pressure.

Diabetes increases risk of CVD but diabetes is not caused by eating sugar. The relative risks of sugar intake with risk of obesity are very modest compared with obesity and physical inactivity.”19 Animal studies More than 100 years of clinical experiments in animals clearly prove that saturated fat causes atherosclerosis. It can be induced in as little as 2 months in pigeons, pigs, dogs and monkeys on diets with added lard, hydrogenated coconut oil, butter, or egg yolks, with added cholesterol. The extent of the CVD increases with the severity of the induced increased cholesterol levels.20-24 Feeding a high-cholesterol, high-fat diet for two years reliably induces atherosclerosis, with risk factor profiles, arterial lesions, and changes in vascular function also seen in humans.25 In comparison monkeys on

low fat control diets (usually a mixture of mostly corn, wheat and soya beans) do not develop atherosclerosis.

PUFA have been proven to protect against atherosclerosis: a moderately atherogenic diet (containing cholesterol) was fed to monkeys, with added fats: SFA (17.5% SFA content), MUFA or PUFA. Remarkably the PUFA diet protected against CHD: after 5 years the extent of atherosclerosis was over twice as large in the MUFA diet, and over 5 times higher in the SFA diet. These changes correlated with the levels of LDLC, which were 61% higher in the SFA diet.26 It is possible for atherosclerosis to diminish through diet alone, by manipulation of serum cholesterol. Rhesus monkeys fed an atherogenic diet for 17 months developed 60% narrowing in the coronary and other arteries. Half the monkeys were then given a low fat diet and half a PUFA-rich diet for 20 months. There was rapid reduction in arterial narrowing to around 20% on both the diets.27 Another study used an atherogenic diet of 1mg/kcal cholesterol to cause raised serum cholesterol, which in turn induced coronary atherosclerosis. The dietary cholesterol was then reduced, which resulted in regression of the atherosclerosis.28 Note that serum cholesterol has to reduce substantially and be maintained for at least 2 years to induce regression of arteriosclerosis: a study reported that monkeys fed an atherogenic diet for 19 months only regressed once the serum cholesterol reduced to less than 5.2 mmol/L, but more severe atherosclerosis (induced over 3 years) required 4 years of dietary-induced cholesterol of less than 5.2mmol/L to trigger regression.29,30 These findings underline the importance of maintaining lower serum cholesterol levels long term.

Regression of CVD in humans Two world-renowned American cardiologists have had success in regressing arterial atherosclerosis in human patients through diet alone. Dr Dean Ornish conducted a trial of a 10% fat plant-based diet on patients who needed cardiac surgery, compared to patients with equally severe heart disease who were put on a 25% fat diet. The plant-based diet included fruit, vegetables, pulses, grains, with occasional egg white and skimmed milk. After one year on the plant-based diet, 82% had regression of their heart disease, despite being on no medication. Arterial scans showed shrinkage of the blockages, LDLC levels were lower by 40%, and the frequency of chest pain was reduced by 91%. The control group actually had worsened atherosclerosis and cardiometabolic risk factors, despite being on medication, with a rise in chest pain frequency of 165%, and no weight loss. The LDLC reduced by only 5%. At 5 years arteriography showed continued shrinking of the blockages in the plant-based group, and there were less than half as many cardiac events than the usual care group. The usual care group had progressively worsening narrowing of the arteries throughout the 5 years.31,32 Dr Caldwell Esselstyn, has had similar success in reversing heart disease using plant-based nutrition.33 He offered seriously ill patients, who had had failed interventions such as angioplasty and bypass surgery, an exclusively plant-based diet, in conjunction with their usual lipid lowering medication. The diet consisted of wholegrains, vegetables, fruit and legumes, with no animal products at all. Of those who maintained the diet, they experienced a profound drop in cholesterol: it reduced from an average of 6.4 mmol/L to an average of 3.5 mmol/L. In addition, symptoms were relieved, and there was no recurrence of coronary events in 12 years. Patients lost weight, blood pressure normalized, and type 2 diabetes, erectile dysfunction, angina, peripheral vascular disease, and carotid disease all improved or resolved. Angiography at 5 years proved that none had progression of the disease, and 70% had significant regression of the coronary blockages.

The evidence above makes it clear that replacing saturated fats with PUFA, plant proteins, wholegrains or MUFA reduces the risk of developing CVD. Protein If protein is substituted for SFA, only plant protein is beneficial: replacing 5% of SFA with animal protein increases risk of CHD by 29%.34 Replacing 1% of energy from long-chain SFA with plant protein reduces CHD risk by 7%.4 The mechanisms for this are numerous,15 including the differential effects of amino acids (animal proteins are rich in the sulphur-containing amino acids): high levels of methionine have been known to induce hypercholesterolaemia, and also raise homocysteine levels, which are risk factors for CVD. Haem iron is associated with greater CVD risk (it is a pro-oxidant).

Processed meat is extremely high in sodium and nitrites and nitrates, which are well-established risk factors for CVD. Advanced glycation end products (formed by the cooking of red and processed meat) increase inflammation and the CVD process. Red meat is a rich source of L-carnitine and phosphatidylcholine, which are metabolised to trimethylamine N-oxide (TMAO), which causes atherosclerosis and increases the risk of CVD.35,36 Interestingly vegans and vegetarians have significantly less carnitine-metabolizing gut bacteria and hence lower circulating levels of TMAO.37 Plant proteins do not contain these components, and in fact contain micronutrients beneficial to blood vessels such as potassium, B and C vitamins, polyphenols, phytosterols, and magnesium. One study showed a 30% reduction in CHD when plant proteins were substituted for carbohydrates or animal proteins.38 It also reported an increased CHD mortality of 44% with red meats. Note that eating meat is more detrimental than eating dairy: when 5% of dairy fat is replaced with 5% animal fat from non-dairy sources, risk of CHD increases by 6%.39 Dietary cholesterol Dietary cholesterol, which is found in meat, poultry, eggs and high fat dairy products, has three important issues: firstly it increases the susceptibility of LDLC to oxidation, which stimulates the process of atherosclerosis, and inhibits the production of beneficial nitric oxide. Secondly it markedly increases levels of cholesterol after eating. Thirdly, at high levels (e.g. 600mg day) it substantially increases SFA’s effects on LDLC (the ‘bacon and egg effect’).40 One egg yolk contains around 200mg.

Harvard School of Public Health advises a maximum of one egg a day, but 3 or less per week in diabetics, due to the increased risk of heart failure and CHD at higher amounts.

Four foods to lower serum cholesterol Apart from replacing SFA with PUFA, plant proteins and wholegrains, there are four foods proven to lower serum cholesterol levels. These can be eaten every day: oats (soluble fibre); soya protein (e.g. soya mince, soya burgers, soya milk, tofu); nuts; and plant sterols (e.g. Flora Pro-Active spread). Aim to eat 10-25g of soluble fibre a day (also found in beans, peas, brown rice, barley, citrus fruits, strawberries, and apples.)

Three healthy diets It is wise to learn from the 3 populations which have very low rates of CVD. On the island of Okinawa in Japan, the low rates of CVD are attributed to a low SFA fat diet consisting mostly of vegetables, sweet potato, soya protein, and fruit with a little bread and rice (meat and fish are eaten only on holidays). Very low CVD rates were also observed in Crete in the 1960’s, in people following the classic Mediterranean diet: low in SFA and consisting of mostly plant foods including fruit, vegetables, grains, nuts, seeds, olive oil, with moderate dairy and wine intake and low meat intake.

The population with the greatest life expectancy in the world are vegetarian Californian Seventh Day Adventists, in whom the risk of CHD death is 27% lower than the meat eating population.41,42 Conclusion The American Heart Association and American College of Cardiology have conducted extensive research on all the available evidence, including the critical studies mentioned above, and concur with NICE guidelines, stating that saturated fat should be less than 7% of total energy intake.7 Only about 5% of US adults consume less than 7%.43 Thus most adults need to reduce saturated fat to reduce their risk of CVD. The SFA should be replaced (in order of greatest benefit first) with PUFA, plant proteins, wholegrains and MUFA. This means minimising meat; replacing butter, palm oil and coconut oil with PUFAs such as rapeseed oil, walnut oil, and flaxseed oil (the latter two both high in essential n-3); and using olive oil (MUFA) for cooking. Note that when heating olive oil the temperature should be kept to a maximum of 180 oC. Soft PUFA-rich margarine containing no trans fats or hydrogenated vegetable oils can also be used. The ideal is to consume less than 20g SFA a day in order to reduce the risk of CVD.

Two key references: 7 Sacks FM, Lichetenstein AH, Wu JHY et al 2017. Dietary fats and cardiovascular disease. A presidential advisory from the American Heart Association. Circulation 135:00-00 doi:10.1161/cir.0000000000000510 15 Briggs MA, Petersen KS, Kris-Etherton PM 2017. Saturated fatty acids and cardiovascular disease: replacements for saturated fat to reduce cardiovascular risk. Healthcare 5:29; doi:10.3390/healthcare5020029

FULL REFERENCES TO DIETARY FAT. A DOCTOR’S REVIEW. 1 NICE clinical guideline CG181 July 2014. Cardiovascular disease: risk assessment and reduction, including lipid modification. 1.2 Lifestyle modifications for the primary and secondary prevention of CVD 2 Farvid MS, Ding M, Pan A et al. 2014. Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies. Circulation 130(18):1568-78. doi: 10.1161/CIRCULATIONAHA.114.010236 3 Jakobsen MU, O’Reilly EJ, Heitmann BL, et al. 2009. Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. The American Journal of Clinical Nutrition.

89(5):1425-1432. doi:10.3945/ajcn.2008.27124.

4 Zong G, Li Y, Wanders AJ et al. 2016. Intake of individual saturated fatty acids and risk of coronary heart disease in US men and women: two prospective longitudinal cohort studies. BMJ 355: i5796 5 Li Y, Hruby A, Bernstein AM et al 2015. Saturated fats compared with unsaturated fats and sources of carbohydrates in relation to risk of coronary heart disease: a prospective cohort study. J Am Coll Cardiol 66:1538-1548

6 Mozaffarian D, Micha R, Wallace S 2010. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis or randomised controlled trial. PLoS Med 7:e1000252 doi:10.1371/journal.pmed.1000252 7 Sacks FM, Lichetenstein AH, Wu JHY et al 2017. Dietary fats and cardiovascular disease. A presidential advisory from the American Heart Association. Circulation 135:00-00 doi:10.1161/cir.0000000000000510 8 Eyres L, Eyres MF, Chisholm A et al. 2016. Coconut oil consumption and cardiovascular risk factors in humans. Nutr Rev 74: 267-280 9 Brassard D, Tessier-Grenier M, Allaire J et al. 2017. Comparison of the impact of SFA from cheese and butter on cardiometabolic risk factors: a randomised controlled trial. Am J Clin Nutr 105(4):800809 10 Engel S, Tholstrup T 2015. Butter increased total and LDL cholesterol compared with olive oil but resulted in higher HDL cholesterol compared with a habitual diet. Am J Clin Nutr 102: 309-315 11 Rosquvist F, Iggman D, Kullberg J et al. 2014 Overfeeding polyunsaturated and saturated fat causes distinct effects on liver and visceral fat accumulation in humans. Diabetes 63(7):2356-68 12 Mensink RP 2016. Effects of saturated fatty acids on serum lipids and lipoproteins: a systematic review and regression analysis. Geneva: WHO 13 Wang DD, Li Y, Chiuve et al. 2016. Association of specific dietary fats with total and cause-specific mortality. JAMA Intern Med 176:1134-1145 14 Ference BA, Ginsberg HN, Graham I et al. 2017. Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J 38(32):24592472. doi: 10.1093/eurheartj/ehx144.

15 Briggs MA, Petersen KS, Kris-Etherton PM 2017. Saturated fatty acids and cardiovascular disease: replacements for saturated fat to reduce cardiovascular risk. Healthcare 5:29; doi:10.3390/healthcare5020029 16 Chowdhury R, Warnakula S, Kunutsor S et al. 2014. Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Ann Intern Med 160:398-406 17 DiNicolantonio JJ 2014. The cardiometabolic consequences of replacing saturated fats with carbohydrates or Ί-6 polyunsaturated fats: Do the dietary guidelines have it wrong? Open Heart 1:e000032. doi:10.1136/openhrt-2013- 000032 18 Sanders TA 2013. Reappraisal of SFA and cardiovascular risk. Proc Nutr Soc 72;4:390-398 19 Sanders TA 5 March 2014. http://www.sciencemediacentre.org/expert-reaction-to-editorial-onsaturated-fats/ 20 Pick R, J Chediak, G Glick 1979. Aspirin inhibits development of coronary atherosclerosis in cynomolgus monkeys (Macaca fascicularis) fed an atherogenic diet. J Clin Invest 63;1:158-162 21 Maruffo CA, Portman OW 1968. Nutritional control of coronary artery atherosclerosis in the squirrel monkey. Atherosclerosis 8;2:237–247

22 Bond MG, Bullock BC, Bellinger DA et al. 1980. Myocardial infarction in a large colony of nonhuman primates with coronary artery atherosclerosis. Am J Pathol 101:675-693 23 Gresham GA, Howard AN, McQueen J et al. 1965. Atherosclerosis in Primates. Br J Exp Pathol 46:1:94-103 24 Moghadasian MH, Frohlich JJ, McManus BM 2001. Advances in experimental dyslipidemia and atherosclerosis. Lab Invest 81;9:1173-83 25 Mahaney MC, Karere GM, Rainwater DL et al. 2017. Diet-induced early-stage atherosclerosis in baboons: Lipoproteins, atherogenesis, and arterial compliance. J Med Primatol 00:1–15.

26 Rudel Ll, Parks JS, Sawyer JK 1995. Compared with dietary monounsaturated and saturated fat, polyunsaturated fat protects African green monkeys from coronary artery atherosclerosis.

Arterioscler Thromb Vasc Biol 15:2010-2110 27 Armstrong ML 1976. Evidence of regression of atherosclerosis in primates and man. Postgrad Med J 52;609: 456–461.

28 Clarkson TB, Klumpp SA 1990. The contribution of nonhuman primates to understanding coronary artery atherosclerosis in humans. ILAR J 32;2:4–8 29 Clarkson TB, Bond MG, Bullock BC et al. 1981. A study of atherosclerosis regression in Macaca mulatta . IV. Changes in coronary arteries from animals with atherosclerosis induced for 19 months and then regressed for 24 or 48 months at plasma cholesterol concentrations of 300 or 200 mg/dl.

Exp. Mol. Pathol 34;345-368 30 Clarkson TB, Bond MG, Bullock BC et al. 1984. A study of atherosclerosis regression in Macaca mulatta . V. Changes in abdominal aorta and carotid and coronary arteries from animals with atherosclerosis induced for 38 months and then regressed for 24 or 48 months at plasma cholesterol concentrations of 300 or 200 mg/dl. Exp. Mol. Pathol 41:96-118 31 Ornish D, Brown SE, Billings JH et al. 1990. Can lifestyle changes reverse coronary heart disease?

The Lifestyle Heart Trial. Lancet 336;8708:129-33 32 Ornish D, Scherwitz L, Billings J et al. 1998. Intensive lifestyle changes for reversal of coronary heart disease. Five-year follow-up of the Lifestyle Heart Trial. JAMA 280:2001-2007 33 Esselstyn CB 2001. Resolving the coronary artery disease epidemic through plant-based nutrition.

Preventive Cardiology 4:171-177 34 Praagman J, Beulens JW, Alssema M et al. 2016. The association between dietary saturated fatty acids and ischaemic heart disease depends on the type and source of fatty acid in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort. Am J Clin Nutr 103:356-365 35 Liu TX, Niu HT, Zhang SY 2015. Intestinal microbiota metabolism and atherosclerosis. Chin Med J 128:2805-11 36 Qi J, You T, Li J, et al. 2017. Circulating trimethylamine N-oxide and the risk of cardiovascular diseases: a systematic review and meta-analysis of 11 prospective cohort studies. J Cell Mol Med doi:10.1111/jcmm.13307 37 Koeth RA, Wang Z, Levison BS 2013. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 19;5:576-85. doi: 10.1038/nm.3145

38 Kelemen LE, Kushi LH, Jacobs DR Jr et al. 2005. Associations of dietary protein with disease and mortality in a prospective study of postmenopausal women. Am J Epidem 161(3):239-49 39 Chen M, Li Y, Sun Q et al. 2016. Dairy fiat and risk of cardiovascular disease in 3 cohorts of US adults. Am J Clin Nutr 104:1209-1217 40 Spence JD, Jenkins DJA, Davignon J 2010. Dietary cholesterol and egg yolks: not for patients at risk of vascular disease. Can J Cardiol 26(9):e336-e339 41 Fraser GE, Shavlik DJ. 2001. Ten Years of Life. Is It a Matter of Choice? Arch Intern Med. 161(13):1645–1652. doi:10.1001/archinte.161.13.1645 42 Le LT, SabatÊ J. 2014. Beyond Meatless, the Health Effects of Vegan Diets: Findings from the Adventist Cohorts. Nutrients. 6(6):2131-2147. doi:10.3390/nu6062131.

43 Rehm CD, Penalvo JL, Afshin A 2016. Dietary intake among US adults, 1999-2012. JAMA 21;315(23):2542-53. doi: 10.1001/jama.2016.7491.