Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis

Zoë Harcombe; Julien S Baker; Stephen Mark Cooper; Bruce Davies; Nicholas Sculthorpe; James J DiNicolantonio; Fergal Grace

doi:10.1136/openhrt-2014-000196

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This article has a correction. Please see:

Correction - February 01, 2015

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Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis

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Re: Evidence from RCTs did not support introduction of dietary fat guidelines in 1977 & 1983
Vivien S. Lund
Published on: 17 March 2016
Randomised controlled trials and diet-heart recommendations
Christine M Williams
Published on: 17 March 2016
Re:Letter to the Editor: Evidence from randomised controlled trials not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
Zoe Harcombe
Published on: 17 March 2016
Letter to the Editor: Evidence from randomised controlled trials not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
Lukas Schwingshackl
Published on: 17 March 2016
Fascinating: So it was basically a political decision
David J Unwin
Published on: 17 March 2016
More contradictions to the dietary guidelines
Uffe Ravnskov
Published on: 17 March 2016

Published on: 17 March 2016
Re: Evidence from RCTs did not support introduction of dietary fat guidelines in 1977 & 1983
- Vivien S. Lund, SACN secretariat
- Other Contributors:
  Alison Tedstone, PhD RNutr, Chief Nutritionist, Louis Levy, PhD RNutr (Public Health), Vicki Pyne, RNutr (Public Health)
Dietary advice that reducing fat and saturated fat consumption will reduce the risk of coronary heart disease was introduced in the UK in 1983. The authors of this systematic review and meta-analysis conclude that evidence from randomised controlled trials, available at the time, did not support that advice.
It is important to highlight that the review looks at the results of just six relatively short-term ra...
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Dietary advice that reducing fat and saturated fat consumption will reduce the risk of coronary heart disease was introduced in the UK in 1983. The authors of this systematic review and meta-analysis conclude that evidence from randomised controlled trials, available at the time, did not support that advice.
It is important to highlight that the review looks at the results of just six relatively short-term randomised controlled trials (RCTs), whose limitations are acknowledged by the authors. In 1983, there was already good evidence that saturated fats in the diet raise blood cholesterol and that blood cholesterol was a modifiable risk factor for coronary heart disease.
More evidence for the effects of saturated fat has accumulated since 1983. Government advice to limit saturated fat intake to no more than 11% of total food energy in order to reduce the risk of cardiovascular disease is based on long standing advice from the Committee on Medical Aspects of Food Policy (COMA) and is endorsed by the Scientific Advisory Committee on Nutrition (2008), which now provides the UK with independent advice on nutrition. The advice is supported by a wealth of evidence and is in line with more recent assessments made by the Institute of Medicine (2005), World Health Organization (2008) and the European Food Safety Authority (2010).
There is good evidence from randomised controlled trials (RCTs) to demonstrate that saturated fat consumption influences cholesterol levels and increases the risk of cardiovascular disease. For example, the RISCK study, a 6 month trial that analysed results from 548 men and women, found that total cholesterol and LDL cholesterol concentrations were significantly lower after consumption of diets lower in saturated fat compared to the control group (Jebb et al. 2010). Skeaff and Miller (2009) conducted a meta-analysis of 16 trials modifying the amount of saturated fat in the diet and found that, in studies which significantly lowered serum cholesterol by replacing saturated fat with polyunsaturated fat, both heart attacks and deaths from heart disease were significantly reduced. More recently a Cochrane Collaboration systematic review (Hooper et al. 2012) concluded that reducing saturated fat by reducing and/or modifying dietary fat intakes lowered the risk of cardiovascular events by 14%.
The combined results of 14 RCTs investigating statins also found that a reduction in LDL-cholesterol of 1mmol/L, sustained over a period of 5 years, reduced major vascular events by 23% (Cholesterol Treatment Trialists' Collaborators, 2005). Chan et al (2011) conducted a meta- analysis of seven trials investigating the effect of intensive lipid lowering using statins. The intensive lipid lowering arm had reduced LDL levels and significantly lower risks for stroke, coronary events, and CVD and CHD deaths.
The UK National Diet and Nutrition Survey (NDNS) rolling programme 2008/2009 - 2011/2012 shows that people in all age/sex groups are still, on average, consuming saturated fat above recommendations (12.6% of food energy for adults aged 19-64 years). The headlines in the press about the review by Harcombe et al, are likely to have had the damaging effect of confusing the public about how to choose a healthy diet. Based on the totality of the evidence, Public Health England will continue to advise people to consume a diet that is low in saturated fat and support the Department of Health's Responsibility Deal incentives to reduce saturated fat in foods.
In addition to focusing on reducing saturated fats, Public Health England continues to advise that we need to eat fewer calories, less salt and sugar and more dietary fibre, fruit and vegetables and oily fish.
Chan DK, O'Rourke F, Shen Q, Mak JC, Hung WT. (2011) Meta-analysis of the cardiovascular benefits of intensive lipid lowering with statins. Acta Neurol Scand. 124(3):188-95.
Cholesterol Treatment Trialists' Collaborators. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90 056 participants in 14 randomised trials of statins. Lancet 2005; 366:1267-78.
Department of Health. 46 Nutritional aspects of cardiovascular disease. Report on Health and Social Subjects. 1994. London: TSO.
EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary Reference Values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. EFSA Journal 2010; 8(3):1461.
Hooper L, Summerbell CD, Thompson R, Sills D, Roberts FG, Moore HJ, Davey Smith G. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev 2012 May 16;5:CD002137. doi: 10.1002/14651858.CD002137.pub3.
IOM (Institute of Medicine). 2005. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academies of Science, Washington DC.
Jebb SA, Lovegrove JA, Griffin BA, Frost GS, Moore CS, Chatfield MD, Bluck LJ, Williams CM, Sanders TA; RISCK Study Group. Effect of changing the amount and type of fat and carbohydrate on insulin sensitivity and cardiovascular risk: the RISCK (Reading, Imperial, Surrey, Cambridge, and Kings) trial. Am J Clin Nutr. 2010 Oct;92(4):748-58.
National Diet and Nutrition Survey: Results from Years 1-4 (combined) of the Rolling Programme (2008/2009 - 2011/12) www.gov.uk/government/uploads/system/uploads/attachment_data/file/310997/NDNS_Y1_to_4_UK_report_Executive_summary.pdf
Scientific Advisory Committee on Nutrition, 24th meeting, 12 June 2008, agenda item 4.
Skeaff CM & Miller J. Dietary fat and coronary heart disease: summary of evidence from prospective cohort and randomised controlled trials. Ann Nutr & Metab 2009;55:173-201.
WHO. 2008. Fats and fatty acids in human nutrition. Joint FAO/WHO Expert Consultation. Food and nutrition paper 91, WHO, Geneva.
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Published on: 17 March 2016
Randomised controlled trials and diet-heart recommendations
- Christine M Williams, Professor
Re: Harcombe et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983:
The claim made by the authors of this paper that guidelines on dietary fat introduced in the 1970s and 1980s were not based on good scientific evidence is misguided and potentially dangerous. Whilst it is important to ensure an ongoing interrogation of the evidence linking d...
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Re: Harcombe et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983:
The claim made by the authors of this paper that guidelines on dietary fat introduced in the 1970s and 1980s were not based on good scientific evidence is misguided and potentially dangerous. Whilst it is important to ensure an ongoing interrogation of the evidence linking diet and heart disease, this must be through an holistic assessment of the evidence base and recognition of the clear improvements in population cholesterol levels and heart health that have taken place over the past 40 years.
In their assessment of the meta-analysis of randomised controlled trial (RCT) data for saturated fat intake and heart disease mortality, Harcombe et al.1 have taken a classical pharmaceutical approach to the evidence, with the assumption that as with drugs, RCTs provide the gold standard for formulating public health guidelines on diet. The assumption that RCTs represent the pinnacle of the evidential hierarchy against which other types of study compare unfavourably has been repeatedly shown to be unproven for diet. In fact such an approach would be inappropriate for most population based recommendations (as was also argued in the accompanying editorial by Bahl 2).
Most dietary guidelines have been developed using an approach to risk assessment which is based on assessing the degree of consistency and quality of the data from a number of different types of studies; convergence of the evidence represents the gold standard for risk assessment in the study of diet-disease relationships. This approach uses RCT data where it is available and with due caution for the extrapolation of the findings to healthy populations, since many are conducted in high risk individuals or those with existing disease. At the time of the introduction of the UK and US guidelines, consistent evidence for cholesterol raising effects of saturated fats was available from animal studies, cross country comparisons, retrospective case control and prospective cohort studies. The RCT studies discussed by Harcombe et al 1 were available to the expert committees at the time the guidelines were drawn up. These findings were in part responsible for the decisions not to recommend complete replacement of dietary saturated fats with polyunsaturated fats, due to possible adverse effects of higher intakes of these fats. At the time the recommendations were made evidence was also available from trials conducted in metabolic ward and semi-free-living settings in volunteer subjects. These showed effects of saturated fats on circulating cholesterol to be so consistent that investigators were able to develop predictive algorithms which would estimate the cholesterol outcome based on the fat composition of the diet being fed.3
The discovery of the LDL receptor in the 1970s 4 paved the way to a molecular based understanding of the mechanisms by which different dietary fatty acids influence the hepatic uptake and excretion of circulating LDL and thereby circulating LDL cholesterol concentrations. So a feasible molecular mechanism was beginning to emerge which subsequently powerfully supported the epidemiological and experimental studies.
In support of their own findings Harcombe et al.1 highlight the recent meta-analyses of the cohort data 5, 6 which has argued that more recent cohort studies have shown lower relative risk ratios for saturated fat than earlier studies. Within these analyses it is astonishing to note the limited attention given to the changes that have taken place in population diets over the past 40 years, since this is a potentially powerful confounding factor in long term cohort studies. Since the 1960s, dietary fat intake in the UK has fallen by 50% -from around 125g/d to less than 83g/d today. Saturated fat intakes have fallen even more dramatically - from around 55g/d to around 30g/d today, with most of this change occurring between 1975 and 1995.7,8 For the cohorts which were initiated in the 1960s and 1970s the baseline diet measured at the outset of the study bears little resemblance to the diet the subjects would have been eating during the subsequent follow up periods. Those few cohort studies which have undertaken repeat diet assessments have confirmed that the risk ratio has reduced as population diet has changed, thereby providing real life evidence of the benefits of the recommended diet. Exactly similar changes are seen for trans fats; where repeat dietary assessment data are available within cohort studies the risk ratio for the population study group has fallen as levels of trans fats in the background diet has reduced. In the Nurses Health Study after an 8 year follow up the odds ratio fell from 1.67 reported in 1993 9 to 1.53 in 1997 10 and to 1.33 in 2005 11. It is intriguing to note the concerns regarding recommendations for saturated fats have not been raised for trans fatty acids despite exactly similar 'limitations' concerning the types and quality of evidence available. There are no RCTs of coronary mortality available for trans fatty acids, with lipoprotein biomarker outcomes used to support reduction in intakes of these fats.
As far as more recent studies are concerned, those established since 1995 demonstrate a much narrower range of saturated fat intakes than was the case in the 1960s and 1970s. The lower risk ratios reflect the fact that significant proportion of the study cohorts are now eating levels of saturated fats that do not elevate LDL cholesterol and lead to risk of heart disease. It should be expected that outcomes from studies conducted since 1995 will be less likely to observe significant effects of either trans or saturated fat on heart disease, precisely because the recommended diets have been beneficial to population heart health. Given the improvements in both levels of cholesterol and rates of heart disease world-wide in those countries which have introduced measures to reduce intakes of saturated fats, it would seem that an RCT, with corresponding ethical approval for its conduct, would surely be required to reverse existing recommendations?
REFERENCES
1. Harcombe Z, Baker JS, Cooper SM, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart 2015;2:e000196.
2. Bahl R. The evidence base for fat guidelines: a balanced diet. Open Heart 2015;2:e000229.
3. Keys A, Parlin RW. Serum-cholesterol response to changes in dietary lipids. Am J Clin Nutr 1966; 19: 175- 181.
4. Goldstein JL, Brown MS. Familial hypercholesterolemia: identification of a defect in the regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity associated with overproduction of cholesterol .PNAS 1973; 70: 2804-2808.
5. DiNicolantonio J. The cardiometabolic consequences of replacing saturated fats with carbohydrates or ?-6 polyunsaturated fats: Do the dietary guidelines have it wrong? Open Heart 2014;1:e000032.
6. Chowdhury R, Warnakula S, Kunutsor S, et al. Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis. Ann Intern Med 2014; 160:398-406.
7. Diet, Physical Activity and Obesity Statistics 2006. British Heart Foundation Statistics Database.
8. National Diet and Nutrition Survey. Results from Years 1-4 (combined) of the Rolling Programme (2008/2009 - 2011/12). Public Health England and the Food Standards Agency.
9. Willett WC, Stampfer MJ, Manson JE, et al. Intake of trans fatty acids and risk of heart disease in women. Lancet 1993; 341: 581-585.
10. Hu FB , Stampfer MJ, Mason JE. et al. Dietary fat intake and risk of coronary heart disease in women. N Engl J Med 1997; 337:1491-1499
11. Oh K, Hu FB, Manson JE. et al. Dietary Fat Intake and Risk of Coronary Heart Disease in Women: 20 Years of Follow-up of the Nurses' Health Study Am. J. Epidemiol 2005; 161: 672-679
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Published on: 17 March 2016
Re:Letter to the Editor: Evidence from randomised controlled trials not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
- Zoe Harcombe, MD
We would like to thank you for your interesting and helpful comments.
We are currently finalising the follow-up paper, which is to consider all RCT evidence for current dietary guidelines before and since their introduction, to see if they have been supported in hindsight. We will review the risk of bias assessment tool, as suggested.
We do accept the role that cohort studies can play but wanted to focu...
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We would like to thank you for your interesting and helpful comments.
We are currently finalising the follow-up paper, which is to consider all RCT evidence for current dietary guidelines before and since their introduction, to see if they have been supported in hindsight. We will review the risk of bias assessment tool, as suggested.
We do accept the role that cohort studies can play but wanted to focus on RCTs to ask if this evidence alone supported the introduced dietary guidelines. One of the authors, ZH, is undertaking a PhD on the topic of the evidence base for dietary fat guidelines and is reviewing RCT and cohort evidence before and after the recommendations were introduced.
The Sydney heart study was excluded for sensitivity analysis and the results remained non-significant. The process was repeated with the exclusion of each study individually and no combination of remaining RCTs could establish a significant result.
We commented on the weight data in the discussion: "Studies of the time report weight, not body mass. Weight changes were not recorded in two studies[1 2]. Two studies noted no significant weight change in intervention or control groups[3 4]. The Research Committee study[5] reported mean weight loss as 7.5% in the intervention group and 4.8% in the control group. Woodhill et al[6] reported a mean weight loss of 6.5% and 6.0% in the intervention and control groups respectively." The weight information available did not serve as an explanation for differences in cholesterol levels.
We stand by our conclusion that, having reviewed evidence available to the committees, the guidelines should not have been introduced.
1. Rose GA, Thomson WB, Williams RT. Corn Oil in Treatment of Ischaemic Heart Disease. BMJ 1965;1(5449):1531-33 doi: 10.1136/bmj.1.5449.1531[published Online First: Epub Date]|.
2. Leren P. The Oslo Diet-Heart Study. Circulation 1970;42: 935-42 doi: 10.1161/?01.CIR.42.5.935 [published Online First: Epub Date]|.
3. Dayton S, Pearce ML, Hashomoto S, Dixon WJ, Tomiyasu U. A Controlled Clinical Trial of a Diet High in Unsaturated Fat in Preventing Complications of Atherosclerosis. Circulation 1969;40(1S2):II-1-II-63 doi: 10.1161/01.cir.40.1s2.ii-1[published Online First: Epub Date]|.
4. Medical Research Council. Controlled trial of soya-bean oil in myocardial infarction: Report of a research committee to the Medical Research Council. The Lancet 1968;292(7570):693-700 doi: http://dx.doi.org/10.1016/S0140-6736(68)90746-0[published Online First: Epub Date]|.
5. Research Committee. Low-fat diet in myocardial infarction: A controlled trial. The Lancet 1965;2(7411):501-4
6. Woodhill JM, Palmer AJ, Leelarthaepin B, McGilchrist C, Blacket RB. Low fat, low cholesterol diet in secondary prevention of coronary heart disease. Advances in experimental medicine and biology 1978;109:317- 30
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None declared
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Published on: 17 March 2016
Letter to the Editor: Evidence from randomised controlled trials not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis
- Lukas Schwingshackl, PhD Student
- Other Contributors:
  Georg Hoffmann
With great interest we read the meta-analysis of Harcombe and co- workers titled "Evidence from randomized controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis" published in volume 2 of the Open Heart Journal [1]. In their article, the authors systematically reviewed randomized controlled trials investigating the associations between dietary fa...
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With great interest we read the meta-analysis of Harcombe and co- workers titled "Evidence from randomized controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis" published in volume 2 of the Open Heart Journal [1]. In their article, the authors systematically reviewed randomized controlled trials investigating the associations between dietary fat, serum cholesterol and the development of all-cause mortality and CHD mortality. Harcombe and colleagues concluded that dietary recommendations were introduced for 220 million US and 56 million UK citizens by 1983, in the absence of supporting evidence from RCTs. Indeed, there has been a lot of debate regarding the potential role of dietary fat in the pathogenesis of CHD, with an intensive debate of the validity of the results [2-4]. In a recently published meta-analysis on dietary fatty acid in the secondary prevention of coronary heart disease, we included overall 12 trials with 7150 patients (with five out of six RCTs similar to the ones included by Harcombe and colleagues) [5]. After performing pairwise meta- analyses as well as uni- and multivariate meta-regression we did not observe any evidence for beneficial effects of reduced/modified fat diets in the secondary prevention of coronary heart disease. Therefore, we concluded that recommending higher intakes of polyunsaturated fatty acids in replacement of saturated fatty acids was not associated with risk reduction. However, we think that some statements in the meta-analysis by Harcombe and colleagues should be interpreted with caution and would like to comment one some basic as well as some methodological issues. The authors state that "RCTs provide the best evidence". RCTs in nutrition research are often prone to inherent methodological constraints. E.g., they sometimes cannot be controlled with "true" placebos, but rather by a limitation of certain aspects of nutrient compositions, food groups or dietary patterns. Other limitations include lack of double blinding, poor compliance and adherence, crossover bias and drop-out. Thus, in the field of nutritional epidemiology, well-designed prospective cohort studies will provide important evidence as well [5 6]. Quality scales such as the PEDro scale used by Harcombe et al. should be avoided. Instead, the Risk of bias assessment tool should be given preference [7]. In addition, "double counts" of the participants in the control group (as done with the study by Rose et al., 1965) should be avoided. The authors neglect to comment on the fact that in the Sydney Diet Heart Study a commercial margarine probably high in trans fatty acids was used to deliver PUFA to the intervention group [8]. A sensitivity analysis excluding this trial would be highly appropriate. Moreover, the reductions in total cholesterol observed in the low-fat group warrants further attention, since it is well known that weight change might represent a potential confounder in the interpretation of blood lipid levels [9]. Although systematic reviews and meta-analyses may help to merge and ultimately enhance evidence based nutritional guidelines, some concerns were expressed regarding the validity and application to nutrition and nutritional sciences [10 11]. Although there are some limitations to incorporate systematic reviews into nutrition research, there are strong reasons to apply them as evidence based approaches for dietary guidelines. First, scientific findings about 'what one should eat' is almost always echoed by media coverage and therefore potentially models public opinion about nutrition. Media coverage makes use of a reductionist and sentimental approach to bring their story to the readers, which may sometimes obscure actual findings of the study. Nutrition research has been criticized on numerous occasions [12]. Systematic reviews and meta- analysis can help to improve nutrition based dietary guidelines by incorporating more homogenous dietary recommendations. However, one has to keep in mind that systematic reviews are only as good as the studies they pool together. Instead of creating some kind of "dietary fat-gate" involving Senator George McGovern (again), Harcombe and co-workers should be more conservative in their conclusions with regard to the limitations of their own meta-analysis as well as the studies included in it.
References
1. Harcombe Z, Baker JS, Cooper SM, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart 2015;2(1) doi: 10.1136/openhrt-2014-000196[published Online First: Epub Date]|.
2. Chowdhury R, Warnakula S, Kunutsor S, et al. Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Annals of internal medicine 2014;160(6):398-406 doi: 10.7326/M13-1788[published Online First: Epub Date]|.
3. Willett WC, Stampfer MJ, Sacks FM. Association of dietary, circulating, and supplement fatty acids with coronary risk. Annals of internal medicine 2014;161(6):453 doi: 10.7326/L14-5018[published Online First: Epub Date]|.
4. Schwingshackl L, Hoffmann G. Association of dietary, circulating, and supplement fatty acids with coronary risk. Annals of internal medicine 2014;161(6):455-6 doi: 10.7326/L14-5018-6[published Online First: Epub Date]|.
5. Schwingshackl L, Hoffmann G. Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression. BMJ open 2014;4(4):e004487 doi: 10.1136/bmjopen-2013- 004487[published Online First: Epub Date]|.
6. Satija A, Yu E, Willett WC, et al. Understanding nutritional epidemiology and its role in policy. Advances in nutrition 2015;6(1):5-18 doi: 10.3945/an.114.007492[published Online First: Epub Date]|.
7. Higgins JP, Green S. Cochrane Handbook of systematic reviews, Version 5.1.0 http://handbook.cochrane.org/. updated March 2011
8. Ramsden CE, Zamora D, Leelarthaepin B, et al. Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis. BMJ 2013;346:e8707 doi: 10.1136/bmj.e8707[published Online First: Epub Date]|.
9. Dattilo AM, Kris-Etherton PM. Effects of weight reduction on blood lipids and lipoproteins: a meta-analysis. The American journal of clinical nutrition 1992;56(2):320-8
10. Blumberg J, Heaney RP, Huncharek M, et al. Evidence-based criteria in the nutritional context. Nutrition reviews 2010;68(8):478-84 doi: 10.1111/j.1753-4887.2010.00307.x[published Online First: Epub Date]|.
11. Mann JI. Evidence-based nutrition: Does it differ from evidence- based medicine? Annals of medicine 2010;42(7):475-86 doi: 10.3109/07853890.2010.506449[published Online First: Epub Date]|.
12. Ioannidis JP. Implausible results in human nutrition research. BMJ 2013;347:f6698 doi: 10.1136/bmj.f6698[published Online First: Epub Date]|.
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Published on: 17 March 2016
Fascinating: So it was basically a political decision
- David J Unwin, GP partner and Trainer
At last I know how these damaging and pernicious guidelines came about. They introduced a dark age of medicine and dogma that continues to effect my practice.
How I struggle to get patients to accept eggs and butter as part of a healthy diet . It's my belief that sugar and other carbohydrates are the real problem.
I have seen great results for 70 patients in my practice with the metabolic syndrome usi...
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At last I know how these damaging and pernicious guidelines came about. They introduced a dark age of medicine and dogma that continues to effect my practice.
How I struggle to get patients to accept eggs and butter as part of a healthy diet . It's my belief that sugar and other carbohydrates are the real problem.
I have seen great results for 70 patients in my practice with the metabolic syndrome using the low carbohydrate, higher fat diet for an average of 13 months. Despite the eggs and butter their cholesterol levels improved along with significant weight loss and improvements in diabetic control.
When will the guidelines be re written to properly reflect what we know about fats. All we seem to have at present is confusion
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Published on: 17 March 2016
More contradictions to the dietary guidelines
- Uffe Ravnskov, Independent researcher
Hopefully the meta-analysis by Harcombe et al. (1) may inspire the authorities to correct their dietary recommendations, because other studies have shown that the intake of saturated fatty acids (SFA) does not increase the risk of cardiovascular disease.
Not only did the authors of the dietary guideline from 1977 and 1983 ignore the dietary trials; they also ignored several unsupportive cohort studies. Before 1...
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Hopefully the meta-analysis by Harcombe et al. (1) may inspire the authorities to correct their dietary recommendations, because other studies have shown that the intake of saturated fatty acids (SFA) does not increase the risk of cardiovascular disease.
Not only did the authors of the dietary guideline from 1977 and 1983 ignore the dietary trials; they also ignored several unsupportive cohort studies. Before 1977 three prospective population studies had shown no significant difference of SFA intake between CHD patients and people free of CHD, and in 1983 five more had been published and with the same result. Together these studies included 1920 patients with CHD and 45615 without (2).
Furthermore, numerous studies published since then have acquitted SFA in various ways. Let me mention only a few of the most important ones.
Today more than 30 population studies have shown the same result as mentioned above, and in seven of ten prospective cohort studies patients with stroke had eaten less SFA than those without; in the other three, no difference was seen (2). Dietary information is of course inaccurate. A more reliable method is to analyse the short fatty acids 12:0-15:0 in the fat cells, because their contents reflect the intake of SFA during the preceding weeks or months. In three case-control studies of patients with CHD and healthy controls no difference was found as regards the content of these fatty acids; in two studies it was even significantly lower in the patients. These studies concerned only patients with first myocardial infarction or patients who were not on a diet, and a diet bias is therefore unlikely (3).
1. Harcombe Z, Baker JS, Cooper SM, et al. Open Heart 2015;2:e000196. doi:10.1136/openhrt-2014-000196 2. Ravnskov U. The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. J Clin Epidemiol 1998;51:443-60. 3. Ravnskov U. Is saturated fat bad? In: Modern Dietary fat intakes in disease promotion. Nutr Health 2010, part 2, p 109-9
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