US dietary guidelines: is saturated fat a nutrient of concern?

US public health dietary advice was announced by the Select Committee on Nutrition and Human needs in 1977 and was followed by UK public health dietary advice issued by the National Advisory Committee on Nutritional Education in 1983. Dietary recommendations in both cases focused on reducing dietary fat intake; specifically to (i) reduce overall fat consumption to 30% of total energy intake and (ii) reduce saturated fat consumption to 10% of total energy intake. The recommendations were an attempt to address the incidence of coronary heart disease. These guidelines have been reiterated in the Dietary Guidelines for Americans since the first edition in 1980. The most recent edition has positioned the total fat guideline with the use of 'Acceptable Macronutrient Distribution Ranges'. The range given for total fat is 20%-35% and the AMDR for saturated fat is given as <10%-both as a percentage of daily calorie intake. In February 2018, the Center for Nutrition Policy and Promotion announced 'The US Departments of Agriculture and Health and Human Services currently are asking for public comments on topics and supporting scientific questions to inform our development of the 2020-2025 Dietary Guidelines for Americans'. Public comments were invited on a number of nutritional topics. The question asked about saturated fats was: 'What is the relationship between saturated fat consumption (types and amounts) during adulthood and risk of cardiovascular disease?' This article is a response to that question.

Dietary fat guidelines have no evidence base: where next for public health nutritional advice?

INTRODUCTION: National dietary guidelines were introduced in 1977 and 1983, by the US and UK governments, with the aim of reducing coronary heart disease (CHD) mortality. The 2 specific dietary fat recommendations were to reduce total fat and saturated fat consumption to 30% and 10% of total energy intake, respectively. METHODS: 4 systematic reviews (3 with meta-analysis) were undertaken to examine the evidence for these dietary fat guidelines: (1) randomised controlled trial (RCT) and (2) prospective cohort (PC) evidence at the time the guidelines were introduced; and (3) RCT and (4) PC evidence currently available. This narrative review examines all evidence collated. RESULTS: The RCT and PC evidence available to the dietary committees did not support the introduction of the dietary fat guidelines. The RCT and PC evidence currently available does not support the extant recommendations. Furthermore, the quality of the evidence is so poor that it could not be relied on had it provided support. CONCLUSIONS: Dietary fat guidelines have prevailed for almost 40 years. The evidence base at the time of their introduction has been examined for the first time and found lacking. Evidence currently available provides no additional support. Public health opinion differed when the guidelines were introduced. Opposition to the guidelines is becoming more strident. Substantial increases in diet-related illness over the past four decades, particularly obesity and type 2 diabetes, indicate that a review of dietary advice is warranted.

Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis.

OBJECTIVES: National dietary guidelines were introduced in 1977 and 1983, by the US and UK governments to reduce coronary heart disease (CHD) mortality by reducing dietary fat intake. Our 2016 systematic review examined the epidemiological evidence available to the dietary committees at the time; we found no support for the recommendations to restrict dietary fat. The present investigation extends our work by re-examining the totality of epidemiological evidence currently available relating to dietary fat guidelines. METHODS: A systematic review and meta-analysis of prospective cohort studies currently available, which examined the relationship between dietary fat, serum cholesterol and the development of CHD, were undertaken. RESULTS: Across 7 studies, involving 89 801 participants (94% male), there were 2024 deaths from CHD during the mean follow-up of 11.9±5.6 years. The death rate from CHD was 2.25%. Eight data sets were suitable for inclusion in meta-analysis; all excluded participants with previous heart disease. Risk ratios (RRs) from meta-analysis were not statistically significant for CHD deaths and total or saturated fat consumption. The RR from meta-analysis for total fat intake and CHD deaths was 1.04 (95% CI 0.98 to 1.10). The RR from meta-analysis for saturated fat intake and CHD deaths was 1.08 (95% CI 0.94 to 1.25). CONCLUSIONS: Epidemiological evidence to date found no significant difference in CHD mortality and total fat or saturated fat intake and thus does not support the present dietary fat guidelines. The evidence per se lacks generalisability for population-wide guidelines.

Evidence from prospective cohort studies did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review.

OBJECTIVES: National dietary guidelines were introduced in 1977 and 1983, by the USA and UK governments to reduce coronary heart disease (CHD) mortality by reducing dietary fat intake. Our 2015 systematic review examined randomised controlled trial (RCT) evidence available to the dietary committees at the time; we found no support for the recommendations to restrict dietary fat. What epidemiological evidence was available to the dietary guideline committees in 1983? METHODS: A systematic review of prospective cohort studies, published prior to 1983, which examined the relationship between dietary fat, serum cholesterol and the development of CHD. RESULTS: Across 6 studies, involving 31 445 participants, there were 1521 deaths from all-causes and 360 deaths from CHD during the mean follow-up of 7.5±6.2 years. The death rates were 4.8% and 1.1% from all-causes and CHD respectively. One study included men with previous heart disease. The death rate from CHD for those with, and without previous myocardial infarction was 20.9% and 1.0% respectively. None of the six studies found a significant relationship between CHD deaths and total dietary fat intake. One of the six studies found a correlation between CHD deaths and saturated dietary fat intake across countries; none found a relationship between CHD deaths and saturated dietary fat in the same population. CONCLUSIONS: 1983 dietary recommendations for 220 million US and 56 million UK citizens lacked supporting evidence from RCT or prospective cohort studies. The extant research had been undertaken exclusively on males, so lacked generalisability for population-wide guidelines.

Problems with the 2015 Dietary Guidelines for Americans: An Alternative.

Abstract The updated 2015 Dietary Guidelines for Americans, published in January 2016, have stirred much controversy since the advisory report first appeared. Several important changes have been made, with some recommendations having greater scientific evidence for their support than others. The focus of this review is to discuss specific recommendations from the 2015 Dietary Guidelines for Americans that lack sound scientific evidence; these include: 1) Allowing approximately half of all grains to be refined; 2) The continued recommendations for fat-free or low-fat dairy and limitation of saturated fat intake to < 10% of calories; 3) Sodium intake < 2,300 mg/day; and 4) Consumption of up to 27 grams/day of "oils" (high in polyunsaturated fat or monounsaturated fat). Based on our review, the aforementioned recommendations found in the updated 2015 Dietary Guideline for Americans may increase the incidence of cardiometabolic disease, diabetes, obesity, dyslipidemia, cardiovascular disease, and possibly cancer.

Problems with the 2015 Dietary Guidelines for Americans. An Alternative.

The updated 2015 Dietary Guidelines for Americans, published in January 2016, have stirred much controversy since the advisory report first appeared. Several important changes have been made, with some recommendations having greater scientific evidence for their support than others. The focus of this review is to discuss specific recommendations from the 2015 Dietary Guidelines for Americans that lack sound scientific evidence; these include: 1) Allowing approximately half of all grains to be refined; 2) The continued recommendations for fat-free or low-fat dairy and limitation of saturated fat intake to <10% of calories; 3) Sodium intake < 2,300 mg/day; and 4) Consumption of up to 27 g/day of "oils" (high in polyunsaturated fat or monounsaturated fat). Based on our review, the aforementioned recommendations found in the updated 2015 Dietary Guidelines for Americans may increase the incidence of cardiometabolic disease, diabetes, obesity, dyslipidemia, cardiovascular disease and possibly cancer.

Comparison of postal and non-postal post-vasectomy semen sample submission strategies on compliance and failures: an 11-year analysis of the audit database of the Association of Surgeons in Primary Care of the UK.

BACKGROUND: Vasectomy occlusive success is defined by the recommendation of 'clearance' to stop other contraception, and is elicited by post-vasectomy semen analysis (PVSA). We evaluated how the choice of either a postal or non-postal PVSA submission strategy was associated with compliance to PVSA and effectiveness of vasectomy. METHODS: We studied vasectomies performed in the UK from 2008 to 2019, reported in annual audits by Association of Surgeons in Primary Care members. We calculated the difference between the two strategies for compliance with PVSA, and early and late vasectomy failure. We determined compliance by adding the numbers of men with early failure and those given clearance. We performed stratified analyses by the number of test guidance for clearance (one-test/two-test) and the study period (2008-2013/2014-2019). RESULTS: Among 58 900 vasectomised men, 32 708 (56%) and 26 192 (44%) were advised submission by postal and non-postal strategies, respectively. Compliance with postal (79.5%) was significantly greater than with non-postal strategy (59.1%), the difference being 20.4% (95% CI 19.7% to 21.2%). In compliant patients, overall early failure detection was lower with postal (0.73%) than with non-postal (0.94%) strategy (-0.22%, 95% CI -0.41% to -0.04%), but this difference was neither clinically nor statistically significant with one-test guidance in 2014-2019. There was no difference in late failure rates. CONCLUSIONS: Postal strategy significantly increased compliance to PVSA with similar failure detection rates. This resulted in more individuals receiving clearance or early failure because of the greater percentage of postal samples submitted. Postal strategy warrants inclusion in any future guidelines as a reliable and convenient option.

Dietary Recommendations for Familial Hypercholesterolaemia: an Evidence-Free Zone.

We have evaluated dietary recommendations for people diagnosed with familial hypercholesterolaemia (FH), a genetic condition in which increased low-density lipoprotein cholesterol (LDL-C) is associated with an increased risk for coronary heart disease (CHD). Recommendations for FH individuals have emphasised a low saturated fat, low cholesterol diet to reduce their LDL-C levels. The basis of this recommendation is the 'diet-heart hypothesis', which postulates that consumption of food rich in saturated fat increases serum cholesterol levels, which increases risk of CHD. We have challenged the rationale for FH dietary recommendations based on the absence of support for the diet-heart hypothesis, and the lack of evidence that a low saturated fat, low cholesterol diet reduces coronary events in FH individuals. As an alternative approach, we have summarised research which has shown that the subset of FH individuals that develop CHD exhibit risk factors associated with an insulin-resistant phenotype (elevated triglycerides, blood glucose, haemoglobin A1c (HbA1c), obesity, hyperinsulinaemia, high-sensitivity C reactive protein, hypertension) or increased susceptibility to develop coagulopathy. The insulin-resistant phenotype, also referred to as the metabolic syndrome, manifests as carbohydrate intolerance, which is most effectively managed by a low carbohydrate diet (LCD). Therefore, we propose that FH individuals with signs of insulin resistance should be made aware of the benefits of an LCD. Our assessment of the literature provides the rationale for clinical trials to be conducted to determine if an LCD would prove to be effective in reducing the incidence of coronary events in FH individuals which exhibit an insulin-resistant phenotype or hypercoagulation risk.

The new European guidelines for prevention of cardiovascular disease are misleading.

Introduction: The European Society of Cardiology and European Atherosclerosis Society (ESC/EAS) have recently published three major revisions of their guidelines for the management of chronic heart disease, blood lipids, and diabetes. Areas covered: We have scrutinized these guidelines in detail and found that the authors have ignored many studies that are in conflict with their conclusions and recommendations. Expert commentary: The authors of the guidelines have ignored that LDL-cholesterol (LDL-C) of patients with acute myocardial infarction is lower than normal; that high cholesterol is not a risk factor for diabetics; that the degree of coronary artery calcification is not associated with LDL-C; and that 27 follow-up studies have shown that people with high total cholesterol or LDL-C live just as long or longer than people with low cholesterol. They have also ignored the lack of exposure-response in the statin trials; that several of these trials have been unable to lower CVD or total mortality; that no statin trial has succeeded with lowering mortality in women, elderly people, or diabetics; and that cholesterol-lowering with statins has been associated with many serious side effects.

Evidence from randomised controlled trials does not support current dietary fat guidelines: a systematic review and meta-analysis.

OBJECTIVES: National dietary guidelines were introduced in 1977 and 1983, by the USA and UK governments, respectively, with the ambition of reducing coronary heart disease (CHD) mortality by reducing dietary fat intake. A recent systematic review and meta-analysis by the present authors, examining the randomised controlled trial (RCT) evidence available to the dietary committees during those time periods, found no support for the recommendations to restrict dietary fat. The present investigation extends our work by re-examining the totality of RCT evidence relating to the current dietary fat guidelines. METHODS: A systematic review and meta-analysis of RCTs currently available, which examined the relationship between dietary fat, serum cholesterol and the development of CHD, was undertaken. RESULTS: The systematic review included 62 421 participants in 10 dietary trials: 7 secondary prevention studies, 1 primary prevention and 2 combined. The death rates for all-cause mortality were 6.45% and 6.06% in the intervention and control groups, respectively. The risk ratio (RR) from meta-analysis was 0.991 (95% CI 0.935 to 1.051). The death rates for CHD mortality were 2.16% and 1.80% in the intervention and control groups, respectively. The RR was 0.976 (95% CI 0.878 to 1.084). Mean serum cholesterol levels decreased in all intervention groups and all but one control group. The reductions in mean serum cholesterol levels were significantly greater in the intervention groups; this did not result in significant differences in CHD or all-cause mortality. CONCLUSIONS: The current available evidence found no significant difference in all-cause mortality or CHD mortality, resulting from the dietary fat interventions. RCT evidence currently available does not support the current dietary fat guidelines. The evidence per se lacks generalisability for population-wide guidelines.

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

OBJECTIVES: National dietary guidelines were introduced in 1977 and 1983, by the US and UK governments, respectively, with the ambition of reducing coronary heart disease (CHD) by reducing fat intake. To date, no analysis of the evidence base for these recommendations has been undertaken. The present study examines the evidence from randomised controlled trials (RCTs) available to the US and UK regulatory committees at their respective points of implementation. METHODS: A systematic review and meta-analysis were undertaken of RCTs, published prior to 1983, which examined the relationship between dietary fat, serum cholesterol and the development of CHD. RESULTS: 2467 males participated in six dietary trials: five secondary prevention studies and one including healthy participants. There were 370 deaths from all-cause mortality in the intervention and control groups. The risk ratio (RR) from meta-analysis was 0.996 (95% CI 0.865 to 1.147). There were 207 and 216 deaths from CHD in the intervention and control groups, respectively. The RR was 0.989 (95% CI 0.784 to 1.247). There were no differences in all-cause mortality and non-significant differences in CHD mortality, resulting from the dietary interventions. The reductions in mean serum cholesterol levels were significantly higher in the intervention groups; this did not result in significant differences in CHD or all-cause mortality. Government dietary fat recommendations were untested in any trial prior to being introduced. CONCLUSIONS: Dietary recommendations were introduced for 220 million US and 56 million UK citizens by 1983, in the absence of supporting evidence from RCTs.