Fats in Foods: Current Evidence for Dietary Advice.

Current discussion of the importance of food fats in the risk of coronary heart disease (CHD) often suffers from preconceptions, misunderstandings, insufficient knowledge, and selective reasoning. As a result, the sustained controversy about dietary fat recommendations can be contradictory and confusing. To clarify some of these issues, the International Expert Movement to Improve Dietary Fat Quality in cooperation with the International Union of Nutritional Sciences (IUNS) organized a symposium at the 21st meeting of the IUNS, October 17, 2017, Buenos Aires, Argentina, to summarize the key scientific evidence underlying the controversy on the relationship between the saturated and unsaturated fat consumption and CHD risk. Presenters also discussed, using examples, the rationale for and implications of the partial replacement of foods rich in saturated fats by those rich in unsaturated fats. Presentations included strategies to fit healthier fats into meals. This report summarizes the symposium presentations.

International Society for the Study of Fatty Acids and Lipids 2016 Debate: For Science-Based Dietary Guidelines on Fats, Meta-Analysis and Systematic Reviews Are Decisive.

This paper summarizes a debate on whether meta-analyses and systematic reviews are decisive in formulating guidelines for dietary fat. Held during the 12th congress of the International Society for the Study of Fatty Acids and Lipids in Stellenbosch, South Africa, September 7, 2016, the debate was hosted by the International Union of Nutritional Sciences and the International Expert Movement to Improve Dietary Fat Quality (IEM, www.theiem.org). Clemens von Schacky, Ludwig Maximilians-University, Munich, Germany, supported the statement, describing the types of weaknesses in individual studies and clinical trials. With examples of how to overcome such limitations, he concluded that nutritional guidelines on fat need a proper scientific basis in which randomized controlled trials (RCTs) with clinical endpoints and their meta-analyses are essential and decisive. In contention, Ingeborg Brouwer, Vrije Universiteit, Amsterdam, declared that recommendations on dietary fat intake should always be based on the totality of the evidence, including physiologic and biochemical knowledge and associations from observational epidemiology. RCTs and meta-analyses have their shortcomings, but well-conducted systematic reviews and meta-analyses support a transparent process for developing dietary fat guidelines. Participants agreed that evidence-based decision-making for dietary guidance should consider all the best available evidence using a transparent, systematic review.

Saturated Fat Consumption and Risk of Coronary Heart Disease and Ischemic Stroke: A Science Update.

At a workshop to update the science linking saturated fatty acid (SAFA) consumption with the risk of coronary heart disease (CHD) and ischemic stroke, invited participants presented data on the consumption and bioavailability of SAFA and their functions in the body and food technology. Epidemiological methods and outcomes were related to the association between SAFA consumption and disease events and mortality. Participants reviewed the effects of SAFA on CHD, causal risk factors, and surrogate risk markers. Higher intakes of SAFA were not associated with higher risks of CHD or stroke apparently, but studies did not take macronutrient replacement into account. Replacing SAFA by cis-polyunsaturated fatty acids was associated with significant CHD risk reduction, which was confirmed by randomized controlled trials. SAFA reduction had little direct effect on stroke risk. Cohort studies suggest that the food matrix and source of SAFA have important health effects.

Dietary Fatty Acids: Is it Time to Change the Recommendations?

Limiting the saturated fatty acid (SAFA) consumption forms the basis of dietary fat recommendations for heart health, despite several meta-analyses demonstrating no link between dietary SAFA and the risk of cardiovascular disease (CVD). Three experts on dietary fat and health discussed the evidence of reducing SAFA intake at a symposium of the Federation of European Nutrition Societies in Berlin, Germany, October 23, 2015. Ronald P. Mensink, Maastricht University, the Netherlands, discussed the evidence linking dietary fatty acids and CVD risk. He emphasized the importance of the replacement nutrient(s) when SAFA intake is reduced. Julie Lovegrove, University of Reading, UK, addressed the question of whether higher intakes of unsaturated fatty acids are beneficial. She discussed the replacement of SAFA by polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA), noting the reduction in CVD risk with PUFA replacement and in CVD risk markers with MUFA replacement of SAFA. Ursula Schwab, University of Eastern Finland, Kuopio, Finland, discussed the importance of dietary patterns in achieving reduced risk of CVD, observing that several dietary patterns following the principles of a health-promoting diet and adapted to local customs, food preferences and seasonality are effective in reducing the risk of CVD, type 2 diabetes and other chronic diseases. This paper summarizes the symposium presentations.

Progressing Insights into the Role of Dietary Fats in the Prevention of Cardiovascular Disease.

Dietary fats have important effects on the risk of cardiovascular disease (CVD). Abundant evidence shows that partial replacement of saturated fatty acids (SAFA) with unsaturated fatty acids improves the blood lipid and lipoprotein profile and reduces the risk of coronary heart disease (CHD). Low-fat diets high in refined carbohydrates and sugar are not effective. Very long-chain polyunsaturated n-3 or omega-3 fatty acids (n-3 VLCPUFA) present in fish have multiple beneficial metabolic effects, and regular intake of fatty fish is associated with lower risks of fatal CHD and stroke. Food-based guidelines on dietary fats recommend limiting the consumption of animal fats high in SAFA, using vegetable oils high in monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA), and eating fatty fish. These recommendations are part of a healthy eating pattern that also includes ample intake of plant-based foods rich in fiber and limited sugar and salt.

ISSFAL 2014 Debate: It Is Time to Update Saturated Fat Recommendations.

This paper summarizes a debate on whether to update recommendations for the consumption of saturated fatty acids (SFA); this debate was held at the 11th congress of the International Society for the Study of Fatty Acids and Lipids in Stockholm, Sweden, June 28-July 2, 2014. Recommendations to reduce SFA intakes are based largely on the premise that high intakes of SFA raise low-density lipoprotein (LDL)-cholesterol levels, which in turn increase the risk of coronary heart disease (CHD). Several systematic reviews question whether reducing SFA intakes lowers CHD risk. Arguing to revise SFA recommendations, Philippe Legrand noted that SFA are heterogeneous in structure and function, are synthesized de novo by humans and only certain SFA in excess have been linked to CHD risk. We cannot consider all SFA as a block. The effects of reducing SFA intakes depend on which nutrients replace them and on which biomarkers or endpoints are assessed, Ronald Mensink observed. The effects of reducing SFA on CHD risk vary with the nutrient of comparison, whether carbohydrates, monounsaturated or polyunsaturated fatty acids. Substitution of SFA with polyunsaturated fatty acids was associated with a lower incidence of cardiovascular disease, while the effects of substitution with monounsaturated fatty acids or high-glycemic index carbohydrates are less clear.

Role of dietary fats in the prevention and treatment of the metabolic syndrome.

A symposium on the health significance of dietary fat in the prevention and treatment of the metabolic syndrome (MetS) was held at the 20th International Congress of Nutrition in Granada, Spain, on September 19, 2013. Four nutrition experts addressed the topics of dietary fat and obesity, effects of dietary fat quality in obesity and insulin resistance, influence of early nutrition on the later risk of MetS and the relative merits of high- or low-fat diets in counteracting MetS. Participants agreed that preventing weight gain and achieving weight loss in overweight and obese patients were key strategies for reducing MetS. Both low-fat and low-carbohydrate diets are associated with weight loss, but adherence to the diet is the most important factor in achieving success. Avoidance of high saturated fats contributes to lower health risks among obese, MetS and diabetic patients. Further, healthy maternal weight at conception and in pregnancy is more important that weight gain during pregnancy for reducing the risk of obesity in the offspring. The effects of different polyunsaturated fatty acids on MetS and weight loss require clarification.

Health significance of fat quality in the diet.

This paper summarizes three presentations on the global and Latin American perspectives on the health significance of fat quality in the diet given at the 16th Congress of the Society of Latin American Nutrition in Havana, Cuba, November 11-16, 2012. Dietary fat quality contributes to the risk of the leading chronic diseases and is more important than fat quantity in reducing the risk of chronic disease mortality, especially from cardiovascular disease (CVD). In many countries, the consumption of saturated fats exceeds the recommended limit of 10% energy (%E) and intakes of polyunsaturated fats (PUFAs) are often below the recommended range of 6-11%E. Consumption of long-chain ω-3 PUFAs is especially low. In many Latin American countries, high consumption of carbohydrates, especially sugars, contributes to obesity, diabetes, hypertension and CVD, while intakes of total fat and PUFAs may be low. Thus, dietary fat recommendations must consider the dietary fat patterns of each country. Nutrition counseling can be effective in teaching individuals and families to modify their food intake patterns and control the major risk factors for chronic disease.

ISSFAL 2010 dinner debate: healthy fats for healthy hearts - annotated report of a scientific discussion.

BACKGROUND/AIMS: The importance of reducing saturated fatty acid intake to prevent cardiovascular disease and recommended intakes for omega-6 polyunsaturated fatty acids (PUFAs) are controversial. Therefore, experts debated these topics at the biennial meeting of the International Society for the Study of Fatty Acids and Lipids (ISSFAL), in May 2010. METHODS: Debate transcripts, debaters' and discussants' reviews and literature citations were the basis of this report. RESULTS: Participants agreed that saturates per se are not 'bad', but that dietary recommendations should emphasize the substitution of unsaturates for part of the saturates. Evidence supporting omega-6 PUFA intakes of 5 to 10% is mixed; some interpret the overall data from diverse studies as consistent with a reduction in the risk of cardiovascular mortality and events. Others assert that randomized controlled trial data suggest that higher intakes of omega-6 PUFAs are not associated with lower risk of heart disease, or may even increase it. CONCLUSIONS: All agreed that a 5-year randomized controlled trial comparing the effects of historically low (2%) with currently high (7.5%) linoleic acid intakes on cardiac endpoints would address the knowledge gap about the effects of different omega-6 PUFA intakes on the risk of heart disease.

n-3 long-chain polyunsaturated fatty acids in type 2 diabetes: a review.

Historically, epidemiologic studies have reported a lower prevalence of impaired glucose tolerance and type 2 diabetes in populations consuming large amounts of the n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) found mainly in fish. Controlled clinical studies have shown that consumption of n-3 LC-PUFAs has cardioprotective effects in persons with type 2 diabetes without adverse effects on glucose control and insulin activity. Benefits include lower risk of primary cardiac arrest; reduced cardiovascular mortality, particularly sudden cardiac death; reduced triglyceride levels; increased high-density lipoprotein levels; improved endothelial function; reduced platelet aggregability; and lower blood pressure. These favorable effects outweigh the modest increase in low-density lipoprotein levels that may result from increased n-3 LC-PUFA intake. Preliminary evidence suggests increased consumption of n-3 LC-PUFAs with reduced intake of saturated fat may reduce the risk of conversion from impaired glucose tolerance to type 2 diabetes in overweight persons. Reported improvements in hemostasis, slower progression of artery narrowing, albuminuria, subclinical inflammation, oxidative stress, and obesity require additional confirmation. Expected health benefits and public health implications of consuming 1 to 2 g/day n-3 LC-PUFA as part of lifestyle modification in insulin resistance and type 2 diabetes are discussed.