Dietary Saturated Fats and Health: Are the U.S. Guidelines Evidence-Based? (original) (raw)
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The recommendation to limit dietary saturated fatty acid (SFA) intake has persisted despite mounting evidence to the contrary. Most recent meta-analyses of randomized trials and observational studies found no beneficial effects of reducing SFA intake on cardiovascular disease (CVD) and total mortality, and instead found protective effects against stroke. Although SFAs increase low-density lipoprotein (LDL) cholesterol, in most individuals, this is not due to increasing levels of small, dense LDL particles, but rather larger LDL particles, which are much less strongly related to CVD risk. It is also apparent that the health effects of foods cannot be predicted by their content in any nutrient group without considering the overall macronutrient distribution. Whole-fat dairy, unprocessed meat, and dark chocolate are SFA-rich foods with a complex matrix that are not associated with increased risk of CVD. The totality of available evidence does not support further limiting the intake of such foods.
Restricting Saturated Fat May Not Be Required to Reduce Risk of Cardiovascular Disease
Topics in Clinical Nutrition, 2019
The purpose of this review was to determine whether the recommendation to reduce saturated fatty acid (SFA) consumption to treat or prevent cardiovascular disease (CVD) is relevant in the context of current peer-reviewed, evidence-based literature. A literature review regarding SFA and CVD was conducted using articles from 2011 to 2018 through PubMed. Three hundred seventy-four articles were found, of which 211 were excluded. The remainder included 37 primary research articles and 21 reviews. All of the publications were examined using the Evidence Analysis Library Quality Criteria. Existing evidence supporting a reduction in SFA to treat/prevent CVD is limited and conflicting.
Saturated fatty acids and coronary heart disease risk: the debate goes on
Current opinion in clinical nutrition and metabolic care, 2015
Recently published meta-analyses of cohort studies and randomized controlled trials (RCTs) have challenged the link between saturated fatty acid (SFA) intake and coronary heart disease (CHD) risk. This review considers the outcome of these studies in the context of other evidence. Recent meta-analyses of cohort studies suggest that reducing SFA intakes has little impact on CHD risk when replaced by carbohydrates. The evidence for benefits on CHD risk of replacing SFA with unsaturated fatty acids in cohort studies is stronger and is also supported by data from a recent Cochrane analysis of RCTs of dietary SFA reduction and CHD risk. This review highlights the challenges of cohort studies involving diet because of the changing patterns of dietary behaviour and other multifactorial risk factors. The studies included are normally conducted over many years and are often dependent on a single measurement of dietary intake. The link between SFA intake, plasma cholesterol, and CHD risk is b...
Saturated fat –a never ending story?
Food & Nutrition Research
Science has no clear message regarding health effects of saturated fats, it seems. Different RCTs, prospective cohort studies and meta-analysis have led to contrasting conclusions. The aim of the present commentary is to discuss some possible reasons for an apparently never-ending fat controversy. They are of a purely scientific nature, which is important to recognize, but unfortunately hard to overcome. First is the placebo problem. In pharmaceutical science, evidence-based medicine is often synonymous with data on verified medical events from long-lasting double-blind randomized placebo controlled trials. In nutritional science the lack of double-blind design and lack of placebo food generate less conclusive data than those achieved in pharmaceutical science. Some scientists may apply the same type of scientific criteria used to evaluate the effects of drugs for foods. This leaves an impression of insufficient data since in this respect the fundamental criteria for evidence based medicine are not present. The next scientific problem is the energy balance equation. In contrast to pharmaceuticals, nutrients contain energy. An increased intake of one nutrient will lead to a decreased intake of another. The effect of change in only one nutrient is then difficult to isolate. Lastly, in nutritional science, generalizability is difficult compared to pharmaceutical science. Food culture interferes with lifestyle and food habits change over time. In conclusion, all available knowledge, from molecular experiments to population studies, must be taken in to account, to convert scientific data into dietary recommendations.
Weighing Evidence of the Role of Saturated and Unsaturated Fats and Human Health
Advances in Nutrition, 2021
The authors' responsibilities were as follows-All authors: wrote and read and approved the final manuscript. Author disclosures: MAB discloses consultancy with Bath and Body Works, grant support from the United Soybean Board and service as an elected board member for the American Society for Nutrition. ER discloses consultancy with Amarin and consultancy, grant support, and personal fees with the California Walnut Commission. The other author reports no conflicts of interest.
American Journal of Clinical Nutrition, 2011
Current dietary recommendations advise reducing the intake of saturated fatty acids (SFAs) to reduce coronary heart disease (CHD) risk, but recent findings question the role of SFAs. This expert panel reviewed the evidence and reached the following conclusions: the evidence from epidemiologic, clinical, and mechanistic studies is consistent in finding that the risk of CHD is reduced when SFAs are replaced with polyunsaturated fatty acids (PUFAs). In populations who consume a Western diet, the replacement of 1% of energy from SFAs with PUFAs lowers LDL cholesterol and is likely to produce a reduction in CHD incidence of ≥2-3%. No clear benefit of substituting carbohydrates for SFAs has been shown, although there might be a benefit if the carbohydrate is unrefined and has a low glycemic index. Insufficient evidence exists to judge the effect on CHD risk of replacing SFAs with MUFAs. No clear association between SFA intake relative to refined carbohydrates and the risk of insulin resistance and diabetes has been shown. The effect of diet on a single biomarker is insufficient evidence to assess CHD risk. The combination of multiple biomarkers and the use of clinical endpoints could help substantiate the effects on CHD. Furthermore, the effect of particular foods on CHD cannot be predicted solely by their content of total SFAs because individual SFAs may have different cardiovascular effects and major SFA food sources contain other constituents that could influence CHD risk. Research is needed to clarify the role of SFAs compared with specific forms of carbohydrates in CHD risk and to compare specific foods with appropriate alternatives.
British Journal of Sports Medicine, 2018
The British Journal of Sports Medicine published an opinion editorial advocating a revision of public health guidance on saturated fat [1]. Here we offer a rebuttal, incorporating evidence-based principles absent in the original editorial, focusing on the quality of the evidence presented and we discuss contradictory evidence in relation to saturated fat, low-density lipoprotein cholesterol (LDL-C), specific dietary interventions, and cardiovascular disease (CVD) alongside future directions. Effects of reducing saturated fat intake on cardiovascular disease The authors cite a 2015 'landmark' meta-analysis of observational studies showing a lack of an association between saturated fat consumption and both all-cause mortality and cardiovascular outcomes [2]. According to best practice evidence-based methods, these types of studies provide low-quality evidence [3]. Indeed, the authors of the cited meta-analysis reported that the likelihood of the reported associations was 'very low'[2], meaning we can have very little confidence in the findings.
Systematic Reviews
Background The health effects of dietary fats are a controversial issue on which experts and authoritative organizations have often disagreed. Care providers, guideline developers, policy-makers, and researchers use systematic reviews to advise patients and members of the public on optimal dietary habits, and to formulate public health recommendations and policies. Existing reviews, however, have serious limitations that impede optimal dietary fat recommendations, such as a lack of focus on outcomes important to people, substantial risk of bias (RoB) issues, ignoring absolute estimates of effects together with comprehensive assessments of the certainty of the estimates for all outcomes. Objective We therefore propose a methodologically innovative systematic review using direct and indirect evidence on diet and food-based fats (i.e., reduction or replacement of saturated fat with monounsaturated or polyunsaturated fat, or carbohydrates or protein) and the risk of important health out...
Journal of the American Heart Association, 2016
Background Saturated fat ( SFA ), ω‐6 (n‐6) polyunsaturated fat ( PUFA ), and trans fat ( TFA ) influence risk of coronary heart disease ( CHD ), but attributable CHD mortalities by country, age, sex, and time are unclear. Methods and Results National intakes of SFA , n‐6 PUFA , and TFA were estimated using a Bayesian hierarchical model based on country‐specific dietary surveys; food availability data; and, for TFA , industry reports on fats/oils and packaged foods. Etiologic effects of dietary fats on CHD mortality were derived from meta‐analyses of prospective cohorts and CHD mortality rates from the 2010 Global Burden of Diseases study. Absolute and proportional attributable CHD mortality were computed using a comparative risk assessment framework. In 2010, nonoptimal intakes of n‐6 PUFA , SFA , and TFA were estimated to result in 711 800 (95% uncertainty interval [UI] 680 700–745 000), 250 900 (95% UI 236 900–265 800), and 537 200 (95% UI 517 600–557 000) CHD deaths per year wor...
One of the most common warnings in dietary guidelines worldwide is to avoid saturated fat. However, there is no clear definition of what a saturated fat is. There are four definitions that have been used to describe saturated fat: amount of saturated fatty acids in grams per 100 grams, % fatty acid profile, iodine value, and solid fat. The current description of “saturated fat” does not distinguish between fats and oils, which are mainly triglycerides of fatty acids, and whole food items, which contain proteins and minerals and much lower amounts of triglycerides. Secondly, the current classification of saturated fat ignores the difference in the cholesterol content of vegetable oils and animal fats. The first definition of saturated fat was based on iodine values which does not give fatty acid composition. This classification is still used today by various dietary guidelines. The use of solid fat as a defining property of saturated fat is based on the melting of a fat at room tempe...