ICYMI: Do saturated fats cause heart disease?
Advice to limit saturated fats has been a basic pillar of the Dietary Guidelines for Americans for 40 years. Yet this advice has never had any substantial scientific backing, according to a large and fast-growing body of scientific literature, which now includes a “State-of-the-Art Review” in the prestigious Journal of the American College of Cardiology, authored by prominent scientists, including the former chair of the 2005 Dietary Guidelines Advisory Committee and a member of the 2015 DGAC who served on the saturated-fat Subcommittee.
The conclusions of this important paper determine that further caps on saturated fats are no longer warranted.
Another paper, just published this week, in the BMJ Evidence-Based Medicine Journal, authored by an international group of 10 experts on heart disease and diet, including five cardiologists, challenges the idea that a diet low in saturated fat is an ‘evidence-based’ recommendation for people with familial hypercholesterolemia (FH).
Taken together, these papers suggest that the “diet-heart hypotheses,” which in the 1950s suggested that eating saturated fat raises the risk of heart disease, is an idea that could never be confirmed, despite multiple large clinical trials testing its efficacy — including quite a few funded by the National Institutes of Health. The papers cited above explain why using LDL-cholesterol as a rationale for condemning saturated fats, as the 2020 DGAC is currently doing, is inadequate.
Since the launch of the DGA in 1980, Americans have been advised to consume a diet “low in saturated fats.” In 2005, the DGA added a formal limit of 10 percent of calories from these fats, and this recommendation has endured since that time. But the past decade has seen a thorough reconsideration of saturated fats, and now, there are close to 20 review papers reexamining the evidence. These have near-universally concluded that saturated fats have no effect on cardiovascular or total mortality.
In addition, there is a growing view that restricting the natural foods containing these fats causes harm by reducing access to the full complement of nutrients essential for human health. For instance, the U.S. Dietary Guidelines, with its current 10% cap on saturated fats, fails to meet nutrient targets for, among other things, iron and choline, which are most easily obtained by eating regular meat and dairy — foods that also happen to contain saturated fats.
Journal of the American College of Cardiology
A group of leading nutrition scientists, including a former member of the 2015 Dietary Guidelines Advisory Committee and the chair of the 2005 DGAC, were among the prominent authors of a “State-of-the-Art Review” in the prestigious Journal of the American College of Cardiology: “Saturated Fats and Health: A Reassessment and Proposal for Food-based Recommendations.” This review found that government limits on saturated fats are not justified by the science.
The JACC abstract reads: “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 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, eggs 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.”
The paper also notes, “These historical facts demonstrate that saturated fats were an abundant, key part of the ancient human diet.”
The JACC paper comes after the group of scientists attended a workshop, “Saturated Fats: A Food or Nutrient Approach?” in February. Members of that workshop wrote a consensus statement, submitted two formal public comments to USDA and sent a letter to the Secretaries of U.S. Departments of Agriculture and Health and Human Services on their findings which concluded that limits on saturated fats are not justified and should be re-examined.
BMJ Evidence-Based Medicine Journal
In a paper published recently in the prestigious journal “BMJ Evidence-Based Medicine,” 10 experts on heart disease and diet, including five cardiologists, reviewed current dietary recommendations for people diagnosed with a genetic disorder, called familial hypercholesterolemia (FH). People with FH have very high levels of serum cholesterol, typically two to four times higher than average.
For decades, people with FH have been instructed by organizations such as the American Heart Association to lower their cholesterol and heart disease risk by minimizing their consumption of saturated fat, which is found in coconut oil and in food from animal sources, such as eggs, cheese and meat.
According to David Diamond, a professor and heart disease researcher at the University of South Florida, the team searched the literature to find any justification for the low saturated-fat diet recommendations for FH. However, they found no evidence to support the dietary guidelines, which was why the title of their paper was that current diet guidelines are in an “evidence-free zone.”
The BMJ abstract reads: “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.”
Dietary Guidelines Subcommittee one-sided and unbalanced
The Dietary Guidelines Advisory Committees’ draft conclusions to maintain the cap on saturated fats are not surprising, given that the five-person subcommittee, according to an analysis by The Nutrition Coalition, is one-sided and unbalanced. This subcommittee includes one of the field’s staunchest foes of saturated fats and not a single person to oppose her. The subcommittee’s conclusions are also unsurprising given that advice to limit saturated fat has been in place for 40 years. These views are deeply rooted in government agencies and university nutrition departments as well as supported by many food and pharmaceutical interests. ❖
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