A Reassessment and Proposal for Food-Based Recommendations
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.
Highlights
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The U.S. Dietary Guidelines recommend the restriction of SFA intake to <10% of calories to reduce CVD. |
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Different SFAs have different biologic effects, which are further modified by the food matrix and the carbohydrate content of the diet. |
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Several foods relatively rich in SFAs, such as whole-fat dairy, dark chocolate, and unprocessed meat, are not associated with increased CVD or diabetes risk. |
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There is no robust evidence that current population-wide arbitrary upper limits on saturated fat consumption in the United States will prevent CVD or reduce mortality. |
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Lowering the consumption of saturated fat has been a central theme of U.S. dietary goals and recommendations since the late 1970s (1). Since 1980, it has been recommended that saturated fatty acid (SFA) intake be limited to <10 percent of total calories as a means of reducing risk for cardiovascular disease (CVD) (1).
In 2018, the U.S. Departments of Agriculture and Health and Human Services asked for public comments in response to the following question: “What is the relationship between saturated fat consumption (types and amounts) and risk of CVD in adults?” (2).
This review aims to address this important question by examining available evidence on the effects of saturated fats on health outcomes, risk factors, and potential mechanisms underlying cardiovascular and metabolic outcomes, which will have implications for the 2020 Dietary Guidelines for Americans.
The relationship between dietary SFAs and heart disease has been studied in about 400,000 people and summarized in a number of systematic reviews of observational studies and randomized controlled trials.
Some meta-analyses find no evidence that reduction in saturated fat consumption may reduce CVD incidence or mortality (3–6), whereas others report a significant—albeit mild—beneficial effect (7,8).
Therefore, the basis for consistently recommending a diet low in saturated fat is unclear. The purpose of this review is to critically evaluate the health effects of dietary SFAs and to propose an evidence-based recommendation for a healthy intake of different SFA food sources.
Conclusions
The long-standing bias against foods rich in saturated fats should be replaced with a view toward recommending diets consisting of healthy foods. What steps could shift the bias?
We suggest the following measures:
1) enhance the public’s understanding that many foods (e.g., whole-fat dairy) that play an important role in meeting dietary and nutritional recommendations may also be rich in saturated fats;
2) make the public aware that low-carbohydrate diets high in saturated fat, which are popular for managing body weight, may also improve metabolic disease endpoints in some individuals, but emphasize that health effects of dietary carbohydrate—just like those of saturated fat—depend on the amount, type and quality of carbohydrate, food sources, degree of processing, etc.;
3) shift focus from the current paradigm that emphasizes the saturated fat content of foods as key for health to one that centers on specific traditional foods, so that nutritionists, dietitians, and the public can easily identify healthful sources of saturated fats; and
4) encourage committees in charge of making macronutrient-based recommendations to translate those recommendations into appropriate, culturally sensitive dietary patterns tailored to different populations.
This is a short exerpt of a long document, see the whole document here jacc.org
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