Saturated Fat and Cardiovascular Disease
Saturated fat, carbohydrate, and cardiovascular disease (2010)
- A focus of dietary recommendations for cardiovascular disease (CVD) prevention and treatment has been a reduction in saturated fat intake, primarily as a means of lowering LDL-cholesterol concentrations. However, the evidence that supports a reduction in saturated fat intake must be evaluated in the context of replacement by other macronutrients. Clinical trials that replaced saturated fat with polyunsaturated fat have generally shown a reduction in CVD events, although several studies showed no effects. An independent association of saturated fat intake with CVD risk has not been consistently shown in prospective epidemiologic studies, although some have provided evidence of an increased risk in young individuals and in women. Replacement of saturated fat by polyunsaturated or monounsaturated fat lowers both LDL and HDL cholesterol. However, replacement with a higher carbohydrate intake, particularly refined carbohydrate, can exacerbate the atherogenic dyslipidemia associated with insulin resistance and obesity that includes increased triglycerides, small LDL particles, and reduced HDL cholesterol. In summary, although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate. Furthermore, particularly given the differential effects of dietary saturated fats and carbohydrates on concentrations of larger and smaller LDL particles, respectively, dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity.
Saturated fat and cardiovascular disease: The discrepancy between the scientific literature and dietary advice (2012)
- Given the large social impact of dietary advice, it is important that the advice have a solid scientific basis. Evidence-based dietary advice should be built on results from all studies available, according to a given methodology. Conclusions should be a valid representation of the summarized results. The association between saturated fat intake and cardiovascular disease was examined. Results from three reports of leading U.S. and European advisory committees were compared with results as they were presented in the articles referred to. Findings were put into perspective with results not included in these reports. Different lines of evidence were included in the different reports. No overlap whatsoever was found in the articles included. Most results from the scientific literature were lacking for most different lines of evidence in all reports. All three reports included the effect of saturated fat on low-density lipoprotein cholesterol in the evidence linking saturated fat to cardiovascular disease, but the effect on high-density lipoprotein cholesterol was systematically ignored. Both U.S. reports failed to correctly describe the results from the prospective studies. Results and conclusions about saturated fat intake in relation to cardiovascular disease, from leading advisory committees, do not reflect the available scientific literature.
RESPONSE TO ABOVE: More discrepancies around saturated fat and cardiovascular diseases (2012)
- In his review on the influence of saturated fat on cardiovascular disease, Robert Hoenselaar pointed to several discrepancies between the official guidelines and the results from the relevant literature. The habit to ignore or misquote results that contradict the dietary guidelines is not new, however. In 1995, I published a review in which I mentioned some contradictory studies that should have been mentioned by the authors of three authoritative American reviews about diet and cardiovascular disease. Only 2 of 12 groups of such studies were quoted correctly and in only one of the reviews. About half the studies were ignored. The rest were quoted irrelevantly, or insignificant findings in favor of the diet–heart hypothesis were inflated, or unsupportive results were quoted as if they were supportive. Only one of six randomized cholesterol-lowering trials with a negative outcome was cited and in only one of the reviews
Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease (2010)
- A reduction in dietary saturated fat has generally been thought to improve cardiovascular health. The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies. Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD. During 5-23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results. A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.
RESPONSE TO ABOVE: Meta-analysis of effect of saturated fat intake on cardiovascular disease: overadjustment obscures true associations (2010)
- The recent article by Siri-Tarino et al, which reported on a meta-analysis of prospective cohort studies evaluating the association of saturated fat with coronary heart disease (CHD), stroke, and cardiovascular disease (CVD) observed that “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.” This finding has generated some interest in the media. However, we believe that the interpretations of the results presented in this article are overstated and could be a result of flaws in the methodologic design of the study.
Reduction in saturated fat intake for cardiovascular disease (2015)
- The findings of this updated review are suggestive of a small but potentially important reduction in cardiovascular risk on reduction of saturated fat intake. Replacing the energy from saturated fat with polyunsaturated fat appears to be a useful strategy, and replacement with carbohydrate appears less useful, but effects of replacement with monounsaturated fat were unclear due to inclusion of only one small trial. This effect did not appear to alter by study duration, sex or baseline level of cardiovascular risk. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats. The ideal type of unsaturated fat is unclear.
Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis (2012)
- Although dietary recommendations have focused on restricting saturated fat (SF) consumption to reduce cardiovascular disease (CVD) risk, evidence from prospective studies has not supported a strong link between total SF intake and CVD events. After adjustment for demographics, lifestyle, and dietary confounders, a higher intake of dairy SF was associated with lower CVD risk. In contrast, a higher intake of meat SF was associated with greater CVD risk. The substitution of 2% of energy from meat SF with energy from dairy SF was associated with a 25% lower CVD risk. No associations were observed between plant or butter SF and CVD risk, but ranges of intakes were narrow. Conclusion: Associations of SF with health may depend on food-specific fatty acids or other nutrient constituents in foods that contain SF, in addition to SF.
Dietary Fiber and Saturated Fat Intake Associations with Cardiovascular Disease Differ by Sex in the Malmö Diet and Cancer Cohort: A Prospective Study (2012)
- This study provides little support for independent effects of specific macronutrients in the causation of ischemic CVD. Saturated fat, long suspected as a causal risk factor of CVD, was generally not associated with disease, although the women with the lowest intake had higher risk of CE than other women – after adjustment for fiber. This illustrates one of the major problems with studies of nutrient intake: the nutrient variables are also, perhaps even primarily, markers of the foods they derive from. Foods contain many nutrients and other bioactive substances that interact in complex ways and may therefore differ in their health effects in ways not captured by differences in the content of single nutrients.
The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010? (2011)
- 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.
Reduction in saturated fat intake improves cardiovascular risks in obese adolescents during interdisciplinary therapy (2014)
- This study raises the possibility that after moderate changes in SFA intake major effects in controlling inflammation and cardiovascular risks are obtained, since L/A ratio and cIMT were down regulated, while adiponectin and A/L ratio were up-regulated. In conclusion, improvements in inflammatory process and cardiovascular risks were observed after moderate change in SFA associated with weight loss therapy in obese adolescents.
Effects of dietary saturated fat on LDL subclasses and apolipoprotein CIII in men (2012)
- Our results show that in the context of a reduced CHO, high beef protein diet, the increase in plasma and LDL cholesterol with high vs low saturated fat is associated with concurrent increases in the concentration of plasma and LDL apoCIII and the mass of large, medium and small LDL particles. The change in total LDL apoCIII was correlated with changes in apoCIII in the LDL IV fraction (ρ=0.66). Consistent with previous reports, the concentration of apoCIII was significantly higher in LDL IV compared with other LDL subfractions. Increased LDL apoCIII has been shown to be an important marker of CVD risk that is independent of standard lipid risk factors and in fact much of the risk ordinarily attributed to LDL appears to be due to LDL particles that contain apoCIII.
Food Sources of Saturated Fat and the Association With Mortality: A Meta-Analysis (2013)
- Early guidelines regarding intake of saturated fat, which remain largely unchanged today, lacked a strong evidence base. These guidelines were derived from assumptions about the causal pathway of disease development, specifically that replacing saturated fat in the diet with polyunsaturated fat lowered total serum cholesterol, which in turn reduced risk of CVD. This is now thought to be an oversimplification of the multiple processes that influence the impact of dietary composition on human health. Our review, which summarizes the currently available evidence, is unable to support a strong recommendation regarding restricting intake of foods high in saturated fat for the prevention of mortality.
Influence of Dairy Product and Milk Fat Consumption on Cardiovascular Disease Risk: A Review of the Evidence (2016)
- Diets higher in SF from whole milk and butter increase LDL-C when substituted for CHO or unsaturated fatty acids, but may also increase HDL-C, which may lower or not alter the TC:HDL-C ratio. Most clinical studies showed that full-fat natural cheese, a highly fermented product, significantly lowers LDL-C compared with butter intake of equal total fat and saturated fat content. Results showing favorable effects of fermented yogurt products on plasma lipids and lipoproteins appear to be strain specific. In studies with yogurts fermented with various probiotic bacterial strains some, but not all, showed favorable effects on blood lipids and lipoproteins. Reliance on the level of a single lipid nutrient (SF) in a food and a single plasma biomarker (LDL-C) may not adequately characterize the cardiovascular impact of complex foods that contain, in addition to SF, multiple nutrients and other bioactive components that reduce CVD risk.
Saturated Fat Intake and Cardiovascular Disease in Japanese Population (2015)
- Three studies have examined the link between saturated fat intake and intraparenchymal hemorrhage, consistently showing an inverse association. However, the association for ischemic stroke is less clear, although it is generally inverse. As for myocardial infarction, the findings in Japanese studies are inconsistent, as are those of Western studies. The JPHC study, however, found a positive association, the first report in Asia. Taken together with the results of the JPHC and Western studies, a saturated fat intake of around 20 g/day (approximately 10% of total energy) may be optimal, which corresponds to 200 g of milk a day and 150 g of meat every other day.
Dietary Fatty Acids and Risk of Coronary Heart Disease in Men The Kuopio Ischemic Heart Disease Risk Factor Study (2014)
- Our results suggest that SFA intake is not an independent risk factor for CHD, even in a population with higher ranges of SFA intake. In contrast, increasing PUFA intake is associated with lower risk of fatal CHD, whether replacing SFA, TFA, or carbohydrates. Further investigation of the effect of MUFA on CHD risk is warranted. Also, because there is evidence that CHD risk cannot be predicted simply on the basis of the fatty acid profile of a food, for example, the content of SFA, more research should be focused on the cardiovascular effect of different foods, food groups, and dietary patterns.