Abstract
Dietary and policy recommendations frequently focus on reducing saturated fatty acid consumption for improving cardiometabolic health, based largely on ecologic and animal studies. Recent advances in nutritional science now allow assessment of critical questions about health effects of saturated fatty acids (SFA). We reviewed the evidence from randomized controlled trials (RCTs) of lipid and non-lipid risk factors, prospective cohort studies of disease endpoints, and RCTs of disease endpoints for cardiometabolic effects of SFA consumption in humans, including whether effects vary depending on specific SFA chain-length; on the replacement nutrient; or on disease outcomes evaluated. Compared with carbohydrate, the TC:HDL-C ratio is nonsignificantly affected by consumption of myristic or palmitic acid, is nonsignificantly decreased by stearic acid, and is significantly decreased by lauric acid. However, insufficient evidence exists for different chain-length-specific effects on other risk pathways or, more importantly, disease endpoints. Based on consistent evidence from human studies, replacing SFA with polyunsaturated fat modestly lowers coronary heart disease risk, with ~10% risk reduction for a 5% energy substitution; whereas replacing SFA with carbohydrate has no benefit and replacing SFA with monounsaturated fat has uncertain effects. Evidence for the effects of SFA consumption on vascular function, insulin resistance, diabetes, and stroke is mixed, with many studies showing no clear effects, highlighting a need for further investigation of these endpoints. Public health emphasis on reducing SFA consumption without considering the replacement nutrient or, more importantly, the many other food-based risk factors for cardiometabolic disease is unlikely to produce substantial intended benefits.
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Introduction
Reducing the consumption of saturated fatty acids (SFA) is a pillar of international dietary recommendations to reduce the risk of cardiovascular disease (CVD) [1–3]. The World Health Organization and the US Dietary Guidelines recommend consuming less than 10%E (percentage of total energy intake) from SFA [4], and the American Heart Association less than 7%E [3]. The strong focus on SFA as a risk factor for CVD originated in the 1960s and 1970s from lines of evidence including ecologic studies across nations, short-term metabolic trials in generally healthy adults assessing total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), and animal experiments that together appeared to provide consistent support that SFA intake increased the risk of coronary heart disease (CHD).
However, several critical questions have remained about the relationship between SFA consumption and CVD risk. First, do health effects of reducing SFA consumption vary depending on whether the replacement nutrient is carbohydrate (CHO), monounsaturated fat (MUFA), or polyunsaturated fat (PUFA)? A historical emphasis on low fat diets has produced drops in SFA consumption in the US and many other nations, but with concomitant increases in CHO, rather than MUFA or PUFA, as the replacement nutrient [1]. Is there strong evidence to support this dietary strategy? Second, do health effects of SFA vary depending on the chain-length, i.e. comparing 12-, 14-, 16-, and 18-carbon SFA? Current dietary recommendations generally focus on overall SFA consumption, without strong attention on specific SFA. Third, what is the relationship between SFA consumption and risk of stroke and type 2 diabetes mellitus? Historically, research on SFA has focused largely on CHD.
Advances in nutritional science in the last two decades now provide a substantial body of evidence to answer these questions (Fig. 1). These include well-conducted randomized controlled trials (RCTs) of SFA nutrient substitutions and multiple risk pathways as endpoints, including multiple lipid and also non-lipid risk factors (rather than only TC and LDL-C); and large prospective cohort studies and meta-analyses of RCTs of SFA consumption and clinical disease endpoints, that provide more direct evidence for effects on disease compared with changes in risk factors alone. Given the complementary strengths and limitations of these newer research paradigms, conclusions can be considered most robust when studies from each paradigm provide concordant evidence for health effects of SFA consumption. Together these research advances provide much stronger evidence for causal inference than data from prior available ecologic studies, limited metabolic studies, and animal experiments.
To elucidate the effects of SFA consumption on CVD risk based on the most current evidence, we reviewed the data from RCTs of multiple risk factors, large prospective cohort studies of disease endpoints, and RCTs of disease endpoints. When sufficient evidence was available, we particularly focused on the potentially different health effects of varying the replacement nutrient; of different chain-length SFA; and of specific effects on CHD, stroke, and diabetes.
Methods
Two investigators independently reviewed the literature for English-language articles published through Sep 2009 by performing searches of Medline, hand-searching of citation lists, and direct contact with experts. Inclusion criteria were any RCT or observational study in adults evaluating SFA consumption and the risk of CHD, stroke, or type 2 diabetes and related risk pathways, including lipids and lipoproteins, systemic inflammation, vascular function, and insulin resistance (1,254 identified articles). Search terms included “saturated fat(s)”, “lipoproteins”, “inflammation”, “blood pressure”, “vascular function”, “insulin resistance”, “cardiovascular diseases”, and “diabetes mellitus”. We focused on identifying RCTs of major risk factors, large prospective cohort studies of disease endpoints, and RCTs of disease endpoints, given strengths of these designs and their complementary limitations. We excluded a priori animal experiments, ecological studies, commentaries, general reviews, and case reports. Studies were independently considered by the two investigators for inclusion; rare differences were resolved by consensus.
Effects on Cardiovascular Risk Factors
Lipids and Lipoproteins
RCTs have established clear multiple effects of SFA consumption on circulating lipids and lipoproteins [5, 6]. Each of these effects varies depending on the comparison nutrient, i.e., the nutrient isocalorically replaced for SFA (Fig. 2). Compared with CHO, SFA intake raises TC and LDL-C, but also lowers triglycerides and raises high-density lipoprotein cholesterol (HDL-C). Given these conflicting directions of effects, effects on apolipoproteins or, even better, a more global risk marker such as the TC:HDL-C ratio may provide the best overall indication of potential effects on CHD risk. Compared with CHO, SFA intake has no significant effects on the TC:HDL-C ratio or ApoB levels, and raises ApoA1 levels. In contrast, consumption of PUFA or MUFA in place of SFA leads to lowering of TC, LDL-C, and ApoB; slight lowering (for PUFA) of HDL-C and ApoA1; little effect on triglycerides; and lowering of the TC:HDL-C ratio. Compared with trans fatty acids (TFA), SFA intake has minimal effects on LDL-C but raises HDL-C and lowers triglycerides and lipoprotein(a), with improvement in the TC:HDL-C ratio [7]. Thus, consideration of which nutrient is being replaced is essential when considering lipid effects or designing dietary guidelines or policy measures related to SFA consumption. Overall, the changes in lipid and apolipoprotein levels predict minimal effects on CHD risk when CHO replaces SFA, benefits when PUFA or MUFA replace SFA, and harms when TFA replace SFA.
Effects of SFA consumption on serum lipids and lipoproteins further vary according to which specific SFA is consumed (Fig. 3) [5]. With CHO consumption as the reference, lauric (12:0), myristic (14:0), and palmitic (16:0) acid raise TC and LDL-C, whereas stearic acid (18:0) does not. All SFA raise HDL-C, but HDL-raising effects are greater as chain-length decreases. Overall, the TC:HDL-C ratio is not significantly affected by myristic or palmitic acid consumption, is nonsignificantly decreased by stearic acid consumption, and is significantly decreased by lauric acid consumption (Fig. 3). These effects suggest little CHD benefit of replacing myristic, palmitic, or stearic acid with CHO, and potential harm of replacing lauric acid with CHO.
Systemic Inflammation
Inflammation independently increases risk of CVD and diabetes [8–11]. Compared with lipid effects, the influence of SFA consumption on inflammation is less well investigated, with mixed results. In a randomized cross-over trial, 20 healthy men consumed a high SFA (22%E SFA), a high MUFA (24%E MUFA), and a high CHO high PUFA (55%E CHO, 8%E PUFA) diet for 4 weeks [12]. At the end of each intervention period, participants were given a fat-rich breakfast (60%E fat) with similar fat composition to that of each diet. Consumption of a butter-rich breakfast (35%E SFA) had no effect on postprandial plasma levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6 or monocyte chemoattractant protein (MCP)-1, compared with an olive oil-rich breakfast (36%E MUFA) or a walnut-rich breakfast (16%E PUFA) [12]. In another cross-over trial of 50 healthy men, consumption of low-chain SFA (12:0–16:0) for 5 weeks (8%E) had no effect on fibrinogen, C-reactive protein (CRP), or IL-6 levels; similar consumption of stearic acid (18:0) increased plasma levels of fibrinogen, but not of CRP or IL-6, compared with CHO [13]. Among hypercholesterolemic subjects (n = 18), a one-month diet with 16.7%E from SFA (butter), compared with 12.5%E from PUFA (soybean oil), resulted in a trend toward higher macrophage production of TNF-α, without effects on IL-6 [14].
Observational studies investigating associations between SFA intake and markers of inflammation are limited [15, 16]. Among 4,900 US adults, dietary SFA intake was not cross-sectionally associated with CRP levels, after adjusting for other risk factors and lifestyle behaviors [15]. Other cross-sectional studies have been very small and/or not multivariable-adjusted [16]. Observational studies of circulating (e.g., plasma) or tissue (e.g., adipose) SFA levels [17, 18] are helpful for investigating effects of metabolism but not of SFA consumption, as circulating and tissue SFA are poorly reflective of dietary SFA due to endogenous synthesis and regulation by lipolysis, lipogenesis, and beta-oxidation [19–22]. Overall, the limited and mixed evidence precludes strong conclusions about potential pro-inflammatory effects of SFA consumption.
Blood Pressure, Endothelial Function, and Arterial Stiffness
Effects of dietary SFA on markers of vascular function including blood pressure, endothelial function, and arterial stiffness are similarly not well characterized [23]. A few observational studies have evaluated SFA intake and incidence of hypertension, with mixed results [24, 25]. Among 30,681 US men followed for 4 years, no significant associations were seen between SFA intake and incident hypertension, after adjusting for age, body mass index, and alcohol consumption [24]. In contrast, among 11,342 US men in the MRFIT study, SFA intake was cross-sectionally positively associated with systolic and diastolic blood pressure, after adjusting for risk factors and lifestyle behaviors, although no adjustments were made for other dietary fats, CHO, or protein [25].
Randomized controlled feeding trials ranging in duration from 3 weeks to 6 months have demonstrated mixed results of SFA intake compared with MUFA, PUFA, TFA, or CHO on measures of blood pressure, endothelial dysfunction, and/or arterial stiffness [23] (Table 1). Among nine trials assessing blood pressure, seven observed no differences between the different diets [26–34]. These trials evaluated a range of SFA consumption levels and replacement nutrients (Table 1). Improvements in BP were seen in two of five RCTs including a comparison to MUFA, one of five RCTs including a comparison to PUFA, and zero of four RCTs including a comparison to CHO. Among four trials assessing indices of endothelial function, three observed differences in brachial artery flow-mediated dilatation (FMD) between the different diets [31, 35–37]. Improvements in endothelial function were seen in two of three RCTs including a comparison to MUFA, one RCT including a comparison to PUFA, and one of three RCTs including a comparison to CHO; endothelial function was worsened in one RCT replacing SFA with TFA. In two trials evaluating arterial stiffness as assessed by pulse wave velocity (PWV) [31, 37], no effects of reducing SFA consumption were seen, including two RCTs including a comparison to MUFA, one RCT including a comparison to PUFA, and two RCTs including a comparison to CHO. Thus, evidence for effects of SFA consumption on vascular function is mixed, with no clear pattern based on underlying population characteristics, SFA consumption levels, or the comparison nutrient, and with most studies suggesting no effects.
Insulin Resistance and Diabetes
SFA has been considered a risk factor for insulin resistance and diabetes mellitus [38], but review of the current evidence indicates surprisingly equivocal findings. SFA consumption inconsistently affects insulin resistance in controlled trials (Table 2) and has not been associated with incident diabetes in prospective cohort studies (Fig. 4) [39–52]. Among generally healthy individuals, most RCTs show no differences in markers of glucose-insulin homeostasis comparing different intakes of SFA versus MUFA, PUFA, or CHO. Findings are more mixed among individuals having or predisposed to insulin resistance. In these individuals, improvements in markers of glucose-insulin homeostasis were seen in three of five RCTs including a comparison to MUFA, one of three RCTs including a comparison to PUFA, and one RCT including a comparison to CHO. Among all these trials, the great majority were short-term (up to several weeks) and surprisingly small (<20 subjects). The two largest trials (n = 162, n = 59) found SFA to worsen several indices of glucose-insulin homeostasis in comparison to MUFA (two trials) or CHO (one trial).
Significant additional insight into effects of dietary fats on glucose-insulin homeostasis can be gained from long-term studies evaluating actual onset of diabetes. Among four large prospective cohort studies, none found independent associations between consumption of either SFA (Fig. 4) or MUFA and onset of diabetes [53–56]. In contrast, three of four cohorts [54] observed lower incidence of diabetes with greater consumption of PUFA and/or vegetable fat [53, 55, 56]. In the large Women’s Health Initiative trial (n = 45,887), SFA intake was reduced in the intervention group from 12.7 to 9.5%E over 8 years as part of overall total fat reduction, largely replaced with CHO [57]. In this large RCT, this significant reduction in SFA consumption had no effect on fasting glucose, fasting insulin, homeostasis model assessment (HOMA) insulin resistance, or incident diabetes (RR = 0.95, 95% CI = 0.90–1.03).
Thus, some evidence from short-term RCTs suggests that SFA consumption in place of MUFA may worsen glucose-insulin homeostasis, especially among individuals predisposed to insulin resistance. However, several long-term observational studies and one large RCT suggest no effect of SFA consumption on onset of diabetes. Further confirmatory results of either harm or no effect in additional appropriately powered studies are needed given the present inconsistency of effects across all studies.
Weight Gain and Adiposity
The role of total dietary fat in obesity has been widely studied due to its high energy content (9 kcal/g) and subsequent potential for weight gain [58–60]. Based on RCTs of weight loss with balanced-intensity interventions (i.e., all individuals receiving similar guidance and follow-up, with only the specific dietary advice varying) and prospective observational studies of weight gain, the %E from total fat does not have strong effects on adiposity compared with overall quality and quantity of foods consumed. Evidence for independent effects of specific dietary fats such as SFA on weight gain or adiposity are much more limited. In two large prospective cohort studies, increases in SFA consumption were associated with very small increases in abdominal circumference [61] or body weight during 8–9 years follow-up [62] compared with CHO, after adjusting for other risk factors and lifestyle and dietary behaviors.
Relationships with Cardiovascular Events
Coronary Heart Disease—Prospective Cohort Studies
Most individual prospective cohort studies have not observed an independent relationship between SFA consumption and incident CHD [63–67]. The relatively small number of published studies, among the many available international cohorts, also raises concern for potential publication bias (i.e., additional unreported null studies). Two recent systematic reviews and meta-analyses, the first including 9 cohorts (11 estimates) evaluating 160,673 individuals [64], and the second including 16 cohorts among 214,182 individuals [68], found no significant association between SFA intake and CHD risk. Comparing the highest to the lowest category of consumption, the pooled RRs in these two meta-analyses were 1.06 (95% CI = 0.96–1.15) and 1.07 (95% CI = 0.96–1.19), respectively. These meta-analyses suggest no overall effect of SFA consumption on CHD events. However, these studies were unable to separately evaluate whether consuming SFA might have different effects on CHD events depending on the nutrient replaced, as would be suggested by differing effects of SFA, depending on the comparison nutrient, on blood lipids and apolipoproteins (Fig. 2).
The best observational evidence to-date of this question is a recent pooled analysis of individual-level data from 11 prospective cohort studies across three continents, including 344,696 individuals with 5,249 CHD events over 4–10 years of follow-up [69]. In fully multivariable-adjusted analyses, SFA consumption was associated with higher CHD risk only in comparison to PUFA. In other words, only consumption of PUFA in place of SFA was associated with lower CHD risk, whereas in fact consumption of CHO or MUFA in place of SFA was associated with higher CHD risk or trends toward higher CHD risk (Fig. 5). These associations were similar when analyses were restricted to CHD deaths only, and were not different in subgroups stratified by either sex or age.
Coronary Heart Disease—Randomized Controlled Trials
Eight RCTs have investigated the effects of consuming PUFA (either total or linoleic acid, LA) in place of SFA on CHD events [70–77]. Most of these trials individually found no significant effects. A recent meta-analysis of these RCTs, including a total of 13,614 participants with 1,042 CHD events, found that CHD risk was lowered by 10% for each 5%E greater PUFA intake replacing SFA [78] (Fig. 5). Many of these trials have important limitations, including for example not being double-blind; incompletely assessing compliance; randomizing sites rather than individuals and having open enrollment and drop-out; and/or including vegetable oils that contained omega-3 PUFA of plant origin that may provide cardiovascular benefits unrelated to decreased SFA intake. Nonetheless, the overall findings from these RCTs of CHD endpoints are consistent with the results from prospective cohorts (Fig. 5).
One large RCT has tested the effect of reducing SFA consumption, replaced largely with CHO, on CHD events. As described, the Women’s Health Initiative trial randomized 46,558 women to lower total fat consumption, that included lowering of SFA consumption by ~3%E over 8 years, and largely replaced with CHO. Even though this was an unbalanced intervention (i.e., the intervention group received extensive dietary counseling, whereas the control group received usual care) that would generally bias toward risk-reduction in the intervention group, there were no significant effects on either incident CHD (RR = 0.93, 95%CI = 0.83–1.05) or total CVD (RR = 0.96, 95%CI = 0.89–1.03) [79]. This absence of benefit for substituting SFA with CHO is consistent with expected effects based on lipid changes (TC:HDL ratio) or observed relationships in prospective cohort studies (Fig. 5).
Stroke: Prospective Cohorts and Randomized Controlled Trials
Among five prospective cohort studies evaluating SFA consumption and incidence of stroke, one of three found SFA to be associated with lower risk of ischemic stroke [80–82], and one of three found SFA to be associated with lower risk of hemorrhagic stroke [80, 83, 84]. Four prospective cohorts have also observed protective associations between animal protein intake, that is often consumed together with SFA, and risk of hemorrhagic stroke [85]. A recent systematic review and meta-analysis of eight prospective cohorts also found that SFA consumption was associated with trends toward lower risk of stroke: comparing the highest to the lowest category of SFA intake, the RR was 0.81 (95% CI = 0.62–1.05) [68]. In the Women’s Health Initiative trial, reduction in SFA consumption did not have a significant effect on incident stroke over 8 years (RR = 1.02, 95% CI = 0.90–1.17) [79]. Thus, overall, SFA consumption does not appear to increase the risk of stroke, and in fact some studies suggest a protective effect. Further investigation of these effects, including independence from potential benefits of animal protein intake, is warranted.
Future Research Directions
The multiple well-designed studies reviewed herein provide substantial evidence for health effects of SFA consumption. However, important questions remain. Although replacement of SFA with CHO appears to provide no overall CVD benefit, indirect lines of evidence suggest that effects could vary depending on overall CHO quality [86–88]. For example, replacing SFA with less processed, higher fiber, lower glycemic index CHO could provide benefit, whereas replacing SFA with more processed, lower fiber, higher glycemic index CHO might have no effects or even be harmful. Effects of replacing SFA with CHO could also vary with an individual's susceptibility to insulin resistance/metabolic syndrome, in whom adverse metabolic effects of highly refined CHO may be more pronounced. Evidence for effects of replacing SFA with MUFA is mixed. Such effects could vary depending on other constituents in MUFA-containing foods (e.g., animal fats vs. vegetable oils), for example due to potentially beneficial phytochemicals and flavanols contained in the latter but not the former. Each of these issues requires direct investigation. Additionally, whereas the substantial differences in blood lipid effects of different chain-length SFA are clear, blood lipids represent only one set of intermediate risk markers. Investigation of the effects of different chain-length SFA on other risk pathways and, more importantly, on disease endpoints is urgently needed to determine the extent to which dietary and policy recommendations should focus on specific SFA rather than overall SFA consumption. Additional investigation of effects of SFA consumption on blood pressure, endothelial function, insulin resistance, diabetes, and stroke (plus stroke subtypes) is also needed, including consideration of potential variation depending on both the replacement nutrients and specific chain-length SFA under consideration. Future research should also evaluate the health effects of specific foods consumed, i.e., SFA intake from different meats versus dairy versus tropical fats, as well as how individual factors, such as age, sex, lifestyle factors, predisposition to insulin resistance, or genetic variation, may alter such responses.
Conclusions
Current public health dietary recommendations often prioritize the reduction of SFA consumption to prevent CVD. A review of the current evidence, particularly findings from well-performed RCTs of risk pathways, large prospective cohorts of disease endpoints, and RCTs of disease endpoints, suggests that this focus may not produce the intended benefits. First of all, substantial evidence indicates that health effects of reducing SFA vary depending on the replacement nutrient. Based on the best evidence from human studies, replacing SFA with PUFA (e.g., vegetables, vegetable oils) lowers CHD risk, whereas replacing SFA with CHO has no benefits. Replacing SFA with MUFA has uncertain effects, based on mixed evidence within and across different research paradigms. Of note, the effects of replacing SFA with PUFA or CHO, but not MUFA, on clinical CHD endpoints could be relatively predicted from the effects of these nutrient substitutions on the TC:HDL-C ratio. Thus, policies that prioritize the reduction of SFA consumption without specifically considering the replacement nutrient may have little or no effects on disease risk, especially as the most common replacement in populations is often CHO.
Second, even under optimal replacement scenarios of SFA for PUFA, the magnitude of likely benefit warrants attention. RCTs of the blood TC:HDL-C ratio, prospective cohorts of disease endpoints, and RCTs of disease endpoints each converge on ~10% reduction in CHD events for 5%E substitution of SFA with PUFA. This approaches the maximal plausible risk reduction in most populations; in the US, for example, such benefit would require overall population decrease from the current 11.5 to 6.5%E SFA consumption. Thus, although recommendations to replace SFA with PUFA appear appropriate, the much larger CVD burdens caused by other dietary factors (e.g., low omega-3, low fruits and vegetables, high trans fat, and high salt) [89] appear to warrant much more attention. Finally, although investigation of individual nutrients provides important information on potential underlying mechanisms of health effects, people make decisions about eating whole foods that contain multiple macro- and micronutrients in various amounts. Thus, food-based scientific research and policy recommendations may be most relevant in the modern era to understand and reduce the pandemics of chronic disease occurring in nearly all nations.
Abbreviations
- BMI:
-
Body mass index
- CHD:
-
Coronary heart disease
- CHO:
-
Carbohydrate
- CRP:
-
C-reactive protein
- CVD:
-
Cardiovascular disease
- FMD:
-
Flow-mediated dilatation
- FSIGTT:
-
Frequently sampled intravenous glucose tolerance test
- GLP-1:
-
Glucagon-like peptide-1
- HBA1c:
-
Glycosylated hemoglobin
- HDL:
-
High-density lipoprotein
- HOMA:
-
Homeostasis model assessment
- IL:
-
Interleukin
- LA:
-
Linoleic acid
- LDL:
-
Low-density lipoprotein
- MCP:
-
Monocyte chemoattractant protein
- MUFA:
-
Monounsaturated fatty acids
- PUFA:
-
Polyunsaturated fatty acids
- PWV:
-
Pulse wave velocity
- RCT:
-
Randomized controlled trial
- SFA:
-
Saturated fatty acids
- TC:
-
Total cholesterol
- TFA:
-
Trans fatty acids
- TNF:
-
Tumor necrosis factor
- USFA:
-
Unsaturated fatty acids
- WHI:
-
Women’s Health Initiative
- %E:
-
Percentage of total energy intake
References
Centers for disease control, prevention (2004) Trends in intake of energy and macronutrients: United States, 1971–2000. Morb Mortal Wkly Rep 53(04):80–82
World Health Organization (2003) Diet, nutrition and the prevention of chronic diseases: report of a joint WHO/FAO expert consultation. World Health Org Tech Rep 916(i–viii):1–149 (Geneva)
Lichtenstein AH et al (2006) Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee. Circulation 114(1):82–96
Dietary Guidelines Advisory Committee (2005) Dietary Guidelines Advisory Committee report. http://www.health.gov/dietaryguidelines/dga2005/report/
Mensink RP et al (2003) Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials. Am J Clin Nutr 77(5):1146–1155
Mozaffarian D, Clarke R (2009) Quantitative effects on cardiovascular risk factors and coronary heart disease risk of replacing partially hydrogenated vegetable oils with other fats and oils. Eur J Clin Nutr 63(Suppl 2):S22–S33
Micha R, Mozaffarian D (2009) Trans fatty acids: effects on metabolic syndrome, heart disease and diabetes. Nat Rev Endocrinol 5(6):335–344
Libby P, Ridker PM, Maseri A (2002) Inflammation and atherosclerosis. Circulation 105(9):1135–1143
Albert CM et al (2002) Prospective study of C-reactive protein, homocysteine, and plasma lipid levels as predictors of sudden cardiac death. Circulation 105(22):2595–2599
Pickup JC (2004) Inflammation and activated innate immunity in the pathogenesis of type 2 diabetes. Diabetes Care 27(3):813–823
Vasan RS et al (2003) Inflammatory markers and risk of heart failure in elderly subjects without prior myocardial infarction: the Framingham Heart Study. Circulation 107(11):1486–1491
Jimenez-Gomez Y et al (2009) Olive oil and walnut breakfasts reduce the postprandial inflammatory response in mononuclear cells compared with a butter breakfast in healthy men. Atherosclerosis 204(2):e70–e76
Baer DJ et al (2004) Dietary fatty acids affect plasma markers of inflammation in healthy men fed controlled diets: a randomized crossover study. Am J Clin Nutr 79(6):969–973
Han SN et al (2002) Effect of hydrogenated and saturated, relative to polyunsaturated, fat on immune and inflammatory responses of adults with moderate hypercholesterolemia. J Lipid Res 43(3):445–452
King DE, Egan BM, Geesey ME (2003) Relation of dietary fat and fiber to elevation of C-reactive protein. Am J Cardiol 92(11):1335–1339
Lennie TA et al (2005) Dietary fat intake and proinflammatory cytokine levels in patients with heart failure. J Card Fail 11(8):613–618
Petersson H et al (2009) Relationships between serum fatty acid composition and multiple markers of inflammation and endothelial function in an elderly population. Atherosclerosis 203(1):298–303
Fernandez-Real JM et al (2003) Insulin resistance, inflammation, and serum fatty acid composition. Diabetes Care 26(5):1362–1368
Poppitt SD et al (2005) Assessment of erythrocyte phospholipid fatty acid composition as a biomarker for dietary MUFA, PUFA or saturated fatty acid intake in a controlled cross-over intervention trial. Lipids Health Dis 4:30
Sun Q et al (2007) Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women. Am J Clin Nutr 86(1):74–81
Baylin A, Campos H (2006) The use of fatty acid biomarkers to reflect dietary intake. Curr Opin Lipidol 17(1):22–27
Hodson L, Skeaff CM, Fielding BA (2008) Fatty acid composition of adipose tissue and blood in humans and its use as a biomarker of dietary intake. Prog Lipid Res 47(5):348–380
Hall WL (2009) Dietary saturated and unsaturated fats as determinants of blood pressure and vascular function. Nutr Res Rev 22(1):18–38
Ascherio A et al (1992) A prospective study of nutritional factors and hypertension among US men. Circulation 86(5):1475–1484
Stamler J et al (1996) Relationship to blood pressure of combinations of dietary macronutrients: findings of the multiple risk factor intervention trial (MRFIT). Circulation 94(10):2417–2423
Margetts BM et al (1985) Blood pressure and dietary polyunsaturated and saturated fats: a controlled trial. Clin Sci (Lond) 69(2):165–175
Puska P et al (1985) Dietary fat and blood pressure: an intervention study on the effects of a low-fat diet with two levels of polyunsaturated fat. Prev Med 14(5):573–584
Sacks FM et al (1987) Effect of dietary fats and carbohydrate on blood pressure of mildly hypertensive patients. Hypertension 10(4):452–460
Storm H et al (1997) Comparison of a carbohydrate-rich diet and diets rich in stearic or palmitic acid in NIDDM patients: effects on lipids, glycemic control, and diurnal blood pressure. Diabetes Care 20(12):1807–1813
Piers LS et al (2003) Substitution of saturated with monounsaturated fat in a 4-week diet affects body weight and composition of overweight and obese men. Br J Nutr 90(3):717–727
Sanders T, Lewis F, Frost G (2009) Impact of the amount and type of fat and carbohydrate on vascular function in the RISCK study. Proc Nutr Soc, vol 68 (in press)
Lahoz C et al (1997) Effects of dietary fat saturation on eicosanoid production, platelet aggregation and blood pressure. Eur J Clin Invest 27(9):780–787
Uusitupa MI et al (1994) Long-term effects of four fat-modified diets on blood pressure. J Hum Hypertens 8(3):209–218
Rasmussen BM et al (2006) Effects of dietary saturated, monounsaturated, and n-3 fatty acids on blood pressure in healthy subjects. Am J Clin Nutr 83(2):221–226
de Roos NM, Bots ML, Katan MB (2001) Replacement of dietary saturated fatty acids by trans fatty acids lowers serum HDL cholesterol and impairs endothelial function in healthy men and women. Arterioscler Thromb Vasc Biol 21(7):1233–1237
Fuentes F et al (2001) Mediterranean and low-fat diets improve endothelial function in hypercholesterolemic men. Ann Intern Med 134(12):1115–1119
Keogh JB et al (2005) Flow-mediated dilatation is impaired by a high-saturated fat diet but not by a high-carbohydrate diet. Arterioscler Thromb Vasc Biol 25(6):1274–1279
Eyre H et al (2004) Preventing cancer, cardiovascular disease, and diabetes: a common agenda for the American Cancer Society, the American Diabetes Association, and the American Heart Association. Circulation 109(25):3244–3255
Galgani JE et al (2008) Effect of the dietary fat quality on insulin sensitivity. Br J Nutr 100(3):471–479
Riserus U, Willett WC, Hu FB (2009) Dietary fats and prevention of type 2 diabetes. Prog Lipid Res 48(1):44–51
Feskens EJ et al (1995) Dietary factors determining diabetes and impaired glucose tolerance: a 20-year follow-up of the Finnish and Dutch cohorts of the seven countries study. Diabetes Care 18(8):1104–1112
Christiansen E et al (1997) Intake of a diet high in trans monounsaturated fatty acids or saturated fatty acids: effects on postprandial insulinemia and glycemia in obese patients with NIDDM. Diabetes Care 20(5):881–887
Vessby B et al (2001) Substituting dietary saturated for monounsaturated fat impairs insulin sensitivity in healthy men and women: the KANWU study. Diabetologia 44(3):312–319
Summers LK et al (2002) Substituting dietary saturated fat with polyunsaturated fat changes abdominal fat distribution and improves insulin sensitivity. Diabetologia 45(3):369–377
Vega-Lopez S et al (2006) Palm and partially hydrogenated soybean oils adversely alter lipoprotein profiles compared with soybean and canola oils in moderately hyperlipidemic subjects. Am J Clin Nutr 84(1):54–62
Paniagua JA et al (2007) A MUFA-rich diet improves postprandial glucose, lipid and GLP-1 responses in insulin-resistant subjects. J Am Coll Nutr 26(5):434–444
Lithander FE et al (2008) No evidence of an effect of alterations in dietary fatty acids on fasting adiponectin over 3 weeks. Obesity (Silver Spring) 16(3):592–599
Schwab US et al (1995) Lauric and palmitic acid-enriched diets have minimal impact on serum lipid and lipoprotein concentrations and glucose metabolism in healthy young women. J Nutr 125(3):466–473
Fasching P et al (1996) No effect of short-term dietary supplementation of saturated and poly- and monounsaturated fatty acids on insulin secretion and sensitivity in healthy men. Ann Nutr Metab 40(2):116–122
Louheranta AM et al (1998) A high-stearic acid diet does not impair glucose tolerance and insulin sensitivity in healthy women. Metabolism 47(5):529–534
Lovejoy JC et al (2002) Effects of diets enriched in saturated (palmitic), monounsaturated (oleic), or trans (elaidic) fatty acids on insulin sensitivity and substrate oxidation in healthy adults. Diabetes Care 25(8):1283–1288
Perez-Jimenez F et al (2001) A Mediterranean and a high-carbohydrate diet improve glucose metabolism in healthy young persons. Diabetologia 44(11):2038–2043
Salmeron J et al (2001) Dietary fat intake and risk of type 2 diabetes in women. Am J Clin Nutr 73(6):1019–1026
van Dam RM et al (2002) Dietary fat and meat intake in relation to risk of type 2 diabetes in men. Diabetes Care 25(3):417–424
Meyer KA et al (2001) Dietary fat and incidence of type 2 diabetes in older Iowa women. Diabetes Care 24(9):1528–1535
Harding AH et al (2004) Dietary fat and the risk of clinical type 2 diabetes: the European prospective investigation of Cancer-Norfolk study. Am J Epidemiol 159(1):73–82
Tinker LF et al (2008) Low-fat dietary pattern and risk of treated diabetes mellitus in postmenopausal women: the Women’s Health Initiative randomized controlled dietary modification trial. Arch Intern Med 168(14):1500–1511
Willett WC, Leibel RL (2002) Dietary fat is not a major determinant of body fat. Am J Med 113(Suppl 9B):47S–59S
Pirozzo S et al (2003) Should we recommend low-fat diets for obesity? Obes Rev 4(2):83–90
Lissner L, Heitmann BL (1995) Dietary fat and obesity: evidence from epidemiology. Eur J Clin Nutr 49(2):79–90
Koh-Banerjee P et al (2003) Prospective study of the association of changes in dietary intake, physical activity, alcohol consumption, and smoking with 9-y gain in waist circumference among 16,587 US men. Am J Clin Nutr 78(4):719–727
Field AE et al (2007) Dietary fat and weight gain among women in the nurses’ health study. Obesity (Silver Spring) 15(4):967–976
Mozaffarian D (2005) Effects of dietary fats versus carbohydrates on coronary heart disease: a review of the evidence. Curr Atheroscler Rep 7(6):435–445
Mente A et al (2009) A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med 169(7):659–669
Oh K et al (2005) Dietary fat intake and risk of coronary heart disease in women: 20 years of follow-up of the nurses’ health study. Am J Epidemiol 161(7):672–679
Leosdottir M et al (2005) Dietary fat intake and early mortality patterns–data from The Malmo Diet and Cancer Study. J Intern Med 258(2):153–165
Pietinen P et al (1997) Intake of fatty acids and risk of coronary heart disease in a cohort of Finnish men: the alpha-tocopherol, beta-carotene cancer prevention study. Am J Epidemiol 145(10):876–887
Siri-Tarino P et al (2010) A meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 91(3):535–546
Jakobsen MU et al (2009) Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. Am J Clin Nutr 89(5):1425–1432
Dayton S et al (1968) Controlled trial of a diet high in unsaturated fat for prevention of atherosclerotic complications. Lancet 2(7577):1060–1062
Leren P (1970) The Oslo diet-heart study: eleven-year report. Circulation 42(5):935–942
Turpeinen O et al (1979) Dietary prevention of coronary heart disease: the Finnish mental hospital study. Int J Epidemiol 8(2):99–118
Burr ML et al (1989) Diet and reinfarction trial (DART): design, recruitment, and compliance. Eur Heart J 10(6):558–567
Watts GF et al (1992) Effects on coronary artery disease of lipid-lowering diet, or diet plus cholestyramine, in the St Thomas’ Atherosclerosis Regression Study (STARS). Lancet 339(8793):563–569
Miettinen M et al (1983) Dietary prevention of coronary heart disease in women: the Finnish mental hospital study. Int J Epidemiol 12(1):17–25
Frantz ID Jr et al (1989) Test of effect of lipid lowering by diet on cardiovascular risk. the Minnesota Coronary Survey. Arteriosclerosis 9(1):129–135
Council Medical Research (1968) Controlled trial of soya-bean oil in myocardial infarction. Lancet 2(7570):693–699
Mozaffarian D, Micha R, Wallace SK (2010) Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med (in press)
Howard BV et al (2006) Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Tria. JAMA 295(6):655–666
He K et al (2003) Dietary fat intake and risk of stroke in male US healthcare professionals: 14 year prospective cohort study. BMJ 327(7418):777–782
Seino F et al (1997) Dietary lipids and incidence of cerebral infarction in a Japanese rural community. J Nutr Sci Vitaminol 43(1):83–99
Gillman MW et al (1997) Inverse association of dietary fat with development of ischemic stroke in men. JAMA 278(24):2145–2150
Iso H et al (2001) Prospective study of fat and protein intake and risk of intraparenchymal hemorrhage in women. Circulation 103(6):856–863
Iso H et al (2003) Fat and protein intakes and risk of intraparenchymal hemorrhage among middle-aged Japanese. Am J Epidemiol 157(1):32–39
Ding EL, Mozaffarian D (2006) Optimal dietary habits for the prevention of stroke. Semin Neurol 26(1):11–23
Jacobs DR, Gallaher DD Jr (2004) Whole grain intake and cardiovascular disease: a review. Curr Atheroscler Rep 6(6):415–423
Thomas D, EJ Elliott (2009) Low glycaemic index, or low glycaemic load, diets for diabetes mellitus. Cochrane Database Syst Rev (1):CD006296
Livesey G et al (2008) Glycemic response and health–a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes. Am J Clin Nutr 87(1):258S–268S
Danaei G et al (2009) The preventable causes of death in the United States: comparative risk assessment of dietary, lifestyle, and metabolic risk factors. PLoS Med 6(4):e1000058. doi:10.1371/journal.pmed.1000058
Harris WS et al (2009) Towards establishing dietary reference intakes for eicosapentaenoic and docosahexaenoic acids. J Nutr 139(4):804S–819S
Lewington S et al (2007) Blood cholesterol and vascular mortality by age, sex, and blood pressure: a meta-analysis of individual data from 61 prospective studies with 55,000 vascular deaths. Lancet 370(9602):1829–1839
Acknowledgments
Supported by the Searle Funds at The Chicago Community Trust and the Bill & Melinda Gates Foundation/World Health Organization Global Burden of Diseases, Injuries, and Risk Factors Study. The founders had no role in the design or conduct of the study; collection, management, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript.
Conflict of interest statement
R. Micha has no conflicts of interest to declare. D. Mozaffarian received ad hoc consulting honoraria (modest) from Nutrition Impact, Unilever, and SPRIM.
Open Access
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
This article is published under an open access license. Please check the 'Copyright Information' section either on this page or in the PDF for details of this license and what re-use is permitted. If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and re-use information, please contact the Rights and Permissions team.
About this article
Cite this article
Micha, R., Mozaffarian, D. Saturated Fat and Cardiometabolic Risk Factors, Coronary Heart Disease, Stroke, and Diabetes: a Fresh Look at the Evidence. Lipids 45, 893–905 (2010). https://doi.org/10.1007/s11745-010-3393-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11745-010-3393-4