Saturated Fat and Cardiovascular Disease: Where Are We?
While a lowered intake of saturated fat has commonly been indicated for improved cardiovascular health, evidence from recent studies such as systematic reviews, meta-analyses and prospective cohort studies indicates that saturated fat is not associated with an increased risk of cardiovascular disease.
A meta-analysis of prospective cohort studies and randomized controlled trials examined the association between fatty acids and coronary disease. A total of 32 prospective cohort studies with data on dietary fatty acid intake were identified. The analysis included 530,525 participants with 15,907 incident coronary outcomes and an average follow-up of 5 to 23 years. The authors also examined 17 observational studies with data on circulating fatty acid composition (i.e., fatty acids in the blood). These studies included 25,721 participants with 5,519 incident coronary outcomes for whom the average follow-up was 1.3 to 30.7 years.1
- Total saturated fatty acid intake was not associated with coronary disease risk (pooled relative risk of 1.02, 95% CI: 0.97-1.07);
- Total circulating saturated fatty acids were not associated with coronary disease risk (pooled relative risk of 1.06, 95% CI: 0.86-1.30);
- Individual circulating fatty acids, such as palmitic and stearic acids, were also not associated with coronary disease risk;
- Margaric acid (a saturated fatty acid found in dairy foods) was significantly associated with a lower risk of coronary disease;
- The authors concluded that the current evidence does not clearly support cardiovascular guidelines that encourage a low intake of total saturated fats.
Another meta-analysis of 26 prospective cohort studies assessed the association between foods high in saturated fat and the risk of mortality.2
- High intakes of milk, cheese, yogurt and butter were not associated with a risk of all-cause mortality compared to low intakes;
- High intakes of total dairy, milk and cheese were not associated with cardiovascular mortality.
A 2010 meta-analysis of prospective cohort studies, which included the follow-up of 347,747 subjects over 5 to 23 years, provided the following evidence on the association between dietary saturated fat and coronary heart disease, stroke and cardiovascular disease:3
- Saturated fat intake was not associated with an elevated risk of coronary heart disease, stroke or cardiovascular disease;
- The pooled relative risks were 1.07 (95% CI: 0.96-1.19, p = 0.22) for coronary heart disease, 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 cardiovascular disease;
- After adjustments for covariates such as age, sex and study quality, the results did not change, and no significant association was observed;
- No association between dietary saturated fat and disease prevalence was found after adjustment for other nutrients and total energy.
In a 2009 systematic review, the following summary of evidence from prospective cohort studies and randomized controlled trials was provided:4
- From the meta-analysis of cohort studies of saturated fat and coronary heart disease, intake of saturated fatty acids was not significantly associated with coronary heart disease death or events;
- The relative risks for the highest compared to the lowest category of saturated fat intake were 1.14 (95% CI: 0.82-1.60, p = 0.431) for coronary heart disease mortality and 0.93 (95% CI: 0.83-1.05, p = 0.269) for coronary heart disease events;
- There was no significant association between saturated fat and coronary heart disease death or events per 5% total energy increase in saturated fatty acids intake;
- From the meta-analysis of randomized controlled trials of dietary fat and coronary heart disease, the relative risk of fatal coronary heart disease was not reduced by fat-modified diets.
Another systematic review of prospective cohort studies and randomized trials examined the evidence for dietary factors in relation to coronary heart disease.5
- Pooled analyses of cohort studies did not show any significant association between higher intakes of saturated fatty acids, meat or milk and coronary heart disease;
- The relative risks were 1.06 (95% CI: 0.96-1.15) for saturated fatty acids, 1.23 (95% CI: 0.98-1.49) for meat, and 0.94 (95% CI: 0.75-1.13) for milk;
- After the dietary exposures were stratified by confounding variables such as dietary assessment tool, sex, geographic region, and type of prevention strategy, the association between saturated fatty acids and coronary heart disease in cohort studies remained statistically insignificant;
- There was no evidence from pooled analyses of randomized controlled trials to support a causal association between saturated fatty acids, meat or milk and coronary heart disease.
In 2012, de Oliveira Otto et al. undertook a prospective cohort study to assess the association between the intake of saturated fat from different food sources and incident cardiovascular events in a multiethnic population. The participants consisted of 5,209 US adults aged 45 to 84 years, and together they represented 36,364 person-years of follow-up.6
- After adjusting for potential confounders, a higher intake of dairy saturated fat was associated with a lower risk of cardiovascular disease, with a hazard ratio of 0.79 (95% CI: 0.68-0.92) for every additional 5 g/d of dairy and 0.62 (95% CI: 0.47-0.82) for every additional 5% of energy from dairy;
- The substitution of 2% of energy from meat saturated fat with energy from dairy saturated fat was associated with a 25% lower risk of cardiovascular disease.
In another prospective cohort study, the association between saturated fatty acid intake and the risk of cardiovascular disease mortality was investigated in 58,453 Japanese adults aged 40 to 79 years.7
- Dietary saturated fatty acid intake was inversely associated with risk of total stroke, intraparenchymal hemorrhage and ischemic stroke;
- After adjustments for confounding variables such as potential cardiovascular disease risk factors and nutrients, the hazard ratios for the highest compared with lowest quintile were 0.69 (95% CI: 0.53-0.89, ptrend = 0.004) for total stroke, 0.48 (95% CI: 0.27-0.85, ptrend = 0.03) for intraparenchymal hemorrhage, and 0.58 (95% CI: 0.37-0.90, ptrend = 0.01) for ischemic stroke;
- There was no association between saturated fatty acids intake and subarachnoid hemorrhage and heart diseases such as ischemic heart disease, cardiac arrest and heart failure.
There is strong evidence to support a lack of association between dietary saturated fat and an increased risk of cardiovascular disease.
Saturated fat derived from dairy has either no impact or a beneficial impact on cardiovascular disease risk.
Further research, especially prospective cohort studies and randomized clinical trials, is needed to evaluate the relationship between different food sources of saturated fat and cardiovascular disease outcomes and mortality.
For more information:
- Replacement of Saturated Fat with Other Nutrients
- Saturated Fat and Cardiovascular Disease Risk Factors
- Chowdhury R et al. Association of dietary, circulating, and supplement fatty acids with coronary risk. Ann Intern Med 2014;160:398-406.
- O’Sullivan TA et al. Food sources of saturated fat and the association with mortality: a meta-analysis. Am J Public Health 2013;103:e31-42.
- Siri-Tarino PW et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010;91:535-46.
- Skeaff CM and Miller J. Dietary fat and coronary heart disease: summary of evidence from prospective cohort and randomised controlled trials. Ann Nutr Metab 2009;55(1-3):173-201.
- Mente A et al. A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med 2009 ;169(7):659-69.
- de Oliveira Otto MC et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. Am J Clin Nutr 2012;96:397-404.
- Yamagishi K et al. Dietary intake of saturated fatty acids and mortality from cardiovascular disease in Japanese: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC) Study. Am J Clin Nutr 2010;92:759-65.