Dietary Saturated Fat And Heart Disease: A Narrative Review

[Mito]

Abstract
The American Heart Association (AHA) recently published a meta-analysis that confirmed their 60-year-old recommendation to limit saturated fat (SFA, saturated fatty acid) and replace it with polyunsaturated fat to reduce the risk of heart disease based on the strength of 4 Core Trials. To assess the evidence for this recommendation, meta-analyses on the effect of SFA consumption on heart disease outcomes were reviewed. Nineteen meta-analyses addressing this topic were identified: 9 observational studies and 10 randomized controlled trials. Meta-analyses of observational studies found no association between SFA intake and heart disease, while meta-analyses of randomized controlled trials were inconsistent but tended to show a lack of an association. The inconsistency seems to have been mediated by the differing clinical trials included. For example, the AHA meta-analysis only included 4 trials (the Core Trials), and those trials contained design and methodological flaws and did not meet all the predefined inclusion criteria. The AHA stance regarding the strength of the evidence for the recommendation to limit SFAs for heart disease prevention may be overstated and in need of reevaluation.

Dietary saturated fat and heart disease: a narrative review

 

[tankasnowgod]

Abstract
The American Heart Association (AHA) recently published a meta-analysis that confirmed their 60-year-old recommendation to limit saturated fat (SFA, saturated fatty acid) and replace it with polyunsaturated fat to reduce the risk of heart disease based on the strength of 4 Core Trials. To assess the evidence for this recommendation, meta-analyses on the effect of SFA consumption on heart disease outcomes were reviewed. Nineteen meta-analyses addressing this topic were identified: 9 observational studies and 10 randomized controlled trials. Meta-analyses of observational studies found no association between SFA intake and heart disease, while meta-analyses of randomized controlled trials were inconsistent but tended to show a lack of an association. The inconsistency seems to have been mediated by the differing clinical trials included. For example, the AHA meta-analysis only included 4 trials (the Core Trials), and those trials contained design and methodological flaws and did not meet all the predefined inclusion criteria. The AHA stance regarding the strength of the evidence for the recommendation to limit SFAs for heart disease prevention may be overstated and in need of reevaluation.

Dietary saturated fat and heart disease: a narrative review

If people really understood the low quality of the "4 Core Trials," they would understand that the AHA and the entire diet-heart hypothesis have nothing to back them up. Those 4 trials all reported their results within a 5 year period, from 1968-1972. Nothing newer or older is considered. Three of the four didn't show any statistically significant mortality benefit from the intervention.

The four are the British Medical Research Council Study, the Los Angeles Veterans Administration Study, The Oslo Diet Heart Study, and The Finnish Mental Hospital Study. They range in length from 2-12 years. Three of them have serious issues.

The British Medical Research Study found CHD mortality of 12.6 in the intervention group, and 12.9 percent in the control group, neither statistically nor clinically significant. The Veterans Administration did see a statistically significant difference (9.7 diet/11 .8 control), but there were more smokers in the control group, and also, a higher number of cancer cases in the diet group. Oslo also suffered from poor randomization, featuring more 60 year old and more overweight subjects in the control group, and the Finnish Mental Hospital Study (one of the few that did see a statistically significant reduction in all cause mortality from the diet intervention, and the only one of the "Core 4" to do so)) employed a "crossover" design, which when studying a chronic disease that can take 20, 30, 40 or more years to develop is just stupid. Insanely stupid!

If really interested, Anthony Colpo does a great job going over the 18 intervention trials for heart disease (the 3 most recent which have abandoned the diet heart hypothesis due to poor results) in his book "The Great Cholesterol Con."