Latest Ecological Data: Saturated Fat Protects Against Heart Disease
I’ve been following a recent debate in the literature between Pederson et al. who argue that dietary saturated fat should be restricted to reduce the risk of heart disease and R. Hoenselaar, who defends the position that this is an unjustified recommendation. In Hoenselaar’s latest rebuttal, he adduces original research showing a significant inverse association between saturated fat and CHD mortality.
In their first piece, Pederson et al. address what they perceive to be “uncertainty” regarding the role of saturated fat in the pathogenesis of CHD. They give a number of boringly predictable arguments that center on the hypercholesterolemic effect exerted by saturated fat . Hoenselaar responded outlining some criticisms . Pederson et al. maintained their contention and continued to justify their evidence in a manner I found thoroughly unconvincing . Hoenselaar has probably ended the entire discussion with his latest rebuttal .
He goes through some evidence cited by Pederson et al. and finds most of it doesn’t actually support their assertions. He then identifies a paper published in 2008 that gives CHD mortality data for the European countries. He uses matching saturated fat intake data for the same year (1998) to ascertain any ecological trends. Here is what he found:
Anybody with two eyes and a brain can see what’s going on. As saturated fat increases, CHD mortality decreases. Hoenselaar notes the correlation coefficient was -0.58 reaching statistical significance (P = < 0.01).
I was quite surprised when I first saw it because I had encountered ecological data before but most of it was saying the opposite, and saying it consistently. For example, in an analysis out of 40 countries, by far most showed significant associations between saturated fat and dietary cholesterol intake and CHD mortality . That being said, Hoenselaar’s analysis was over 20 years more recent, was age-adjusted and used data restricted to European countries only.
While ecological analyses such as this have their uses, they only show a non-directional, unadjusted correlation between two independent variables. Ecological data is generally the weakest of all epidemiological evidence and some have considered it even weaker than case-control studies and tantamount to animal studies . Hence, this graph proves absolutely nothing and shouldn’t ever be used by itself to prove anything. I have begun to and will in the near future cover extensive literature that shows saturated fat does not cause CHD. The present ecological investigation can only be employed as part of a larger, more comprehensive collection of data that includes stronger epidemiological and experimental studies to make a scientifically acceptable case.
Whatever you make of it, its an interesting development and a good one to keep in mind. I’m not sure what my next post will be on but it will have something to do with saturated fat again. Till then.