First let me apologize if this story has all ready been covered today, and for my awkward question formatting. I've been a lurker for a few months here, but this is my first post.
This recently published longitudinal study by Frank Hu of the Harvard School of Public Health was caught by NPR and is making it's daily rounds.
To give NPR credit, they cover the article accurately and include the contrasting viewpoints and alternative explanations offered by other researchers known in the field. There were a few points that I took away from both the article and the news coverage that I thought might be interesting talking points.
Correlation of Intake of Dietary Heme and Myocardial Infarction (MI) I had never heard of this! The studies they list to support this statement (references 17-20 in the scholarly article) seem to suggest that the interaction of intake on heme iron and rates of MI is only significant when the highest and lowest quartile of participants were compared, and that overall iron consumption had no association with frequency of MI. What does this mean? Heme iron is bound, not free, and it simply doesn't make sense to me that it should increase the risk of MI. Thoughts?
Listed Covariables The authors also report that increased consumption of red and processed meat also correlated with increased seditivity, decreased intake of fruits, vegetables and whole grains, increased likelihood for smoking, to be obese, etc. It seems to me more likely that these covariables are also confounds to their study. Correct me if I'm wrong, but it seems to me that the authors were unable to adjust their analysis to control for these confounds, or if they did, their findings were non-significant and thus not reported. I find this a bit of an egregious oversite! Again, thoughts?
Quality of Red Meat and PUFA ratio Though the authors state the found mortality rate was slightly attenuated when they controlled for saturated fatty acids (SFAs), and thus suggest that SFAs might act as a mechanism for decreased coronary health. However there is no mention given to the average quality of the meat consumed (was it factory farmed? pastured?) and the possible interaction of oxidized poly-unsaturated fatty acids (PUFAs) after cooking. I think at least addressing the quality of the meat would be a fair point to make, and am frankly surprised the researchers didn't, though given that this study began more than 20 years ago, perhaps it wasn't something that was thought of at it's initiation.
I suppose that this post is really more a wish to start a discussion than pose a direct question. Does this study raise worrying points? Aside from the potential association of Heme Iron and increased risk of MI, the greatest worry I take away is that doctors will be reading this and informing their opinions on what I believe to be poorly conducted and badly substantiated research.