Minnesota Coronary Experiment—Trying To See In A Blizzard?

Posted by Michael Dansinger, MD on Apr 19, 2016 2:20:07 PM


I was startled last week by new research study findings that have unexpectedly “transported” me back to my own origins and fundamental assumptions. This study originated in Minnesota in the 1960’s—and so did I. The newly published results of the Minnesota Coronary Experiment, conducted nearly a half-century ago, have made headlines and raised uncertainty and controversy about how dietary intake causes heart disease and atherosclerosis.The study caused me to remember the much simpler times of my youth, and the many blizzards I endured. It caused me to think about how my grandfather died of premature heart disease in Minnesota in the late 1970’s, around the time animal fat was proven to cause heart disease. It caused me to reexamine how far we’ve advanced our understanding of how unhealthy food causes cardiovascular disease, and how far we still need to advance toward prevention. The results of this study caused me to strengthen my resolve to look for more clarity, even in the face of obscurity, toward a deeper understanding of heart disease and how to better prevent it.

The study design and results have been summarized in many different ways and interpreted differently by various experts. The study had certain strengths and limitations, and can be either praised or criticized, or both. The results raise more questions than they answer, which is not unusual for research studies. 

One of the key findings of the Minnesota Coronary Experiment was that the investigators and authors were unable to confirm that a “cholesterol-lowering” diet that reduced animal fat (by replacing it with corn oil), would lead to reduced cardiovascular disease events. Some critics say the study duration (three years) was not long enough to let the test diet work, others say that the test diet might have worked if they used olive oil (instead of corn oil) to replace animal fat. Some wonder whether animal fat causes heart disease at all. Some wonder whether the study was never published (until recently) because the original investigators felt the study wasn’t a fair test. In any case, the mainstream nutrition community has largely dismissed the results as contributing little to our understanding, rather than suggesting that animal fat might be harmless after all.

The “cholesterol-lowering” diet in the experiment reduced total cholesterol levels from an average of 208 mg/dL, to around 177 mg/dL. We have no measurements of LDL (bad) cholesterol, small-dense LDL (superbad) cholesterol, HDL (good) cholesterol, large HDL (super-good), indicators of inflammation such as C-reactive protein, or blood levels of any of the other sophisticated cardiovascular risk factors we can use today to unmask hidden risk and gain insights on how unhealthy diets cause cardiovascular disease. How I wish we could have seen the full picture these blood markers could have provided.

Despite the ambiguity raised by this study, it reminds me of three important concepts in heart disease prevention and reversal:

  1. There is no single best diet or eating strategy for heart disease prevention. Heart disease is complex, and the optimal eating strategy for any individual depends on their unique mix of clinical characteristics.
  1. The connection between food, atherosclerosis, and heart disease cannot be interpreted by looking only at blood levels of total cholesterol. We need to look at the full mix of factors known to link diet to heart disease, including all the blood markers of heart disease risk such as small-dense LDL, large HDL, fatty acid profiles, inflammatory markers, and others we’ve learned about since that study was done.
  1. We beat heart disease by achieving normal healthy levels of ALL the indicators of heart disease risk, not just total cholesterol. Multiple studies indicate the more effectively we normalize an individual’s combination of heart disease risk factors, the more effectively we beat heart disease—one patient at a time. 

In summary, trying to understand how diet affects heart disease without the right blood tests is like trying to drive safely in a snowy blizzard. If you can’t see clearly it’s very difficult to safely get from your starting point to your destination. I know, first-hand, how problematic this can be! 


Topics: About Stroke, Diabetes and CVD, Clinical and Science