But only if you are high risk to begin with, much less otherwise. Not a headline likely to motivate you to make major dietary changes, but one more in touch with the complex realities of prevention of cardiovascular disease than the message of the “TimesCast” my wife sent me as a link by email today.
The video reported on a new NEJM report touting a primary prevention article showing a 30% reduction in cardiovascular end points in a study comparing an augmented Mediterranean Diet to a control group of patients counseled to just reduce their dietary fat. At the headline level this sounds really exciting. We had a salad full of beans and greens for dinner, and fish is on the menu for tomorrow. Still, this is a great example of how statistics can be presented to exaggerate a benefit or risk. Let’s look at the data of this study, which seems to be nicely designed and executed.
Headline: 30% reduction in Cardiovascular events with Mediterranean Diet!
- This population was a high risk population where enrolled members either had diabetes, or three cardiovascular risk factors like hypertension, smoking, overweight or obesity, high LDL, low HDL or a family history of premature coronary artery disease. Of these I only have overweight, so my likelyhood of a cardiac event is probably less than 1/3 that of those in the study.
- The absolute risk reduction in this high risk population was 3 events per 1000 participant years. This is accurately described as a 30% relative reduction from 11.2 to 8.0 events per 1000 patient years, but a 0.3% reduction in absolute risk per year is considerably less exciting. Given that our family has a far lower innate risk given no smoking, no hypertension, good lipid levels, and no family history of premature coronary disease the number for us is likely closer to a 0.1% absolute risk reduction per year.
Does this mean the value of the Mediterranean Diet is insignificant? Heck no. I strongly recommend it, and hope Kay keeps cooking this way and I believe we will be healthier for the change. I just want to keep the expectations of benefits real.
For more about the Medeterranean diet see a prior post: Dr. Pullen Lives the Medeterranean Diet.