 We know from the work of Drs. Ornish and Esselstyn that switching to a plant-based diet can reverse heart disease, open up arteries in some cases without drugs, without surgery. But because our first symptom of heart disease may be our last sudden cardiac death, it's best not to wait until atherosclerosis progresses that far. To predict the risk of dying from a heart attack, sure we can measure risk factors, such as cholesterol levels and blood pressure, but wouldn't it be nice to actually see what's going on inside our arteries before it's too late? Well, our imaging technologies are so good now that we can, but the required dose of radiation delivered to the chest is so high that a young woman getting just a single scan, for example, may increase her lifetime risk of breast cancer and lung cancer by between around 1 and 4%. Our carotid arteries, though, which connect our heart to our brain, come close enough to the surface in our necks that we can visualize their arterial wall using harmless sound waves with ultrasound. OK, so how do the arteries of those eating plant-based diets compare to those eating the standard American diet? Researchers found some vegans and found out. Here's the standard American diet group. This is the thickness of the inner wall of their carotid arteries, where the atherosclerotic plaque builds up, considered a predictor of all cause and cardiovascular mortality. That same inner layer was significantly slimmer in vegans, but so were the vegans themselves. Those eating the standard American diet were, on average, overweight, with a BMI over 26, while the vegans were a Trim 21. That's 36 pounds lighter, on average. So maybe the only reason those eating meat eggs and dairy had thickened arterial walls was because they were themselves overweight. Maybe the diet per se had nothing to do with it directly. To solve the riddle, one would have to find a group still eating the standard American diet, but as slim as a vegan. To find a group that fit and trim in our society, they had to use long-distance endurance athletes, who ate the same crappy American diet, but ran an average of 48 miles per week for 21 years. You run almost two marathons a week for 20 years, you can be as slim as a vegan, no matter what you eat. So where did they fall on the graph? Both the vegans and the conventional diet group were sedentary, a little less than an hour of exercise a week. The endurance runners were here. So it appears if you run an average of about a thousand miles a year, you can rival some couch potato vegans. It doesn't mean you can't do both, though, but it may be easier to just eat plants.