Love your arteries?
Maybe it wasn’t a fair food fight. In this corner, a fatty, greasy, sausage-egg-cheese delight with a side of home fries. A fast-food meal that millions of Americans have come to crave.
And in the other corner, a tasty example of the Mediterranean diet: Salmon, almonds, and veggies cooked in olive oil, rich in unsaturated fats and anti-oxidants.
By holding constant the calories (600 apiece), salt, carbohydrates and protein, the test compared the impact of junk-food saturated fats against the unsaturated fats and healthy fatty acids found in the Med diet.
We guess you know where we’re going: the Med diet is healthier. One massive, meaty meal managed to measurably maul the arteries, the same calorie count in the Mediterranean meal was benign to the arteries in a short-term test with long-term implications.
Stopping the slow decline
Anil Nigam, director of research at the Cardiovascular Prevention and Rehabilitation Centre at the University of Montreal, used a simple measure to look for damage to an artery: its ability to rebound after a temporary blockage. First they pumped up a blood pressure cuff to stifle circulation for five minutes, then released the pressure. As the artery (located in the elbow) responded, they made an ultrasound snapshot of the blood vessel.
Nigam presented the results this week at the Canadian Cardiovascular Congress.
During the blockage, “the forearm, deprived of oxygen, was releasing all these substances to try to dilate the artery to compensate,” says Nigam, an associate professor of medicine, who focuses on preventing cardiovascular disease.
Normally, after circulation was restored, the artery would swell 7 percent to 10 percent beyond its original size to enhance blood flow. But that did not occur two and four hours after the junk-food meal.
The technical term for this failure, endothelial dysfunction, refers to the cells that line the inside of the artery.
Endothelial dysfunction is a bad omen, says Nigam. “Before a person develops overt atherosclerosis [a buildup of cholesterol in the arteries], the first thing we notice is endothelial dysfunction.” If preventive action is not taken, the slide toward atherosclerosis has started.
After the research subjects ate the Mediterranean meal, however, their arteries expanded normally.
First in class
Researchers already knew that one meal could cause temporary dysfunction, but this was the first demonstration that a Mediterranean meal did not impair the arterial response, Nigam says.
Nigam says it’s more realistic to test a full meal rather than to test the individual nutrients it contains. That approach, he says, “can show contradictory responses. For olive oil, one study shows it’s bad for the arteries, and another shows that it’s good.”
Individual components are not how we eat, he notes. “Diet components can have additive or synergistic effects, and we need to use a holistic approach in these type of studies.”
So what is the junk food doing to the arteries? “We don’t have an exact answer,” says Nigam. Nutrients from a meal “are absorbed as free fatty acids in the blood stream, and those produced from saturated fat are perhaps more toxic to the arteries relative to the polyunsaturated fatty acids.”
Could food be medicine?
The high-fat meal had about twice as much saturated fat, no omega 3 fatty acids, and very little polyunsaturated fatty acids, both considered healthy nutrients.
Although in general the Mediterranean meal was neutral to the arteries, it actually benefited people with high levels of a harmful fat called triglyceride in their blood, which is associated with metabolic syndrome, cardiovascular disease and diabetes. “There is potential that this group could see a benefit, and show an improvement in endothelial function” after a Mediterranean meal, Nigam says.
The recent study is just one more reason to advise patients to choose healthy food, and perhaps less of it. “This shows that each meal can be toxic to you,” says Nigam. “Endothelial dysfunction is the first evidence that fat buildup, atherosclerosis, is going to happen, and over the long term, that means an increased risk of cardiovascular disease, heart attack and dying.”
— David J. Tenenbaum