Eating Pizza and Dynamic Cerebral Autoregulation. Huh?

We know that the MIND diet encourages us to consume a polyunsaturated fat called "olive oil," but warns us against saturated fats.  Like the cheese in that pizza.  That's not fair.  So why do they tell us that?

Well according to some new research, even one meal high in saturated fat impairs blood flow to the brain.  And we associate brain blood flow problems with the development of Alzheimer's disease.  

"Dynamic cerebral autoregulation (DCA)" is a process likened to a shock absorber in the brain with respect to blood pressure and blood flow.  Blood vessels must remain flexible to accommodate sudden changes in blood pressure such as occur during exercise.  Or even just getting up out of a chair.  DCA ensures blood flow to the brain remains stable despite routine changes in blood pressure, but it depends on flexible blood vessels.  

Levels of fat in the blood rise and peak after around four hours after eating a meal high in saturated fat.  This is thought to cause blood vessels to become stiffer and lose some of their flexibility.  If so, this could disrupt DCA, restricting blood flow around the body, including to the brain.  This concept is not new, but how well is the brain protected when this occurs?  According to some new research, maybe not very well.

The researchers employed about 20 young men and about 20 older men for the study.  They fed them a big milk shake with about the same calorie count and fat content as a fast food meal -- 1,362 calories and 130g of fat.  Using ultrasound, they then measured the effects of the meal on their vascular system over a four-hour period while they exercised periodically. 

What did they find?   The high-fat meal impaired the ability of the blood vessels associated with heart health to open.  This was true in both young and old participants, although it was about 10% worse in the older cohort.  So the impairments reduced the body's ability to buffer changes in blood pressure.  This can easily suggest to us that consuming saturated fat -- even once -- can affect the vascular system in a way that promotes the development of Alzheimer's disease.  Sad news, I'm afraid.

But it gets worse.  The authors published earlier research in which they found saturated fats caused an increase in unstable, cell-damaging molecules, called free radicals, and caused a decrease in the nitric oxide molecules that help blood vessels relax and open.  The relaxed blood vessels are supposed to allow blood to transport oxygen and glucose around the body -- including to the brain.  Less nitric oxide means less flexible blood vessels, which means poorer blood flow to the brain.  This appears to be the link to problems with DCA.  (BTW, the discovery of the effect of nitric oxide on the vascular system was good for a Nobel Prize in 1998.)

Here's an article about the research.  Here's a link to the actual research.