Monday, November 09, 2009

Olive Oil Vs. Walnuts: Guess Which Won

This is one of the studies from my previous post about walnuts:

A Walnut Diet Improves Endothelial Function In Hypercholesterolemic Subjects, Circulation, 2004

It compared two diets. Both were a Mediterranean diet - emphasizing vegetables and fish, and limiting red and processed meats, whole-fat dairy foods, and eggs. There was one difference: one diet replaced some olive oil and other sources of monounsaturated fat (olives, avocados) with walnuts.

The walnut diet was better:
"Compared with the Mediterranean diet, the walnut diet improved endothelium-dependent vasodilation and reduced levels of vascular cell adhesion molecule."

"Compared with the Mediterranean diet, the walnut diet produced significant reductions in total cholesterol and LDL cholesterol."
The benefit of walnuts may go beyond (or act synergistically to) its fatty acid profile. For example, walnuts contain good amounts of the amino acid L-arginine, certainly compared to almost-all-fat olive oil, and L-arginine can lower blood pressure, that is...

L-arginine is used to make nitric oxide, a compound that helps dilate blood vessels, lowering blood pressure. (L-arginine is good for erectile dysfunction too, for the same blood-vessel-dilating reason). An aside - dark chocolate also increases nitric oxide, and may be partly responsible for its heart benefits.

Just one study.
Photo: Bix


Perovskia said...

"Compared with the Mediterranean diet, the walnut diet improved endothelium-dependent vasodilation and reduced levels of vascular cell adhesion molecule."

..Can you explain this in english for me, please? :) That was all 'greek' to me. Thanks :)

Bix said...


Eating walnuts caused blood vessels to expand and allow more blood through.


Eating walnuts may reduce plaque in arteries.

(How that last one about plaque works: "vascular cell adhesion molecule" or VCAM for short, calls in immune cells to heal damaged blood vessels. That can clog the artery. If you reduce VCAM, you reduce the clog.)

Steve Parker, M.D. said...

Nice pic, Bix. I didn't realize photography was another one of your talents.


RB said...

I eat walnuts and olives. Are olives as good as olive oil?

Bix said...

Thanks, Steve. I was glad to have the sun.

ElDoubleVee said...

I see oil and walnuts as two different foods. Where I would use one I wouldn't substitute the other. I wouldn't mix walnuts and red wine vinegar for a salad dressing. How can you come up with a valid study when there are two very different foods, in consistency and in use? It seems to me you would either add or subtract a food from the diet not substitute. What's the control group? If you were testing two oils or two types of nut I would get it but I don't see the validity of this study.

Bix said...

Well, they used a crossover design, where each person undergoes both parts of the study - so each person serves as their own control.

It's a fair criticism though that a nut is not a useful replacement for oil.

I think it's noteworthy that, before the study began, all participants were instructed on a Mediterranean diet. They followed that diet for 4 weeks, the "equilibrium period." There was a statistically significant reduction in cholesterol during that period, which points to the benefit of just eating more veg and less meat.

Ruby said...

Interesting. I assumed that walnut oil has a lower smoke point than olive oil, but I just looked it up and they're the same - 320 degrees. (Extra virgin olive oil, that is.)

I like using walnut oil in salads, but I would not have cooked with it because I figured it had a low smoke point. I see that I could cook with it in some lower heat scenarios. I use grapeseed oil for high heat.

virginia said...

I've been eating walnuts daily for a month, but not 28 halves/day!

I carefully counted, scooped into a measuring cup, and 28 halves spill over the top of a half-cup scoop.

It's worth a try.