Mediterranean Diet and Atherosclerosis

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What happens inside the arteries going to the hearts and brains of those who add nuts or extra virgin olive oil to their diet?

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The heart of a traditional Mediterranean diet is mainly vegetarian, much lower in meat and dairy, and uses fruit for dessert.  So, no surprise those eating that way had very low heart disease rates compared to those eating standard Western diets. This landmark study, though, has been cited to suggest that all types of fat, animal or vegetable, are associated with the appearance of new atherosclerotic lesions in our coronary arteries, feeding our hearts.

About a hundred men were given angiograms at baseline and then two years later, looking for the development of lesions like this, before and after, all the while monitoring their diets every year. Only about 1 in 20 eating lower fat diets had new lesions, compared to about 8 in 20 on more typical American diets around 33% or more fat.  But when they drilled down, though, only three types of fat appeared to significantly increase the likelihood of the appearance of new, lesions: lauric, oleic, and linoleic. Lauric acid is a saturated fat, found in coconut oil, and palm kernel oil, which is found in junk food—whipped cream and candy bars. Oleic from the Latin word oleum for olive oil, but that’s not where these men were getting their oleic acid from. The top sources for Americans are basically cake, chicken, and pork, and linoleic comes mostly from chicken. So, the study really just showed that people eating lots of junk, chicken, and pork tended to close off their coronary arteries. To see if major sources of plant fats, like olive oil or nuts, help or hurt, ideally, we’d do multi-year randomized study where you take thousands of people and have a third eat more nuts, a third eat more olive oil, and a third do essentially nothing to see who does better.

And that’s exactly what they did. The PREDIMED study took thousands of people at high risk for heart disease in Spain, who were already eating a Mediterranean-ish diet, and randomized them into three groups for a couple years, one with added extra virgin olive oil, one with added nuts, and a third group that was told to cut down on fat, but they didn’t; so, basically ended up as a no dietary changes control group. What happened to the amount of plaque in their arteries over time?

Whereas there was significant worsening of carotid artery thickening and plaque in the no dietary change control group, those in the added nuts group showed a significant reversal in thickening, an arrest in plaque progression. There were no significant changes in the added olive oil group.

The richness of the plant-based Mediterranean diet in potentially beneficial foods, such as fruit, vegetables, beans, nuts, whole grains, and olive oil, is believed to explain its cardioprotective effects.  However, these results suggest nuts are a preferable source of fat compared to olive oil, and may delay the progression of atherosclerosis, the harbinger of future cardiovascular events such as stroke. Adding nuts appeared to cut the risk of stroke in half.

Note, though, they were still having strokes. Half as many strokes; so, the nuts appeared to be helping, but they were still eating a diet conducive to strokes and heart attacks. All three groups had basically the same heart attack rates, the same overall death rates. That’s what Dr. Ornish noted when he wrote in: there was no significant reduction in the rates of heart attack, death from cardiovascular causes, or death from any cause, just that stroke benefit. But hey, that’s something. A Mediterranean diet is certainly better than what most people are consuming, but even better may be a diet based on whole plant foods, shown to reverse heart disease, not contribute to it. The authors of the study replied that they didn’t wish to detract from Ornish’s work, noting that Mediterranean and plant-based diets actually share a great number of foods in common. Yes, Ornish’s diet can reverse heart disease— but, the Mediterranean diet proponents argue, the major problem with Ornish’s diet is that it doesn’t taste good;  so, hardly anyone sticks to it.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Images thanks to Philippe Put via Flickr.

The heart of a traditional Mediterranean diet is mainly vegetarian, much lower in meat and dairy, and uses fruit for dessert.  So, no surprise those eating that way had very low heart disease rates compared to those eating standard Western diets. This landmark study, though, has been cited to suggest that all types of fat, animal or vegetable, are associated with the appearance of new atherosclerotic lesions in our coronary arteries, feeding our hearts.

About a hundred men were given angiograms at baseline and then two years later, looking for the development of lesions like this, before and after, all the while monitoring their diets every year. Only about 1 in 20 eating lower fat diets had new lesions, compared to about 8 in 20 on more typical American diets around 33% or more fat.  But when they drilled down, though, only three types of fat appeared to significantly increase the likelihood of the appearance of new, lesions: lauric, oleic, and linoleic. Lauric acid is a saturated fat, found in coconut oil, and palm kernel oil, which is found in junk food—whipped cream and candy bars. Oleic from the Latin word oleum for olive oil, but that’s not where these men were getting their oleic acid from. The top sources for Americans are basically cake, chicken, and pork, and linoleic comes mostly from chicken. So, the study really just showed that people eating lots of junk, chicken, and pork tended to close off their coronary arteries. To see if major sources of plant fats, like olive oil or nuts, help or hurt, ideally, we’d do multi-year randomized study where you take thousands of people and have a third eat more nuts, a third eat more olive oil, and a third do essentially nothing to see who does better.

And that’s exactly what they did. The PREDIMED study took thousands of people at high risk for heart disease in Spain, who were already eating a Mediterranean-ish diet, and randomized them into three groups for a couple years, one with added extra virgin olive oil, one with added nuts, and a third group that was told to cut down on fat, but they didn’t; so, basically ended up as a no dietary changes control group. What happened to the amount of plaque in their arteries over time?

Whereas there was significant worsening of carotid artery thickening and plaque in the no dietary change control group, those in the added nuts group showed a significant reversal in thickening, an arrest in plaque progression. There were no significant changes in the added olive oil group.

The richness of the plant-based Mediterranean diet in potentially beneficial foods, such as fruit, vegetables, beans, nuts, whole grains, and olive oil, is believed to explain its cardioprotective effects.  However, these results suggest nuts are a preferable source of fat compared to olive oil, and may delay the progression of atherosclerosis, the harbinger of future cardiovascular events such as stroke. Adding nuts appeared to cut the risk of stroke in half.

Note, though, they were still having strokes. Half as many strokes; so, the nuts appeared to be helping, but they were still eating a diet conducive to strokes and heart attacks. All three groups had basically the same heart attack rates, the same overall death rates. That’s what Dr. Ornish noted when he wrote in: there was no significant reduction in the rates of heart attack, death from cardiovascular causes, or death from any cause, just that stroke benefit. But hey, that’s something. A Mediterranean diet is certainly better than what most people are consuming, but even better may be a diet based on whole plant foods, shown to reverse heart disease, not contribute to it. The authors of the study replied that they didn’t wish to detract from Ornish’s work, noting that Mediterranean and plant-based diets actually share a great number of foods in common. Yes, Ornish’s diet can reverse heart disease— but, the Mediterranean diet proponents argue, the major problem with Ornish’s diet is that it doesn’t taste good;  so, hardly anyone sticks to it.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Images thanks to Philippe Put via Flickr.

Doctor's Note

I bring up the Ornish back-and-forth in my 2015 annual live review, Food as Medicine: Preventing and Treating Our Most Dreaded Diseases with Diet, and directly address the accusation that plant-based diets are marked by poor compliance for disease prevention and reversal.

For more on the famous PREDIMED trial and the body of evidence surrounding Mediterranean diets, I’ve got a bunch of good videos for you:

What might happen to the arteries of someone who goes on a low-carb diet. You don’t want to know. (But if you’re really curious, see: Low Carb Diets and Coronary Blood Flow.)

What we eat doesn’t only have an impact on the structure of our arteries over the long-term (i.e., the thickening and narrowing described in the video), but the function of our arteries within hours of consumption. To see what your breakfast may have done to your arteries, check out:

Note, though, the benefits of plant-based nutrition can be undermined by vitamin B12 deficiency if you don’t include a regular reliable source in your diet. See Vitamin B12 Necessary for Arterial Health.

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