"Mediterranean Diet and Atherosclerosis"
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, was 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.
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, 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 a multi-year randomized study
where you take thousands of people
and have a third eat nuts, a third eat more olive oil,
and a third do essentially nothing to see who does better.
And that's exactly what was done.
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,
though these results suggest that nuts really are a preferable source of fat
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:
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 may reverse heart disease, but the Mediterranean
diet proponents argue, the major problem with Ornish's
diet is that it doesn't taste good and so hardly anyone sticks to it.