The heart-healthy benefits of
the so-called Mediterranean diet are well known,
but new research suggests the eating plan may
reduce the risk of Alzheimer's
People who carefully followed the Mediterranean
diet -- heavy on fish, fruits and vegetables,
monounsaturated fats such as those found in
olive oil, and low on meat and dairy products
-- had a 40 percent lower risk of developing
Alzheimer's than those who ate the conventional
"That is a pretty significant effect,"
said Dr. Nikolaos Scarmeas, assistant professor
of neurology at Columbia University Medical
Center and leader of the study.
While a number of studies have shown that the
Mediterranean diet decreases the risk of heart
disease, this is the first research to show
a benefit in terms of mental function, he said.
The finding appears in the April issue of the
Annals of Neurology.
The study involved 2,258 New York City residents,
who were divided into three groups, depending
on how faithfully they followed the diet. For
an average follow-up of four years, the rate
of Alzheimer's disease was 20 percent lower
for those in the middle third of adherence,
and 40 percent lower for those who stuck closest
to the plan, the report said.
Scarmeas said it's the diet as a whole, not
any single element of it, that's responsible
for the beneficial effect. And the fact that
there is "a combination of many beneficial
food items" in the diet makes it hard to
determine exactly how the plan works, he added,
but there's ample room for speculation.
One possibility is that the Mediterranean diet
has the same beneficial effects on blood vessels
in the brain as in the heart, reducing the risk
of blockage, Scarmeas said. It could also be
that the foods in the diet are rich in beneficial
antioxidants, or that the diet lowers the incidence
of harmful inflammation, he said.
"We tried to single out which of the components
of the diet are driving its effect, but none
of them is prominently responsible," Scarmeas
said. "But, when we put them together,
the effect was there."
Dr. Dimitrios Trichopoulos, professor of cancer
prevention and epidemiology at the Harvard School
of Public Health, who has done similar studies
of the benefits of the Mediterranean diet, called
the new research "intriguing."
"The authors seem to have done very good
work," he said. "They used a diet
score we have developed over the years. At face
value, I think the study is a good one. This
is speculation, but reasonable speculation.
One has to do further work to duplicate the
finding, but the results are intriguing."
There has been "a general idea" that
the incidence of Alzheimer's disease is lower
in regions where the Mediterranean diet prevails,
Trichopoulos said. "The assumption has
always been there, so that fits with this study,"
Trichopoulos agreed that the beneficial results
"are not the effect of individual components
but the entire diet. Small effects have a collective
Trichopoulos said he follows the Mediterranean
diet, which, Scarmeas noted, includes "moderate
consumption of alcohol, usually in the form
of wine during dinner."