Mediterranean diet plus olive oil or nuts associated with improved cognitive function
Supplementing the plant-based Mediterranean diet with antioxidant-rich
extra virgin olive oil or mixed nuts was associated with improved
cognitive function in a study of older adults in Spain according to an article published
online by JAMA Internal Medicine.
Emerging evidence suggests associations between dietary habits and
cognitive performance. Oxidative stress (the body's inability to
appropriately detoxify itself) has long been considered to play a major
role in cognitive decline. Previous research suggests following a
Mediterranean diet may relate to better cognitive function and a lower
risk of dementia. However, the observational studies that have examined
these associations have limitations, according to the study background.
Emilio Ros, M.D., Ph.D., of the Institut d'Investigacions Biomediques
August Pi Sunyer, Hospital Clinic, Barcelona, and Ciber Fisiopatología
de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III,
Madrid, and coauthors compared a Mediterranean diet supplemented with
olive oil or nuts with a low-fat control diet.
The randomized clinical trial included 447 cognitively healthy
volunteers (223 were women; average age was nearly 67 years) who were at
high cardiovascular risk and were enrolled in the Prevencion con Dieta
Mediterranea nutrition intervention.
Of the participants, 155 individuals were assigned to supplement a
Mediterranean diet with one liter of extra virgin olive oil per week;
147 were assigned to supplement a Mediterranean diet with 30 grams per
day of a mix of walnuts, hazelnuts and almonds; and 145 individuals were
assigned to follow a low-fat control diet.
The authors measured cognitive change over time with a battery of
neuropsychological tests and they constructed three cognitive composites
for memory, frontal (attention and executive function) and global
cognition. After a median of four years of the intervention, follow-up
tests were available on 334 participants.
At the end of the follow-up, there were 37 cases of mild cognitive
impairment: 17 (13.4 percent) in the Mediterranean diet plus olive oil
group; eight (7.1 percent) in the Mediterranean diet plus nuts group;
and 12 (12.6 percent) in the low-fat control group. No dementia cases
were documented in patients who completed study follow-up.
The study found that individuals assigned to the low-fat control diet
had a significant decrease from baseline in all composites of cognitive
function. Compared with the control group, the memory composite improved
significantly in the Mediterranean diet plus nuts, while the frontal
and global cognition composites improved in the Mediterranean diet plus
olive oil group. The authors note the changes for the two Mediterranean
diet arms in each composite were more like each other than when
comparing the individual Mediterranean diet groups with the low-fat diet
control group.
"Our results suggest that in an older population a Mediterranean diet
supplemented with olive oil or nuts may counter-act age-related
cognitive decline. The lack of effective treatments for cognitive
decline and dementia points to the need of preventive strategies to
delay the onset and/or minimize the effects of these devastating
conditions. The present results with the Mediterranean diet are
encouraging but further investigation is warranted," the study
concludes.
The Mediterranean Diet
Has Varied Effects on Cognitive Decline Among Different Race-Specific
Populations
While
the Mediterranean diet may have broad health benefits, its impact on cognitive
decline differs among race-specific populations, according to a new study
published in the Journal of Gerontology.
The
team of researchers, including Ben-Gurion University of the Negev (BGU Prof.
Danit R. Shahar RD, Ph.D, analyzed an NIH/NIA prospective cohort study [Health
ABC] conducted over eight years in the U.S. to measure the effects of adherence
to a Mediterranean diet. Prof. Shahar is affiliated with the BGU S. Daniel
Abraham International Center for Health and Nutrition, Department of Public
Health, Faculty of Health Sciences.
The Mediterranean-style diet (MedDiet) has
fewer meat products and more plant-based foods and monounsaturated fatty acids
from olive and canola oil (good) than a typical American diet.
To
assess the association between MedDiet score and brain function, the
researchers used data of several Modified Mini-Mental State Examinations (3MS)
on 2,326 participating older adults (70-79).
The 3MS is an extensively used and validated instrument designed to
measure several cognitive domains to screen for cognitive impairment and
commonly used to screen for dementia.
"In
a population of initially well-functioning older adults, we found a significant
correlation between strong adherence to the Mediterranean diet and a slower
rate of cognitive decline among African American, but not white, older adults.
Our study is the first to show a possible race-specific association between the
Mediterranean diet and cognitive decline.”
The
researchers note that further studies in diverse populations are necessary to
confirm association between the MedDiet and cognitive decline, and to pinpoint
factors that may explain these results.
Mediterranean diet linked
to preserving thinking and memory skills
Those who more closely followed the
Mediterranean diet were 19 percent less likely to develop problems with their
thinking and memory skills according to research is published in the April 30,
2013, print issue of Neurology®, the
medical journal of the American Academy of Neurology.
"Since there are no definitive
treatments for most dementing illnesses, modifiable activities, such as diet,
that may delay the onset of symptoms of dementia are very important," said
Georgios Tsivgoulis, MD, with the University of Alabama at Birmingham and the
University of Athens, Greece. Tsivgoulis is also a member of the American
Academy of Neurology.
Data came from the REasons for Geographic
and Racial Differences in Stroke (REGARDS) study, a national sample of the
general population. For the study, dietary information from 17,478
African-American and Caucasian people with an average age of 64 was reviewed to
see how closely they adhered to a Mediterranean diet. They were also given
tests that measured memory and thinking abilities over an average of four
years. A total of 17 percent of the participants had diabetes. Seven percent of
the participants developed impairments in their thinking and memory skills
during the study.
The study found that in healthy people,
those who more closely followed the Mediterranean diet were 19 percent less
likely to develop problems with their thinking and memory skills. There was not
a significant difference in declines between African-Americans and Caucasians.
However, the Mediterranean diet was not associated with a lower risk of
thinking and memory problems in people with diabetes.
"Diet is an important modifiable
activity that could help in preserving cognitive functioning in late
life," said Tsivgoulis. "However, it is only one of several important
lifestyle activities that might play a role in late-life mental functioning.
Exercise, avoiding obesity, not smoking cigarettes and taking medications for
conditions like diabetes and hypertension are also important."
Mediterranean Diet Boosts Ageing Brain
A Mediterranean diet with added extra
virgin olive oil or mixed nuts seems to improve the brain power of older people
better than advising them to follow a low-fat diet, indicates research
published online in the Journal of
Neurology Neurosurgery and Psychiatry.
The authors from the University of
Navarra in Spain base their findings on 522 men and women aged between 55 and
80 without cardiovascular disease but at high vascular risk because of
underlying disease/conditions.
These included either type 2 diabetes or
three of the following: high blood pressure; an unfavourable blood fat profile;
overweight; a family history of early cardiovascular disease; and being a
smoker.
Participants, who were all taking part in
the PREDIMED trial looking at how best to ward off cardiovascular disease, were
randomly allocated to a Mediterranean diet with added olive oil or mixed nuts
or a control group receiving advice to follow the low-fat diet typically
recommended to prevent heart attack and stroke
A Mediterranean diet is characterised by
the use of virgin olive oil as the main culinary fat; high consumption of
fruits, nuts, vegetables and pulses; moderate to high consumption of fish and
seafood; low consumption of dairy products and red meat; and moderate intake of
red wine.
Participants had regular check-ups with
their family doctor and quarterly checks on their compliance with their
prescribed diet.
After an average of 6.5 years, they were
tested for signs of cognitive decline using a Mini Mental State Exam and a clock
drawing test, which assess higher brain functions, including orientation,
memory, language, visuospatial and visuoconstrution abilities and executive
functions such as working memory, attention span, and abstract thinking.
At the end of the study period, 60
participants had developed mild cognitive impairment: 18 on the olive oil
supplemented Mediterranean diet; 19 on the diet with added mixed nuts; and 23
on the control group.
A further 35 people developed dementia:
12 on the added olive oil diet; six on the added nut diet; and 17 on the low
fat diet.
The average scores on both tests were
significantly higher for those following either of the Mediterranean diets
compared with those on the low fat option.
These findings held true irrespective of
other influential factors, including age, family history of cognitive
impairment or dementia, the presence of ApoE protein--associated with
Alzheimer's disease--educational attainment, exercise levels, vascular risk
factors; energy intake and depression.
The authors acknowledge that their sample
size was relatively small, and that because the study involved a group at high
vascular risk, it doesn't necessarily follow that their findings are applicable
to the general population.
But they say, theirs is the first long
term trial to look at the impact of the Mediterranean diet on brain power, and
that it adds to the increasing body of evidence suggesting that a high quality
dietary pattern seems to protect cognitive function in the ageing brain.
Potential benefits of
adherence to the Mediterranean diet on cognitive health.
A review in the Proceedings of The Nutrition Society Dec 2012 updated available
knowledge on the relationship between adherence to the Mediterranean diet
(MeDi) and cognitive decline, risk of dementia or Alzheimer's Disease (AD), and
analyzed the reasons for some inconsistent results across studies. The traditional
MeDi has been recognised by the United Nations Educational Scientific and
Cultural Organisation as an Intangible Cultural Heritage of Humanity. This
dietary pattern is characterised by a high consumption of plant foods (i.e.
vegetables, fruits, legumes and cereals), a high intake of olive oil as the
main source of fat, a moderate intake of fish, low-to-moderate intake of dairy
products and low consumption of meat and poultry, with wine consumed in
low-to-moderate amounts during meals.
Beyond the well-known association between
higher adherence to the MeDi and lower risk of mortality, in particular from
CVD and cancer, new data from large epidemiological studies suggest a
relationship between MeDi adherence and cognitive decline or risk of dementia.
Mediterranean Diet Good For Brain
According to a study in the February,
2012 issue of Archives of Neurology,
one of the JAMA/Archives journals, a Mediterranean-style diet (MeDi) may be
healthier for the brain. Researchers have discovered that a MeDi diet is
associated with reduced damage of small blood vessels in the brain.
White matter hyperintensities (WMHs) are
markers of chronic small vessel damage and can be seen using brain magnetic
resonance imaging (MRI).
The researchers explain:
"Although diet may be an important
predictor of vascular disease, little is known about the possible association
between dietary habits and WMHs. Studies have suggested that consumption of a
MeDi [Mediterranean Diet] is associated with a reduced risk of the metabolic
syndrome, coronary heart disease, stroke and cognitive disorders, but no
studies to date, to our knowledge, have examined the association between a MeDi
and WMH volume (WMHV)."
To examine this association, data from
966 participants in the Northern Manhattan Study were assessed by Hannah
Gardener, Sc.D., of the University of Miami Miller School of Medicine and her
team. In order to evaluate dietary patterns during the previous year, the
researchers gave participants a food frequency questionnaire. The researchers
then used the answers from the questionnaire to determine a MeDi compliance
score. The team measured WMHV by quantitative brain MRI.
The researchers found that on a MeDi
scale from 0 to 10:
* 11.6% of participants scored 0 to 2
* 15.8% scored 3
* 23% scored 4
* 23.5% scored 5
* and 26.1% of participants scored
between 6 to 9
In addition they discovered that men and
had higher MeDi scores than women, as well as those who reported moderate to
heavy levels of physical activity. Furthermore, results showed that individuals
with a MeDi score of 6+ had lower BMI.
Results from the study indicate that
among participants, those who consume a MeDi have a lower burden of WMHV. This
connection was independent of vascular and sociodemographic risk factors including
smoking, blood lipid levels, physical activity, BMI, history of cardiac
disease, hypertension, and diabetes. The researchers found that the only
component of the MeDi score that was independently linked to WMHV was the ratio
of monounsaturated to saturated fat.
Mediterranean Diet Associated With Slower
Rate of Cognitive Decline
The Mediterranean diet, rich in
vegetables, fish, and olive oil and moderate in wine and alcohol, is associated
with slower rates of cognitive decline in older adults, according to
researchers at Rush University Medical Center.
The results are published in the American Journal of Clinical Nutrition.
Included in the study were 3,759 older
residents of the South side of Chicago who are part of the Chicago Healthy
Aging Project, an ongoing evaluation of cognitive health in adults over the age
of 65. Every three years, the study participants, age 65 and older, underwent a
cognitive assessment that tested such things as memory and basic math skills.
Participants also filled out a questionnaire on the frequency with which they
consumed 139 food items ranging from cereals and olive oil to red meat and
alcohol.
The researchers then analyzed how closely
each of the study participants adhered to a Mediterranean diet, which includes daily
consumption of such foods as fruit, vegetables, legumes, olive oil, fish,
potatoes and nonrefined cereals, as well as wine.
Out of a maximum score of 55, which would
indicate complete adherence to the Mediterranean diet, the average study
participant scored 28. Those with the higher scores were also the individuals
whose cognitive tests showed a slower rate of decline, even when other factors
that might account for the result, such as education level, were considered.
The researchers also analyzed how closely
study participants adhered to the Healthy Eating Index—2005, which is based on
the recommendations from the 2005 Dietary Guidelines for Americans. Higher
scores indicating closer adherence to this index, which gives less weight to
fish, legumes and moderate alcohol intake, did not correspond with differences
in rates of cognitive decline.
Christy Tangney, PhD, lead author of the
study and associate professor of clinical nutrition at Rush University, said
that the results add to other studies showing that a Mediterranean diet reduces
the risk of heart disease, certain cancers and diabetes.
“The more we can
incorporate vegetables, olive oil, and fish into our diets and moderate wine
consumption, the better for our aging brains and bodies,” Tangney said.
Mediterranean Diet = Slower Cognitive
Decline
In an examination of the association
between adherence to a Mediterranean-type diet and cognitive performance and
risk of dementia, researchers found that high adherence to the diet was
associated with slower decline in some measures of cognitive function but was
not associated with decreased risk for dementia, according to a study in the
August 12. 2009 issue of JAMA.
Higher adherence to a Mediterranean-type
diet is linked to lower risk for mortality and chronic diseases, and
"might also have protective effects against cognitive decline in older
individuals, because it combines several foods and nutrients potentially
protective against cognitive dysfunction or dementia, such as fish,
monounsaturated fatty acids, vitamins B12 and folate, antioxidants (vitamin E,
carotenoids, flavonoids), and moderate amounts of alcohol," the authors
write. But its association with cognitive decline has been unclear.
Catherine Féart, Ph.D., of the Université
Victor Ségalen Bordeaux 2, Bordeaux, France, and colleagues examined whether
adherence to a Mediterranean diet was associated with change in cognitive
performance and with lower risk of all-cause dementia or Alzheimer disease. The
study included 1,410 individuals (age 65 years or older) from Bordeaux, France,
who were part of the Three-City cohort in 2001-2002 (a study of vascular risk
factors of dementia) and were re-examined at least once over 5 years. Adherence
to a Mediterranean diet (scored as 0 to 9) was computed from a food frequency
questionnaire and 24-hour recall.
Cognitive performance was assessed on 4
neuropsychological tests: the Mini-Mental State Examination (MMSE), Isaacs Set
Test (IST), Benton Visual Retention Test (BVRT), and Free and Cued Selective
Reminding Test (FCSRT). New cases of dementia (n = 99) were validated by an
independent expert committee of neurologists.
After adjusting for age, sex, education,
marital status, energy intake, physical activity, depressive symptomatology,
taking 5 medications/day or more, apolipoprotein E genotype, cardiovascular
risk factors, and stroke, the researchers found that higher Mediterranean diet
score was associated with fewer MMSE errors. But performance on the IST, BVRT,
or FCSRT over time was not significantly associated with Mediterranean diet
adherence, especially in those who remained free from dementia over 5 years.
Mediterranean diet adherence was not associated with the risk for incident
dementia, although the statistical strength of the data to detect a difference
was limited.
"The Mediterranean diet pattern
probably does not fully explain the better health of persons who adhere to it,
but it may contribute directly. A Mediterranean diet also may indirectly
constitute an indicator of a complex set of favorable social and lifestyle
factors that contribute to better health. Further research is needed to allow
the generalization of these results to other populations and to establish
whether a Mediterranean diet slows cognitive decline or reduces incident
dementia in addition to its cardiovascular benefits," the authors
conclude.
Mediterranean diet fights Alzheimer disease
Elderly
individuals who had a diet that included higher consumption of fruits,
vegetables, legumes, cereal and fish and was low in red meat and poultry and
who were physically active had an associated lower risk of Alzheimer disease,
according to a study in the August 12, 2009 issue of JAMA.
Research
regarding the effect physical activity can have on the risk of Alzheimer
disease (AD) or dementia has shown mixed results, as has the effect of dietary
habits. Their combined association has not been investigated, according to
background information in the article.
Nikolaos
Scarmeas, M.D., of Columbia University Medical Center, New York, and colleagues
examined the association between physical activity and risk of AD and also the
effect of physical activity and adherence to a Mediterranean-type diet on AD
risk. The study included 2 groups that consisted of 1,880 community-dwelling
elderly residents of New York city without dementia at the start of the study,
for whom there was both diet and physical activity information available.
Standardized neurological and neuropsychological measures were administered
approximately every 1.5 years from 1992 through 2006.
The
participants received measurements of their adherence to a Mediterranean-type
diet (scale of 0-9; categorized as low, middle, or high) and their physical
activity (sum of weekly participation in various physical activities, weighted
by the type of physical activity [light, moderate, vigorous]; categorized into
no physical activity, some, or much, also low or high), separately and
combined. A higher score for diet was obtained with higher consumption of
fruits, vegetables, legumes, cereals, and fish; lower consumption of meat and
dairy products; a higher ratio of monounsaturated fats to saturated fats and
mild to moderate alcohol consumption.
Individuals
were followed up for an average of 5.4 years, during which a total of 282
developed AD. In considering only physical activity, the researchers found that
more physical activity was associated with lower risk for developing AD.
"Compared with physically inactive individuals, report of some physical
activity was associated with a 29 percent to 41 percent lower risk of
developing AD, while report of much physical activity was associated with a 37
percent to 50 percent lower risk," the authors write.
When
considered simultaneously, both physical activity and Mediterranean diet
adherence were significantly associated with AD incidence. According to the
researchers, "Belonging to the middle diet adherence tertile was
associated with a 2 percent to 14 percent risk reduction, while belonging to
the highest diet adherence tertile was associated with a 32 percent to 40
percent reduced risk. Similarly, compared with individuals with no physical
activity, individuals reporting some physical activity had a 25 percent to 38
percent lower risk for AD, while individuals reporting much physical activity
had a 33 percent to 48 percent lower risk for AD."
The
authors also write, "Compared with individuals with low physical activity
plus low adherence to a diet (absolute AD risk, 19 percent), high physical
activity plus high diet adherence was associated with a 35 percent to 44
percent relative risk reduction (absolute AD risk, 12 percent). … Absolute AD
risks declined from 21 percent in the group with no physical activity plus low
diet adherence to 9 percent in the group with much physical activity plus high
diet adherence."
"In
summary, our results support the potentially independent and important role of
both physical activity and dietary habits in relation to AD risk. These
findings should be further evaluated in other populations."
Mediterranean diet may
lower risk of brain damage that causes thinking problems
A Mediterranean diet may help people
avoid the small areas of brain damage that can lead to problems with thinking
and memory, according to a study released today that were presented at the
American Academy of Neurology's 62nd Annual Meeting in Toronto April 10 to
April 17, 2010.
The study found that people who ate a
Mediterranean-like diet were less likely to have brain infarcts, or small areas
of dead tissue linked to thinking problems.
The Mediterranean diet includes high
intake of vegetables, legumes, fruits, cereals, fish and monounsaturated fatty
acids such as olive oil; low intake of saturated fatty acids, dairy products,
meat and poultry; and mild to moderate amounts of alcohol.
For the study, researchers assessed the
diets of 712 people in New York and divided them into three groups based on how
closely they were following the Mediterranean diet. Then they conducted MRI
brain scans of the people an average of six years later. A total of 238 people
had at least one area of brain damage.
Those who were most closely following a
Mediterranean-like diet were 36 percent less likely to have areas of brain
damage than those who were least following the diet. Those moderately following
the diet were 21 percent less likely to have brain damage than the lowest
group.
"The relationship between this type
of brain damage and the Mediterranean diet was comparable with that of high
blood pressure," said study author Nikolaos Scarmeas, MD, MSc, of Columbia
University Medical Center in New York and a member of the American Academy of
Neurology. "In this study, not eating a Mediterranean-like diet had about
the same effect on the brain as having high blood pressure."
Previous
research by Scarmeas and his colleagues showed that a Mediterranean-like diet
may be associated with a lower risk of Alzheimer's disease and may lengthen
survival in people with Alzheimer's disease. According to the present study,
these associations may be partially explained by fewer brain infarcts.
Mediterranean Diet
Associated with Lower Risk of Cognitive Impairment
Eating
a Mediterranean diet appears to be associated with less risk of mild cognitive
impairment—a stage between normal aging and dementia—or of transitioning from
mild cognitive impairment into Alzheimer’s disease, according to a report in
the February, 2009 issue of Archives of
Neurology, one of the JAMA/Archives journals.
“Among
behavioral traits, diet may play an important role in the cause and prevention
of Alzheimer’s disease,” the authors write as background information in the
article. Previous studies have shown a lower risk for Alzheimer’s disease among
those who eat a Mediterranean diet, characterized by high intakes of fish,
vegetables, legumes, fruits, cereals and unsaturated fatty acids, low intakes
of dairy products, meat and saturated fats and moderate alcohol consumption.
Nikolaos
Scarmeas, M.D., and colleagues at Columbia University Medical Center, New York,
calculated a score for adherence to the Mediterranean diet among 1,393
individuals with no cognitive problems and 482 patients with mild cognitive
impairment. Participants were originally examined, interviewed, screened for
cognitive impairments and asked to complete a food frequency questionnaire
between 1992 and 1999.
Over
an average of 4.5 years of follow-up, 275 of the 1,393 who did not have mild
cognitive impairment developed the condition. Compared with the one-third who
had the lowest scores for Mediterranean diet adherence, the one-third with the
highest scores for Mediterranean diet adherence had a 28 percent lower risk of
developing mild cognitive impairment and the one-third in the middle group for
Mediterranean diet adherence had a 17 percent lower risk.
Among
the 482 with mild cognitive impairment at the beginning of the study, 106
developed Alzheimer’s disease over an average 4.3 years of follow-up. Adhering
to the Mediterranean diet also was associated with a lower risk for this
transition. The one-third of participants with the highest scores for
Mediterranean diet adherence had 48 percent less risk and those in the middle
one-third of Mediterranean diet adherence had 45 percent less risk than the
one-third with the lowest scores.
The
Mediterranean diet may improve cholesterol levels, blood sugar levels and blood
vessel health overall, or reduce inflammation, all of which have been
associated with mild cognitive impairment. Individual food components of the
diet also may have an influence on cognitive risk. “For example, potentially
beneficial effects for mild cognitive impairment or mild cognitive impairment
conversion to Alzheimer’s disease have been reported for alcohol, fish,
polyunsaturated fatty acids (also for age-related cognitive decline) and lower
levels of saturated fatty acids,” they write.
