Alzheimer's, Dementia & Mental Health

Mediterranean Diet Lowers Risk of Cognitive Impairment, Stops Slide to Alzheimer’s

Previous studies have also shown a lower risk for Alzheimer's disease among those who eat a Mediterranean diet

Feb. 9, 2009 - Eating a Mediterranean diet, long associated with better health, appears to also lower the 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 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.

Additional studies are needed to confirm the role of this or other dietary factors in the development of cognitive impairment and Alzheimer's disease, they conclude.

This work was supported by grants from the National Institute on Aging.

What is the Mediterranean Diet?

By American Heart Association

There's no one "Mediterranean" diet. At least 16 countries border the Mediterranean Sea. Diets vary between these countries and also between regions within a country. Many differences in culture, ethnic background, religion, economy and agricultural production result in different diets. But the common Mediterranean dietary pattern has these characteristics:

  ● high consumption of fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds
  ● olive oil is an important monounsaturated fat source
  ● dairy products, fish and poultry are consumed in low to moderate amounts, and little red meat is eaten
  ● eggs are consumed zero to four times a week
  ● wine is consumed in low to moderate amounts

Does a Mediterranean-style diet follow American Heart Association dietary recommendations?

Mediterranean-style diets are often close to our dietary recommendations, but they don’t follow them exactly. In general, the diets of Mediterranean peoples contain a relatively high percentage of calories from fat. This is thought to contribute to the increasing obesity in these countries, which is becoming a concern.

People who follow the average Mediterranean diet eat less saturated fat than those who eat the average American diet. In fact, saturated fat consumption is well within our dietary guidelines.

More than half the fat calories in a Mediterranean diet come from monounsaturated fats (mainly from olive oil). Monounsaturated fat doesn't raise blood cholesterol levels the way saturated fat does.

The incidence of heart disease in Mediterranean countries is lower than in the United States. Death rates are lower, too. But this may not be entirely due to the diet. Lifestyle factors (such as more physical activity and extended social support systems) may also play a part.

Before advising people to follow a Mediterranean diet, we need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease. See the Lyon Diet Heart Study entry in this Guide for more information.

American Heart Association – click for more

Related AHA publications:

  ● Easy Food Tips for Heart-Healthy Eating (also in Spanish) 
  ● "How Can I Cook Healthfully?" and "How Do I Follow a Low-Fat Diet?" in Answers By Heart kit (also in Spanish kit)

Mediterranean Diet Pyramid

The Mediterranean diet pyramid shown above is based on the traditional diets of people in Greece, Crete, and southern Italy in the early 1960's.

More at Hormel Foods – click here