The Mediterranean diet—with an emphasis on fruits, vegetables, whole grains, olive oil, and fish—has been extolled in studies for cancer prevention and heart-health benefits. But it may protect against Alzheimer's disease, too, according to a recent study published in the Annals of Neurology (2006, vol. 59, no. 6). Research showed that people who adhered to a Mediterranean diet significantly cut their risk for Alzheimer's, a disease affecting 4.5 million Americans.

For four years, researchers at Columbia University followed 2,258 individuals with an average age of 77, but no initial signs of dementia. Scientists evaluated their adherence to the Mediterranean diet every one and a half years. At the end of the study, 262 participants had developed Alzheimer's disease; after adjustments for several factors—including age, gender, ethnicity, and body mass index—people with the highest adherence to a Mediterranean diet had a 40 percent lower risk of Alzheimer's than subjects with the lowest adherence.

Although past research on Alzheimer's disease has concentrated on individual dietary components, lead author Nikolaos Scarmeas, MD, assistant professor at Columbia University Medical Center, says the Mediterranean diet as a whole—rather than its specific components—is most likely responsible for the results. "An overall dietary pattern is likely to have a greater effect on health than a single nutrient," he says.