In a large epidemiological study, researchers found that people who drank three or more servings of fruit and vegetable juices per week had a 76 percent lower risk of developing Alzheimer's disease than those who drank juice less than once per week.
The Vanderbilt University Medical Center study handled by Qi Dai — M.D., Ph.D., assistant professor of medicine — and colleagues appears in this month's issue of The American Journal of Medicine.
The researchers followed a subset of subjects from a large cross-cultural study of dementia, called the Ni-Hon-Sea Project, which investigated Alzheimer's disease and vascular dementia in older Japanese populations living in Japan; Hawaii; and in Seattle, Wash.
After controlling for possible confounding factors like smoking, education, physical activity and fat intake, the researchers found that those who reported drinking juices three or more times per week were less likely to develop signs of Alzheimer's disease than those who drank less than one serving per week.
Originally, researchers suspected that high intakes of antioxidant vitamins (vitamins C, E and beta carotene) might provide some protection against Alzheimer's disease, but recent clinical studies have not supported this hypothesis.
Dai began to suspect that another class of antioxidant chemicals, known as polyphenols, could play a role. Polyphenols are nonvitamin antioxidants common in the diet, and particularly abundant in teas, juices and wines. Most polyphenols exist primarily in the skins and peels of fruits and vegetables.
Yet, however promising the study results appear, Dai cautioned that it's important that the general public not jump the gun regarding the single value of juice as a preventive measure for Alzheimer's disease.