The study, funded by grants from the National Institute on Aging, looked at 1,946 men and women in the Chicago area aged 65 and older, through a six-year period.
The participants were tested for short-term and delayed memory by recounting elements of a story that had just been read to them. They were also tested using flashcards with symbols and numbers. All participants did gradually worsen over time, but those who ate more than two servings of vegetables a day showed about 40 percent less mental decline than those who ate few or no vegetables.
Lead study author Martha Clare Morris said the results of the people who ate a lot of vegetables were what would be expected from participants about five years younger. It was also noted that the group that ate more vegetables were also more likely to be physically active, suggesting a connection between mind and body health, said neuroscientist Maria Carillo, director of medical and scientific relations for the Alzheimer's Association.
The results -- reported in this week's issue of the journal Neurology -- suggested that green leafy vegetables such as spinach, kale and collards appeared to provide the greatest benefit, most likely because they contain healthy amounts of the antioxidant vitamin E, the researchers said. Morris suggested the benefits might be reinforced by the healthy fats that are often eaten with vegetables, such as salad oils, which improve the absorption of antioxidants.
The researchers only studied mental decline, and did not account for any participants developing Alzheimer's disease, and they noted that the study does not prove vegetables positively impact cognitive decline, but adds to growing evidence that suggests it to be true.
"There's no question about it. A plant-based diet is the optimum diet for longevity, disease prevention and peak cognitive function," said Mike Adams, a holistic nutritionist and author of "The Seven Laws of Nutrition." "At the same time, diets high in the consumption of meat and animal products, including dairy, slow the brain while accelerating aging. If you want to live a long, healthy, disease free life, get your nutrition from plants and superfoods."
###