Puja Agarwal, an assistant professor at Rush University in Chicago, uses population studies to explore how specific foods may play a role in preventing Alzheimer’s disease and dementia. Photo courtesy of Ruch University
March 8 (UPI) -- People who eat a leafy green-rich diet along with other fruits and vegetables may develop fewer signs of Alzheimer's-associated amyloid plaques and tau tangles in their brains, according to a new study by researchers from Rush University in Chicago.
The study, published Wednesday in the journal Neurology, the medical journal of the American Academy of Neurology, followed 581 people with an average age of 84 years.
It found that the study suggested that those who ate the green leafy diet, along with vegetables, fruits, whole grains, olive oil, beans, nuts and fish may have fewer amyloid plaques and tau tangles in their brain than people who do not consume such diets.
The study probed participants following the MIND and Mediterranean diets.
While some elements in the two diets are similar, the Mediterranean diet recommends vegetables, fruit and three or more servings of fish per week.
The MIND diet prioritizes green leafy vegetables like spinach, kale and collard greens along with other vegetables prioritizing berries over other fruit, and recommends one or more servings of fish per week.
Both diets recommend small amounts of wine.
"These results are exciting -- improvement in people's diets in just one area -- such as eating more than six servings of green leafy vegetables per week, or not eating fried foods -- was associated with fewer amyloid plaques in the brain similar to being about four years younger," the study's author, Puja Agarwal, of Chicago's Rush University, said in a statement.
Amyloid plaques result from the gradual buildup of protein fragments between neurons, which form when Alzheimer's disrupts the brain's normal disposal process for the proteins. This eventually impacts cognitive function, according to the Alzheimer's Association.
Dead and dying nerve cells contain tangles, which consist of twisted strands of tau protein. The tangles destroy a vital cell transport system, the organization says.
"While our research doesn't prove that a healthy diet resulted in fewer brain deposits of amyloid plaques, also known as an indicator of Alzheimer's disease, we know there is a relationship. Following the MIND and Mediterranean diets may be one way that people can improve their brain health and protect cognition as they age."
The participants agreed to donate their brains at death to advance research ondementia. They were asked to complete annual questionnaires asking how much they ate of food items in various categories.
The participants died an average of seven years after the start of the study. Shortly before death, 39% of them had been diagnosed with dementia. When examined after death, 66% met the criteria for Alzheimer's disease.
With the aid of autopsies after death and adjusting for age at death, sex, education, total calorie intake -- and whether people had a gene linked to a greater risk of Alzheimer's disease -- researchers found people who scored highest for adhering to the Mediterranean diet had average plaque and tangle amounts in their brains similar to being 18 years younger than people who scored lowest.
Researchers also found people who scored highest for adhering to the MIND diet had average plaque and tangle amounts similar to being 12 years younger than those who scored lowest.
A MIND diet score one point higher corresponded to typical plaque amounts of participants who were 4.25 years younger.
"Our finding that eating more green leafy vegetables is in itself associated with fewer signs of Alzheimer's disease in the brain is intriguing enough for people to consider adding more of these vegetables to their diet," Agarwal said. "Future studies are needed to establish our findings further."
The Rush University study comes on the heels of another published in November that found that people who ate and drank more foods with flavonols -- found in certain fruits and vegetables, including kale, tomatoes, apples and oranges, plus tea and wine -- may have slower memory decline in older age.
The results of that study, which also appeared in Neurology, the journal of the American Academy of Neurology, found that those who consumed the highest level of flavonols, an average of seven servings of dark leafy greens a week or one serving of dark, leafy greens a day, had a 32% decrease in their rate of cognitive decline.