A diet that is rich in seafood, fruit, vegetables, nuts and olive oil may lower the risk of dementia, a new study suggests.
An analysis of data from more than 60,000 seniors revealed that choosing to follow a Mediterranean diet reduces a person’s likelihood of developing dementia by nearly one quarter, even among those with genes that put that at greater risk, according to the report published Monday in the medical journal BMC Medicine.
“The main take home message from this study is that, even for individuals with a higher genetic risk, consuming a more Mediterranean-like diet could reduce the likelihood of developing dementia,” said the study’s lead author, Oliver Shannon, a lecturer in human nutrition and aging at Newcastle University.
Among people whose food choices least resembled a Mediterranean diet, “around 17 in every 1,000 individuals developed dementia during the approximately nine year study follow-up period,” Shannon said in an email.
In contrast, among people whose food choices most resembled a Mediterranean diet, “only around 12 of every 1,000 individuals developed dementia,” he added.
What is a Mediterranean diet?
A Mediterranean diet is filled with healthy plant-based foods such as vegetables, nuts and legumes. It's rich in whole grains, fruits and olive oil and fish.
The people in the study were also typically eating less red or processed meat, sweets and pastries and drinking fewer sugar sweetened beverages, Shannon said.
Prior studies have been mixed on whether a Mediterranean diet can help stave off dementia. In fact, a study published in October that looked at medical records from 28,025 Swedes found that the diet did not protect against dementia. In contrast, another study published in May, which included nearly 2,000 older adults, found that diets high in foods associated with inflammation — in contrast to the Mediterranean diet, which appears to be anti-inflammatory — were linked with faster brain aging seen on MRI scans and a greater risk for the development of dementia.
To take a closer look at the impact of a Mediterranean diet on dementia risk, Shannon and his colleagues turned to the U.K. Biobank, which from 2006 to 2010 recruited men and women aged 4 to 69 from across England, Scotland and Wales. The prospective study currently has more than half a million participants.
The recruits filled out a touch-screen questionnaire, participated in a verbal interview and provided biological samples and measures of physical function. Later on, the recruits received scans, were assessed for multiple health outcomes and provided information on their diets, some at multiple times during the study. The Biobank was able to keep track of the participants’ health through linked electronic medical records.
An added dimension to the new study was the inclusion of genetic information in the form of an Alzheimer’s risk score that was devised in earlier research.
“The risk score was constructed using around 250,000 individual genetic variants which have been associated with Alzheimer’s disease, which is the most common form of dementia,” Shannon explained.
For the new study, the researchers focused on 60,298 participants who were in their 60s at recruitment. During an average follow-up of nine years, 882 individuals developed dementia.
When the researchers crunched their data, they found that individuals whose food consumption most closely mirrored the Mediterranean diet were 23% less likely to develop dementia during the years covered by the study.
According to Newcastle's Shannon, to have the perfect Mediterranean diet score, weekly consumption should include:
- Olive oil as the main cooking fat.
- 2 or more servings of vegetables per day.
- 3 or more servings of fruit per day.
- Less than 1 serving of red/processed meat per day.
- Less than 1 serving of butter, margarine or cream per day.
- Less than 1 sugar-sweetened drink per day.
- 3 or more servings of legumes, such as beans, lentils or peanuts, per week.
- 3 or more servings of fish per week.
- Less than 2 servings of sweets or pastries per week.
- 3 or more servings of nuts per week.
- More white meat than red meat in the diet.
- 2 or more servings of a tomato-based sauce per week.
The new research adds to the mounting evidence that diet can impact the risk of dementia even in people who are at a higher risk because of their genes, said Dr. Thomas Wisniewski, a professor of neurology, pathology and psychiatry and director of the Alzheimer’s Disease Research Center and the Center for Cognitive Neurology at NYU Langone.
“This study with really good numbers and a fairly substantial effect size is showing that, indeed, it is brain protective to follow a Mediterranean diet,” Wisniewski said. “It’s positive news and certainly something that everyone can do relatively easily. So it’s good news.”
Reducing the risk of dementia
Diet “is one of the lifestyle things I discuss with all of my patients,” Wisniewski said. “The other thing we typically discuss with patients is the importance of staying physically and mentally active."
Other important ways to reduce risk of dementia include:
- Getting adequate sleep.
- Controlling blood pressure.
- Having healthy cholesterol and blood glucose levels.
All of those are interventions everyone can take to keep their brain healthy and reduce the risk for dementia development,” said Shannon.
The new study found almost a one-quarter reduction in risk for dementia, Wisniewski said. “That’s a pretty big risk reduction, by doing something that is not that challenging,” he added.
While it’s not known exactly how the Mediterranean diet could reduce the risk of dementia, it likely has multiple effects, ranging from reducing antioxidants, helping to tamp down inflammation, and improving the status of the microbiome, Wisniewski said.
With no good medication to treat dementia, experts have been focusing on lifestyle factors that may have some bearing on risk, said Dr. Emily Rogalski, a cognitive neuroscientist and professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine.
At the moment, it's unclear if there is a point when it’s too late to protect against dementia.
“But giving up and saying it’s too late is probably not the right attitude to take," she said.
“We used to think we were born with all the brain cells we were ever going to have and that the brain was not that plastic, or malleable or resilient,” Rogalski said. “We’ve learned over the past couple of decades that there is room for adaptation and change.”