Following a well-balanced diet that’s rich in fruits and vegetables and low in sugar can have many benefits to your health, including reducing a person’s risk of dementia. However, a popular and well-recommended meal plan known as the Mediterranean diet may not lower the odds of developing dementia as previous research had suggested.
The Mediterranean diet is a plant-based diet that includes foods like fruits, vegetables, potatoes, whole grains, legumes, seeds, fish, healthy fats (such as olive oil) and a low intake of meats, dairy products, fried foods, sugar and saturated fats. The American Heart Association recommends the diet to promote health, control blood sugar and prevent chronic diseases.
However, according to a 20-year study published in the medical journal Neurology, researchers found that neither conventional dietary recommendations or a modified Mediterranean diet were significantly associated with a reduced risk of developing dementia or Alzheimer’s.
“While our study does not rule out a possible association between diet and dementia, we did not find a link in our study, which had a long follow-up period, included younger participants than some other studies and did not require people to remember what foods they had eaten regularly years before,” said Isabelle Glans, MD, in SciTechDaily.
Glans and her colleagues followed 28,000 people (average age of 58) from Sweden who did not have dementia at the start of the study for more than 20 years. The participants were asked to fill out a daily food diary and complete a food frequency questionnaire and an interview. At the end of the study, 1,943 people (6.9%) were diagnosed with dementia, including Alzheimer’s disease and vascular dementia.
After the researchers adjusted for age, gender and education levels, they did not find a link between a conventional diet or the Mediterranean diet and a reduced risk of dementia.
Why might there be no association between the Mediterranean diet and a lower risk of dementia?
Scott Braunstein, MD, medical director at Sollis Health in Beverly Hills, California, told Seasons there could be several reasons for the lack of an association, including confounding risk factors that may not have been included, such as obesity, hypertension, physical activity levels, depression, social isolation, smoking and others. He also said depending on patients’ reports of compliance with the diet, self-reporting could have been unreliable.
“Mediterranean diet, which tends to be higher in vegetables and lower in saturated fats, has been found to be associated with lower incidence of dementia in past studies,” he said. “However, given the number of other confounding factors involved, in addition to depending on the reliability of people’s self-reporting on their diet, it is not surprising that this study could not find an association.”
Furthermore, a major part of the Mediterranean diet is about incorporating olive oil. The study used a modified Mediterranean diet scoring questionnaire that did not ask about olive oil, but instead asked how much vegetable oil was consumed, Megan Wong, RD, a registered dietitian at AlgaeCal, told Seasons.
“The problem with this is that not all vegetable oils are created equal. This study used participant data from a Nordic population, and the Nordic diet favors canola oil,” she said. “So, if a participant’s diet included zero olive oil and lots of canola oil, this counted as following a Mediterranean diet.”
Wong added canola oil is high in omega-6 fatty acids that contribute to inflammation, an underlying cause of dementia. On the other hand, olive oil is antioxidant-rich and anti-inflammatory and has been linked to improved memory in animal studies.
The researchers noted that because their study took place over 20 years, the results may not have included changes in dietary habits, lifestyle changes, or newly co-occurring medical conditions over time.
Should I stick with the Mediterranean Diet?
Braunstein encourages people who currently follow the Mediterranean diet to stick with it, despite what this study found. That’s because there are other potential benefits to this diet, including lower risk of heart attack, stroke, obesity and diabetes, which should contribute to a longer, healthier lifespan.
“The Mediterranean diet tends to be low in saturated fats and red meat, higher in vegetables and legumes, which generally leads to improved cholesterol, lower cardiac disease and stroke, and overall better health.”
Wong also encourages adults to not change eating habits based only on the findings from this study because this diet promotes healthy foods that are widely studied for benefiting the brain, heart, bones, immune system and more.
“It’s important to read entire study articles to have a better understanding of how the study was conducted and if the conclusions can be applied to you,” she said.
Furthermore, she said older adults who follow this diet in combination with the MIND diet can lower their risk of cognitive decline including a lower risk of Alzheimer’s disease—up to 53% in some cases.
A study published in 2021 found small to moderate improvements in several cognitive domains after participants followed the Mediterranean diet for three years compared to a control group that did not. In addition, a 2022 study from Harvard University found that following a green Mediterranean diet that was low in red meat intake also protected the brain from “attenuated age-related brain atrophy.”
What else can I do to lower dementia risk?
If you’re looking for other ways to lower your dementia risk, Braunstein recommends diets that are lower in ultra-processed foods, such as soft drinks, chips, candy, hot dogs, etc.
He also recommends getting enough physical activity and sleep, which have been found to have strong associations with a lower risk of dementia.
“Studies have shown that as little as 12 minutes of daily exercise is enough to lower risk of dementia, and studies show that people who sleep at least 7 hours nightly during their 40s and 50s have a lower risk of developing dementia.”