Eating a high-quality diet is thought to support cognitive health in several ways.Rawpixel/Getty Images
Studies have consistently found that healthy diet patterns are tied to protection against dementia.
What is less certain, though, is if diet makes a difference once Alzheimer’s disease-related brain changes are already under way.
Now, a new study suggests that following a healthy diet still matters.
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According to the findings, eating a less inflammatory diet appears to lower dementia risk in people already showing biological signs linked to Alzheimer’s disease.
Here’s a breakdown of the study, its key takeaways, plus easy ways to increase the anti-inflammatory potential of your everyday diet.
About the latest research
The new study, published in June in JAMA Network Open, sought to determine whether healthy eating patterns could modify dementia risk in older adults with blood biomarkers indicating Alzheimer’s-related brain changes or other signs of brain cell damage.
To do so, the researchers analyzed data from adults without dementia, ages 60 and older, who took part in the Swedish National Study on Aging and Care. A total of 1,865 participants, with an average age of 70, were followed for up to 15 years.
At the start of the study, researchers measured three blood biomarkers linked to Alzheimer’s disease and other signs of damage or stress in the brain. They also assessed participants’ diets, lifestyle habits and health status, updating this information at follow-up visits three and six years later.
Participants’ diet information was used to assess adherence to three dietary patterns: a Mediterranean-style diet, the Alternative Healthy Eating Index and the Reverse Empirical Dietary Inflammatory Index, which measures the inflammatory potential of a person’s diet (a higher score denotes a more anti-inflammatory diet). Higher adherence scores for each dietary pattern indicate a higher quality diet.
Each diet pattern highlights different aspects of diet quality, and they all emphasize vegetables, fruits, nuts and whole grains while limiting more inflammatory foods such as red and processed meats and sugary drinks.
Better diets, especially less inflammatory ones, tied to lower dementia risk
Across all participants, healthier diet patterns were associated with a lower likelihood of developing dementia.
When the researchers analyzed participants according to their levels of blood biomarkers, however, they found striking results.
Greater adherence to all three diet patterns was generally associated with a lower risk of dementia among people with lower levels of blood biomarkers.
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Notably, only a less inflammatory diet pattern was associated with a lower risk of dementia among participants who at the start of the study had elevated blood biomarkers indicating Alzheimer’s-related brain changes or other signs of brain-cell injury.
Among participants with higher levels of a biomarker called p-tau217, for example, greater adherence to a less inflammatory diet was associated with a 29 per cent lower risk of dementia.
Similar risk reductions were seen in people with higher levels of two blood biomarkers associated with nerve cell damage and inflammation.
These findings suggest that all three healthy dietary patterns may help earlier in the disease process, and an anti-inflammatory dietary pattern may continue to be beneficial even when blood biomarkers indicate a higher biological risk of Alzheimer’s disease.
Strengths, limitations
The study’s strengths include its large sample size, long follow-up period and repeated dietary assessment.
It also involved a comprehensive dementia diagnosis process, which included clinical assessment, cognitive testing, as well as reviewing medical and death records.
While this new evidence is stronger than many previous studies because it included blood biomarkers associated with Alzheimer’s disease, it remains observational.
As such, the study can’t prove that healthy diet patterns directly prevented or delayed dementia.
Even so, the findings support the concept of “cognitive resilience,” the brain’s ability to maintain normal thinking and memory despite underlying Alzheimer’s-related changes.
Even when biological risk markers were elevated, an eating pattern with lower inflammatory potential was linked to a lower risk of dementia and a later onset of the disease.
How a less inflammatory diet may protect the brain
Eating a high-quality diet is thought to support cognitive health in several ways.
The current study suggests that reducing diet-related inflammation may be one explanation. Chronic inflammation is widely recognized as a risk factor for dementia.
Healthier diets may also protect brain cells from free radical damage (oxidative stress), improve insulin sensitivity, promote vascular health and foster a healthy gut microbiome.
Planning meals around anti-inflammatory foods
To increase the anti-inflammatory potential of your diet, aim for half your plate to be filled with vegetables and/or fruit. (Don’t discount frozen produce.)
Include leafy greens, cruciferous vegetables such as broccoli, cauliflower and cabbage, colourful bell peppers, tomatoes and sweet potato. When it comes to fruit, reach for berries, cherries, oranges, apples and pears.
Depending on the meal, fill one-quarter of your plate with either whole grains, such as oats, brown rice, farro, quinoa and whole grain pasta, or pulses such as chickpeas, black beans, lentils or kidney beans.
Fill the remaining of your plate with healthy protein whether it’s fish, seafood, poultry, tofu, tempeh or pulses.
Flavour meals with herbs and spices, which provide anti-inflammatory polyphenols.
Build snacks around nuts, seeds and fruit. Aim for about one-quarter cup of nuts or seeds each day.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.
