A solid connection between a Mediterranean diet and cognitive health has remained somewhat elusive. This is most likely because so many studies rely on participants’ self-reporting of their dietary intake, a notoriously unreliable means of collecting data.
A new study takes a different approach to measuring diet and selecting cases and controls. The study was conducted in two French regions; one was the discovery cohort and the other was used to validate the findings. The researchers used a nested case-control study design in each city to reduce bias between cases and controls.
In both cases, people with cognitive decline after 12 years of follow-up and the controls, those without cognitive decline at follow-up, were selected from the same regional cohort (the “nest”).
The authors overcame inaccuracies in diet recall by using biomarkers in blood samples taken at baseline to measure how much different components of a Mediterranean diet had reached participants’ bloodstreams.
Using blood serum biomarkers rather than participants’ recollections, the new study has found that people eating a Mediterranean diet are less likely to experience age-related cognitive decline.
The authors of the study developed a scoring system that measures individuals’ adherence to the Mediterranean diet. They call their system MDMS, which stands for “Mediterranean Diet Metabolomic Score.”
The researchers analyzed the participants’ blood serum for the presence of metabolites that result from the cellular processing of certain foods, resulting in an MDMS score.
Data from the Three City, or 3C Cohort, study provided the basis for the analysis. This was a study of dementia involving people from three cities in two French regions who were 65 years old or older. The regions were Bordeaux and Dijon.
None of the individuals had dementia at the outset of the 3C study in 1999–2000 when cognitive tests were administered. The participants were repeatedly tested every two to three years over a period of 12 years to capture any development of dementia.
At the outset of the 3C study, researchers took blood samples from the participants to measure 72 metabolites of interest.
In the new study, individuals from the Bordeaux region whose MDMS test results showed the greatest adherence to the Mediterranean diet were 10% less likely to develop mild cognitive impairment than people with lower test scores. In the Dijon region, they were 9% less likely to do so.
The study is published in the journal Molecular Nutrition and Food Research.
Metabolomics — studying a person’s metabolites — provides a greater degree of certainty regarding the foods a study participant is consuming.
According to Dr. Austin Perlmutter, internal medicine physician and New York Times bestselling author, the metabolites tracked in this study are proxies for key components of the Mediterranean diet. These include “polyphenolics as well as omega-3 fatty acids including DHA and EPA, all of which have been linked to better cognitive health.”
He noted that “a diet rich in polyphenols including, in particular, quercetin and kaempferol has been correlated with slower cognitive decline, while consuming more omega-3 fatty acids is supported as a preventive strategy for Alzheimer’s.”
The MIND diet is a combination of the Mediterranean and DASH diets.
Dr. Perlmutter noted that the Mediterranean diet has also been linked to better memory and less brain atrophy in older people.
Alba Tor-Roca, Alex Sánchez-Pla, Aniko Korosi, Mercè Pallàs, Paul J. Lucassen, Pol Castellano-Escuder, Ludwig Aigner, Raúl González-Domínguez, Claudine Manach, Francisco Carmona, Esteban Vegas, Catherine Helmer, Catherine Feart, Sophie Lefèvre-Arbogast, Jeanne Neuffer, Hyunah Lee, Sandrine Thuret, Cristina Andres-Lacueva, Cécilia Samieri, Mireia Urpi-Sarda. A Mediterranean Diet-Based Metabolomic Score and Cognitive Decline in Older Adults: A Case–Control Analysis Nested within the Three-City Cohort Study. Molecular Nutrtition and Food Research. First published: 24 October 2023 https://doi.org/10.1002/mnfr.202300271
Bordeaux. Dijon. (2023). Mediterranean diet may slow age-related cognitive decline. MedicalNewsToday. Retrieved November 30, 2023 from https://www.medicalnewstoday.com/articles/mediterranean-diet-may-slow-age-related-cognitive-decline