This study lasted over twelve years and had 840 study subjects over 65 years old from the Bourdeaux and Dijon regions of France. Over the twelve year study period assessments of cognition were performed fives times for each of the study subjects.

Healthy diet and cognitive performance

According to professor C. Andrés-Lacueva, University of Barcelona, biomarkers obtained from the participants’ serum that indicate the presence or absence of parts of the Mediterranean diet, established the parameters that were measured for the study . The association with cognitive impairment was then evaluated.

The study used baseline levels of saturated and unsaturated fatty acids, the gut microbiome and other phytochemicals in serum. These indicators have been recognized as consistent with exposure to the food groups of the Mediterranean diet.

The these metabolites levels were analyzed  and the results were published in the scientific journal Molecular Nutrition & Food Research – entitled, A Mediterranean Diet‐Based Metabolic Score and Cognitive Decline in Older Adults: A Case–Control Analysis Nested within the Three‐City Cohort Study.

The results of the the study showed a protective association between a higher on the score of the Mediterranean diet scale based on serum biomarkers and less cognitive decline in the elderly.

Biomarkers to study the benefits of the diet

According to M. Pallàs, professor at the University of Barcelona, “the use of dietary pattern indices based on food-intake biomarkers is a step forward towards the use of more accurate and objective dietary assessment methodologies that take into account important factors such as bioavailability.”

Researcher Dr. Alba Tor-Roca, explained “we found that adherence to Mediterranean diet assessed by a panel of dietary biomarkers is inversely associated with long-term cognitive decline in older people. These results support the use of these indicators in long-term follow-up assessments to observe the health benefits associated with the Mediterranean diet or other dietary patterns and therefore, guide personalized counselling at older ages.” This study was done in collaboration with Nutrition Science departments from France, The United Kingdom, the Netherlands, and Austria

Funding was obtained through the International Joint Program Initiative called  “A Healthy Diet for a Healthy Life”.

This scientific research is not the first to show a benefit from following a Mediterranean diet for cognition in the elderly. Studied from a  different perspective the University of Edinburgh in Scotland performed a study which involved brain CT scans and the measurement of brain volume in 1,000 subjects performed over a three year period. Loss of brain volume in crucial areas of the brain associated with cognitive decline were assessed , and their results indicated that a Mediterranean diet may slow this crucial loss of brain volume. This was published in the medical/ scientific journal Neurology, the official journal of the American Academy of Neurology. Lead researcher M. Luciano, PhD. says “as we age the brain shrinks and we lose brain cells which can effect learning and memory. This study ads to the body of evidence suggesting the Mediterranean diet has a positive impact on brain health.”

With regard  to the study of specific nutrients and cognition, research out of the UC Davis Alzheimer’s Disease Center showed that elderly people with low levels of Vitamin D showed a decline in cognitive function three times faster than those with healthy Vitamin D levels. Researcher Joshua Miller studied Vitamin D levels in 400 people of an average age of 76 over a five year period and concluded, ” there is enough evidence to recommend that people in their sixties and older discuss taking Vitamin D supplements with their physician“. Fish and nuts which are a characteristic feature of the Mediterranean diet are excellent sources of vitamin D. Charles DeCarli, director of the Alzheimer’s Disease Center at UC Davis commented, “we expected to see declines (in cognition) in individuals with low Vitamin D status. What was unexpected was how profoundly and rapidly low Vitamin D impacts cognition…this is a vitamin deficiency that can be easily treated and that has other health consequences.”

More generally the Mediterranean diet involves eating much less processed foods than the Average Western diet, and processed foods with their higher levels of sugars and saturated fats have been associated with the development of disease overall, cognitive decline included. Highly Processed foods have less nutrient content than unprocessed foods and this may lead to nutritional deficiencies-like Vitamin D deficiency- which would be one reason for the promotion of dementia. Furthermore, along another avenue of possible causation, processed foods tend to have a more acidic effect on the blood than a diet which is less acidic- more alkaline. Excess acidity in the diet is felt to promote more underlying inflammation in the body, which is associated with the development and progression of aging, disability and disease.