Writing in the open-access journal Frontiers in Nutrition the team found those on a Mediterranean diet had slower rates of cognitive decline, reduced progression to Alzheimer's disease, and improvements in brain function.
Additionally, the researchers found these outcomes were not restricted to the Mediterranean region. The positive cognitive effects of sticking to the diet were similar in all evaluated papers in the review.
The benefits were not exclusive to older individuals. Two of the included studies focused on younger adults and both found improvements in cognition.
The Med diet has long been associated with reducing the incidence of cardiovascular disease, cancer, and diabetes, high blood pressure and obesity – conditions that make up metabolic syndrome.
With the news that this diet, which has a strong emphasis on fruits, vegetables, and fish, helps to preserve higher cognitive functions and the capacity to learn, it is likely that the ageing population will reap the benefits as the population are living to unprecedented ages.
Neurocognitive decline as people age has been well researched. Abilities that involve speed of thought and memory slowly weaken from the third decade of life. Speed of retrieval from short-term memory has shown a 50% decline from the third to the eighth decade of life.
As a result of their findings, the researchers, from Swinburne University of Technology in Australia, pointed towards inflammation and oxidative stress as the main culprits of declining health and brain function.
This, they thought could be effectively addressed as a modifiable risk factor through improved nutrition along with stress, education, psychological well-being, and exercise.
All in all, the team assessed research between 2000 and 2015. The focus of these studies centred on whether a Mediterranean Diet could impact cognitive processes over time.
With very few controlled clinical trials that look at nutrition and increased physical activity on cognition in older individuals, only 18 research papers were selected.
Data that formed a major part of the team’s conclusions include number of participants, gender, and age, study design and country of origin; sample size; Mediterranean Diet assessment; cognitive assessments used and study outcomes.
“The Mediterranean Diet offers the opportunity to change some of the modifiable risk factors," explained lead author Roy Hardman from Swinburne University.
"These include reducing increasing micronutrients, improving vitamin and mineral imbalances, changing lipid profiles by using olive oils as the main source of dietary fats, improving polyphenols in the blood, and maybe changing the gut microbiota, although this has not been examined to a larger extent yet."
Similar studies have identified factors that affect cognitive responses that relate to food intake. There is evidence that low or moderate intake of alcohol may reduce cardiovascular and neurocognitive risk. However, heavy drinkers tending to suffer more heart attacks and dementia.
The dietary B-complex vitamins B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenate), B6, B9 (folate) and B12 (cobalamin), are important known regulators of neurotransmitter health.
A deficiency in basic B vitamins (folic acid, B6, and B12) in the diet may impact on the rate of neurodegeneration linked with mild cognitive impairment.
It has also been suggested that increased seafood consumption and omega-3 polyunsaturated fats may have beneficial effects on cognitive function in the long-term.
Source: Frontiers in Nutrition
Published online ahead of print, doi.org/10.3389/fnut.2016.00022
“Adherence to a Mediterranean-Style Diet and Effects on Cognition in Adults: A Qualitative Evaluation and Systematic Review of Longitudinal and Prospective Trials.”
Authors: Roy Hardman et al.