Field Notes
Med Diet Reduces Risk of Cognitive Decline in Older People
Older people who follow a Mediterranean diet are at a lower risk of cognitive decline, according to a study published in the journal Molecular Nutrition and Food Research. The study provides new evidence for a better understanding of the biological mechanisms related to the impact of the diet on cognitive health in the aging population.
The study is led by Mireia Urpí-Sardá, PhD, an adjunct lecturer and member of the Biomarkers and Nutritional & Food Metabolomics research group of the Faculty of Pharmacy and Food Sciences, the Institute for Nutrition and Food Safety, the Food and Nutrition Torribera Campus of the University of Barcelona (UB), and the CIBER on Frailty and Healthy Ageing (CIBERFES).
This European study, part of the Joint Programming Initiative "A Healthy Diet for a Healthy Life" was carried out over 12 years and involved 840 people over age 65 (65% of whom were women) in the Bourdeaux and Dijon regions of France.
Healthful Diet and Cognitive Performance
According to Cristina Andrés-Lacueva, PhD, a UB professor and head of the CIBERFES group, "Within the framework of the study, a dietary metabolomic index has been designed—based on biomarkers obtained from the participants' serum—on the food groups that form part of the Mediterranean diet. Once this index is known, its association with cognitive impairment is evaluated."
In the study, baseline levels of saturated and unsaturated fatty acids, gut microbiota-derived polyphenol metabolites, and other phytochemicals in serum that reflect individual bioavailability were chosen as biomarkers. Some of these indicators haven’t only been recognized as marks of exposure to the main food groups of the Mediterranean diet but also have been held responsible for the health benefits of the Mediterranean dietary pattern.
The metabolome or set of metabolites—related to food and derived from gut microbiota activity—was studied through a large-scale quantitative metabolomic analysis from the serum of the participants without dementia, from the beginning of the study. Cognitive impairment was assessed by five neuropsychological tests over 12 years.
As a result, the study reveals a protective association between the score of the Mediterranean diet based on serum biomarkers and cognitive decline in older people.
Biomarkers to Study the Diet’s Benefits
According to Mercè Pallàs, PhD, a professor at the UB Neurosciences Institute, "The use of dietary pattern indices based on food-intake biomarkers is a step forward toward the use of more accurate and objective dietary assessment methodologies that take into account important factors such as bioavailability."
Expert Alba Tor-Roca, MPH, first author of the study and CIBERFES researcher at the UB, explains, "We found that adherence to the 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."
— Source: University of Barcelona
Whole Grains Associated With Less Memory Decline in African Americans
Consuming a few servings of whole grains each day may reduce the risk of cognitive decline among older African Americans, according to RUSH researchers.
The researchers found that white subjects in their study experienced fewer benefits from eating whole grains. The results were published online in Neurology, the journal of American Academy of Neurology.
“By consuming more whole grains such as breads, pasta, rice, crackers, cereals, quinoa, and even popcorn, we saw a slower cognitive decline specifically in the group of African Americans,” says study author Xiaoran Liu, PhD, an assistant professor of internal medicine at RUSH Medical College in Chicago.
“Black people had more whole grains in their diet than the white population in our study. Previous evidence suggests eating whole grains was protective of heart disease and Black people are more likely to develop heart disease” Liu says. “This may be a contributing factor in why we saw more of a benefit in Black people. With rapidly aging populations, this highlights the need for more studies to explore this association to tailor dietary recommendations and help find ways to delay dementia.”
Black participants who reported eating more servings of whole grains had lower levels of decline almost equivalent to being 8.5 years younger over the 10-year period of observation.
The analysis included 3,326 people with an average age of 75 without dementia with 1,999, or 60%, being Black participants. The participants were followed for an average of six years and were asked to fill out a questionnaire on how much and how often they ate whole grains. Annual cognitive and memory tests were conducted where the participants were asked to remember lists of words and numbers in the correct order.
“With Alzheimer’s disease and dementia affecting millions of Americans, finding ways to prevent the disease is a high public health priority,” Liu says. “It’s exciting to see that people could potentially lower their risk of dementia just by increasing their consumption of whole grains by a couple of servings a day.”
Five groups of participants were organized by the amount of whole grains consumed. The group that consumed the least amount of grains ate the equivalent of less than half a serving per day, or 1/2 oz. The group with the highest amount of grains consumed about 2.7 servings each day, nearly 3 oz.
“Whole grains are rich in vitamins B and E, and other antioxidants. They have a lot of fiber, which has been linked to a lot of health benefits, particularly related to brain health. So, we do see a lot of evidence in terms of whole grains being protective in lowering heart disease risk, and we know what’s good for the heart may also be good for the brain,” Liu says.
— Source: RUSH