Older adults with high levels of key nutrients in their blood exhibit more efficient brain connectivity and perform better on cognitive tests, according to a new study published in the journal NeuroImage.
Researchers from the University of Illinois (U of I) at Urbana-Champaign analyzed 32 key nutrients in the Mediterranean diet, which previous research has shown is linked to better brain functioning in old age. A traditional Mediterranean-style diet includes a high intake of fish, fruits, nuts, vegetables, cereal foods and potatoes and reduced meat and dairy consumption. The study involved 116 healthy adults ages 65 to 75.
“We wanted to investigate whether diet and nutrition predict cognitive performance in healthy older adults,” said University of Illinois postdoctoral researcher Christopher Zwilling, Ph.D., who led the study with U of I psychology professor Dr. Aron Barbey in the Beckman Institute for Advanced Science and Technology.
The research team found that specific patterns of nutrient biomarkers in the blood were associated with better brain health and cognition.
The nutrients included the following:
- omega-3 fatty acids, which are abundant in fish, walnuts and Brussels sprouts;
- omega-6 fatty acids, found in flaxseed, pumpkin seeds, pine nuts and pistachios;
- lycopene, a vivid red pigment in tomatoes, watermelon and a few other fruits and vegetables;
- alpha- and beta-carotenoids, which give sweet potatoes and carrots their characteristic orange color;
- vitamins B and D.
The researchers relied on some of the most rigorous methods available for examining nutrient intake and brain health, Barbey said. Rather than asking participants to complete food-intake surveys, which would require the accurate recall of what and how much food they ate, the team looked for patterns of nutrient biomarkers in the blood.
The team also used functional magnetic resonance imaging (fMRI) to carefully analyze the efficiency with which various brain networks performed.
“The basic question we were asking was whether diet and nutrition are associated with healthy brain aging,” Barbey said. “And instead of inferring brain health from a cognitive test, we directly examined the brain using high-resolution brain imaging.”
Functional MRIs can indicate the efficiency of individual brain networks, he said.
“Efficiency has to do with how information is communicated within the network,” Barbey said. “We looked at ‘local efficiency’ — how well information is shared within a spatially confined set of brain regions — and also ‘global efficiency,’ which reflects how many steps are required to transfer information from any one region to any other region in the network.”
“If your network is more efficiently configured, then it should be easier, on average, to access relevant information and the task should take you less time,” he said.
After participants completed several cognitive exams, the researchers discovered a strong link between higher levels of several nutrient biomarkers in the blood and better performance on specific tests. These nutrients, which appeared to work synergistically, included omega-3 and omega-6 fatty acids, carotenoids, lycopene, riboflavin, folate, vitamin B12 and vitamin D.
The analysis also revealed that a pattern of omega-3s, omega-6s and carotene was linked to better functional brain network efficiency.
Different nutrient patterns appeared to support the efficiency of different brain networks. For example, higher levels of omega-3 fatty acids reflected the positive relationship between a healthy frontoparietal network and general intelligence. The frontoparietal network supports the ability to focus attention and engage in goal-directed behavior.
“Our study suggests that diet and nutrition moderate the association between network efficiency and cognitive performance,” Barbey said. “This means that the strength of the association between functional brain network efficiency and cognitive performance is associated with the level of the nutrients.”
To test the stability of the nutrient-biomarker patterns over time, the researchers invited 40 participants back for a second analysis roughly two years after the first tests. Similar nutrient patterns persisted in this subset of the original group.