The consumption of omega-3 and omega-6 fatty acids, even from nuts and oils, has been linked to higher fluid intelligence and the integrity of brain structures in older age, according to two studies from researchers at the University of Illinois.

The research team, led by MD/PhD student Marta Zamroziewicz, analysed the relationships between the polyunsaturated fatty acid content and the brain structure of healthy elderly adults aged between 65 and 75.

“A central goal of research in nutritional cognitive neuroscience is to understand how these nutrients affect brain health. Some of [them] are thought to be more beneficial than others,” said Zamroziewicz.

According to her, the research carried out in Illinois differed from other similar studies in that instead of focusing on only one or two fatty acid, these two studies inspected a nutrient group.

The first study, published in the journal Nutritional Neuroscience, examined the links between several omega-3 fatty acids in the blood, the relative sizes of the structures in the frontal and parietal cortices of the brain and the subjects’ performance in tests of fluid intelligence – solving problems they had never encountered before.

The team found a relationship between higher levels of three omega-3 fatty acids – ALA, stearidonic and ecosatrienoic acid – and fluid intelligence, along with the increased size of the left frontoparietal cordices.

“A lot of research tells us that people need to be eating fish and fish oil to get neuroprotective effects from these particular fats, but this new finding suggests that even the fats that we get from nuts, seeds and oils can also make a difference in the brain,” Zamroziewicz said.

Most of previous research had concentrated on the DHA and EPA omega-3 fatty acids from fish, but according to Zamroziewicz most people in the Western hemisphere do not eat enough of them to see the benefits.

The second study indicated that the size of the fornix – a nerve fibre bundle in the centre of the brain – was associated with a balance of omega-3 and omega-6 fatty acids in the blood, and that a larger fornix coincided with memory preservation in the elderly.

“These findings have important implications for the Western diet, which tends to be misbalanced with high amounts of omega-6 fatty acids and low amounts of omega-3 fatty acids,” said Zamroziewicz.

“These two studies highlight the importance of investigating the effect of groups of nutrients together, rather than focusing on one at a time,” she concluded.