Studies reveal intelligence, mood, and memory benefits of diets higher in omega-3s and lower in omega-6s 03/08/2007
More good news about omega-3s, brain function, and mood emerged this week, from presentations at the American Psychosomatic Society's 65th annual scientific conference in Budapest, Hungary.
A team of researchers from the University of Pittsburgh presented the omega-3-affirming results of three studies at this conference in this ancient, picturesque city bisected by the Danube.
These were the findings of the team, led by Sarah Conklin, Ph.D.
Study 1: Omega-3s may boost grey matter and brain function
High blood levels of omega-3 fatty acids have been associated with reduced odds of mild to moderate depression.
Dr. Conklin's team decided to see whether consumption of omega-3s might work by building more grey matter in an area of the brain implicated in depression, called the anterior cingulate cortex (ACC).
The recruited 55 participants—23 men and 22 women—who then completed a standard test for depression and two 24-hour diet surveys.
To measure grey matter volumes in the ACC, the subjects underwent high resolution structural MRIs.
They found that higher intake of omega-3 fatty acids was associated with having more grey matter in a region of the ACC where lesser amounts are associated with being depressed. More to the point, those with the most grey matter in this region had the lowest scores on the depression test: that is, they were the happiest participants.
The Pittsburgh researchers expressed the implications this way: “As low grey matter volume in these brain regions have been associated with clinical depression, the current data suggest that the ACC may play a role in the antidepressant effects mediated by dietary intake of long chain omega-3 fatty acids” (Conklin SM, Gianaros PJ, Hariri AR et al 2007).
This makes sense for at least two reasons:
- Animal research shows a strong link between levels of DHA in red blood cells and DHA in the brain.
- Omega-3 DHA can promote the growth of small outgrowths of neuronal cell membranes called neurites, which adds gray matter and improves brain function (see “Omega-3s Boost Brain Networks Critical to Memory Capacity”).
The lesson seems to be that if you eat more fatty fish, you'll develop more brain where it matters to maintain good mood.
Study 2: Higher dietary omega-3/omega-6 ratio boosts intelligence and memory
The second paper presented in Budapest indicates that the imbalance between omega-6 and omega-3 polyunsaturated fatty acids in the American diet may be hurting our brains (Muldoon MF, Conklin S, Ryan CM et al 2007).
These fatty acids have opposing effects in cell membranes, and in laboratory animals, a dietary deficiency of omega-3 impairs learning and memory.
The Pittsburgh team hypothesized that the ratio between omega-6 arachidonic acid (AA) and omega-3 docosahexaenoic acid (DHA) is related to cognitive performance and memory.
To test this idea, they enrolled 166 subjects were 116 generally healthy men and women aged 30-55, and measured their blood levels of these key omega-3 and omega-6 fatty acids.
Then, the quality of the participants' basic brain functions were measured using standard tests for intelligence, short-term memory, and delayed memory.
As they suspected, a higher omega-6:omega-3 ratio was associated with lower intelligence.
The omega-6: omega-3 ratio ad no effect on short term memory, but a high omega-6:omega-3 ratio was associated with poor performance on tests of delayed memory (logical memory recall and visual reproduction recall).
Accordingly, the Pittsburgh-based researchers penned this conclusion: “These results support speculation that high intake of omega-6 fatty acids and/or deficient consumption of omega-3 fatty acids may disadvantage cognitive function.” (Muldoon MF, Conklin S, Ryan CM et al 2007)
Study 3: High omega-3/omega-6 ratio improves mood and behavior
Dr. Conklin's group knew that a relative deficiency of omega-3s and high tissue levels of omega-6s are both associated with depression and anti-social behavior.
In an earlier study, they'd observed this link between fatty acid ratios in a group of adults with high cholesterol levels, with respect to differences in mood, neuroticism and impulsivity.
In their new study, they sought to test those findings in 116 healthy adults: 66 women and 50 men (Conklin SM, Manuck SB, Yao JK et al 2007).
The researchers measured the participants' fasting blood levels of omega-6 arachidonic acid (AA) and omega-3s (EPA and DHA).
The participants completed a series of tests gauging depression, personality, impulsiveness, hostility, and anger, with these results:
- Higher levels of omega-6 AA were associated with higher odds of having mild-to-moderate depression.
- Higher levels of omega-3 EPA were associated with less impulsivity, hostility, and cynicism.
- Higher levels of omega-3 EPA and DHA were associated with less anger.
The lesson here seems to be that people's mood, mental performance, and social interactions may benefit from boosting their intake of omega-3s (fish, fish oil, flax oil, and leafy greens) and cutting back on sources of omega-6 fatty acids, which come primarily from common vegetable oils (other than olive and macadamia), processed/packaged/restaurant foods, and standard, grain-fed meats and poultry.
- Conklin SM, Gianaros PJ, Hariri AR et al. Dietary intake of the long-chain omega-3 fatty acids is associated with increased grey matter volume in the perigenual cingulated cortex. Abstract 1669. American Psychosomatic Society 65th Annual Meeting. Budapest, Hungary – March 7-10, 2007. Accessed online March 8, 2007 at http://www.psychosomatic.org/events/2007APSabstractsforjournal.pdf
- Muldoon MF, Conklin S, Ryan CM et al. Cognitive function and omega-6 and omega-3 fatty acid balance. Individual Abstract Number: 1734. American Psychosomatic Society 65th Annual Meeting. Budapest, Hungary – March 7-10, 2007. Accessed online March 8, 2007 at http://www.psychosomatic.org/events/2007APSabstractsforjournal.pdf
- Conklin SM, Manuck SB, Yao JK et al. Serum phospholipid polyunsaturated fatty acids are associated with mood, behavior, and personality in healthy community adults. Abstract 1718. American Psychosomatic Society 65th Annual Meeting. Budapest, Hungary – March 7-10, 2007. Accessed online March 8, 2007 at http://www.psychosomatic.org/events/2007APSabstractsforjournal.pdf