Encouraging animal research from France supports evidence that omega-3 fatty acids play a key role in mood health … and expands our grasp on how they work in the brain.
French scientists tested the effects of feeding mice a diet that was relatively low in omega-3 fatty acids and high in the omega-6 fatty acids that predominate in most vegetable oils (Lafourcade M et al. 2011).
As they said in a press release, this imbalanced fat intake “had deleterious consequences on synaptic functions and emotional behaviors.” (INSERM 2011)
In other words, it messed with brain systems and chemicals that maintain mood.
As our readers know, the average American’s diet suffers from the same kind of “omega-imbalance”, which is associated with major health conditions from cardiovascular disease and osteoporosis to depression and dementia.
For our past coverage of this topic, see the “Omega-3 / Omega-6 Balance” section of our news archive, and for an overview, see “Report Finds Americans Need More Omega-3s ... and Far Fewer Omega-6 Fats”.
The average American’s diet is grossly imbalanced in favor of omega-6 fats, primarily from the vegetable oils most commonly used in homes and in packaged or prepared foods (corn, canola, soy, safflower, sunflower). Omega-6s also abound in soy milk, poultry, and red meats.
Olive oil, macadamia nut oil, and special “hi-oleic” safflower and sunflower oils are the only oils low in omega-6s.
Most researchers estimate that Americans consume 20 to 40 times as much omega-6 as omega-3 fatty acids … when we should be eating the two types in roughly equal amounts, consuming no more than three grams of omega-6 fats for every gram of omega-3 fats.
This extreme imbalance reduces the amounts of omega-3s that can get into our cells … a “blocking” effect that has broad, deep health implications for brain and overall health.
French study finds omega-3s affect key mood-related systems
Prior animal research showed that omega-3s foster growth of cells in the brain’s hippocampus region and promote connections between those cells … an effect associated with reduced depression risk and symptom severity (Venna VR et al. 2008).
And clinical findings by NIH psychiatrist Joe Hibbeln, M.D., show that people with higher blood levels of omega-3 fatty acids have more serotonin and dopamine – two key mood-related neurotransmitters – in their spinal fluid (Hibbeln JR et al. 1998).
Now, findings from INSERM – France’s equivalent to the U.S. National Institutes of Health – add another reason why omega-3s and the omega balance matter to mood (Lafourcade M et al. 2011).
A team led by Drs. Olivier Manzoni and Sophie Layé wanted to test the idea that feeding mice an omega-imbalanced diet starting before birth would influence brain systems involved in depression and anxiety.
The INSERM team fed mice a life-long diet imbalanced in omega-3 and omega-6 fatty acids.
They found that the resulting shortage of omega-3s and overload of omega-6 fats disturbed communication between brain cells (neurons).
Critically, this was the first research to show the omega-imbalanced diet virtually shut down their brain cells’ CB1R cannabinoid receptors, which play a key role in between-cell communications (i.e., neurotransmission).
And the “neuronal dysfunction” induced by an omega-imbalanced diet was accompanied by depressive behaviors among the mice.
Among omega-3 deficient mice, the usual effects produced by cannabinoid receptor activation disappeared, along with the critical antioxidant effects exerted by the brain’s cannabinoid compounds.
The researchers discovered that the omega-3 deficient diet impaired synaptic plasticity – the ability to form new connections in the brain – in at least two areas (prefrontal cortex and nucleus accumbens) involved in reward, motivation, and emotional regulation.
These parts of the brain contain a large number of CB1R cannabinoid receptors and have important functional connections with each other.
Drs. Manzoni and Layé noted that their results “… corroborate clinical and epidemiological studies which have revealed associations between an omega-3/omega-6 imbalance and mood disorders.” (INSERM 2011)
Critically, these findings provide another biological explanation for the statistical associations repeatedly found between diets low in omega-3s – which are now common, worldwide – and mood disorders such as depression.
Human evidence supports omega-3s’ hypothetical mood-regulation role
Five years ago, the American Psychiatric Association concluded that people who consume higher amounts of omega-3s from fish (EPA and DHA) enjoy lower risks of depression and related mood disorders (Freeman MP et al. 2006).
For that story, see “Top Psych Panel Says Omega-3s Deter Depression, Bipolar Disorder”.
Then, two years ago, the results of the largest-ever clinical trial found that omega-3 fish oil significantly benefited the half of clinically depressed participants who did not also have a diagnosed anxiety disorder (Lesperance F et al 2009).
In fact, fish oil appeared to help these people about as much as the leading class of antidepressant drugs ... selective serotonin re-uptake inhibitors (SSRIs) such as Prozac and Paxil. (See “Fish Oil Rivals Antidepressants in Clinical Trial.”)
For more research on omega-3s and mood, see the “Omega-3s & Brain Health” section of our news archive.
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INSERM (Institut National de la Santé et de la Recherche Médicale). A deficiency of dietary omega-3 may explain depressive behaviors. January 30, 2011. Accessed at http://www.eurekalert.org/pub_releases/2011-01/ind-ado012811.php
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