Omega-3 fatty acids, vitamin D may control brain serotonin

Eating fish and soaking up some sun may protect brain health, a new study suggests.
Vitamin D and marine omega-3 fatty acids may reduce the symptoms associated with a broad array of brain disorders by controlling brain serotonin, scientists say.
In a previous study, researchers found that vitamin D regulates the conversion of the essential amino acid tryptophan into serotonin and this may influence the development of autism, particularly in developing children with poor vitamin D status.
Serotonin affects a wide-range of cognitive functions and behaviours including mood, decision-making, social behaviour, impulsive behaviour, and even plays a role in social decision-making by keeping in check aggressive social responses or impulsive behaviour.

Many clinical disorders, such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), bipolar disorder, schizophrenia, and depression share as a unifying attribute low brain serotonin.
"In this paper we explain how serotonin is a critical modulator of executive function, impulse control, sensory gating, and pro-social behaviour," said Rhonda P Patrick, from Children's Hospital Oakland Research Institute, in the new study published in the FASEB Journal.

"We link serotonin production and function to vitamin D and omega-3 fatty acids, suggesting one way these important micronutrients help the brain function and affect the way we behave," Patrick said.
Eicosapentaenoic acid (EPA) increases serotonin release from presynaptic neurons by reducing inflammatory signalling molecules in the brain known as E2 series prostaglandins, which inhibit serotonin release.

EPA, however, is not the only omega-3 that plays a role in the serotonin pathway.
Docosahexaenoic acid (DHA) also influences the action of various serotonin receptors by making them more accessible to serotonin by increasing cell membrane fluidity in postsynaptic neurons.
The study sheds light on the mechanistic links that explain why low vitamin D, which is mostly produced by the skin when exposed to sun, and marine omega-3 deficiencies interacts with genetic pathways, such as the serotonin pathway, that are important for brain development, social cognition, and decision-making, and how these gene-micronutrient interactions may influence neuropsychiatric outcomes, researchers said.

The study suggests that optimising intakes of vitamin D, EPA, and DHA would optimise brain serotonin concentrations and function, possibly preventing and ameliorating some of the symptoms associated with these disorders without side effects.