Many studies have demonstrated that fish oils and vitamin D help improve cognitive function, but what exactly is the mechanism of action? In an article just published in FASEB Journal, serotonin is described as the possible missing link, explaining why vitamin D and fish oil may have such a significant effect on neurological disorders.

Previous research has demonstrated that vitamin D helps regulate the conversion of tryptophan to serotonin, the neurotransmitter that affects a variety of cognitive functions including mood, decision-making, social behavior, impulsive behavior, and social decision-making. Many brain-based disorders, such as autism spectrum disorder (ASD), ADHD, schizophrenia, bipolar disorder, and depression commonly have low brain serotonin.

This 2015 study explains how serotonin is a critical modulator of executive function, impulse control, sensory gating, and pro-social behavior. Researchers link serotonin production and function to vitamin D and omega-3 fatty acids, which suggests one way that these important nutrients help the brain function and affect our behavior.
Eicosapentaenoic acid (EPA) helps increase the release of serotonin from presynaptic neurons by reducing inflammatory signaling molecules in the brain known as E2 series prostaglandins. These inflammatory prostaglandins inhibit serotonin release, and thus negatively impact serotonin in the brain. Docosahexaenoic acid (DHA) also plays a role in the serotonin pathway. This essential fatty acid helps make several serotonin receptors more accessible to serotonin by increasing cell membrane fluidity in postsynaptic neurons.

We typically recommend taking 5-10,000 iu Vitamin D per day.