Omega-3 Fatty acids, vitamin D may control brain serotonin levels  affecting behavior and brain health.

Although essential marine omega-3 fatty acids and vitamin D have been shown to improve   cognitive   function and behavior in the context of certain brain disorders, the underlying mechanism has been unlear. In a new paper, serotonin is explained as the possible missing link tying together why vitamin D and marine omega-3 fatty acids might improve the symptoms associated with a broad array of brain disorders.

Many clinical disorders, such as autism spectrum disorder (ASD), attention deficeit hyperactivity disorder (ADHD), bipolar disorder and depression have been linked to low levels of vitamin D and omega-3. They also have been found to share another common trait, which is low brain serotonin levels. A new study published in the FASEB Journal discusses the mechanistic links that explain how low vitamin D and marine omega-3 deficiencies interacts with the serotonin pathway, that are important for brain development and social cognition, and could influence neuropsychiatric outcomes (Patrick & Ames 2015).   

In the brain, serotonin acts as a neurotransmitter affecting the wiring and structure of the brain as well as a wide range of cognitive functions and behaviors including mood, social behavior and impulse control. Low levels of serotonin have been found to impair memory, planning, social behavior and increase impulsiveness and aggression.

 Vitamin D, which is a steroid hormone that controls about 1,000 genes, many in the brain, activates a gene which produces an enzyme leading to higher levels of serotonin.

Omega-3 fatty acids is another important micronutrient linked to serotonin production and function. Eicosapentaenoic acid (EPA) increases serotonin release from presynaptic neurons by reducing inflammatory signaling molecules in the brain known as E2 series prostaglandins, which inhibit serotonin release and suggests how inflammation may negatively impact serotonin in the brain. 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.

Research has also shown that a gene affected by vitamin D tends to decrease serotonin production in the gut and other tissues. High levels of serotonin in the gut, where 90% of serotonin is usually found, can cause intestinal problems which are often associated with autism.

The publications suggests that optimizing intakes of vitamin D, EPA and DHA would optimize brain serotonin concentrations and functions and possibly relieve some of the symptoms associated with these disorders without side effects.