While previous studies have established that omega-3 and vitamin D are beneficial in improving cognitive function and behaviour, the exact mechanisms relating to this were unknown.
Co-author of the study, Dr Bruce Ames from the Children's Hospital Oakland Research Institute (CHORI), suggests that omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and vitamin D work together to maintain healthy levels of serotonin in the brain.
“This synergy of omega-3 and vitamin D can be explained in part by their effects on the serotonin system: vitamin D regulates serotonin synthesis, EPA influences serotonin release, and DHA improves membrane embedded serotonin receptor accessibility,” says the study.
According to the researchers, low serotonin levels in normal individuals are associated with antisocial behaviour, increased uncontrolled aggressive behaviour and self-injury.
The study, published in the FASEB Journal, also suggests that mental illnesses are less prevalent among women due to a protective effect provided by oestrogen, which increases brain serotonin synthesis.
Supplementation: ‘practical and relevant’
According to Ames, many sufferers of mental illness are deficient in micronutrients, particularly vitamin D and omega-3 fatty acids.
“This may explain why supplementation with these essential micronutrients has been shown to be effective for treating symptoms associated with ADHD, bipolar disorder, schizophrenia, impulsive behaviour, depression, and obsessive compulsive disorder,” they say.
“Vitamin D and omega-3 fatty acid supplementation would be a safer therapeutic treatment than serotonin enhancing drugs, which often have negative side effects,” says the study. According to the NHS, side effects of selective serotonin re-uptake inhibitors (SSRIs) include anxiety, nausea and blurred vision.
While the researchers call for further clinical trials to determine the optimal doses of vitamin D, EPA and DHA for each specific illness, there is great scope for success in supplementation.
“Vitamin D and omega-3 supplementations are practical interventions and are of great therapeutic relevance because of the massive and widespread vitamin D and omega-3 deficiencies in the United States and in particular populations.”
According to the study, 70% of adults and 67% of children aged 1–11 years in the United States do not have adequate levels of vitamin D even when fortification and supplementation are taken into account.
Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), told Nutraingredients: “I've known for many years that EPA and DHA are intimately involved in serotonergic pathways, but I never gave much thought about the role of vitamin D in the regulation of serotonin synthesis.
Reading this article was like putting pieces of a puzzle together. Given that the majority of the American population is considered to be vitamin D deficient, as well as consuming inadequate amounts of omega-3s, it stands to reason that the impact of supplementation on multiple mental health conditions with a combination thereof may extend well beyond the benefits of supplementing with omega-3s alone. In the name of public health, Ames' hypothesis needs to be explored,” said Rice.
The first part of this two-part study suggested that adequate levels of vitamin D are required to produce serotonin in the brain where it acts as a neurotransmitter, affecting social behaviour.
In this second part, Ames and Patrick extended their research to include omega-3 fatty acids, as well as applying their findings to ADHD, bipolar disorder, schizophrenia and impulsive behaviour.
Source: The FASEB Journal
Published online ahead of print February 24, 2015, doi: 10.1096/fj.14-268342, see link
"Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar, schizophrenia, and impulsive behavior"
Authors: Rhonda P. Patrick and Bruce N. Ames