Vitamin D insufficiency seems to be a continued issue over the past few years and has gained widespread media attention. We know vitamin D is important for our bone health, but can it also improve our mental health? Before we dive into this topic, we need to first understand how to get vitamin D and how it is processed in the body.
Vitamin D comes in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is manufactured where it can be used to fortify foods that do not already contain this nutrient. Vitamin D3 is synthesized from the skin with exposure to sunlight and available in some animal products naturally. Over-the-counter supplements can contain either form of vitamin D as well, but D3 has been shown to be more potent in absorption than D2. According to GoodRx, vitamin D2 in supplement form is indicated for treating rickets, hypoparathyroidism, and familial hypophosphatemia. Whereas vitamin D3 is prescribed as a supplement to boost blood levels.
The most significant natural source of vitamin D for most people is through sunlight. As Vitamin D3 is synthesized in the skin, it gets transported via blood to the liver where it is then converted into calcidiol (also known as 25-hydroxyvitamin D). Calcidiol gets carried to the kidneys where it is then converted to the active form, calcitriol. When we get vitamin D from food sources, it is absorbed by the intestinal wall and carried through the blood to the liver.
Foods which contain vitamin D include salmon and other fatty fish, egg yolks, and sun-exposed mushrooms such as maitake. However, given the limited food sources naturally containing vitamin D, some foods have been fortified (added to) by companies such as dairy and dairy alternatives, orange juice, and cereals.
According to the Institute of Medicine (IOM) it is recommended for healthy individuals to get at least 600 IU daily1 while The Endocrine Society recommends at least 1,000 to 2,000 IU daily for maintaining sufficient vitamin D blood levels2. Some people may have difficulty with vitamin D absorption requiring higher amounts via supplementation. To determine how much you need to supplement (if at all), consult your doctor to measure your blood levels as there can be a risk of vitamin D toxicity if too much is consumed.
Vitamin D is necessary for improving absorption of calcium and phosphorus for bone health. But what links vitamin D to mental health? Research has shown a lack of vitamin D resulting in insufficiency, or in severe cases, a deficiency may be related to the development of mental illnesses such as depression and Alzheimer’s disease among other neuropsychiatric disorders. Vitamin D helps regulate calcium levels on neurons of the brain. In the case of depression, it is proposed that neuronal calcium levels are increased in the absence of sufficient vitamin D promoting depression.3 It is hypothesized the lack of vitamin D and omega-3 fatty acids from the diet can lead to dysfunction of serotonin action in the brain leading to depression and other neuropsychiatric disorders such as schizophrenia.4
Alzheimer’s disease and dementia are a result of chronic inflammation of the brain over time whereas vitamin D acts to reduce inflammation. A study published in Neurology consisting of 1,658 non-demented elderly participants, showed 171 participants developed dementia with 102 of those cases being diagnosed Alzheimer’s disease. Those same participants were found to have below optimal vitamin D blood levels. It was determined the risk of developing dementia and Alzheimer’s increased significantly when blood levels fell below 50 nmol/L.5
More research is needed in nutrition’s role on mental health, but as more studies become available, the connection between vitamin D and mental illnesses becomes more clear.
Sources
- Vitamin D Fact Sheet. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h6
- Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. https://academic.oup.com/jcem/article/96/7/1911/2833671
- Vitamin D and Depression: Cellular and Regulatory Mechanisms. http://pharmrev.aspetjournals.org/content/69/2/80.long
- Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior. http://www.fasebj.org/doi/abs/10.1096/fj.14-268342
- Vitamin D and the risk of dementia and Alzheimer disease. http://n.neurology.org/content/83/10/920.short