The Vitamin Receptor in the Brain that Influences Brain Function
By Dr. Jen Morganti, NEEDS Education Director
Do you know your vitamin D level? I mean the actual number, not just being told that it's "within normal range." The normal range is now being reconsidered, and if you aren't at least on the high side of "normal," you may be too low. It's important information because vitamin D deficiency has been linked to many diseases, including osteoporosis, inflammation, depression, Seasonal Affective Disorder, nervous system problems, Rheumatoid arthritis, inflammatory bowel disease, cardiovascular disease, and musculoskeletal pain. Vitamin D's anti-inflammatory activity seems to be one of the underlying mechanisms that make it so effective at alleviating these conditions. And as it turns out, having adequate vitamin D is critical to your body's ability to slow or prevent diseases related to your brain, such as Alzheimer's Disease, depression, and even schizophrenia.
Vitamins D2 and D3 are the primary forms, both of which are eventually converted via the liver and kidneys to the more bioactive form, the pro-hormone calcitriol. Vitamin D3, also known as cholecalciferol, can be obtained from food (animal sources), supplements, and from sun exposure, which is then converted to a usable form by cells in the skin. D2 (ergocalciferol) is derived from fungal or plant sources and less efficient at converting to usable calcitriol than D3. Vitamin D2 is also made synthetically, but this form can be toxic in large doses and should be avoided entirely. A wide range of the body's tissues have vitamin D receptors and, like the kidneys, have the ability to convert preliminary forms of vitamin D to calcitriol. The presence of vitamin D receptors throughout the body indicates that this nutrient is critical to many metabolic processes.
Vitamin D may influence issues related to our brain and nerve function because of pervasive vitamin D receptors in these areas. Vitamin D is critical to nerve conduction, nerve cell growth, and aids memory and learning. An infant born with vitamin D deficiency may be hindered in brain development. In the adult, if a brainrelated problem begins to develop, vitamin D can trigger receptors that may slow the progression of that disease. A deficiency in vitamin D doesn't necessarily cause brain dysfunction, but it may limit the ability to put brakes on the progression of brain issues.
Vitamin D may be protective in Alzheimer's Disease (AD), or at least slow its progression. It does this through its anti-inflammatory mechanism. Inflammation contributes to the development of amyloid plaques, found in the brain of AD patients, and animal studies show that vitamin D can slow the rate at which they develop. Test tube studies show that when vitamin D is added to cell cultures from AD patients, it helps clear the plaque.
As for clinical research, a six-year study looked at vitamin D levels in elderly who developed cognitive decline and AD. They found that for those who had the lowest levels of the vitamin (<20 ng/dl), there was double the risk of developing dementia (125% increased risk) as compared to those who were moderately deficient. And there was a 120% increased risk to develop AD within the lowest D group, and 69% increased risk for those with moderately low D levels. The researchers carefully evaluated whether the deficiency was a cause or effect of the disease, and determined that the deficiency occurred long before the disease, so it was unlikely that the disease caused the deficiency. And in Parkinson's disease, a related condition, it can help slow progression.
Schizophrenia is another condition related to cognitive function that may be influenced by D levels. Like vitamin-D deficiency risk factors, schizophrenia is more prevalent in higher latitudes, in people with darker skin, and in cold climates. A meta-analysis (review of many studies) evaluated the correlation between schizophrenia and vitamin-D deficiency, and found that over 65% of patients with schizophrenia had very low vitamin-D levels. They determined that the low D levels insignificantly increased the risk of developing schizophrenia.
Depression is also common in over 30% of patients who have suffered from a stroke, in part due to the repercussions the stroke has on their lifestyle. A study looked at poststroke patients and found that in those suffering from depression, their average vitamin D levels were very low (under 10 ng/ml) as compared to patients without depression, who averaged higher levels of vitamin D.
Depression is also common among women who have Polycystic Ovarian Syndrome (PCOS). PCOS is a condition in women of child-bearing years, where cysts grow on the ovaries, causing hormone imbalances and infertility complications. In women with PCOS, depression rates are generally about 40%. In a small study, it was found that there were lower levels of vitamin D in women struggling with PCOS and experiencing depression as compared to women who did not have depression linked to their PCOS diagnosis.
If you are suffering from any of the aforementioned conditions, it may be worthwhile to find out your vitamin D levels. Many progressive physicians are aiming for levels over 50 ng/mL. If your level is below that, consider taking 5,000 IU vitamin D daily, or more. It can take some time to raise levels, so be patient and stick with it.
Thomas J. Littlejohns, William E. Henley, Iain A. Lang, et al. Vitamin D and the risk of dementia and Alzheimer disease. Neurology published online August 6, 2014
Naqvi S, et al. Predictors of depression in women with polycystic ovary syndrome. Archives of Women's Mental Health, 2014.
Yue, W. et al. Association of Serum 25-Hydroxyvitamin D with Symptoms of Depression After 6 Months in Stroke Patients. Neurochemical Research, 2014.
Valipour, Saneei, & Esmaillzadeh. Serum Vitamin D Levels in Relation to Schizophrenia: A Systematic Review and Meta-Analysis of Observational Studies. Journal of Clinical Endocrinology and Metabolism, 2014.