Vitamin D Deficiency and Neurologic Disease

by Robert L, Updated Jan. 4, 2022

One of the most important things I did in my recovery from cervical dystonia was to correct my vitamin D deficiency.  In 2015, when I first started having significant neck pain, my blood vitamin D level was tested to be 10 ng/mL (25 nmol/L).  Less than 20 ng/mL is considered deficient and my then naturopathic doctor asked me to try to boost levels all the way to 60-80 ng/mL, using blood monitoring.  This is a higher level than is normally recommended, so monitoring was needed to ensure that I stayed below 100 ng/mL.  

Adding 15 minutes of sun exposure per day (face and hands only, as it was cold out) plus supplementing 2,000 IU vitamin D per day got my vitamin D blood levels up to hover around 20 ng/mL.  As it turns out, this still-deficient vitamin D level was mostly due to enzyme deficiencies (genetics).  My ND unfortunately moved out of state in 2017 and I neglected to keep working on my vitamin D deficiency.  My levels remained around 20 ng/mL and my cervical dystonia started in beginning of 2018.  At the time I did not know sufficient vitamin D was needed to keep my immune, detox, and repair systems running properly.

Vitamin D is a signaling molecule (hormone), which has receptors in almost every cell in the body, including neurons [1].   Deficiency is fairly common in the general population due to genetics, diets low in fatty fish, and lack of sun exposure or use of sunscreen. Deficiency does not appear to cause neurologic disease directly and most people with deficiency typically have no signs of common systemic diseases except perhaps diabetes.   However, vitamin D deficiency hampers our bodies’ ability to fight infections such as dysbiosis, and slows our production of specialized proteins needed to reduce neuroinflammation, and detoxify and repair neurons.

Below are some systemic diseases where vitamin D deficiency has been found to be more common than in the general population or healthy controls  Cervical dystonia has not been studied yet, but many muscle and hyperkinetic conditions have been shown to have a higher than normal prevalence of vitamin D deficiency, and vitamin D deficiency correction has often been shown to help.  Additionally, correcting deficiency may help with hair loss and COVID-19 hospitalization risk.

Selected Motor, Neurologic, and Digestive System Associations with Vitamin D Deficiency

Disease or Disorder Deficiency Finding Notes


Parkinson's Disease
Long term higher serum vitamin D concentrations reduced risk of Parkinson disease by 67% [2]
Supplementation slowed disease progression in Fokl TT genotype subgroup [9]
Hyperkinetic Movement Disorders
High prevalence of vitamin D deficiency [3]
Restless Legs Syndrome helped by Vitamin D supplementation [4] [Note 1]
Childhood Tic Disorders
Higher prevalence of vitamin D deficiency with tic disorders [5]
Supplementation reduced severity


Chronic Neck Pain and Muscle Spasm
Vitamin D deficiency and insufficiency can cause or worsen neck and back pain and muscle spasm [22]
Supplementation for 12 weeks reduced pain by 70%
Chronic Lower Back Pain
High prevalence of hypovitaminosis D in the chronic lower back pain population [15]
Supplementation recommended
Post-Shingles Neuropathic Pain
Vitamin D deficiency associated with higher spontaneous and brush-evoked pain [20]
Diabetic Peripheral Neuropathy
Severe vitamin D deficiency was an independent risk factor for painful diabetic painful neuropathy and increased inflammatory cytokines [18]
Vitamin D deficiency correction recommended to reduce various forms of pain and balance issues [19]
Gout Pain
Vitamin D supplementation lowers serum uric acid in prediabetic patients with hyperuricaemia [23]
High uric acid can cause gout pain attacks. Allopurinol is often prescribed, but can have serious side effects [23]


Dysautonomia (POTS, Blood Pressure Control)
Vitamin D deficiency was significantly correlated with impaired cardiac autonomic functions [24]
Cardiac autonomic dysfunction improved after Vitamin D replacement in otherwise apparently healthy individuals
Vitamin D levels much lower in ADHD [6]
Supplementation reduced severity
Autism Spectrum Disorder [Note 2]
Vitamin D deficiency common in children with ASD [7]
Supplementation reduced severity of certain behaviors
Generalized Anxiety Disorder [Note 2]
Vitamin D deficiency is associated with anxiety and depression [10]
Supplementation reduces Generalized Anxiety Disorder [11]. Anxiety disorders often pre-date Parkinson's Disease by years [28].
Obsessive Compulsive Disorder [Note 2]
Vitamin D deficiency is associated with OCD in children [12]
Hyposmia (reduced sense of smell) [Note 2]
Vitamin D deficiency associated with smell dysfunction in children


Inflammatory Bowel Disease [Note 2]
Vitamin D deficiency in IBD is prevalent and associated with poor outcomes [8][14]
Supplementation recommended to help control disease
Dysbiosis and Immune System Function [Note 2]
Vitamin D modulates the gut’s microbial composition, affecting dysbiosis, and plays a relevant role in maintaining immune system function [21]


  1.  Some studies show no improvement of RLS with supplementation, but all studies have time limitations, usually 2 months.  It took me more than 15 months of vitamin D and other supplementation for my RLS symptoms to completely end.
  2. A condition commonly associated with dystonia or Parkinson’s Disease


There are several mechanisms how vitamin D deficiency could contribute to neurologic disease. 

  1. Vitamin D deficiency goes hand in hand with inflammatory bowel disease and dysbiosis [8][14]. Dysbiosis can cause leaky gut (what researchers call intestinal permeability) and absorption of toxins and incompletely cleaved proteins (leading to more inflammation).
  2. Vitamin D modulates calcium channel (Ca2+ ) signaling and Reactive Oxygen Species levels, so deficiency can contribute to aging and disease [16].  Calcium channels also regulate dopamine and GABA release (very important in movement disorders).
  3. Vitamin D deficiency can impair SLC30A10 production, which is needed to maintain manganese homeostasis.  Low level manganese toxicity is likely to be the single biggest contributor to my dystonia, and can cause Parkinsonism and Parkinson’s Disease as well.  I will write about manganese in a separate article. 

These mechanisms are fairly complex and not perfectly clear, even to researchers.  However, it seems pretty clear that if you have CD, PD, or a neurologic prodromal symptom such as reduced sense of smell, tinnitus, reduced hearing, restless legs syndrome, or major sleep disturbances, it makes sense to ask your healthcare provider for a vitamin D screening test. 

It is important to recognize that you have to be patient for results from correcting vitamin D deficiency.  Dysbiosis and manganese toxicity can take a long time to clear even after target vitamin D levels are reached, and other adjustments or treatments may be needed in tandem.

Treatment Options

Vitamin D Sources

Sunlight:  The body is able to generate vitamin D with sun exposure (UV-B).  In fact, lifetime estimated sun exposure is correlated with a significantly reduced risk of developing multiple sclerosis [27].  This may have been due to increased vitamin D production, along with other immunological benefits.

Diet: Some foods, such as oily fish, red meat, liver, and egg yolks are high in vitamin D.  However, due to issues such as the neurotoxin mercury in fish, it does not appear feasible to dietarily correct vitamin D deficiency when neurological disease is already present.

Supplementation: If your vitamin D level is sufficient, then it can be risky to supplement.   Too-high levels of vitamin D can mess up signaling and cause issues such as excess absorption of minerals like calcium.

Vitamin D blood-level testing is available from mail-in labs and some national blood-draw labs, even without a prescription.  However, I’d strongly advise finding a doctor who will do a whole round of blood tests, not just vitamin D, in order to support your systemic health.  In my experience, the doctors most interested in this approach are NDs, followed by holistic, integrative, or functional medicine MDs. 

Recommended Vitamin D Levels

The Vitamin D Council’s recommendation for vitamin D levels is 50 ng/mL (125 nmol/L), based on levels found in hunter-gatherers in Africa, without supplementation [17].  This is higher than the 30 ng/mL listed by many labs as “sufficient”, but lower than what my NDs would normally target.  

Other Considerations

Vitamin K: Many vitamin D supplements come with vitamin K to help avoid dangerous side effects of D such as excessively high calcium in the blood (hypercalcemia) and excessive urination frequency.  However, too much vitamin K can also be risky, and K is not usually tested.  So it is important to get supplements from reputable sources, since errors in manufacturing like the wrong amount of K can have major consequences.  My ND normally vettes all the brands he recommends, so I normally stick with those brands, or those that are manufactured in USA or Europe with an ISO 9001 (Good Manufacturing Practices) certification.

Currently, instead of K supplementation, we are ensuring we have enough leafy greens, broccoli, fermented foods, and other sources of vitamin K in out diet.  There is no known risk of vitamin K overdose from food sources and these food sources can have other big benefits in neurologic disease, which I’ll discuss in another article.

Iron: Low iron stores can increase absorption of manganese from food.  Vitamin D supplementation may exacerbate this effect by increasing the number of transports that can absorb either iron or manganese from food.  Since excess manganese can drive dopamine dysfunction and motor / neurologic diseases (which I’ll explain in another article), it is important to check for iron deficiencies.  In fact, 42.3% of restless legs syndrome patients without anemia had iron deficiency [25][26].  It is important to check before supplementation, because excessive iron can also cause serious issues.

Additional Links

  • More info on vitamin D:
  • Unit converter for vitamin D:
  • Importance of maintaining proper trace mineral levels such as magnesium, calcium, iron, zinc, copper, selenium levels when supplementing with vitamin D:
    • Vitamin D increases the number of transports for these trace minerals, and heavy metals can hitch a ride when these trace minerals are insufficient. 
    • Note that homeostasis of many of these trace minerals is particularly important to neurotransmitter function. Improper levels can cause neurologic / motor disease such as Huntington’s Disease (inherited calcium dyshomeostasis) and Wilson’s Disease (inherited copper dyshomeostasis).


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