Vitamin D regulates the expression of hundreds of genes and is integral to biological functions that affect every bodily system. Vitamin D insufficiency or deficiency can trigger several generalized symptoms that you may have associated with other health conditions.
It’s also called the sunshine vitamin since your skin makes vitamin D when exposed to ultraviolet light from the sun.[1] Vitamin D performs many functions within the body, including maintaining adequate levels of calcium and phosphate, essential for normal bone mineralization.[2]
It helps reduce inflammation, which is necessary for the modulation of cell growth and immune function. Vitamin D also affects genes that help regulate cell differentiation and apoptosis (routine cell death).
The main indicator of your vitamin D level is 25-hydroxyvitamin D (25OHD). Data collected from the National Health and Nutrition Examination Survey in 2005-2006 showed a deficiency prevalence of 41.6 percent in the U.S. population.[3] However, as I discuss later in this article, as many as 80 percent of people may be deficient in vitamin D.
It’s important to note that how the measurement of insufficiency and deficiency is defined depends on the serum concentrations used. Some researchers use a level of 20 nanograms per milliliter (ng/mL) or 50 nanomoles per liter (nmol/L); the ng/mL is used most frequently in the United States and nmol/L is the standard in Europe.
14 Signs You Might Have a Vitamin D Deficiency
During cold and flu season, and the COVID-19 pandemic, it is essential to maintain healthy levels of vitamin D to help reduce your risk of viral and bacterial illness.[5,6] A blood test is the best way to determine your vitamin D levels, but here are some symptoms that may indicate your levels are low.Nearly half of all adults are affected by muscle pain.[7] Researchers believe most of those adults are deficient in vitamin D. Some studies have suggested that nerves have vitamin D receptors that affect the perception of pain. In one animal model, research demonstrated a vitamin D-deficient diet can induce deep muscle hypersensitivity that wasn’t connected to low levels of calcium.[8]
Vitamin D regulates the level of calcium in your body necessary to protect bone health.[9] Vitamin D deficiency can cause your bones to soften a condition called osteomalacia. This may be a precursor to osteoporosis.
This is a common symptom of a variety of different health conditions, including sleep deprivation. Researchers have found that supplementing vitamin D can improve the symptoms of fatigue suffered by cancer patients.[10]
In one study[11] using 174 adults with fatigue and stable medical conditions, the researchers found 77.2 percent were deficient in vitamin D. After normalizing their level, the fatigue symptoms improved significantly.
Vitamin D deficiency is as common in athletes as in non-athletes. Vitamin D is crucial for muscle development, strength, and performance. Older adults taking a vitamin D supplement have a reduced risk of falls and improved muscle performance.[12]
Correction through oral supplementation or sensible sun exposure may reduce symptoms of stress fractures, musculoskeletal pain, and frequent illness. Vitamin D also has a direct effect on muscle performance. In one paper from the Journal of the American Academy of Orthopaedic Surgeons, the author wrote:[13]
“Higher serum levels of vitamin D are associated with reduced injury rates and improved sports performance. In a subset of the population, vitamin D appears to play a role in muscle strength, injury prevention, and sports performance.”
Vitamin D is also essential for your brain health. Symptoms of deficiency can include dementia caused by an increase of soluble and insoluble beta-amyloid, a factor in Alzheimer’s disease.[14] Research has also found an association with depression15] that may be linked to the function of vitamin D buffering higher levels of calcium in the brain.[16]
Vitamin D deficiency in pregnant women can increase the risk of autism and schizophrenic-like disorders in the baby.[17] One study of people with fibromyalgia found a vitamin D deficiency was more common in those who had anxiety and depression.[18] Another looked at vitamin D deficiency in obese subjects and found a relationship between low levels of vitamin D and depression.[19]
The mechanism linking vitamin D and poor sleep quality hasn’t been identified. But research has found people with low levels of vitamin D have poor quality sleep and a higher risk of sleep disorders.[20]
Excessive sweating, especially on your head, or a change in your pattern of sweating, can indicate a vitamin D deficiency.[21]
Vitamin D is crucial to the proliferation of keratinocytes and plays an important role in your hair cycle. The vitamin D receptor appears to play a role in the anagen phase of hair growth, leading researchers to conclude, “Treatments that upregulate the vitamin D receptor may be successful in treating hair disorders and are a potential area of further study,” they wrote in a study published in Dermatology Online Journal in 2010.[22]
Evidence from animal models suggests that vitamin D is critical in the development of the inner ear,[25] which affects balance and coordination. Analysis of people with vestibular neuritis, characterized by vertigo, showed lower serum vitamin D levels than in people without vestibular neuritis.[26]
How vitamin D affects obesity hasn’t been identified. However, data do show there is a high probability of deficiency in people who are obese.[29]
COVID-19 and Vitamin D Deficiency
Around 80 percent of people with COVID-19 are deficient in vitamin D.Since then, mounting evidence has revealed this is indeed the case as researchers have repeatedly found that higher levels of vitamin D reduce the rate of positive tests, hospitalizations, and mortality related to this infection.
One study,[34] released in late 2020, assessed the serum 25OHD levels of patients hospitalized with COVID-19 to evaluate the influence it might have on the severity of the disease. The researchers found 82.2 percent of those with COVID-19 were vitamin D deficient (levels lower than 20 ng/mL).
Interestingly, they also found those who were deficient had a greater prevalence of cardiovascular disease, high blood pressure, high iron levels, and longer hospital stays. A second study[35] found similar results for people who only tested positive for COVID-19.
Recently, data showed people who received supplemental vitamin D3 while hospitalized with COVID-19 had reduced admissions to the ICU by 82 percent and reduced mortality by 64 percent.[36]
Editor’s note: This preprint study has since been pulled due to “concerns about the description of the research in this paper,”[37] but an archived version is still available.
Before the paper was removed, this information triggered British MP David Davis to call for a reevaluation of the official recommendations for vitamin D. He tweeted, “The findings of this large and well-conducted study should result in this therapy being administered to every COVID patient in every hospital in the temperate latitudes."[38]
He added that the demonstration of the “clear relationship between vitamin D and COVID mortality is causal,” and his government should raise the availability of free vitamin D supplements to vulnerable populations. Other experts also called for official vitamin D recommendations.[39]
Magnesium and Vitamin K2 Optimize Your Vitamin D3 Supplement
Vitamin K2 MK-7 and magnesium both play an important role in your overall health and in the bioavailability and application of vitamin D in your body. If you’re not using magnesium and vitamin K2, you could need nearly 2.5 times more vitamin D, which GrassrootsHealth discovered in its D*action project.[42]More than 10,000 individuals provided information about supplement use and overall health status to GrassrootsHealth since they began conducting large-scale population-based nutrient research in 2007.[43]
That information has led to the recommendation that vitamin D blood levels between 40 ng/ml and 60 ng/ml (100 nmol/L to 150 nmol/L) are safe, effective, and lower overall disease incidence and health care costs. As reported by GrassrootsHealth from their data:[44]
In practical terms, this means when you take vitamin K2 and magnesium with vitamin D, you need far less vitamin D to achieve a healthy level.
- [1] National Institutes of Health, Vitamin D
- [2] Oregon State University, Vitamin D
- [3] Cureus, 2018;10(6)
- [4] [42] [44] GrassrootsHealth Magnesium and Vitamin K2 Combined Important for Vitamin D Levels
- [5] Harvard Gazette, February 15, 2017
- [6] DermatoEndocrinology, 2012;4(2)
- [7] [8] Journal of Neuroscience, 2011;31(39)
- [9] U.S. Pharmacist, 2009;34(3)
- [10] [11] North American Journal of Medical Sciences, 2014;6(8)
- [12] Current Opinions in Clinical Nutrition and Metabolic Care, 2009;12(6)
- [13] Journal of the American Academy of Orthopaedic Surgeons, 2018;26(8)
- [14] Cureus, 2018;10(7) Abstract
- [15] Neuropsychiatry, 2017;7(5)
- [16] [17] Cureus, 2018;10(7)
- [18] Clinical Rheumatology, 2007;26:551
- [19] Journal of Internal Medicine, 2008; doi.org/10.111/j.1365-2796.2008.02008.x
- [20] Nutrients, 2018;10(10)
- [21] Science Care, January 10, 2017
- [22] Dermatology Online Journal, 2010;16(2):3
- [23] Advances in Wound Care, 2019;8(2)
- [24] Today’s Wound Clinic, 2016;10(11)
- [25] Biochemical and Biophysical Research Communications, 2016;478(2)
- [26] Frontiers in Neurology, 2019; doi.org/10.3389/fneur.2019.00863
- [27] Science Daily, April 3, 2011
- [28] International Journal of Nanomedicine, 2018;13:455
- [29] Medicina, 2019;55(9)
- [30] Inflammation and Allergy - Drug Targets, 2013;12(4)
- [31] Critical Care, 2014;8(6)
- [32] University of Exeter, August 6, 2014
- [33] JAMA Neurology, 2015;72(11)
- [34] The Journal of Clinical Endocrinology and Metabolism, 2020; doi.org/10.1210/clinem/dgaa733
- [35] JAMA, 2020;3(9):e2019722
- [36] Preprints, The Lancet, January 22, 2021; doi.org/10.2139/ssrn.3771318
- [37] Europe PMC January 21, 2021
- [38] The Sun, February 14, 2021
- [39] Irish Times, February 15, 2021
- [40] Scandinavian Journal of Rheumatology, 2009;38(2):149
- [41] Journal of Nutrition and Metabolism, 2017;2017:6254836
- [43] GrassrootsHealth.net