Hypovitaminosis D is a deficiency of vitamin D that may result from inadequate nutritional intake of the nutrient from food and/or inadequate exposure to sunlight, or more rarely disorders that limit vitamin D absorption or impair vitamin D conversion into active metabolites. Currently the recommended daily allowance (RDA) for vitamin D established by the Institute of Medicine (IOM) and the U.S. National Academy of Sciences (NAS) is 600 international units per day for persons under 70 years of age, and 800 IU per day thereafter.

Vitamin D deficiency is recognized as a worldwide health problem associated with an array of maladies such as rickets in children, increased risk of common cancers, autoimmune diseases, hypertension, infectious diseases and depression. Some researchers believe Hypovitaminosis D may also precipitate or exacerbate musculoskeletal pain, fibromyalgia, osteopenia, osteoporosis and fractures in adults. Causes of Vitamin D deficiency have been attributed to wearing of sunscreen to reduce the risk of skin cancers from sun exposure, which significantly reduces vitamin D synthesis in the skin. Compounding the problem is the fact that few foods naturally contain vitamin D and even intake of vitamin D-rich foods is often inadequate to satisfy vitamin D requirements, and that improving vitamin D status could result in positive effects on public health and potentially reduce health care costs for many chronic diseases.

However, the optimum level of Vitamin D intake from food and supplementation is an issue of controversy, with some advocates, including some clinicians specializing in treatment of chronic widespread pain (CWP) disorders like fibromyalgia and myofacial pain syndrome, believe that Vitamin D supplementation far higher than the IOM/NAS 600-800 IU RDAs are warranted.

Earlier this year, two teams of researchers from Canada and the US. respectively released studies indicating that the official RDAs for vitamin D are ten times lower than what the human body actually needs. Leader of the U.S. team, Dr. Cederic Garland, an adjunct professor at the University of California, San Diego’s Department of Family and Preventive Medicine in La Jolla, California, told RelaxNews “The error has broad implications for public health regarding disease prevention and achieving the stated goal of ensuring that the whole population has enough vitamin D to maintain bone health.”

In an Open Access letter published in the journal Nutrients entitled “A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D” Nutrients 2014, 6(10), 4472-4475; doi:10.3390/nu6104472) Professor Paul J. Veugelers and postdoctoral fellow/Epidemiologist/Biostatistician John Paul Ekwaru of the University of Alberta School of Public Health at Edmonton, Alberta, Canada, argue that “The public health and clinical implications of the miscalculated RDA for vitamin D are serious. With the current recommendation of 600 IU, bone health objectives and disease and injury prevention targets will not be met,” and recommend that the RDA for vitamin D be reconsidered “to allow for appropriate public health and clinical decision-making.”

The U.S. research team, which includes Dr. Garland, Robert Heaney of Creighton University at Omaha, Nebraska, Carole Baggerly and Christine French of GrassrootsHealth in Encinitas, California, and Edward Gorham of the University of California, San Diego, Department of Family and Preventive Medicine at La Jolla, also in a letter published in Nutriients, present data from a different cohort entirely, including many individuals with vitamin D intakes spanning a range from zero to above 10,000 IU per day, noting that while the 3875 IU intake value they estimate is needed needed to achieve at least 20 ng/mL (50 nmol/L) Vitamin D levels in 97.5 perent of the population is lower than the estimate of Drs. Veugelers and Ekwaru, both estimates are roughly an order of magnitude higher than the published IOM value.

Pertaining to Vitamin D levels associated with fibromyalgia and other chronic pain disorders, a paper published in the current September/October 2015 Issue of the journal Pain Physician (2015 Sep-Oct;18(5):- Vol 18 Issue 5″ by a team of researchers at the National Taiwan University Hospital and National Taiwan University College of Medicine in Taipei, Taiwan, entitled “Is Serum Hypovitaminosis D Associated with Chronic Widespread Pain Including Fibromyalgia? A Meta-analysis of Observational Studies.”

The coauthors, Ming-Yen Hsiao, MD, Chen-Yu Hung, MD, Ke-Vin Chang, MD, Der-Sheng Han, MD, PhD, and Tyng-Guey Wang, MD., note that “Chronic widespread pain (CWP) is a global musculoskeletal disorder leading to disability and a reduced quality of life,” and that “low levels of serum vitamin D ha[ve] long been proposed to be associated with CWP, but previous research remains inconclusive.” The objective if their study was to determine whether hypovitaminosis D is independently associated with CWP syndromes.

Electronic databases were searched for studies published up to November 2014 comparing prevalence of hypovitaminosis D and serum vitamin D levels between participants with and without CWP. Crude and adjusted odds ratios (ORs) of hypovitaminosis D with CWP were also calculated. Subgroup analysis according to gender, threshold of hypovitaminosis, and definition of patients was performed, as well as meta-regression to test the linear relationship between crude ORs and the latitude of study locations.

The twelve studies analyzedcumulatively comprised 1,854 patients with CWP, that patient group showing a significantly higher risk of hypovitaminosis D than the control group, a finding that leads the researchers to conclude that there is a positive crude association between hypovitaminosis D and CWP, and the association was likely to remain after adjusting confounding factors. They note that use of a cut-off value of hypovitaminosis D (8 – 10 ng/mL) could better define the population with and without CWP, and that further prospective follow-up studies are warranted to clarify the causal relationship between hypovitaminosis D and CWP.

The Taiwanese team’s conclusions are consistent with those of a 2014 study published in the Journal of Advances in Internal Medicine entitled “Study of hypovitaminosis D as a cause of chronic widespread pain in patients presenting to rheumatology clinic” (Journal of Advances in Internal Medicine Vol 3, No 1 (2014 DOI: http://dx.doi.org/10.3126/jaim.v3i1.10694) by Nepalese researchers Binit Vaidya, Shweta Nakarmi, Arvind Chaudhary, Poojan Batajoo, and Nija Rajbhandari who suggest that deficient vitamin-D levels are likely to be associated with chronic muscular pains.

The researchers conducted a prospective open labeled study at a rheumatology clinic from December 2009 to December 2012 in which patients with chronic widespread pain and bone pains of three months duration or longer were included. Hypothyroidism, chronic renal failure and other rheumatological diagnoses other than fibromyalgia were excluded. Visual analogue score (VAS) for pain and serum Vitamin-D levels were measured. Patients with low Vitamin-D were given oral Vitamin-D 60,000 IU for 6 months, with response to therapy evaluated using improvement in VAS.

Among 1680 patients whose cases were studied, Hypovitaminosis-D was seen in 1388 of which 27 had severe deficiency with Vitamin D levels. After 6 months of treatment, no improvement was seen in 196 patients and all non-responders had fibromyalgia overlap. Vitamin- D level was checked again in non-responders and repeat vitamin-D levels were still low in 10 of them.

From tese data the investigators conclude that Hypovitaminosis-D can be a significant cause of chronic widespread pain in the general population and seems to aggravate the pain of fibromyalgia, with improvement from the 60,000 IU supplementation treatment rapid and better in severe cases.

Sources:
NIH National Library of Medicine
Nutrients
Pain Physician
Journal of Advances in Internal Medicine
RelaxNews
Wikipedia