Elsevier

Public Health

Volume 124, Issue 6, June 2010, Pages 350-359
Public Health

Original Research
Addressing vitamin D deficiency in Canada: A public health innovation whose time has come

https://doi.org/10.1016/j.puhe.2010.03.003Get rights and content

Summary

There is disturbing evidence of widespread vitamin D deficiency in many population groups, particularly within nations at high latitude. Numerous recent studies in the scientific literature associate vitamin D deficiency with a colossal increase in morbidity and mortality. Since Canada is at higher latitude, this review assesses the vitamin D status within the Canadian population. This review was prepared by assessing available medical and scientific literature from Medline, as well as by reviewing several books and conference proceedings. A standard 25(OH)D level of 75–80 nmol/l or more was used to indicate vitamin D sufficiency. Between 70% and 97% of Canadians demonstrate vitamin D insufficiency. Furthermore, studies assessing 25(OH)D levels of vitamin D at 25–40 nmol/l reveal that many Canadians have profoundly deficient levels.

Repletion of vitamin D3 with 2000 IU/day for those not receiving judicious sun exposure and those with no contra-indications would likely achieve normalized levels in more than 93% of patients, without risk of toxicity. Explicit directives regarding vitamin D assessment and management are urgently required.

Introduction

Involved in the regulation and expression of over 900 genes,1 vitamin D (VTD) has recently been recognized as an essential hormone required for innumerable physiological processes. Despite abundant evidence that VTD inadequacy is associated with widespread and assorted health problems including many cancers, heart disease, diabetes, infectious illnesses and autoimmune disorders,2, 3 numerous studies suggest an ongoing epidemic of VTD deficiency in Canada. With little risk and minimal cost, restoration of VTD adequacy with innovative public health interventions and low-cost supplementation may have the potential to ameliorate extensive suffering and dramatically improve the health and well-being of Canadians.

As ultraviolet B (UVB) rays from sunshine are the major source of VTD production in most people, various clinical studies show that high latitudes – where UVB sunlight intensity is too weak for extended periods to induce sufficient VTD skin synthesis for many people – have a major impact on VTD production. For example, reports in the literature suggest that 26.27% of Israelis (at 32°N), 57% of study participants in Boston (at 42°N) and 61–70% of Finns (at 64°N) have 25(OH)D levels lower than 37.5 nmol/l.4, 5, 6 Living at latitudes between 43° and 55°N, most Canadians are at high risk for VTD deficiency. This review was designed to assess the VTD status of the Canadian population as a whole.

There is ongoing discussion in the literature regarding optimal VTD status as measured by the main circulating metabolite, 25(OH)D. It has been known for some time, that 25(OH)D levels above 78 nmol/l are required to avoid increases of parathyroid hormone,7 and that absorption of calcium, magnesium and phosphate is maximized at values above 85 nmol/l.8 Levels of at least 90 nmol/l are suggested for genomic stability and prevention of cancer.9 With the existing state of knowledge, however, a cut-off value for VTD deficiency had previously been assigned as 75 nmol/l; a level that has been used in many studies. However, it has recently been suggested that ideal levels range from 100 to 150 nmol/l; values typically found in individuals with regular sun exposure living in sunny climates. Although toxicity is a distinct possibility with excessively high levels (above 250 nmol/l), the human body appears to have self-regulatory mechanisms to prevent toxicity, and thus the margin of safety is much higher than previously thought.10

Section snippets

Methodology

In this paper, an assessment of the VTD status in Canadians is performed by summarizing available published studies of 25(OH)D levels in population groups in Canada. This review was prepared by assessing available medical and scientific literature from Medline, as well as by reviewing several books and conference proceedings. Searching techniques included keyword searches with terms related to VTD and related disease. Available publications were reviewed, and incorporation of data was confined

Results

Recent Canadian research using a 25(OH)D level of 72–80 nmol/l as the standard for VTD adequacy demonstrates that 70–97% of the Canadian population in various clinical settings have an inadequate VTD status3, 12, 13, 14, 15, 16, 17 (Studies 1–7 in Table 1). Studies using values as low as 25–40 nmol/l as a cut-off show that 14–60% of various populations are affected18, 19, 20, 21, 22, 23, 24, 25, 26 (Studies 8–16 in Table 1).

Currently, the mean 25(OH)D level in the Canadian studies in Table 1 is

Discussion

Recent reviews of the literature highlight abundant evidence confirming the plethora of benefits of achieving improved VTD levels in the adult as well as the paediatric population.3, 28 Many studies demonstrate that VTD sufficiency significantly diminishes risk for acquiring several malignancies including prostate, colon, breast, pancreatic and lung cancers.2, 3, 28 The risk of assorted musculoskeletal conditions is lessened and rates of fatal stroke, hypertension, diabetes and incident

Concluding thoughts

A review of the available medical literature suggests that most Canadians have VTD insufficiency, with a considerable proportion of the population sustaining a severe deficiency. Rather than a spurious finding in one report, VTD inadequacy has been discovered repeatedly in various subpopulations within the country, and appears to be a consistent finding in all the population studies performed thus far in Canada.

Based on considerable evidence in the literature, innovative public health

Ethical approval

None sought.

Funding

None declared.

Competing interests

None declared.

Public health recommendations regarding VTD3 use in Canada

  • 1.

    Patients without regular sun exposure and who have no contraindications should be counselled to supplement with VTD3 2000 IU/day. Summer sun exposure in northern latitudes may reduce requirements for supplementation to 1000 IU/day from May to September.

  • 2.

    At-risk individuals should have a 25(OH)D assessment as some individuals will require more than 2000 IU/day to achieve optimal levels.

  • 3.

    As the half-life for VTD is approximately

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