Original ResearchVitamin D deficiency is common among adults in Wallonia (Belgium, 51°30′ North): findings from the Nutrition, Environment and Cardio-Vascular Health study
Introduction
Vitamin D deficiency is a worldwide problem that impacts all age, sex, socioeconomic, and educational and ethnic groups, with major human and financial consequences [1], [2]. Vitamin D status can be assessed by the determination of serum 25-hydroxyvitamin D (25(OH)D) concentration, the predominant circulating form of vitamin D. Although experts agree on the use of 25(OH)D to determine vitamin D status, the 25(OH)D threshold level defining vitamin D deficiency is still a matter of much debate. The Institute of Medicine (IOM) recently reported that a 25(OH)D level of at least 50 nmol/L (20 ng/mL) is largely sufficient and that the Recommended Dietary Allowance of 600 IU/d for ages 1 to 70 years should meet the requirements of 97.5% of the population. In addition, the IOM expert panel indicated that the only effects of vitamin D for which a “reasonably” evidence-based target value may be currently proposed are those on the bone health [3]. By contrast, according to the Endocrine Society group, vitamin D deficiency corresponds to 25(OH)D concentrations less than 50 nmol/L (20 ng/mL) and insufficiency to concentrations in the range of 50 to 75 nmol/L (20-30 ng/mL) [4]. Furthermore, experts of the Endocrine Society recommended a 25(OH)D level higher than 75 nmol/L to maximize the effect of vitamin D on musculoskeletal health and mineral metabolism and to provide most noncalcemic benefits for health. The discordance between the 2 conclusions is not surprising given the target difference between the guidelines. The IOM threshold is intended for public health policies, whereas the Endocrine Society group makes recommendations for clinical health care.
If severe vitamin D deficiency characterized by rickets in children and osteomalacia in adults is a rare condition in developed countries, subclinical vitamin D deficiency/insufficiency is highly prevalent and a potential risk factor for osteoporosis, falls, and fractures in the elderly [1], [5], [6]. Besides the important skeletal functions of vitamin D, a multitude of ecologic and observational studies have shown associations between low vitamin D and potential “nonskeletal” effects, notably increased risk of some cancers, cardiovascular disease, autoimmune diseases, infections, asthma and allergy, and all-cause mortality [7], [8], [9].
Diet and sunlight are the 2 main sources of vitamin D in humans. Only a limited number of foods naturally contain vitamin D. The well-known and significant one is marine fatty fish, barely consumed by Belgians [10]. Although several foodstuffs are enriched with vitamin D in the United States and Canada, the Belgian legislation on food fortification is quite restrictive. Margarine is the only food item that requires to be enriched with vitamin D [11], [12].
The major source of vitamin D comes from exposure to solar ultraviolet B (UVB) radiations (wavelength, 290-315 nm). Vitamin D is produced endogenously from 7-dehydrocholesterol in the epidermis of the skin after adequate exposure [1]. However, in Belgium (latitude 51° North), the amount of UVB photons reaching the surface of the earth is insufficient for almost 6 months of the year (October-March) to allow the skin photosynthesis of vitamin D [13]. The determinants of vitamin D status are multifactorial and include environmental and personal characteristics. Many environmental factors including latitude, season, time of day, and ozone pollution in the atmosphere diversify the number of solar UVB photons reaching the earth and influence the cutaneous production of vitamin D. Likewise, personal factors including age, skin pigmentation, body fat content, clothing, and sunscreen use inhibit cutaneous vitamin D synthesis and bioavailability [14], [15]. Low-vitamin-D diet coupled with insufficient exposure to sunshine is indicative of poor vitamin D status in Belgium. Contemporary lifestyle is also associated with reduced sun exposure (decreased outdoors activities) and use of UVB-blocking sunscreen. Obesity, another determinant of vitamin D status, is also highly prevalent in developed countries.
Despite numerous potential health effects reported, data on vitamin D status at a population level in Belgium are limited. Three studies have focused on 25(OH)D levels, but none was carried out in a representative sample of adults and determinants of vitamin D status were only briefly studied. In 2004, MacFarlane et al [16] conducted a study on 126 presumably healthy volunteers aged 21 to 65 years but during the late winter months. The prevalence of vitamin D deficiency was also assessed among 401 subjects aged 40 to 60 years, and the only determinant linked with serum 25(OH)D was ethnicity [17]. Serum 25(OH)D3 concentrations were also determined in 542 adults in the 1980s [18]. As noted recently by Cashman and Kiely [2], there is an ongoing need to assess vitamin D status in representative populations within Europe. Because of the paucity of Belgian data, the present research based on data collected from the Nutrition, Environment and Cardio-Vascular Health (NESCaV) cross-sectional survey was conducted to assess the vitamin D status in the general population of the province of Liège (Wallonia, Belgium) and to identify its potential determinants and relationship with vitamin D supplementation. First, it was hypothesized that vitamin D deficiency is common in the general population, particularly among subjects without vitamin D supplementation. Second, several determinants such as winter conditions, age, obesity, and lack of sun exposure are supposed to be indicative of poor vitamin D status. To test these hypotheses, the research objectives were (1) to determine the vitamin D status, using serum 25(OH)D concentrations, not only globally but also in subgroups of vitamin D supplement users and nonusers, and (2) to test the potential effects of subject characteristics on the prevalence of vitamin D deficiency in the 2 subgroups.
Section snippets
Study design
Data on vitamin D were available from the NESCaV, a population-based, cross-sectional survey of cardiovascular risk factors in Wallonia (Belgium, 51°30′ North). The survey was conducted between May 2010 and March 2012 by the Department of Public Health of the University of Liège jointly with the University Hospital within the framework of the European interregional program “INTERREG IVA.” The design of NESCaV has been described in detail elsewhere [19]. The protocol of the study was approved by
Characteristics of the participants
Of the 915 subjects, 208 (23.1%) reported vitamin D supplementation with a median (IQR) intake of 21 539 (14 213-43 944) IU/mo. Most supplemented subjects (79%) reported taking an ampoule containing an oily solution of 25 000 IU of cholecalciferol, whereas the others took multivitamins containing between 200 and 480 IU/tablet.
The characteristics of the participants are summarized in Table 1. Nearly all participants (99.8%) had vitamin D intakes lower than the nutritional levels recommended by the IOM
Discussion
To our knowledge, this is the first study to assess vitamin D status in a representative, population-based sample of apparently healthy individuals in Wallonia. We found that at least 4 of 10 participants had insufficient levels of 25(OH)D, whereas 44.7% had vitamin D deficiency (<50 nmol/L) and 34.9% vitamin D insufficiency (50-75 nmol/L). From these findings, the hypothesis that vitamin D deficiency is common in the general population of Wallonia is clearly confirmed. Given the limited number
Authorship
A.H. was involved in the research design and data collection of this work. She also drafted the manuscript. A.F.D. performed the statistical analyses and contributed to the critical discussion of the results. S.S. was involved in the design, data collection, and coordination of the NESCaV survey in Wallonia. P.K. as the co-promoter of the study provided counseling throughout the research project. J.P.C. as head of the central laboratory of the University Hospital of Liège supervised the
Acknowledgment
The present work benefited from the NESCaV project, financed by the European Regional Development Fund under the INTERREG IVA program in the Greater Region, the Walloon Region, and the Federation Wallonia-Brussels (NESCAV No. 39/GR/3/3/056).
References (37)
- et al.
Vitamin D and musculoskeletal health, cardiovascular disease, autoimmunity and cancer: recommendations for clinical practice
Autoimmun Rev
(2010) - et al.
Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies
Am J Clin Nutr
(2012) Who, what, where and when—influences on cutaneous vitamin D synthesis
Prog Biophys Mol Biol
(2006)- et al.
Decreased bioavailability of vitamin D in obesity
Am J Clin Nutr
(2000) - et al.
Hypovitaminosis D in a normal, apparently healthy urban European population
J Biochem Mol Biol
(2004) - et al.
Evaluation of automated immunoassays for 25(OH)-vitamin D determination in different critical populations before and after standardization of the assays
Clin Chim Acta
(2014) - et al.
Serum 25-hydroxyvitamin D: distribution and determinants in the Swiss population
Am J Clin Nutr
(1992) - et al.
Including food 25-hydroxyvitamin D in intake estimates may reduce the discrepancy between dietary and serum measures of vitamin D status
J Nutr
(2014) - et al.
Plasma 25-hydroxyvitamin D and its determinants in an elderly population sample
Am J Clin Nutr
(1997) Vitamin D deficiency
N Engl J Med
(2007)
Towards prevention of vitamin D deficiency and beyond: knowledge gaps and research needs in vitamin d nutrition and public health
Br J Nutr
Dietary reference intakes for calcium and vitamin D
Evaluation, treatment, and prevention of vitamin D deficiency: an endocrine society clinical practice guideline
J Clin Endocrinol Metab
Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomised controlled trials
Br Med J
Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials
Arch Intern Med
The nonskeletal effects of vitamin D: an endocrine society scientific statement
Endocr Rev
National food consumption survey: results
Cited by (24)
Worldwide vitamin D status
2023, Feldman and Pike's Vitamin D: Volume Two: Disease and TherapeuticsA critical update on the role of mild and serious vitamin D deficiency prevalence and the COVID-19 epidemic in Europe
2022, NutritionCitation Excerpt :Pearson correlation (two-tailed) tests were performed using IBM SPSS version 25.0 software. A total of 20 European countries satisfying the inclusion and exclusion criteria were selected for the analysis [25–44] (Table 1). Countries and territories excluded because of their limited population or lower number of COVID-19 tests were Andorra, the Channel Islands, the Faeroe Islands, Gibraltar, Iceland, the Isle of Man, Liechtenstein, Luxembourg, Malta, Monaco, Montenegro, San Marino, and Vatican City.
A dynamic online nomogram predicting severe vitamin D deficiency at ICU admission
2021, Clinical NutritionCitation Excerpt :However, other non-classical functions have been discovered that are related to the presence of alpha-1-hydroxylase and vitamin D receptors in many tissues of the body and to the ability of vitamin D to modulate the expression of certain genes through binding to these receptors, allowing it to exert an effect on the regulation of hormonal secretion, the control of the immune response, as well as on cell proliferation and differentiation [2]; a pathophysiological pathway that could possibly explain the association between hypovitaminosis D with cancer and cardiovascular diseases [3]. Over the last decade, a high prevalence of hypovitaminosis D has been reported in the general population, identifying, among other factors, geographic location, seasonal variations and sun exposure as determinants in its development [4] and was also demonstrated among the Belgian population [5,6]. Normal values are defined by a cut-off of 30 ng/mL by the Endocrine Society's Clinical Practice Guidelines [7].
Impact of vitamin D deficiency on COVID-19
2021, Clinical Nutrition ESPENGlobal Overview of Vitamin D Status
2017, Endocrinology and Metabolism Clinics of North AmericaAssessment of vitamin D levels, awareness among Lebanese pharmacy students, and impact of pharmacist counseling
2017, Journal of Epidemiology and Global HealthCitation Excerpt :Despite the adequate sunshine in Middle Eastern countries and more particularly in Lebanon, the incidence of hypovitaminosis D is high in all age groups, even in young individuals [15,16]. Several studies conducted all over the world, and particularly in Middle Eastern countries, mainly Lebanon, have shown low vitamin D levels in school children and postmenopausal women [17–19]. There is a high risk of low vitamin D levels in the Lebanese population since there is a lack of vitamin D fortified food.