Nutrihealth Study: Seasonal Variation in Vitamin D Status Among the Slovenian Adult and Elderly Population

Abstract

Several studies conducted around the world showed substantial vitamin D insufficiency and deficiency among different population groups. Sources of vitamin D in the human body include ultraviolet B (UVB)-light-induced biosynthesis and dietary intake, but people’s diets are often poor in vitamin D. Furthermore, in many regions, sun exposure and the intensity of UVB irradiation during wintertime are not sufficient for vitamin D biosynthesis. In Slovenia, epidemiological data about vitamin D status in the population were investigated through a national Nutrihealth study—an extension to the national dietary survey SI.Menu (2017/18). The study was conducted on a representative sample of 125 adult (18–64 years) and 155 elderly (65–74 years old) subjects, enrolled in the study in different seasons. Their vitamin D status was determined by measuring the serum 25-hydroxy-vitamin D (25(OH)D) concentration. Thresholds for vitamin D deficiency and insufficiency were 25(OH)D levels below 30 and 50 nmol/L, respectively. Altogether, 24.9% of the adults and 23.5% of the elderly were found to be vitamin D deficient, while an insufficient status was found in 58.2% and 62.9%, respectively. A particularly concerning situation was observed during extended wintertime (November–April); vitamin D deficiency was found in 40.8% and 34.6%, and insufficient serum 25(OH)D levels were observed in 81.6% and 78.8%, respectively. The results of the study showed high seasonal variation in serum 25(OH)D levels in both the adult and elderly population, with deficiency being especially pronounced during wintertime. The prevalence of this deficiency in Slovenia is among the highest in Europe and poses a possible public health risk that needs to be addressed with appropriate recommendations and/or policy interventions.

Prevalence of vitamin D is not associated with the COVID-19 epidemic in Europe. A critical update of the existing evidence

“…<20 ng/ml or <50 nmol/l). 25,27,31,34,[39][40][41]43,[45][46][47] The size of study population which was used to retrieve data for the prevalence of Vit D deficiency varied from 280 (Slovenia) 43 to 74.235 subjects (Italy). 37 As of February, 4 th We also examined the relationships between COVID-19 infections, recoveries and deaths with the mean vitamin D concentration of each country, as can been seen in the Supplementary Material, but again no significant correlation was found.…”

“…<20 ng/ml or <50 nmol/l). 25,27,31,34,39-41,43,45-47 The size of study population which was used to retrieve data for the prevalence of Vit D deficiency varied from 280 (Slovenia) 43 to 74.235 subjects (Italy). 37…”

“…10,21,22 According to the outcomes of our study, in several of the European countries included in this analysis, more than 50% of the adult population was Vit D deficient, which constitutes a factor that should not be disregarded in the planning of public health preventive measures. 25,27,31,34,[39][40][41]43,[45][46][47] Factors that can influence Vit D concentration include the fluctuations of sunlight exposure among seasons, 48 especially the negligible amount of sunlight during winter and cloud covers during summer could potentially reduce the cutaneous synthesis of Vit D in some less south located countries, 49,50 as well as extend of clothing coverage and sunscreen use. 51,52 Furthermore, dietary sources of Vit D are limited and the obesity epidemic in the Europe, which is also related to poorer dietary choices, can worsen its deficiency.…”

Socio-Demographic and Knowledge-Related Determinants of Vitamin D Supplementation in the Context of the COVID-19 Pandemic: Assessment of an Educational Intervention

“…Therefore, substantial proportions of the European population rely on dietary vitamin D and body stores to maintain a sufficient vitamin D status during the extended winter season, and quite a high prevalence of vitamin D deficiency is reported in many countries worldwide (30)(31)(32)(33). Alarmingly, in a very recent nationally representative study for Slovenia (34), during the extended winter season vitamin D deficiency was found in about 80% of adults (18-74 years), while almost 40% had a severe vitamin D deficiency, with serum 25(OH)D levels below 30 nmol/l.…”

An Approach to Investigate Content-Related Quality of Nutraceuticals Used by Slovenian Consumers: A Case Study with Folate and Vitamin D Supplements

“…Another relevant example involves food supplements intended for supplementing vitamin D. In many countries, an extremely high prevalence of vitamin D deficiency has been reported, particularly during winter periods [34][35][36], due to seasonal variations in the efficiency of the ultraviolet B (UVB)-induced biosynthesis of vitamin D in human skin [37]. In Slovenia, for example, about 80% of the adult population was found to have insufficient vitamin D levels between October and April [35]. Though there are differences between countries, the recommended daily intake of vitamin D for adults (in the absence of endogenous synthesis) is usually between 15 and 20 µg [38,39].…”