Vitamin D Deficiency: Health at Risk for Many Europeans

Thirteen percent of the European Union population, regardless of age or ethnicity, suffers from vitamin D deficiency. This percentage represents a true pandemic and highlights a serious public health issue; vitamin D is essential for preventing bone deformities such as rickets in children and osteomalacia in adults.

These are some of the data reported by a project funded by the European Union, published last month in the American Journal of Clinical Nutrition, which involved numerous research centers across different countries of the old continent.

Vitamin D, an indispensable hormone for health

The actions of vitamin D are attributed to its active metabolite, namely 1,25-dihydroxycholecalciferol [1,25(OH)2 D3] or calcitriol. The main source of vitamin D in humans is skin exposure to sunlight, but it can also be obtained through diet. However, few foods naturally contain it: fatty fish, dried mushrooms, whole milk products, and eggs. Currently, vitamin D deficiency is estimated to be extremely widespread worldwide. 

Recent data indicate that, similar to many other industrialized nations, this deficiency affects about 70-80% of the elderly Italian population. 25(OH)D is the main circulating metabolite of vitamin D and, although measurement techniques are not yet fully standardized, its determination represents the most accurate method to estimate the vitamin’s reserves in the body. Moreover, while there is general agreement on the importance of preventing vitamin D deficiency, there is more heterogeneity regarding which 25(OH)D level defines hypovitaminosis. Conversely, it is almost universally recognized that 25(OH)D concentrations below 25-30 nanomoles per liter indicate vitamin D deficiency and signal risk for metabolic bone diseases.

Thousands of individuals in Europe suffer from vitamin D deficiency

The data collected in this study are part of a four-year project called ODIN, which started at the end of 2013. The project represents a multidisciplinary approach involving a team of experts from 19 European Union countries. The study revealed that, regardless of age and ethnicity, 13% of the 55,844 European individuals included in the research had average vitamin D levels below 30 nanomoles per liter throughout the year. This percentage increased to 17.7% from October to March and decreased to 8.3% from April to November. 

Among ethnic subgroups with darker skin, the prevalence of 25(OH)D levels below 30 nmol/L was 3 to 71 times higher compared to populations with lighter skin, depending on the country studied. In the case of deficiency defined as 25(OH)D concentration below 50 nmol/L, the overall prevalence rose to 40.4%. Vitamin D deficiency in Europe can be described as a pandemic, but the distribution of 25(OH)D blood levels data across the European Union is highly variable in quality.

A study using a standardized protocol

Previous investigations into vitamin D status in Europe used different data analysis methods, resulting in varying outcomes. This latest report instead employs a specific protocol: the VDSP program, which the researchers themselves described as "a solid platform on which to build public health" in Europe. Thanks to this protocol, it was possible for the first time to obtain internationally comparable data and reanalyze the results of numerous population studies. All values were combined with those from 4 previously standardized studies, providing data on a population of more than 54,000 European citizens of all ages.

Vitamin D hypovitaminosis: a widespread problem

Over the past 15 years, vitamin D has captured the attention of scientific and medical communities, regulatory agencies, the food industry, and citizens. This is demonstrated by the increase in scientific literature, requests for medical tests to determine vitamin D status, a series of dietary recommendation reassessments, sales of supplements, and the growing number of vitamin D-fortified food products on the market. 

In 1975, there were about 250 scientific articles concerning vitamin D; 30 years later, in 2007, this number rose to around 1,600, and by 2013 it had reached 3,774. Strategies to counteract vitamin D deficiency have been discussed in various European countries over the decades. Recently, Sweden expanded its list of fortified foods to help address the issue, largely due to low sunlight levels in the country. Meanwhile, an increase in rickets cases in the United Kingdom highlighted the need for similar mandatory or voluntary initiatives.

A deficiency requiring public health interventions

The results from the project highlight that vitamin D deficiency is indisputable throughout Europe, with prevalence rates requiring public health interventions. According to the researchers who conducted the study, these data provide clear evidence of vitamin D deficiency and suggest that European policy strategies should aim to ensure vitamin D intake to protect most of the population. 

Source: K. D. Cashman et al. “Vitamin D deficiency in Europe: pandemic?” American Journal of Clinical Nutrition 2016 Apr;103(4):1033-44.