Vitamin D deficiency 2.0: an update on the current status worldwide

Abstract

Vitamin D testing and the use of vitamin D supplements have increased substantially in recent years. Currently, the role of vitamin D supplementation, and the optimal vitamin D dose and status, is a subject of debate, because large interventional studies have been unable to show a clear benefit (in mostly vitamin D replete populations). This may be attributed to limitations in trial design, as most studies did not meet the basic requirements of a nutrient intervention study, including vitamin D-replete populations, too small sample sizes, and inconsistent intervention methods regarding dose and metabolites. Vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] < 50 nmol/L or 20 ng/ml) is associated with unfavorable skeletal outcomes, including fractures and bone loss. A 25(OH)D level of >50 nmol/L or 20 ng/ml is, therefore, the primary treatment goal, although some data suggest a benefit for a higher threshold. Severe vitamin D deficiency with a 25(OH)D concentration below <30 nmol/L (or 12 ng/ml) dramatically increases the risk of excess mortality, infections, and many other diseases, and should be avoided whenever possible. The data on a benefit for mortality and prevention of infections, at least in severely deficient individuals, appear convincing. Vitamin D is clearly not a panacea, and is most likely efficient only in deficiency. Given its rare side effects and its relatively wide safety margin, it may be an important, inexpensive, and safe adjuvant therapy for many diseases, but future large and well-designed studies should evaluate this further. A worldwide public health intervention that includes vitamin D supplementation in certain risk groups, and systematic vitamin D food fortification to avoid severe vitamin D deficiency, would appear to be important. In this narrative review, the current international literature on vitamin D deficiency, its relevance, and therapeutic options is discussed.

Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths

“…A recent review on the status of vitamin D deficiency worldwide stated that because of inadequate evidence from clinical trials, "a 25(OH)D level of >50 nmol/L or 20 ng/mL is, therefore, the primary treatment goal, although some data suggest a benefit for a higher threshold" [147]. A companion article in the same issue of the journal stated, "although 20 ng/mL seems adequate to reduce risk of skeletal problems and ARTIs, concentrations above 30 ng/mL have been associated with reduced risk of cancer, type 2 diabetes mellitus, and adverse pregnancy and birth outcomes" [148].…”

<p>Associations Between Serum 25-Hydroxyvitamin D Levels and Thyroid Function Parameters in Previously Healthy Children Aged 6 to 24 Months</p>

“…16 According to the definition used in this crosssectional study of children aged 6-24 months, our findings are in agreement with the findings of other reports that show a high prevalence of vitamin D deficiency and insufficiency. 6 Of the children without overt thyroid diseases, 2.9% were detected with hypothyroidism. Statistically, a significant association was found between vitamin D deficiency and the risk of hypothyroidism.…”

“…2,3 Testing of vitamin D levels has substantially increased in recent years, and emerging evidence suggests that vitamin D insufficiency is a common condition worldwide. 4,5 Vitamin D insufficiency, defined as 25-hydroxyvitamin D [25(OH)D] level < 75 nmol/L, is estimated to affect 40% of the population, 6 and it might be a novel risk factor for some chronic diseases. Consequently, many studies have disclosed the possible role of vitamin D in non-skeletal clinical outcomes, including autoimmune diseases, infectious diseases, metabolic syndromes, and cardiovascular disorders.…”

The Sun’s Vitamin in Adult Patients Affected by Prader–Willi Syndrome

“…Reduced intake of food containing vitamin D, less sunlight exposure, and scarce or absent physical activity (with preference given to indoor leisure activities) are all conditions that contribute to an increased risk of vitamin D deficiency in PWS adults. Taking into account the growing evidence of bidirectional, albeit debatable, relationships between vitamin D, obesity, and several chronic diseases [1,2,[10][11][12][13]61,62], the importance of a sufficient vitamin D status could be of strategic relevance to managing the metabolic consequences of PWS in adults, in addition to the prevention and the treatment of bone alterations in these patients. Thus, trained nutritionists should be an integral part of any multidisciplinary care team, in order to ensure the adequate intake and/or supplements of micronutrients such as vitamin D.…”