The Importance of Preventing Vitamin D Deficiency

See article vol. 31: 524-539

Vitamin D deficiency is a global health concern that is associated with various diseases. The influence of vitamin D on bone metabolism is so important that such a deficiency may cause fractures and a reduction in bone mineral density. Natural foods provide a limited intake of vitamin D. Vitamin D is a fat-soluble vitamin that is mainly produced in the skin after exposure to sunlight. UV-B rays convert 7-dehydrocholesterol, a precursor of cholesterol, to pre-vitamin D3, which then isomerizes to cholecalciferol (Vitamin D3.) Vitamin D3 transforms into calcidiol (25(OH)D), which subsequently transforms into the active form, calcitriol (1.25 (OH) 2D). 1.25(OH)2D maintains calcium and phosphorus homeostasis through vitamin D receptor (VDR).

Recent studies have reported that vitamin D is involved in energy metabolism, inflammation, and the immune response. Furthermore, vitamin D deficiency has been reported to influence respiratory diseases, rheumatoid arthritis, cancer, diabetes, and pregnancy-related complications ¹⁾ . Vitamin D deficiency is generally defined by the serum 25(OH)D concentration. Most authors consider 25(H)D concentrations in the range of 30 ng/ml or higher to be sufficient and ＜12 ng/ml to indicate severe deficiency ²⁾ . According to recent studies, 26% of Europe’s general population and 40% of the United States’ general population are deficient (with serum 25(OH)D concentrations ＜30 nmol/L) in vitamin D. However, the frequency of vitamin D deficiency has tended to decrease year by year, with the spread of supplement usage being a possible cause of this phenomenon. However, there is concern that in many low- and lower-middle-income nations, the prevalence of vitamin D deficiency is increasing compared to that in Europe and North America. Therefore, Vitamin D Food Fortification supplementation has recently been prioritized for the prevention and treatment of vitamin D deficiency ³⁾ .

Reports of a correlation between vitamin D deficiency and dyslipidemia have occasionally appeared, although it is unclear whether there is an interaction between the two. Vitamin D deficiency is associated with an increased incidence of cardiovascular events ⁴⁾ . However, many randomized controlled trials have reported that vitamin D supplementation does not affect cardiovascular events ^{5 , 6)} . In contrast, a small randomized clinical trial showed that vitamin D supplementation can decrease the oxidized LDL levels in diabetic patients ⁷⁾ . Vitamin D supplementation has been reported to be effective in enhancing the effects of statin treatment and reducing side effects ¹⁾ .

Chen et al. indicated that vitamin D deficiency is associated with atherogenic dyslipidemia in young and middle-aged adults. They previously reported that vitamin D deficiency is associated with small dense low-density lipoproteins in middle-aged adults ^{8 , 9)} . The authors identified a large number of young adult patients with severe vitamin D deficiencies. They found that the negative associations between 25(OH)D levels and different biomarkers of atherogenic dyslipidemia (TCHO, TG, non-HDL-C, and LDL subpopulations) were independent of BMI and insulin resistance. Dysregulation of cholesterol and vitamin D metabolism occurs with aging, and this correlates with an increase in age-related diseases, but it is not clear how these two dysregulations are interrelated ¹⁰⁾ . It is important to note that, even in young adults, vitamin D deficiency is associated with unfavorable lipid profiles. Cardiovascular disease results from the accumulation of multiple risk factors and the duration since the onset of these risk factors. The early detection of the Vitamin D status may be effective not only for maintaining healthy bone metabolism, but also for preventing the occurrence of future cardiovascular events.

Although severe vitamin D deficiency dramatically increases the risk of infection and death, vitamin D supplementation is not necessary for the entire population. Although supplementation is effective in cases of vitamin D deficiency, few studies have shown that it is effective as a preventive measure. In addition, the problems of excessive supplement intake and sun exposure time should also be considered, and more debate on the indications and methods of appropriate vitamin D supplementation is therefore required. Although rare, very high supplement intake can lead to vitamin D intoxication. The exposure time to UV-B radiation required to produce the necessary amounts of vitamin D is not high, and excessive exposure time may cause skin cancer and various dermatological disorders ¹¹⁾ . Moderate exposure to sunlight and the intake of foods rich in vitamin D (e.g., fatty fish, egg yolk, and mushrooms), especially in winter when there is little sunlight, are therefore considered to be beneficial for preventing vitamin D deficiency and maintaining good health.

Conflicts of Interest

None.