Vitamin D: recent advances, associated factors, and its role in combating non-communicable diseases

Abstract

The field of nutrigenomics has produced numerous studies indicating the impact of vitamin D on various disease conditions. Trace elements of this vitamin in the body play a significant role in the regulation of body metabolism. This immunomodulatory vitamin plays a role in management of both communicable (viz. respiratory illness like COVID-19 and Respiratory tract infections) and non-communicable diseases e.g., cancer, osteomalacia, diabetes, and cardiovascular diseases. Deficient levels, i.e., vitamin D deficiency in body can lead to the onset of chronic non-communicable illnesses. Vitamin D plays a direct and sometimes indirect role in the progression (when deficient) and prevention (when sufficient) of non-communicable diseases. This essential nutrient may be obtained through dietary intake or supplements. However, the absorption of it relies on various factors, including the presence of complementary nutrients, chemical forms, and external stimuli such as UV-B and a healthy gastrointestinal tract. This review discusses vitamin D absorption and its role in non-communicable diseases with updates on methods for evaluating and fortifying this vitamin in varied diets. We also briefly highlight recommended dietary allowances by age group, absorption difficulties, and its significance in non-communicable disorders.

Fig. 1. Average number of deaths (in million), due to most common NCDs i.e.

Cardiovascular and respiratory diseases and diabetes in America (top left), Europe (top right), South-East Asia (bottom left) and India (bottom right) during 2009–2019. Adopted from: WHO, world health statistics. (This Figure was created by the authors).

Fig. 2. Process of vitamin D synthesis and regulation in body.

(This Figure was created by the authors).

Fig. 3. Role of vitamin D in the inhibition of cancer cells by targeting genes associated with cell proliferation pathways.

(IGBP- Immunoglobin binding protein; p21- also known as wildtype activating factor-1/cyclin-dependent kinase inhibitor protein-1; VEFG-Vascular endothelial growth factor). (This Figure was created by the authors).

Fig. 4. Regulation of the biosynthesis of vitamin D - regulated protein: VDR is intracellular and can bind to 1,25(OH)₂D₃.

This causes VDR to bind to the retinoid X receptor (RXR), translocate to the nucleus, and bind to the regulator site in the promotor region of DNA sequence elements. This in turn boost the synthesis of vitamin D-regulated proteins. (VDR: Vitamin D receptor; RXR: retinoid X receptor; VDRE: Vitamin D Response Element). (This Figure was created by the authors).