The Sunny Side of Vitamin D

While there are conflicting studies on the utility of vitamin D supplementation, it continues to be prescribed as go to ambrosia in many disease states. The cardio-protective, anti-cancer & even bone density enhancing properties of vitamin D are yet to be fully understood [1]. However, this does not entirely belittle the benefits of vitamin D supplementation. Cochrane datasets hold testimony to the advantage that vitamin D supplementation offers in Pre-eclampsia, gestational diabetes & low birth weight babies [2]. Nutritional rickets is a disease which has existed since medical history has been documented. Though vitamin D supplementation seems to thwart disease progression in children the same results are not evident when vitamin D supplements are given to adults. Many large RCTs have generated new results regarding the effects of vitamin D supplementation on the adult skeleton. The VITAL Bone Health study, aimed at evaluating the effects of vitamin D on bone structure and architecture, is a well-known example among physicians. The study included a cohort of 771 participants (men aged over 50 years and women aged over 55 years who had never taken vitamin D supplements in their lifetime. The same subjects were given supplements & evaluated at baseline and after 2 years. Supplemental vitamin D (compared with placebo) had no effect on 2 years changes in areal Bone Mineral Density (BMD) at the spine, femoral neck, total hip or whole body, or on measures of bone structure. This conclusion remained valid in a subgroup analysis, including individuals with the lowest vitamin D status (as measured by total 25OHD) at baseline.

New technology allows the direct measurement of free (non-protein-bound) 25OHD as an alternative strategy to define vitamin D status. In participants of the VITAL trial with the lowest directly measured free 25OHD concentrations, vitamin D supplementation generated a slight increase in spine areal BMD (0.75% in the vitamin D group versus 0% in the placebo group; P=0.043) and attenuation in loss of total hip areal BMD (-0.42% in the vitamin D group versus -0.98% in the placebo group; P=0.044).Clinical significance & implication of this marginal increase is debatable [3]. Vitamin D is a nutrient which plays a pivotal role in homeostasis beyond the musculoskeletal system. Genetic mechanisms & genes responsible for Vitamin D synthesis are being extensively studied & estimation of 25OHD levels is becoming ever increasingly common. It could be hypothesized that genetic mechanisms can determine the bio-availability of vitamin D. A single yardstick such as estimation of 25OHD levels cannot be applied to determine candidates for vitamin D supplementation. With advanced tools such as next generation sequencing & microarrays genetic such genetic mechanisms are likely to be studied with more rigor & our understanding of the sunshine vitamin is bound to grow in the near future.

1. Djade C, Porgo T, Zomahoun H, Perrault‐Sullivan G, Dionne CE (2019) Incidence of shoulder pain in 40 years old and over and associated factors: A systematic review. European Journal of Pain 24(1): 39-50.
2. Blyth F, Briggs A, Schneider C, Hoy D, March L (2019) The global burden of musculoskeletal pain-where to from here? American Journal of Public Health 109(1): 35-40.
3. Thiruvarangan S, Shaminy T (2021) Diagnostic accuracy of clinical tests to diagnose subacromial impingement syndrome: A systematic review. International Journal of Research Publications 78(1): 80-100.
4. Lewis J, McCreesh K, Roy J, Ginn K (2015) Rotator cuff tendinopathy: Navigating the diagnosis-management conundrum. Journal of Orthopaedic & Sports Physical Therapy 45(11): 923-937.
5. Hegedus E, Cook C, Brennan M, Wyland D, Garrison J, et al (2009) Vascularity and tendon pathology in the rotator cuff: A review of literature and implications for rehabilitation and surgery. British Journal of Sports Medicine 44(12): 838-847.