Vitamin D deficiency in sun drenched India - can d-lightful sunlight be a respite? - sunlight d lemma

Abstract

Vitamin D is one of the oldest hormones; 500 million-years old phytoplankton species in Sargasso Sea were found to contain large amount of ergosterol (Vitamin D2 precursor). Ergosterol is transferred along the food chain into the sea food, where it is stored and concentrated. Vitamin D was essential for calcium and bone homeostasis to cope with higher gravity in terrestrial animals. In humans Vitamin D is synthesized on exposure to mid-day sunlight (UV-B rays 290-315 nm). The widespread Vitamin D deficiency [25(OH)D< 20 ng/ml] in India appear to be due to changes in lifestyle-sun shy attitude, dress code and, lack of dietary calcium. Experimental studies from India have shown that, Indians can synthesise enough Vitamin D on exposure to sunlight. Vitamin D orchestrates the "Ca-Vitamin D-Parathyroid hormone endocrine axis. Calcitriol, the active form of Vitamin D follows either of the two-pathways. Genomic responses-takes anything from few hours to days to become fully manifest (osseous benefits); Chemical messengers that transmits signals and rapid responses (RR) which vary from few seconds to an hour (non-osseous benefits e.g., insulin secretion, intestinal calcium absorption). Association with Vitamin D deficiency has been reported in hypertension, diabetes, psoriasis, Chron's disease, multiple sclerosis, prostatic and colonic cancer. For osseous benefits the Vitamin D levels should be above >20ng/ml, while for non-osseous benefit requires 25(OH)D levels >30 ng/ml. Adequate dietary calcium intake of 1gm/day has to be ensured.