Calcium and Vitamin D in Human Health: Hype or Real?

Publication date: Available online 16 December 2017
Source:The Journal of Steroid Biochemistry and Molecular Biology
Author(s): Sunil J. Wimalawansa, DSc.Mohammed S. Razzaque, Nasser M. Al-Daghri
The incidence and the prevalence of vitamin D deficiency are increasing worldwide. It is estimated that over 50% of population in the world have low in vitamin D (i.e., hypovitaminosis D; levels below 30 ng/mL). 80% of our vitamin D requirement comes from the ultraviolet rays from sunlight, and for the remainder, we rely from the diet and supplements. The latter become important when one is exposing to less than optimal amounts of sunlight, inability of the skin to generate vitamin D efficiently, and/or having secondary causes that leads to increase catabolism of vitamin D. The normal serum vitamin D level is thought to be about 30 ng/mL (75 nmol/L); a range between 30 and 60 ng/mL (75 and 150 nmol/L). The Institute of Medicine (IOM) report of 2011 suggests, 600 IU is adequate for people below the age 71 who are not exposed to sunshine. Although IOM amount might be of relevance to the ambulatory healthy individuals, in disease conditions, very few patients would manage to reach serum vitamin D level above 30 ng/mL, which most scientists consider the minimum adequate level for optimal health. While the natural way to obtain vitamin D is through safe sunlight exposure, an additional daily intake of 1,000 IU of vitamin D is needed for people with lighter-skin color. With suboptimal sun exposure in those with dark-skinned and older adults need an additional 2,000 IU/day or more, vitamin D to maintain serum 25-hydroxyvitamin D levels over 30 ng/mL; the safe upper limit of oral daily supplementation is considered as 5,000 IU. However, vulnerable groups including those who are disabled, obese, and those with gastrointestinal abnormalities and/or malabsorption syndromes, institutionalized people (e.g., nursing homes and in prisons), and during pregnancy and lactation, needs approximately 4,000 IU per day for optimal physiological activities. Vitamin D is critical for enhancing gastrointestinal calcium absorption and mineralization of the osteoid tissue. In is also important for other physiological functions, such as muscle strength and neuromuscular coordination, release of hormones, subduing autoimmunity, and curtailing the development of certain cancers.



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