Skeletal Muscle Strength,Bone Mineral Homeostasis and Th1 and Th2 Cytokines Expression in Asian Indians With Chronic Hypovitaminosis D Before and After Oral Cholecalciferol Supplementation

Vitamin D is an essential nutrient that plays an important role in calcium metabolism and bone health. In recent years, biomarkers like PTH, calcium absorption have been used to define relevant biological indices of vitamin D nutritional status. Several studies from India have shown wide prevalence of vitamin D deficiency (VDD) in India. Goswami et al studied serum 25 (OH)D levels and its functional significance in apparently healthy subjects residing in Delhi and showed low serum 25(OH)D values in all the groups (Am J Clin Nutr 2000). Its functional significance is currently under evaluation.

Relevant studies assessing functional significance of VDD in Asian Indians are summarized below (Am J Clin Nutr 2000).

A) Goswami et al while reporting low serum 25(OH) D concentrations in healthy subjects in Delhi, showed a higher serum PTH levels & significant inverse relation between serum 25(OH) D and PTH levels ( r = -0.6303, p < 0.001) in all the three groups (soldiers, physicians & nurses, depigmented persons) studied in winter (Am J Clin Nutr 2006) B) Effects on BMD Recently,we have analyzed relationship between BMD and serum 25(OH) D in 105 apparently healthy Asian Indian. The cohort of 105 subjects was split into 2 groups at a serum 25(OH) D cutoff of 9.0 ng/mL. The mean serum iPTH was significantly higher in the group 1 (<9.0 ng/ml)than in the group 2 subjects (53.1±31.3 and 39.3±17.5 pg/mL, respectively; P=0.012).The mean BMD values of the total hip, including femoral neck, trochanter, and intertrochanter, were significantly (P = 0.001) lower in group 1 than in group 2.

C) Effect of VDD on intestinal calcium absorption in Asian Indians with chronic hypovitaminosis D and its change after cholecalciferol supplementation was studied recently at our Department of Endocrinology and Metabolism. Study subjects were 29 apparently healthy volunteers [17 M, 12 F, mean (SD) age = 28.4 ± 6.4 year] with low serum 25(OH)D levels [mean (SD) = 7.6 ± 4.8 ng/ml]. Intestinal calcium absorption was assessed by 'calcium load test' (PAK test) (10) using 1 gm of oral elemental calcium load before and after (n = 26) supplementation with oral cholecalciferol (60,000 IU/week for eight weeks). This study showed that the vitamin D Deficiency is physiologically relevant in terms of intestinal calcium absorption in Asian Indians (Journal of Human Nutrition and dietetics 2010).

Recently in a randomized control trial we have shown significant improvement in the muscle strength and walking distance after dual supplementation with cholecalciferol and calcium (Clin Endocrinol 2010). In the current study we plan to study this aspect further by recruiting four groups to study the effect of calcium and vitamin D supplementation alone or in combination as a dual supplementation. Baseline evaluation (Before vitamin D supplementation) would include serum total calcium, inorganic phosphorus, alkaline phosphatase, intact PTH and 25(OH) D assays, hand grip muscle strength and surface EMG testing. Hand grip would be done will be done using a computerized dynamometer in the Department of Physical Medicine and Rehabilitation under the guidance of Professor U Singh, Head, Department of Physical Medicine & Rehabilitation, AIIMS. Handgrip strength will be measured in right hand by dynamometer. The average of two measurement of grip strength will be used for analysis (in kg).