Vitamin D status and its relationship with bone mineral density in healthy Asian Indians

Abstract

Synthesis of vitamin D takes place in the skin under the effect of sunlight. The Indian subcontinent is situated between 8.4 degrees N and 37.6 degrees N latitudes and has adequate sunshine throughout the year. Thus, it has been presumed that Indians are vitamin D sufficient. We measured serum 25-hydroxy vitamin D [25(OH)D] ( n=92) and 1,25-dihydroxy vitamin D [1, 25(OH)(2)D] ( n=65) levels in healthy hospital staff, using (125)I radioimmunoassay. Serum intact parathyroid hormone (PTH) concentration was estimated by immunoradiometric assay. Bone mineral density was estimated using a dual energy X-ray absorptiometer (Hologic QDR 4500A). Using a serum 25(OH)D level of 15 ng/ml as a cutoff, 66.3% (61/92) of the subjects were found to be vitamin D deficient. Of these, 20.6% (19/92) subjects had severe vitamin D deficiency (<5 ng/ml), 27.2% (25/92) had moderate vitamin D deficiency (5-9.9 ng/ml), while 18.5% (17/92) had mild vitamin D deficiency (10-14.9 ng/ml). When a serum 25(OH)D level of 20 ng/ml was used as a cutoff, 78.3% subjects were diagnosed to be vitamin D deficient/insufficient. The serum 1,25(OH)(2)D level was within the normal range (40.6+/-20.1 pg/ml; mean +/- SD). Mean (+/-SD) serum intact PTH, estimated in a limited number of subjects (n=15), was 72.3 (+/-21.0) pg/ml (range 36-100 pg/ml). There was a significant correlation between daily sun exposure and 25(OH)D levels (r=0.731, P<0.001). The serum 25(OH)D level correlated with BMD at the femoral neck and Ward's triangle (r=0.50, P=0.020 and r=0.46, P=0.037, respectively). Our findings show that vitamin D deficiency is common in urban north Indian hospital staff. The possible reasons include inadequate sunlight exposure and skin pigmentation in Indians. The serum 1,25(OH)(2)D level is not a good indicator of vitamin D deficiency. A low serum 25(OH)D level is possibly one of the reasons for lower bone mineral density among Indians.

Vitamin D status and metabolic syndrome in Asian Indians

“…7,14,15 We observed an inverse relationship of serum 25-OH-D with BMI in this study that has been previously accounted by the solubility and storage of the compound in enlarged fat mass. 16 Interestingly, Asian Indians have been included in the category of 'metabolically obese normal weight' group, as they tend to have more disproportionately higher total body fat at any given BMI compared with those of the other ethnicities 7,17 that might also lead to a false characterization of individuals as vitamin D deficient, based on their serum estimates.…”

Vitamin D supplementation in patients with nonalcoholic fatty liver disease: A randomized controlled trial

“…It is also highly prevalent across all age groups ranging from newborns to postmenopausal women. In three different studies from North India, 96% of neonates,23 91% of healthy school girls,24 and 78% of healthy hospital staff were found to have hypovitaminosis D 25…”

Current Scenario of Prevalence of Vitamin D Deficiency in Ostensibly Healthy Indian Population: A Hospital Based Retrospective Study

“…Earlier countrywide studies have reported vitamin D deficiency as being very prevalent in India [1] even healthy young soldiers and sports woman with sufficient intake of calcium, adequate sun exposure and regular exercise regimen were found to be vitamin D deficient [7,17]. Studies have shown that the 25(OH) D levels are directly proportional to the duration of exposure to sunlight [7,18]. The amount of UV light at a geographical location depends on the length the sun's rays which have to travel through the atmosphere, where it is more or less absorbed.…”