Maintenance of Vitamin D Sufficiency With Oral Vitamin D Supplementation in Malaysian Women of Malay and Indian Ethnicity With Post Menopausal Osteoporosis

Much research on vitamin D status has focused on seasonal variations in serum 25(OH)D levels in populations living at high altitudes and those of light-skinned Caucasian extraction, with little work done in multi ethnic populations living closer to the equator with regards to Vitamin d supplementation, prevalence, predictors and associations of hypovitaminosis D - the assumption, perhaps being vitamin D deficiency is unlikely in locations of plentiful sunshine. There is a dearth of studies on Vitamin D status in a group of subjects at especially high risk of falls/fractures i.e. post-menopausal women with osteoporosis living in South-East Asia. It is possible that differences in geography and ethnicity/culture amongst women with post menopausal osteoporosis (PMO) in Malaysia may necessitate supplemental Vitamin D doses that differ from those prescribed to North American Caucasians.

There is no unified consensus on the dose of Vitamin D supplementation. Neither is there agreement on definitions of sufficiency with some researchers targeting levels of serum 25(OH)D of >20ng/ml and others aiming for levels above 30ng/ml. The Institute of Medicine (IOM) 2010 guidelines, aiming for a lower serum 25(OH)D target of 20ng/ml, advocates maintenance doses of 600 IU/day in Postmenopausal women aged 51-70 and 800 IU/day for those aged >70 years. On contrary, the Endocrine Society 2011 guidelines state that maintenance doses up to 1500-2000 IU/day may be required to attain a higher optimal target of >30ng/ml. On addition, the 2014 National Osteoporosis Foundation Guidelines recommended that the Vitamin D level should be brought up to approximately 30ng/ml, and to maintain at this level taking into account those with limited sun exposure, obese and dark skin individuals, the daily requirement ranges from 800-2000 IU/day.

The investigators therefore designed a prospective randomized controlled trial comparing efficacy and safety of a low (900 IU/day) and high (1800IU/day and 3300IU/day) maintenance dose of Cholecalciferol (Vitamin D3) amongst community dwelling Indian and Malay with PMO living in Kuala Lumpur, Malaysia.

Hypothesis of the study is despite abundant exposure to sunlight, which is the main Vitamin D supplier, those who dress conservatively and individuals with darker skin may require a higher dose of Vitamin D to maintain sufficiency (>30ng/ml).