The optimum serum 25(OH)D level for patients with bone disorders like osteoporosis is 30 ng/dL (International Osteoporosis Foundation 2010, Endocrine Society 2011). For older adults (>50 years) at risk for osteoporosis, a serum 25(OH)D level of 30 ng/ml is also preferable (IOF).There is lack of unanimity in international guidelines on this issue (IOF, Endocrine Society, Institute of Medicine (IOM), National Osteoporosis Society (NOS) although evidence does suggest that for those who have osteoporosis or those who are prone to osteoporosis, levels of 30 ng may be most appropriate.For other patient groups or population, those who do not have osteoporosis, or dont have bone conditions, serum 25OHD values of 20 ng/ml may be considered adequate. Many Indians may require supplementation to achieve this level (IOF 2010) There is insufficient data to suggest that levels above 40 ng/ml provide any additional benefit. Therefore, serum 25(OH)D levels between 20-40 ng/ml are optimum for most population. For those who are at higher risk for osteoporosis, the elderly or those who already have bone disease, serum 25(OH)D levels should be kept above 30 ng/ml i.e. between 30 and 40 ng per ml.