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 don t 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.