Abstract
Vitamin D is very important for bone metabolism as well as for the prevention of various diseases, such as type 2 diabetes, cardiovascular disease and different types of cancer. Although vitamin D deficiency is widespread and an important public health problem, there exists controversy in the scientific community, with no established standard definition of adequate and deficient vitamin D status. To add new information on this topic, the aim of this brief opinion paper is to identify and discuss the optimal 25(OH)D concentration (range) for a reduction in the risk of various disease outcomes by summarizing dose-response reporting meta-analyses.