PARATHYROIDS, BONE AND MINERAL METABOLISM: Edited by Seth M. ArumThe ongoing D-lemma of vitamin D supplementation for nonskeletal health and bone healthCharoenngam, Nipitha,b; Shirvani, Arasha; Holick, Michael F.aAuthor Information aVitamin D, Skin and Bone Research Laboratory, Section of Endocrinology, Nutrition, and Diabetes, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA bDepartment of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand Correspondence to Michael F. Holick, PhD, MD, Vitamin D, Skin and Bone Research Laboratory, Section of Endocrinology, Nutrition, and Diabetes, Department of Medicine, Boston University Medical Center, 85 E Newton St., M-1013, Boston, MA 02118, USA. Tel: +1 617 358 6139; e-mail: email@example.com Current Opinion in Endocrinology & Diabetes and Obesity: December 2019 - Volume 26 - Issue 6 - p 301-305 doi: 10.1097/MED.0000000000000508 Buy Metrics Abstract Purpose of review The goal of this review is to give some perspective on the results and conclusions of three recent randomized controlled vitamin D intervention studies that have challenged the health benefit of vitamin D supplementation for reducing risk for cardiovascular disease, cancer, all-cause mortality and type 2 diabetes and improving bone health. Recent findings Vitamin D supplementation to adults who were vitamin D sufficient or insufficient did not reduce risk for developing cardiovascular disease, cancer, type 2 diabetes nor increases bone mineral density (BMD). Patients who were vitamin D deficient with cancer and received vitamin D reduced risk for mortality by 25% and prediabetic adults who were vitamin D deficient and received vitamin D reduced their risk of developing type 2 diabetes by 62%. Older adults receiving 4000 and 10 000 IUs of vitamin D3 daily for 3 years had reduced radial BMD but had no change in either total hip areal bone density or bone strength in the radius and tibia. Summary Caution is needed when evaluating results and conclusions from randomized controlled trials that investigate health benefits of vitamin D; most studies suggest health benefits when vitamin D supplementation is provided to vitamin D deficient populations and little benefit when given to populations that are vitamin D sufficient/insufficient. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.