The scientific evidence that vitamin D reduces risk of many types of conditions and diseases and improves disease outcomes is moderately strong.  However, the allopathic/Western medical system in charge of medical policy considers vitamin D to be inexpensive competition and has done everything possible to cast doubt on vitamin D and block its approval for use by physicians for preventing or treating disease. How they use the Disinformation Playbook was spelled out in 2018.  One way this Playbook is used is to demand verification of vitamin D’s effects through randomized controlled trials (RCTs). Read more.