Vitamin D: Bolus Is Bogus-A Narrative Review.

In this review we summarize the impact of bolus versus daily dosing of vitamin D on 25(OH)D and 1,25(OH)D levels, as well as on key countervailing factors that block vitamin D functions at the cellular level. Further, we discuss the role of bolus versus daily dosing of vitamin D for several health outcomes, including respiratory infections and coronavirus disease 2019 (COVID-19), rickets, falls and fractures, any cancer, and cancer-related mortality. This discussion appears timely because bolus doses continue to be tested for various disease outcomes despite a growing amount of evidence suggesting lack of efficacy or even detrimental effects of bolus dosing of vitamin D for outcomes where daily dosing at modest levels was effective in the vitamin D deficient.

1,24(S)-dihydroxyvitamin D2, an endogenous vitamin D2 metabolite, inhibits growth of breast cancer cells and tumors.

Background: 1,24-Dihydroxyvitamin D2 (1,24(OH)2D2) is a naturally occurring metabolite of vitamin D2 with low calcemic activity and potent antiproliferative activity. We evaluated the activity of 1,24(OH)2D2 in breast cancer models.

Materials And Methods: The antiproliferative activity of 1,24(OH)2D2 was quantitated against human and murine breast cancer cell lines.