Large Study Finds No Long-Term Kidney or Vascular Harm From Routine Vitamin D Supplements

Overview

• A DKFZ analysis tracking about 500,000 UK participants for 13 years found no increase in atherosclerosis or kidney stones among regular vitamin D users.
• In the cohort, 4.3% reported regular vitamin D use and 20.4% took multivitamins containing it, with typical EU doses between 400 and 4,000 IU daily, according to the study authors.
• Reported adverse effects in clinical trials appeared from roughly 10,000 IU per day, and overdose physiology centers on elevated blood calcium that can lead to kidney stones and vascular calcification.
• The German Nutrition Society recommends 20 micrograms (800 IU) daily when sunlight is insufficient, defines deficiency below 25–30 nmol/L, and a neurologist cites levels above 50 nmol/L as an ideal target.
• Recent analyses suggest vitamin D insufficiency has risen since the pandemic, with more than one third of Germans below about 50 nmol/L and roughly 15% in true deficiency as estimated by the RKI.