Vitamin DWhat vitamin D blood level is too low?
Updated 3 Nov 2026
Short answer
A blood test measures 25(OH)D. US experts consider 50 nmol/L (20 ng/mL) or more enough for most people. Below 30 nmol/L (12 ng/mL), the risk of deficiency rises.[1] Above 125 nmol/L (50 ng/mL), side effects become possible.[1]
Low levels are more common in breastfed babies, older adults, people with dark skin or little sun, and people with obesity.[1] Gut conditions that limit fat absorption, such as Crohn's disease or celiac disease, and gastric bypass surgery also lower it.[1] Results differ between laboratories, because the tests are not fully standardized.[1]
Sources (1)
- Vitamin D: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
More about vitamin d
What is vitamin D?How do you get vitamin D from sunlight and food?What is vitamin D used for?Is vitamin D safe?Does vitamin D prevent fractures?Does vitamin D prevent colds and other respiratory infections?For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.