Sufficient: 20-30 ng/ml, or 50-75 nmol/L. Safe upper limit: 60 ng/ml, or 150 nmol/L. Toxic: Above 150 ng/mL, or 375 nmol/L.How much vitamin D should you take for optimal health?
aily intake of 1,000 to 4,000 IU or 25 to 100 micrograms of vitamin D is sufficient to ensure optimal blood levels for most people. According to the National Institutes of Health, the upper limit of safety is 4,000 IU. Without consulting a healthcare professional, make sure you don’t take more.