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Calculate optimal vitamin D supplementation based on your levels and risk factors
This calculator provides general guidance. Vitamin D needs vary significantly between individuals. Testing your blood level (25-hydroxy vitamin D) is the best way to determine your needs. High-dose supplementation should be supervised by a healthcare provider.
| Level (ng/mL) | Status | Suggested Dose |
|---|---|---|
| <12 | Severely Deficient | 5,000-10,000 IU/day |
| 12-20 | Deficient | 2,000-5,000 IU/day |
| 20-30 | Insufficient | 1,000-2,000 IU/day |
| 30-50 | Optimal | 600-1,000 IU/day |
| 50-100 | Adequate | Maintenance only |
| >100 | Potentially Toxic | STOP supplements |
To convert nmol/L to ng/mL, divide by 2.5 (e.g., 50 nmol/L = 20 ng/mL)
Yes, vitamin D toxicity is possible with very high doses (typically >10,000 IU/day for extended periods). Toxicity causes hypercalcemia with symptoms like nausea, weakness, kidney problems, and cardiac issues. Levels above 100 ng/mL are concerning. Always monitor levels if taking high doses.
With adequate supplementation, levels typically improve within 2-3 months. Severe deficiency may take longer. For faster correction, doctors sometimes prescribe a "loading dose" (50,000 IU weekly for 8-12 weeks). Retest after 8-12 weeks to assess progress.
Yes! Vitamin D is fat-soluble, meaning it's absorbed much better when taken with a meal containing fat. Taking it with your largest meal of the day can increase absorption by up to 50% compared to taking it on an empty stomach.
It depends. 10-30 minutes of midday sun exposure on arms and legs a few times per week can produce adequate vitamin D in fair-skinned individuals. However, factors like latitude, season, skin tone, sunscreen use, and age significantly affect production. Most people in northern latitudes need supplementation, especially in winter.
Vitamin D is fat-soluble and gets sequestered in fat tissue, making it less available to the rest of the body. People with obesity typically need 2-3 times more vitamin D to achieve the same blood levels as those at normal weight. Higher doses should be guided by blood testing.
Vitamin D helps your body absorb calcium, but they don't need to be taken together. However, if you're taking vitamin D to support bone health, ensure you're getting adequate calcium through diet or supplements (1000-1200mg/day for most adults). Vitamin K2 may also help direct calcium to bones.
This calculator provides general guidance based on common recommendations. Individual needs vary. Blood testing is the most accurate way to determine your vitamin D status and supplementation needs. High-dose vitamin D supplementation should be monitored by a healthcare provider. This information does not constitute medical advice.