What vitamin D supplement dosage is recommended for a level of 48 ng/mL?

Maintenance Dosing for Vitamin D Level of 48 ng/mL

For a vitamin D level of 48 ng/mL, which is already in the optimal range (30-80 ng/mL), you should take 800-2,000 IU daily for maintenance. 1

Understanding Your Current Status

Your level of 48 ng/mL is well within the optimal target range of 30-80 ng/mL recommended by the Endocrine Society and other guideline organizations. 1, 2 This means you are vitamin D sufficient and do not require correction—only maintenance to prevent levels from declining. 1

Recommended Maintenance Dosing

Standard maintenance approach:

• 800-1,000 IU daily is appropriate for most adults to maintain adequate levels 1, 3
• 1,500-2,000 IU daily is reasonable if you have risk factors for deficiency (obesity, dark skin, limited sun exposure, malabsorption, chronic illness) 1, 4

The general rule of thumb is that 1,000 IU daily increases serum 25(OH)D by approximately 10 ng/mL, though individual responses vary. 1 Since you're already at 48 ng/mL, maintenance dosing prevents decline rather than building levels further. 1

Dosing Frequency Options

Daily dosing is physiologically preferred, but alternatives exist for convenience: 1

• Daily: 800-2,000 IU
• Weekly: Equivalent weekly dose (e.g., 7,000-14,000 IU once weekly) 1
• Monthly: Approximately 60,000 IU monthly (equivalent to ~2,000 IU daily) 4

Avoid single annual mega-doses (≥500,000 IU), as these have been associated with adverse outcomes including increased falls and fractures. 1, 2

Safety Parameters

• 2,000 IU daily is considered absolutely safe by most international authorities 1, 4
• Doses up to 10,000 IU daily over several months have not caused adverse events in studies 1
• The upper safety limit for serum 25(OH)D is 100 ng/mL—your current level of 48 ng/mL provides a comfortable safety margin 1, 2, 4
• Toxicity typically occurs only when daily intake exceeds 100,000 IU or levels exceed 100 ng/mL 1, 2

Monitoring Strategy

• Recheck your 25(OH)D level in 3-6 months after starting maintenance dosing to ensure levels remain stable in the 30-80 ng/mL range 1
• If levels drop below 30 ng/mL, increase your maintenance dose 1
• Consider seasonal variation—levels are typically lowest after winter 1

Common Pitfalls to Avoid

• Don't stop supplementation entirely unless you have consistent, adequate sun exposure year-round, as most people cannot maintain optimal levels from sun and diet alone 5
• Don't assume you need high-dose correction—your level of 48 ng/mL does not represent deficiency and does not require loading doses like 50,000 IU weekly 1
• Ensure adequate calcium intake (1,000-1,200 mg daily) alongside vitamin D supplementation, as vitamin D enhances calcium absorption 1, 2
• Vitamin D3 (cholecalciferol) is preferred over vitamin D2 (ergocalciferol) for maintenance supplementation 1

Special Considerations

If you have any of the following conditions, you may need the higher end of the maintenance range (1,500-2,000 IU daily): 1, 4

• Obesity
• Dark skin pigmentation
• Limited sun exposure (indoor lifestyle, northern latitude)
• Malabsorption disorders
• Diabetes or other chronic illnesses