What is the recommended dosing for vitamin D (Vit D) supplementation in adults with deficiency or for prevention?

From the Guidelines

For adults with vitamin D deficiency, the recommended treatment is typically 50,000 IU of vitamin D2 or D3 once weekly for 8-12 weeks, followed by maintenance therapy of 1,000-2,000 IU daily. For prevention in adults with normal levels, a daily supplement of 600-800 IU is generally sufficient, with 800-1,000 IU recommended for older adults (over 70) who have higher requirements 1. Those at high risk for deficiency, such as individuals with limited sun exposure, darker skin, or certain medical conditions affecting absorption, may need 1,000-2,000 IU daily for prevention.

Key Considerations

• Vitamin D supplementation is important because it helps maintain bone health by promoting calcium absorption, supports immune function, and may have other health benefits.
• The body can produce vitamin D when skin is exposed to sunlight, but many people don't get sufficient sun exposure, especially in northern latitudes or during winter months.
• Taking supplements with food containing some fat improves absorption since vitamin D is fat-soluble.
• Blood tests measuring 25-hydroxyvitamin D levels can help determine if supplementation is needed and monitor treatment effectiveness.

Prevention and Treatment

• According to the Institute of Medicine, daily dietary vitamin D intake of 600 IU in adults aged 18 to 70 years and 800 IU in adults older than 70 years should be sufficient to meet the needs of 97.5% of the adult population 1.
• The NCCN Bone Health in Cancer Care Task Force recommends 1200 mg of calcium (from all sources) and 800 to 1000 IU of vitamin D daily for adults older than age 50, and also for younger patients at risk for cancer treatment–associated bone loss 1.

Important Notes

• Vitamin D toxicity (hypercalcemia, hyperphosphatemia, and activation of bone resorption) is uncommon but may occur with daily doses of more than 50,000 IU per day that produce 25(OH) D levels larger than 150 ng/mL 1.
• Sun exposure to prevent vitamin D deficiency is not generally recommended because it increases the risk for skin cancer associated with UVB radiation 1.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION THE RANGE BETWEEN THERAPEUTIC AND TOXIC DOSES IS NARROW. Vitamin D Resistant Rickets: 12,000 to 500,000 IU units daily. Hypoparathyroidism: 50,000 to 200,000 IU units daily concomitantly with calcium lactate 4 g, six times per day. The recommended dosing for vitamin D supplementation is individualized and should be done under close medical supervision. The dosage range for specific conditions is:

• Vitamin D Resistant Rickets: 12,000 to 500,000 IU units daily
• Hypoparathyroidism: 50,000 to 200,000 IU units daily 2

From the Research

Vitamin D Dosing Recommendations

The recommended dosing for vitamin D supplementation in adults with deficiency or for prevention varies based on several factors, including the individual's risk of deficiency, age, body mass index (BMI), and serum 25-hydroxyvitamin D level.

• For adults with obesity, liver disease, or malabsorption syndromes, daily doses of 7000 IU or intermittent doses of 30,000 IU/week may be considered for a prolonged time as prophylactic or maintenance doses 3.
• For the treatment of possible vitamin D deficiency without assessment of 25(OH)D in these groups, intermittent doses of 30,000 IU twice weekly or 50,000 IU per week may be considered for a 6-8-week period only 3.
• A daily vitamin D supplementation with 2000 IU (50 µg) may be considered a simple, effective, and safe dosage to prevent and treat vitamin D deficiency in the adult general population 4.
• The American Academy of Pediatrics recommends that infants and children receive at least 400 IU per day from diet and supplements, while evidence shows that vitamin D supplementation of at least 700 to 800 IU per day reduces fracture and fall rates in adults 5.
• In persons with vitamin D deficiency, treatment may include oral ergocalciferol (vitamin D2) at 50,000 IU per week for eight weeks, followed by maintenance dosages of cholecalciferol (vitamin D3) at 800 to 1,000 IU per day from dietary and supplemental sources 5.

Predictive Equation for Replacement Doses

A predictive equation has been developed to guide vitamin D replacement dose in patients, taking into account factors such as starting serum concentration of 25-hydroxyvitamin D, age, body mass index (BMI), and serum albumin concentration 6.

• The equation is: Dose = [(8.52 - Desired change in serum 25-hydroxyvitamin D level) + (0.074 × Age) - (0.20 × BMI) + (1.74 × Albumin concentration) - (0.62 × Starting serum 25-hydroxyvitamin D concentration)]/(-0.002).
• The required dose may be calculated from the predictive equations specific for ambulatory and nursing home patients.

Clinical Guidelines

The National Osteoporosis Society published a guideline on the management of vitamin D deficiency in adult patients with, or at risk of developing, bone disease, recommending the measurement of serum 25(OH) vitamin D to estimate vitamin D status in specific clinical scenarios 7.

• The guideline sets the following serum 25OHD thresholds: <30 nmol/l is deficient; 30-50 nmol/l may be inadequate in some people; >50 nmol/l is sufficient for almost the whole population.
• For treatment, oral vitamin D3 is recommended with fixed loading doses of oral vitamin D3 followed by regular maintenance therapy when rapid correction of vitamin D deficiency is required.