Vitamin D₃ and calcidiol are not equipotent.

Area of Science:

• Endocrinology
• Nutritional Science
• Gerontology

Background:

• Vitamin D deficiency is prevalent in post-menopausal and elderly populations globally.
• Maintaining adequate Vitamin D levels is crucial for bone health and optimizing response to osteoporosis treatments.
• International guidelines recommend Vitamin D3 supplementation within a 600-2000 IU daily range.

Purpose of the Study:

• To compare the efficacy of Vitamin D3 and calcidiol (25(OH)D3) in raising serum 25(OH)D levels in post-menopausal osteoporotic women.
• To investigate potential over-dosage issues with calcidiol prescriptions in Spain, where it's commonly used at equivalent doses to Vitamin D3.
• To provide evidence for adjusting therapeutic guidelines regarding Vitamin D metabolites.

Main Methods:

• A convenience study involving four groups of ten post-menopausal osteoporotic women (average age 67) with Vitamin D deficiency.
• Each group received a different daily or equivalent weekly/bi-weekly regimen of either Vitamin D3 or calcidiol (25(OH)D3).
• Serum 25(OH)D levels were measured at baseline, 6 months, and 12 months for all groups.

Main Results:

• Calcidiol (25(OH)D3) demonstrated significantly higher potency in increasing serum 25(OH)D levels compared to Vitamin D3.
• In the medium to long term, calcidiol was found to be 3-6 times more potent in achieving target 25(OH)D serum concentrations.
• Different administration frequencies of calcidiol (daily, weekly, bi-weekly) showed varying but consistently higher efficacy than Vitamin D3.

Conclusions:

• Vitamin D3 and calcidiol are not equipotent in raising serum 25(OH)D levels.
• Calcidiol is a more potent and faster-acting metabolite, necessitating careful dosage adjustments to prevent potential over-dosage.
• Therapeutic guidelines for osteoporosis management should be updated to reflect the differential potency of Vitamin D metabolites.