From the Guidelines
Your current vitamin D dosage of 28,000 units weekly is appropriate and can be continued, as it has successfully maintained your vitamin D level at 36 ng/mL, which is within the normal range [30-100 ng/mL] 1. This dosage equates to approximately 4,000 IU daily, which is within safe supplementation ranges for most adults. Key points to consider include:
- The importance of vitamin D for calcium absorption, bone health, immune function, and mood regulation 1
- The storage of vitamin D in fat tissue, making consistent supplementation more important than daily intake 1
- The recommendation to recheck vitamin D levels in 6-12 months to ensure they remain in the optimal range 1
- The low risk of vitamin D toxicity at your current dosage, but the importance of monitoring for symptoms such as nausea, vomiting, weakness, or kidney problems 1 It is also worth noting that:
- Vitamin D levels should ideally be maintained at 30 ng/mL or higher for bone health 1
- Different forms of vitamin D, such as D2 (ergocalciferol) and D3 (cholecalciferol), have different effects on 25(OH)D concentrations, with vitamin D3 potentially being more effective in raising and maintaining levels 1
From the Research
Vitamin D Levels and Supplementation
- The current vitamin D level is 36 ng/mL, and the user is taking 28,000 units of vitamin D weekly 2.
- A study published in the Journal of Bone Metabolism in 2018 found that a maintenance dose of 2,000 IU of vitamin D3 is not enough to keep 25(OH)D levels above 30 ng/mL 2.
- Another study published in Nutrients in 2015 estimated that doses of 1,885,2,802, and 6,235 IU per day are required for normal weight, overweight, and obese individuals, respectively, to achieve natural 25(OH)D concentrations 3.
Ideal Vitamin D Dosage
- The ideal vitamin D dosage once deficiency and insufficiency are treated is still unclear 2.
- A study published in Nutrients in 2015 suggested that the Recommended Dietary Allowance (RDA) for vitamin D is not desirable or feasible due to the large extent of variability in 25(OH)D concentrations 3.
- The study proposed recommendations be articulated in the form of an optimal intake that minimizes the risk for both low and high serum 25(OH)D concentrations 3.
Vitamin D and Chronic Kidney Disease
- Vitamin D deficiency has been linked to many different pathologies, especially morbimortality in patients with chronic kidney disease 4.
- A study published in Nutrients in 2021 reviewed the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest, including chronic kidney disease, dialysis, and renal transplant 5.
- Another study published in the American Journal of Physiology-Renal Physiology in 2013 found that chronic vitamin D deficiency has adverse long-term actions on proteinuria, interstitial inflammation, renal function, and cardiovascular disease in polycystic kidney disease 6.