Timing of Vitamin D3 and B12 Supplementation
You do not need to wait any specific time between taking vitamin D3 and vitamin B12 supplements—they can be taken together without concern for interaction.
No Known Drug-Drug Interaction
- Vitamin D3 (cholecalciferol) and vitamin B12 (cobalamin) have no documented pharmacokinetic or pharmacodynamic interactions with each other 1.
- Both vitamins are routinely prescribed together in multivitamin formulations for post-bariatric surgery patients and other populations requiring supplementation, with no timing separation recommended 1, 2.
- The bariatric surgery guidelines explicitly recommend daily concurrent supplementation of vitamin D (3000 IU/day) and vitamin B12 (250-350 μg/day) without any mention of timing separation 1.
Context: When Timing Matters (But Not Here)
The evidence about medication timing primarily addresses bile acid sequestrants (cholestyramine, colestipol, colesevelam), which can bind to fat-soluble vitamins and other medications in the gastrointestinal tract:
- Bile acid sequestrants may interfere with absorption of fat-soluble vitamins (A, D, E, K) and should be separated from other medications by at least 1 hour before or 4-6 hours after administration 1.
- However, you are not taking bile acid sequestrants, so this timing concern does not apply to your situation.
Practical Administration
- Take both vitamin D3 and B12 at whatever time is most convenient for adherence—morning, evening, or with meals 1.
- Vitamin D3 is fat-soluble and may have slightly better absorption when taken with a meal containing some dietary fat 3, 4.
- Vitamin B12 (especially sublingual forms) can be taken with or without food 1.
Important Caveat
Do not take calcium and iron supplements together, as calcium can interfere with iron absorption 2. If you are taking calcium with your vitamin D3, separate iron supplementation by at least 2 hours.