Supplement·Interactions·Reviewed June 9, 2026
Vitamin B12 interactions.
Vitamin B12 has 24 documented interactions in the NutriStack database: 1 to avoid or watch closely, 9 that need timing or caution, and 14 that work synergistically. The full list, with what each pairing does, is below.
Vitamin B12 at a glance.
A quick, data-grounded summary. The full table is below.
Vitamin B12 has 24 documented interactions in the NutriStack database: 1 to avoid or watch closely, 9 that need timing or caution, and 14 that work synergistically. The full list, with what each pairing does, is below.
Everything that interacts with vitamin b12.
Every supplement and medication in the NutriStack database with a documented interaction with this substance, highest-severity first. Open any pair for the mechanism and sources.
| Substance | Interaction | What happens |
|---|---|---|
| Colchicine | Conflict | Colchicine causes dose-dependent, reversible malabsorption of vitamin B12 by reducing the number of intrinsic factor-vitamin B12 receptors in the... details → |
| Cimetidine | Caution | Cimetidine reduces gastric acid and pepsin secretion enough to impair the release of dietary B12 from food protein. The Kaiser study linked two or... details → |
| Esomeprazole | Caution | Long-term esomeprazole therapy reduces vitamin B12 absorption. PPIs suppress the gastric acid and pepsin needed to liberate dietary B12 from food... details → |
| Famotidine | Caution | Long-term famotidine therapy can lower vitamin B12 status by reducing acid-pepsin-dependent release of B12 from food. The Kaiser case-control study... details → |
| Lansoprazole | Caution | Lansoprazole reduces vitamin B12 absorption from food over years of use. The Kaiser Permanente case-control study linked two or more years of any... details → |
| Metformin | Caution | Long-term metformin use (typically >6 months) reduces vitamin B12 absorption by 10-30%, leading to deficiency in up to 30% of chronic users. B12... details → |
| Omeprazole | Caution | Long-term omeprazole use significantly impairs vitamin B12 absorption. Gastric acid and pepsin are required to release B12 from food proteins before... details → |
| Pantoprazole | Caution | Pantoprazole, like all PPIs, impairs vitamin B12 absorption by suppressing gastric acid needed to release B12 from food proteins. The risk increases... details → |
| Rabeprazole | Caution | Rabeprazole can reduce absorption of food-bound vitamin B12 during prolonged therapy. |
| Vitamin C | Timing Sensitive | High-dose vitamin C (>500mg) may destroy vitamin B12 when taken simultaneously. The acidic environment created by high-dose ascorbic acid can... details → |
| Betaine HCL | Synergy | Adequate stomach acid is needed to release vitamin B12 from food proteins, so betaine HCL may support B12 liberation and absorption in people with... |
| Calcium | Synergy | Calcium may actually assist B12 absorption. Some evidence suggests calcium helps release B12 from food and supports intrinsic factor binding. |
| Combined Oral Contraceptive | Synergy | Combined oral contraceptives are associated with lower serum vitamin B12 levels in multiple observational and review studies. Although clinical... details → |
| Iron | Synergy | Both iron and B12 are essential for red blood cell production. Deficiency in either causes anemia. |
| Iron Bisglycinate | Synergy | Both iron bisglycinate and B12 are essential for red blood cell production. Deficiency in either causes anemia. |
| L-Methionine | Synergy | Methionine is recycled from homocysteine via B12-dependent methionine synthase; adequate B12 is required to handle methionine load without raising... |
| Methylfolate | Synergy | B9 (folate) and B12 work together in the methionine cycle. B12 deficiency can be masked by high folate intake. details → |
| Niacinamide | Synergy | B vitamins are often used together to support methylation, red blood cell production, and energy metabolism. |
| Nicotinamide Riboside | Synergy | Fatigue and low-energy symptoms attributed to declining NAD+ overlap substantially with symptoms of vitamin B12 deficiency, which is a far more... |
| Phenytoin | Synergy | Phenytoin therapy is associated with lower vitamin B12 levels and higher homocysteine in multiple studies. B12 deficiency can cause anemia,... details → |
| Pterostilbene | Synergy | Pterostilbene is frequently paired with NAD precursors to support sirtuin activity. Methyl-group sufficiency, supported by B12 and folate, becomes... |
| Trimethylglycine | Synergy | Adequate B12 ensures the methionine synthase pathway functions, so that methyl groups from both folate and betaine are used efficiently and... |
| Vitamin B6 | Synergy | B6, B12, and folate work together to metabolize homocysteine. All three are needed for optimal methylation. |
| Vitamin B9 | Synergy | B9 (folate) and B12 work together in the methionine cycle. B12 deficiency can be masked by high folate intake. details → |
The full vitamin b12 profile.
Benefits, dosing by goal, forms, and the cited evidence for this supplement.
Common vitamin b12 questions.
Quick answers drawn from the table above.
What interacts with Vitamin B12?
In the NutriStack database, Vitamin B12 has 24 documented interactions with other supplements and medications. The most notable include Colchicine, Cimetidine, Esomeprazole, Famotidine, and Lansoprazole.
What should you not take with Vitamin B12?
Vitamin B12 is flagged against 1 substance in the database, including Colchicine. Review these with a clinician before combining, especially alongside prescription medications.
What works well with Vitamin B12?
Vitamin B12 pairs synergistically with Betaine HCL, Calcium, Combined Oral Contraceptive, Iron, and Iron Bisglycinate in the NutriStack database. Synergy still depends on dose and timing; open any pair for the detail.
Can you take Vitamin B12 with Colchicine?
NutriStack classifies the Vitamin B12 and Colchicine pairing as conflict: Colchicine causes dose-dependent, reversible malabsorption of vitamin B12 by reducing the number of intrinsic factor-vitamin B12 receptors in the ileal mucosa. Chronic... Monitor vitamin B12 levels annually in patients on chronic colchicine therapy. Consider prophylactic B12 supplementation (1000 mcg sublingual daily...
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