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WeightCited

Vitamin B12 for Slow Metabolism

C

B12 deficiency impairs mitochondrial fatty acid oxidation. Observational study (n=9,075) found deficiency associated with higher BMI (OR 1.32). Metformin depletes B12 in 10-30% of users. Correction restores energy levels and exercise capacity.

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            C

        

        

            
The Bottom Line

            
            
B12 deficiency impairs mitochondrial fatty acid oxidation. Observational study (n=9,075) found deficiency associated with higher BMI (OR 1.32). Metformin depletes B12 in 10-30% of users. Correction restores energy levels and exercise capacity.

            
            
        

    











    
    

        
        

            

  
Key Statistics





            


    

        
5

        
Studies

    

    

        
9000

        
Participants

    

    

        
            
            ↑
            
        
        
Positive

    

    

        C

        
Grade

    




        


        
        

        
        
        

            

  
Dosage & Usage





            
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units


            
            

                
Commonly Used Dosages

                

                    
                    

                        
vegans:

                        
250-1,000 mcg/day

                    

                    
                    

                        
general:

                        
2.4 mcg/day (RDA)

                    

                    
                    

                        
metforminusers:

                        
1,000 mcg/day

                    

                    
                    

                        
supplementation:

                        
500-1,000 mcg/day methylcobalamin

                    

                    
                

                
                

                    Upper limit: No established UL (water-soluble, excess excreted)
                

                
            

            

            

            
            

                Best taken: Morning (may provide energy boost); sublingual for better absorption; separate from vitamin C (
            

            
        

        

        
        
        

            

  
Safety & Side Effects





            

                
                

                    
Reported Side Effects

                    
    
                        
                        
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                            ⚠
                            Acne (rare, at high doses)
                        
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                            ⚠
                            Diarrhea (rare)
                        
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                            ⚠
                            Generally very well tolerated
                        
    • 
                        
                    

                

                

                
                

                    
Known Interactions

                    
    
                        
                        
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                            ●
                            Metformin (depletes B12 — monitor levels)
                        
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                            ●
                            Proton pump inhibitors (reduced absorption)
                        
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                            H2 receptor antagonists (reduced absorption)
                        
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                            ●
                            Colchicine (reduced absorption)
                        
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                        Tolerable upper intake: No established UL (water-soluble, excess excreted)
                    

                

                
            

            

                Always consult your healthcare provider before starting any supplement.
            

        

        

        
        
        

            

  
Frequently Asked Questions





            




    
    

        
            Does Vitamin B12 help with Slow Metabolism?
            
        
        

            Based on 5 studies with 9,000 participants, there is limited but promising evidence that Vitamin B12 may support Slow Metabolism management. Our evidence grade is C (Some Evidence).
        

    

    
    

        
            How much Vitamin B12 should I take for Slow Metabolism?
            
        
        

            Studies have used various dosages. A commonly studied range is 250-1,000 mcg/day. Always consult your healthcare provider before starting any supplement regimen.
        

    

    
    

        
            Are there side effects of Vitamin B12?
            
        
        

            Reported side effects may include Acne (rare, at high doses), Diarrhea (rare), Generally very well tolerated. Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
        

    

    
    

        
            How strong is the evidence for Vitamin B12 and Slow Metabolism?
            
        
        

            We rate the evidence as Grade C (Some Evidence). This rating is based on 5 peer-reviewed studies with 9,000 total participants. The overall direction of effect is positive.
        

    

    




        

        

        
        
        

            

  
Related Evidence





            

                
                

                    
Other ingredients for Slow Metabolism

                    

                        
                        
                            B-Complex
                            C

                        
                        
                    

                

                

                
                

                    
Vitamin B12 for other conditions

                    

                        
                        
                            Post-Bariatric Nutritional Support
                            B

                        
                        
                    

                

                
            

        

        

    


    
    












    

        FDA Disclaimer:
        These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.