Is Vitamin B12 Deficiency Linked to Metformin?
Vitamin B12 is a crucial nutrient that plays a significant role in maintaining healthy nerve cells, producing DNA, and forming red blood cells. However, a growing concern has emerged regarding the link between vitamin B12 deficiency and the use of metformin, a commonly prescribed medication for type 2 diabetes. Metformin is known for its effectiveness in managing blood sugar levels, but research suggests that it may also interfere with vitamin B12 absorption, leading to deficiency.
### How Metformin Affects Vitamin B12 Absorption
Metformin appears to affect vitamin B12 absorption through several mechanisms. One of the primary ways is by reducing the calcium-dependent channels that facilitate the binding of the intrinsic factor-vitamin B12 complex to cubilin receptors in the terminal ileum. This process is essential for vitamin B12 absorption, and when it is impaired, less vitamin B12 is absorbed by the body[1]. Additionally, metformin may decrease the secretion of intrinsic factor from gastric parietal cells, further contributing to reduced vitamin B12 absorption[1].
Another mechanism involves metformin’s impact on gut bacteria. It seems that metformin can increase the uptake of vitamin B12 by certain bacteria, such as *Bacteroides ovatus*, leading to increased competition for available dietary vitamin B12. This results in less vitamin B12 being absorbed by the human body[5].
### Prevalence of Vitamin B12 Deficiency in Metformin Users
Studies have shown that the prevalence of vitamin B12 deficiency among patients taking metformin is significant. For instance, one study found that about 23.84% of patients on metformin had vitamin B12 deficiency, while another 20.64% had borderline deficiency levels[1]. These figures highlight the need for regular monitoring of vitamin B12 levels in patients using metformin, as recommended by health authorities.
### Factors Influencing Vitamin B12 Deficiency
Several factors can influence the risk of vitamin B12 deficiency in metformin users. These include the patient’s age, the dosage of metformin, and the duration of treatment. Older patients or those taking higher doses of metformin for longer periods may be at a greater risk of developing vitamin B12 deficiency[2].
### Concomitant Use of Other Medications
The risk of vitamin B12 deficiency can be further increased when metformin is used alongside other medications, such as proton pump inhibitors (PPIs). The concomitant use of metformin and PPIs has been associated with a higher risk of vitamin B12 deficiency in patients with type 2 diabetes[3].
### Conclusion
While metformin is an effective treatment for type 2 diabetes, its potential to cause vitamin B12 deficiency is a concern that should not be overlooked. Regular monitoring of vitamin B12 levels and awareness of the factors that increase the risk of deficiency can help manage this issue effectively. Patients on metformin should consult their healthcare providers about the potential risks and consider supplementation if necessary.
