PCOS Nutrition Center Articles/Blog
New Metformin Warning: Mandatory Supplementation with Vitamin B12
- By Angela on April 13, 2016 under PCOS Supplements, PCOS Treatment
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The most common medication used in women with PCOS is the insulin-sensitizer metformin. Research is strongly showing that long-term use of metformin and at high doses (1.5mg or higher daily) can deplete levels of vitamin B12. A deficiency of vitamin B12 can cause permanent neurological and nerve damage as well as mood changes and decreased energy. Here’s what you need to know to avoid a vitamin B12 deficiency if you take metformin.
Metformin is a medication that became available in the U.S. in 1995 for the treatment of type 2 diabetes. Metformin is the most widely used medication used to lower insulin levels in those with polycystic ovary syndrome. Other names for metformin include glucophage, glucophage XR, glumetza, and fortamet.
Metformin lowers blood glucose levels in three ways:
- It suppresses the liver’s production of glucose.
- It increases the sensitivity of your liver, muscle, fat, and cells to the insulin your body makes.
- It slows the absorption of carbohydrates you consume
Metformin use may affect the absorption of vitamin B12 possibly through alterations in intestinal mobility, increased bacterial overgrowth, or alterations of the vitamin B12-intrinsic factor complex. Metformin can cause a malabsorption in B12 due to digestive changes, which leads to the binding of B12-intrinsic factor complex (intrinsic factor is needed to absorb B12 in the gut) and a reduction of B12 absorption.
Vitamin B12 Deficiency in Metformin Users
The largest study thus far to examine the link between metformin and vitamin B12 is the Diabetes Prevention Program Outcomes Study (DDPOS). This study looked at B12 levels of individuals with prediabetes who took 850 mg Metformin 2x/day and compared them to those taking a placebo. At 5 years, 4.3% of the metformin users had low levels of B12 ( 4 ng/mL).
B12 Deficiency Among Metformin Users With PCOS
Studies done investigating metformin use in women with PCOS are severely lacking. There is much more data on people with diabetes who take metformin with the majority of the evidence showing metformin decreases B12 levels. As for studies done in women with PCOS, here is what the evidence shows: