So many women with PCOS are prescribed Metformin (an insulin-sensitizing drug) to manage their Polycystic Ovarian Syndrome. And for good reason too. Metformin has been shown to improve many aspects of PCOS, including weight loss, fertility and improved testosterone levels (1). But, it also leads to Vitamin B12 deficiency if used at high doses or for long periods of time. So, here’s what you need to know about Metformin and Vitamin B12 deficiency with PCOS.
What is Metformin?
As I have already mentioned, Metformin is an insulin sensitizing drug that is often prescribed for women withPCOS. It works by decreasing absorption of glucose through the intestines, lowering the amount of glucose produced by the liver and making the body more sensitive to the insulin that is being produced.
The overall effect of Metformin use for PCOS is lowered testosterone levels, improved ovulation and fertility as well as a more regular menstrual cycle.
This is all sounding good, right? Well, it is good although there are some nasty side effects. A full discussion on Metformin is not going to be dealt with now, though. I really want to hone in on Metformin’s effect of Vitamin B12 levels as this could be affecting you right now.
Vitamin B12
Vitamin B12 is a vitamin that is vital for the body’s functioning. It is important for red blood cell formation, neurological function and DNA formation. If you are deficient in this important vitamin, it could lead to anaemia and neurological problems. (including memory loss – something that I have seen cropping up more often in PCOS communities). (2)
Metformin and Vitamin B12
Right, so this is where it gets interesting. Recent studies have shown that Metformin decreases Vitamin B12 levels, particularly when used long-term and when taken at high doses. Women with PCOS do tend to take Metformin at high doses for a long period of time and are therefore at risk of Vitamin B12 deficiency.
So, if you are taking Metformin, you may be tempted to start taking a Vitamin B12 supplement. Not so fast, though. Metformin lowers Vitamin B12 absorbency because it alters a Calcium-based reaction that allows the body to absorb the vitamin.
So, Calcium supplementation is what you are after, not Vitamin B12 (3).
Calcium
Okay, so now we know we need more Calcium to counteract the Vitamin B12 deficiency caused by Metformin. Before you rush off to stock up on milk and cheese, remember that Dairy is a no-no for women with PCOS. So, where does that leave us? Well, you can get calcium from other dietary sources, or you can take a calcium supplement.
Dietary sources of Calcium
There are so many sources of calcium, apart from dairy. Here is a great table from the National Osteoporosis Foundation.
The thing is though, research suggests you should be taking about 1200mg per day of Calcium to combat the Vitamin B12 deficiency (4). It is going to be difficult to source that amount of Calcium from your diet alone. So, I would recommend taking a Calcium supplement.
Calcium Supplementation
This seems to be quite a controversial subject at the moment but the research does suggest supplementation. So, with that in mind, I would recommend taking a slow release Calcium Citrate as calcium citrate seems to have less side effects than calcium carbonate.
Apart from this Vitamin B12 Deficiency, there are other reasons you may want to reconsider taking Metformin for PCOS.
Summing it Up
So, to sum it up, if you are taking high doses of Metformin to manage your PCOS or have been taking it for a long time, you may be at risk of Vitamin B12 deficiency. You can combat this by taking a Calcium supplement to increase Vitamin B12 absorption. However, before you do start taking any supplements, please speak with your doctor first!
Are you taking Metformin? I’d love to hear your thoughts and experiences with it in general! Leave me a comment below!
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116 Responses
I have been taking metformin for several years, at a dose of 2000mg per day. I still have not had a natural menstrual cycle in 17 years, and throughout several failed rounds of IVF even Norethisterone has failed to induce a period.
I have recently been suffering from extreme exhaustion, falling asleep randomly, aching limbs and feeling like my body is closing down on me, after some blood tests my GP diagnosed that I was very low in Vit B12.
I have started a supplement which has helped in a small way, but I still feel so tired. I am going to try the calcium and see what result it has.
I’m only 34 but I feel like my PCOS has stripped me of all of my femininity over the years, I have no periods, hirsutism, hair loss, and weight issues, as well as not being able to conceive even with the aid of IVF.
I’ve been on metformin since September of 2017. To be 100% aside from a bit of diarrhea at tye beginning, I have had zero negative side effects. Memory is still on point, if not clearer and my cycle is the most regular it has ever been. Along with cycle regulation, I’ve also noticed my cervical mucus follow a natural cycle now as well. Before starting metformin, I can only recall one time that I had EWCM, now I see it more often than not. I do take a prenatal vitamin and have since before I started the metformin, so maybe that has something to do with my ease of use, I’m not sure. I do feel like I’ve read a LOT of horror stories about metformin, which ALMOST terrified me into not taking it but I am glad that I decided to go forward with it. Yes, apparently it can have negative side effects for many women but not all.
I used Metformin for a few years, in Central America it seems to be a common prescription for PCOS and even by dietitians for weight loss (which is terrifying). I recently have went off of it trying to handle my symptoms in other ways – I always feel relying on medication can’t be that good considering from an evolutionary standpoint our bodies it is not natural and is trying to modify our human body. Anyways, Tarryn you refer to using Metformin over a long period of time and at a high dose. Could you define long period of time and high dosage?
I have no problem with taking it and it is making my life SO much better, but I would also like to know what “long period of time” and “high dosage” means.
My blood sugar reports are normal. Inspire of that my doctor prescribed glycomet tablets (metformin), 500mg to be taken twice a day. I was having problems after taking this medication. Feeling dizzy, diarrhoea n headache.So I stopped the medication. Is this normal?
The dizzy spells goes away it happend to me it almost took two months to feel normal again.
I was diagnosed with PCOS and endometriosis 40 years ago. My period started but never stopped. The treatment was either hysterectomy, at 14, or lots of curettes, 18 of them in 5 years till I stopped as they did nothing. The scaring did cause my to have an emergency caesar and not be able to have any more kids. Lots of stays in hospital to increase my blood levels and 3 transfusions. Started Metformin 15 years ago for type 2 Diabetes, got up to taking Jamumet 1000mg twice a day. Still get told by lots of Gynos over the years that PCOS doesn’t harm in any way and you can’t do anything about it. 5 years ago I started to do my own research and realise that I’ve never met a doctor that knows what’s going on. Hair growth? I did rival Santa with the beard. got so bad I couldn’t wax as the hair was so strong. Lost most of the hair on my head. gained over 50kg, could sleep all day but not at night. Can’t retain a thought. T3 at 2.8, a hormone not recognised in Australia, so no help there. I started Cyprone, testosterone blocker, my hair stopped falling out and my beard went white and I’m back to waxing. I stopped the Jamumet and went back to 500mg Metformin at meals as I don’t snack and have started losing weight finally. Slow release is bad for me as I’ve never done slow release well. I tried Duromine once to lose weight and took the tab at night as it took so long to kick in. I begged for a Hysterectomy for years as I couldn’t handle not being able to walk for the pain 2-3 days a month. Finally got one 13 years ago and I thought all my troubles would go. Was I wrong. There’s so much bad info out there, most of which I got from doctors. I’m sure there are good ones, I just haven’t found one. What I’m saying is you know your own body and how you feel. Try things out, don’t give up immediately, do your research, so much easier these days, you are always learning. I’m always low in Iron even though most of my diet is veg, veg smoothies and small serves of meat. High Calcium even though I don’t like dairy. I make my own stock which gives me the calcium. Now after reading this I find that I need Calcium Citrate as I’m only high in Carbonate. Thanks so much, now I can drop the B12 and see how that goes. Thanks so much as what you say makes more sense than I’ve ever heard.
I have been using metformin for 2 weeks now and i feel sick to my stomach everytime i take it. Should i feel this way? Is it part of the side effects. The doctor says it will help me with my fertility and help me conceive. I am also taking vitamin D(celciferol)once a week. i think i need some vitamin B12 as i have been experiancing memory loss for a while now. Any suggestions??
Have been taking metformin 5 years now, at first I dreaded taking it because it made me feel so ill and the stomach cramps and diarrhoea was so bad, I changed to taking it halfway through a meal instead of before and it helped a lot, these symptoms lasted around a month then slowly got better, I lost around 1.5 kgs a week, my periods returned and I was pregnant the 8th week of taking them. 5 years on and I have bad memory, very foggy mind, insomnia and very low iron, I’m looking into this more now I have read this article on b12 and metformin, Doctors don’t seem to know much I take 4 x 500mg a day, and have spent a lot of time researching.
Hi, I have been taking Metformin 500 mg for three months now, When I first started I felt all sorts of things going on in my body. I felt sick to my stomach, some diarrhea, some constipation, burning, burning feet, cold, chills, headaches. I just experienced a lot of changes very quickly. Eventually most have gone at least I think so. I take drugs for my heart. I did not want Metformin because I don’t think I need it. My A1c numbers was 6.2 and then I am told the number should be 4.0 or 5.0 something. Why all of the changes? One test I was told said 7.2? I check the Doctors Website and read up on diabetes. I was told hat numbers for people with heart disease and high pressure and at age 65 and over the A1c numbers are allowed to be higher! So what’s up with doctors wanting every body on Metformin? It boggles my mind that all we hear on tv are diabetes commercials. 4 out of five seems to be. I was reading some notes from care sync and it said that my doctor said I was taking vitamin b and vitamin d. I am taking d, but I have certainly not taken any b. He never told me too but he told my insurance company that he told me and that I was taking it. That is not true. When I questioned him, he said oh, I have no problem with you taking vit b. I said that is not my question, should I or should I not/ He said oh yeah. I said yeah what? b1 b12 b6 or what? He said just take b complex! I am perplexed and I don’t like my health being played with. Lately I have been having almost falling out spells but somebody always there to catch me. What could be wrong. He told me yesterday to just go ahead and get a heart transplant. Doctor is there anything I can do and what should I do because I may be being treated and not for anything wrong with me but could be creating problems in me. I don’t have a menstrual cycle, but I did have fibrous tumors in 1986 and they were removed. They were removed because I was having to get blood transfusion about every 10 to 12 days because of anemia. They removed the reproductive parts to save me from that and to save my life? So, I was told. Who can I go to and who can I get the truth from? Please. There is so much more to my story. I do want you to know that I am alive because of Jesus Christ! I pray, trust and believe in God! God bless all of you. Don’t just settle for anything.
Hello, hope you are feeling better. I on medformin now for three months. At month two I started having burning in my feet. I’m so scared is this medformin damaging the nerves in my feet. Please let me know if you have any further information. Thank you
Gee you have had it rough you poor thing…hope you find a good doctor..an everything turns around for your health.
All the best X.
I wish I would have read this article 7 years ago. Now I just got word that I am anemic and have vitamin B deficiency. I swear I thought I was going crazy…I could not remember things from my childhood or even something that happen a few years ago. I feel so dumb to not have done more research on this.
Can this feed into depression?
I got given metaformin. It didn’t agree with me what so ever. It made me feel like my mind was in another universe. I always tired and felt so sick all the time. I told doctors I stop taking it. They said was my dose. It wasn’t the med just doe5sn’t agree with me.
I have PCOS and currently have low B12 Levels I am having injections to raise my b12 levels and due my last injection next week, I am trying everything to loose weight but nothing is working, I want to ask my doctor to prescribe Metformin however can this effect my B12 further? also could they be related can having one cause the other? last year I was also diagnosed with cervical cancer and had to have my cervix and lower womb removed could the cancer be also be related or have been caused or causing my other health problems?? haven’t had much look with fertility/health I am so fed up with feeling tired, overweight and down
OK quick question I’ve been on 500 milligrams metformin 3 times a day for about 4 years and I have had a lot of problems with my memory, as well as being so tired I could sleep multiple times everyday all day if I take the calcium should that actually fix the memory issues?
I am taking metformin for almost 2 years and yes I am experiencing memory lose and I dont like it. Until i came across with this article. Will buy calcium suppliments for my B12.