Pernicious Anaemia Society

Advice on supplements in-between injections, I don't want to over-dose

On Monday, I'm having my 6th and final loading injection, then I'm onto 3 monthly injections, to be reviewed in a year. I'm feeling loads better now, which is a huge relief.

My GP thinks my b12 deficiency is due to diet, and as my blood levels rose from 150 to 214, in less than two weeks, once I started taking 50mcg twice daily cyanocobalamin, I suspect she's right. My symptoms were still quite bad though, so she offered injections, as a quick boost.

So once I've had my last injection on Monday, I'll be making a huge effort to eat more meat and fish, but want to take a low dose b12 supplement, just as a precaution in case there are still gaps in my diet. The doctor thinks that an improved diet will keep my levels up, but given how dreadful I felt prior to the injections, I want to give myself the best chance of keeping my levels high.

I'm considering taking Boots 10mcg B12, once a day? And even though 10mcg is almost four times the RDA, i gather you don't absorb the whole dosage, and also I hope to be getting more B12 from my improved diet.

Can anyone advise if 10mcg per day is too much in-between injections, working on the assumption that I don't have an absorption problem? The other option is a A-Z daily multivitamin, which contains 2.4mcg of B12? But I'm concerned that could leave me a bit lacking if I have day without fish?

4 Replies

You can't overdose on B12

You can't overdose on B12 so 4 x RDA definitely isn't going to do you any harm. Its also going to be pretty insignificant until the levels from the injections start to fall. If you don't have an absorption problem then your body should be able to recycle some of the B12 from the injections and rebuild the stores in the liver so supplementation shouldn't be necessary at all for quite a while - probably 6 months.

Further test results are likely to be meaningless now so thing to do is keep a diary of symptoms just in case they start return. There is an awful lot more to treating a B12 deficiency than just getting B12 into your blood. testing in 6 months might be more meaningful - but only if it shows that your levels are very low again - which would indicate that despite expectations that it is dietary it isn't.

You need folate as well but best form is from diet.

There are some vitamins and minerals that you can overdose on but if your taking an A-Z the doses should be well within safe limits - would only be a problem if you started taking significant multiple doses.....

Personally a bit sceptical that it is diet as it doesn't sound as if you have avoided B12 foods entirely, but guess it could be.

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Thank you Gambit. So if I've understood you correctly (and if I don't have an absorption problem.......) then I don't need to think about supplements just yet, and my body should be quite happy with the loading dose injections, which should keep me going til my next injection in 3 months?

I've already stocked up on B12-rich foods, and will take a Boots A-Z multivitamin daily, just to be on the safe side. So even if I don't quite get enough B12 from my diet, the multivitamin will plug the gaps. Well that's the theory!

What I'm wary of, is taking any mega supplements that would disguise an absorption problem, but I also want to stay well between injections. I suppose the next three months will be something of an experiment.


Yes, you have understood the implications of it not being absorption that is the problem.

Hope it works out.

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Hopefully you are all set now and will continue to feel better.

Just be aware that this might be the start of your body not absorbing B12 from your diet and you may need more than you would expect, sorry!

To get a noticeable effect you may need much higher levels. It is safe and sublinguals are available from relatively low levels up to 5000 mcg (5mg) online (e.g. Amazon).

I hope you find what works for you! :-)

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