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Metformin B12 depletion, how many people here actually supplement and has it shown up on bloodwork

Posted by student748 in Longevity & Anti-Aging - 3 points, 4 comments.

Been reading up on metformin for longevity purposes and the B12 thing keeps coming up. For what it is worth the mechanism makes sense to me, something about it interfering with calcium-dependent absorption in the terminal ileum. But i'm keen to hear from people actually taking it whether they've seen B12 drop on labs or whether supplementing is just assumed necessary.

I'm considering low dose metformin alongside weekly rapamycin but stacking two things that both mess with cellular energy pathways feels like a lot to jump into at once. The AMPK activation overlap seems complementary on paper but i wonder if anyone here has done both and felt anything off, like fatigue or just flat energy.

Also curious if people split the dose or take it all at once. The GI stuff sounds rough based on what i've read, does it settle after a few weeks or is it ongoing. Not keen to trade gut comfort for theoretical longevity benefits if it's going to wreck my training days.

Anyone got real-world experience with this combo or metformin solo at the lower end of the range.

Comments

  • lifter_mel: I've been looking at metformin for longevity too but the B12 thing is exactly what put me off starting yet. From what I read the depletion can take months to show up and even then it depends on your baseline. Would be keen to see if anyone here actually has before/after bloods rather than just supplementing blindly... I'm a bit skeptical of the "just take B12 and you're fine" approach without checking labs first. The rapamycin stack does sound like a lot to jump into at once, I'd probably start
  • earlyelle: Fwiw i think your instinct to start one at a time is spot on, stacking two things that both hit energy pathways and then trying to figure out which one made you feel rubbish sounds like a nightmare. On the B12 bit, i'd definitely want baseline labs before starting anything, otherwise you're just guessing whether a drop happened. Supplementing blindly seems a bit daft when a blood test is cheap enough, reckon most people just can't be bothered with the hassle.
  • greg_codes: Yeah the before/after bloods thing is spot on. I had B12 checked before starting metformin and again about 4 months in, dropped maybe 15% from baseline. Wasn't deficient but the trend was clear. Ngl i just started sublingual B12 after that and rechecked, came back up fine. But yeah starting one thing at a time is smart as, stacking two energy pathway compounds blind is a rough idea.
  • student748: Chur for that, exactly the kind of real before/after i was hoping someone had. 15% drop at 4 months is a pretty clear trend even if you weren't deficient, good call catching it early. Did you go with methylcobalamin or cyanocobalamin for the sublingual? Seen conflicting stuff on which form actually absorbs better for people on metformin specifically. For what it is worth i'll probably just start the rapa first and leave metformin for later once i've got baseline labs sorted, seems like the less

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