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Metformin for longevity, anyone actually notice the B12 thing or is it overblown

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

Been reading up on metformin for longevity stuff and the AMPK activation angle makes sense to me on paper. Mimics caloric restriction signalling and all that. For what it is worth i feel like i already get some of that effect from just doing massive training weeks, but obviously thats not the same pathway exactly.

The thing that keeps catching my eye is the B12 depletion side effect. Some people say its a real issue over months of use, others seem to brush it off. I know the half-life is short so its not like its building up in your system, but the B12 thing is more about chronic interference with absorption right? Not pharmacokinetics.

Anyone here been on metformin long enough to actually see B12 drop on bloodwork? Did you just supplement and carry on or did it make you rethink the whole thing? Keen to hear from people whove actually tracked it rather than just read about it.

Also wondering if the GI stuff settles after a few weeks, i know spermidine gave me a bit of a rough gut at first and that calmed down. Guessing metformin might be similar but maybe worse? The profile says diarrhoea and metallic taste which sounds pretty rough tbh.

Comments

  • raj_j: Honestly the B12 thing is real but I think people frame it wrong. It's not like metformin poisons your B12, it messes with calcium-dependent absorption in the gut over time. So it creeps up on you slow. I ran metformin for about 8 months, low dose, 500mg twice a day. My B12 went from mid-range to borderline low around month 6. Didn't feel anything obvious from it but bloodwork don't lie. Started a methyl B12 sublingual and it came back up fine. Just carried on. The GI stuff though, that was th
  • student748: Chur thats exactly the kind of real-world tracking i was after. Month 6 is heaps longer than i expected to see it show up, good to know its a slow creep not a fast drop. Did you get baseline B12 before starting or were you comparing to older bloodwork? For what it is worth the sublingual methyl B12 approach seems smart as, bypasses the gut absorption issue entirely. And yeah nah the GI stuff is what worries me more than the B12 honestly, cant be doing long runs with gut issues.
  • busypriya: The calcium-dependent absorption angle makes sense, that's the ileal uptake mechanism relying on intrinsic factor and calcium at the brush border. Ngl I've seen the same slow creep pattern in people running metformin long-term, month 6ish seems to be the sweet spot for it showing up on labs. Sublingual methyl B12 sidesteps the gut issue entirely which is probably why it worked so well for you. The GI stuff usually settles after a few weeks but those first 3 weeks are no joke...
  • student748: Cheers for that, really helpful. Actually havent started metformin yet, still weighing it up, so the sublingual methyl B12 thing is good to know for if i do go ahead. For what it is worth the month 6 timeline for labs showing it is exactly the kind of real-world detail i was after. Did you see the B12 drop happen even with sublingual supplementation or did that keep levels stable?

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