Homocysteine + B vitamins question for GLP-1 users
16 posts
Quick question for the lab crowd. Pulled homocysteine for first time after 6 months on tirz (7.5mg), result was 14.2 umol/L. Lab ref range says <11.4.
My B12 was 412 pg/mL (in range 200-1100). Folate 9.4 (in range).
Everything else on the CMP/CBC fine. No neuropathy, no fatigue.
Reading suggests GLP-1s can subtly interfere with B12 absorption over time. Is that actually a known thing or overblown? And if I supplement, methyl-B12 vs cyano?
10 Replies
40 posts
GLP-1s slow gastric emptying, which CAN reduce intrinsic factor-B12 complex formation over long courses. The effect is small and variable but real. 6 months in is a reasonable window to see it start.
29 posts
Serum B12 of 412 is 'in range' but it's in the 'functionally low' zone — most research suggests B12 deficiency symptoms start showing up below 500 and full sufficiency wants >600. Your elevated homocysteine is consistent with mild B12 inadequacy despite the 'normal' label.
Get MMA (methylmalonic acid). That's the sensitive marker. If MMA is elevated you have a functional B12 issue.
- Sermorelin · 300 mcg · pre-bed · sub-Q
- Ipamorelin · 200 mcg · pre-bed · sub-Q
16 posts
Ordering MMA now. What homocysteine value would you consider 'back to normal' after supplementation — under 8? under 10?
50 posts
Anecdotally — I was in the same situation (homocysteine 13.8 at 8 months on tirz). Started methyl-B12 1mg sublingual + methylfolate 400mcg. Retested at 4 months, homocysteine was 6.8. So it's fixable.
- Tirzepatide · 5 mg · weekly · sub-Q
117 posts
Methyl- vs cyano- B12: for most people cyano is fine (the body converts it). Methyl-B12 is advantageous if you have MTHFR variants or really low B12 and want faster repletion. Evidence is weaker than internet-supplement-bro culture suggests.
16 posts
Helpful, thanks. Going to start methyl-B12 + methylfolate and retest in 8 weeks.
36 posts
Worth noting for others: this is why I suggest adding a B-complex as a default for anyone on GLP-1s beyond 3-4 months. Cheap insurance.
10 posts
Also consider TMG/betaine if homocysteine stays stubborn. Separate methylation pathway.
36 posts
Your numbers aren't that bad honestly. 14.2 is elevated but not alarming, and your B12/folate are both solidly in range so I wouldn't panic about absorption issues yet. That said, the GLP-1 thing is real enough that adding a B-complex is basically free and you'd want to retest in 8-12 weeks anyway to see if it moves. Skip the MTHFR rabbit hole unless you retest and still see stubborn elevation despite supplementing, that's when it gets relevant.