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ForumsLab Results & BiomarkersFerritin and iron studies on GLP-1 — reduced intake considerations

Ferritin and iron studies on GLP-1 — reduced intake considerations

BethLabQueen Mon, Jun 1, 2026 at 2:50 AM 3 replies 237 viewsPage 1 of 1
BethLabQueen
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Jun 1, 2026 at 2:50 AM#1

Writing this once so I can stop repeating it across threads. It is about micronutrient cover, and it is deliberately narrow — everything I am not confident about is marked as such.

What is actually established

A sustained drop to 1,100 or 1,200 calories reliably under-delivers a predictable set: B12, vitamin D, iron, folate, zinc and magnesium. Two of those are worth testing rather than guessing because the tests are cheap and the symptoms overlap with everything else — ferritin and B12. The rest a decent multivitamin covers, and there is no benefit in megadosing any of them.

The condition it depends on

The caveat that iron should be tested before supplementing, not after. Supplementing iron into normal stores is unpleasant at best and harmful in haemochromatosis.

The practical version

Cheap and worth having: ferritin, B12, vitamin D. Everything else on the deficiency list is adequately covered by a standard multivitamin at ordinary doses.

What I am not sure about

What I am trying to establish is which deficiencies actually show up when intake drops this far, and which are worth testing rather than supplementing blind. I have searched first, so if this is covered somewhere point me at it and I will read it.

— BethLabQueen · corrections welcome and will be edited into this post with credit
24 2maya_sedona, stefan_berlin, Dr.EM_Chicago and 21 others
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mike.trainer_LA
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Jun 1, 2026 at 3:00 AM#2
BethLabQueen said:
A sustained drop to 1,100 or 1,200 calories reliably under-delivers a predictable set: B12, vitamin D, iron, folate, zinc and magnesium.

Vitamin and mineral labs to check while on micronutrients — my doctor orders these quarterly:

  • B12: Can drop due to reduced GI absorption. Mine went from 650 to 380 — now supplementing.
  • Iron/Ferritin: Reduced food intake = reduced iron. Ferritin dropped from 56 to 23. Supplementing.
  • Vitamin D: Was already low (23 ng/mL), now taking 5000 IU daily.
  • Folate: Stable, no issues.
  • Zinc: Slightly low, added a multivitamin with zinc.

Nutritional deficiencies are a real risk when you're eating significantly less. Don't skip your labs!

25 3newstart_MO, mia_MS2, LeilaHI and 22 others
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PharmacoVig_BOS
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Jun 1, 2026 at 3:10 AM#3
BethLabQueen said:
A sustained drop to 1,100 or 1,200 calories reliably under-delivers a predictable set: B12, vitamin D, iron, folate, zinc and magnesium.

Iron studies on micronutrients — important especially for women:

MarkerBaselineMonth 6After Supplementation
Ferritin592759
Iron896487
TIBC339409339
Transferrin Sat29%19%30%

My ferritin cratered at month 6 from reduced dietary intake. Iron bisglycinate 36mg with vitamin C brought it back up. Don't wait for anemia symptoms — test proactively.

26 4DataDave, Dr.GutHealth, amsterdam_pete and 23 others
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Dr.EndoIndy
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Jun 1, 2026 at 3:20 AM#4
PharmacoVig_BOS said:
Iron studies on micronutrients — important especially for women: Marker Baseline Month 6 After Supplementation Ferritin 59 27 59 Iron 89 64 87 TIBC…

Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 89 → 97 fL. This flagged potential B12 or folate deficiency.

Sure enough, B12 had dropped from 620 to 340 pg/mL. Started B12 injections monthly and MCV normalized within 2 months. GLP-1 agonists can impair B12 absorption — this is a real clinical concern that deserves routine monitoring.

Last edited: Jun 1, 2026 at 6:20 AM
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josh_phd_bmore
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Jun 1, 2026 at 4:12 AM#5
mike.trainer_LA said:
Vitamin and mineral labs to check while on micronutrients — my doctor orders these quarterly: B12: Can drop due to reduced GI absorption.

Adding a me-too, because a thread of one person's experience is not much use. Posting only so the count is not one.

28 6tampaLisa73, KarenAZ_mom, zoe_NC and 25 others
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