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Vitamin B12 monitoring — anyone have experience?

TomTeleRx Tue, Jan 21, 2025 at 12:37 AM 32 replies 2,172 viewsPage 1 of 7

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TomTeleRx

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Jan 21, 2025 at 12:37 AM#1

Read the primary source rather than the write-up and the two do not agree, so here is what is actually in it.

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.

Where I think it is weakest: the subgroup findings are the part I trust least — with enough subgroups something is always significant, and these were not all pre-registered.

What would genuinely help is knowing which deficiencies actually show up when intake drops this far, and which are worth testing rather than supplementing blind. If the honest answer is that nobody knows, that is a useful answer and I would rather have it.

Note on sourcing:
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.

5 0pete_manc_UK, anna.melb_AU, mark_tokyo and 2 others

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COA_Karl

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Jan 21, 2025 at 12:50 AM#2

TomTeleRx 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:

Marker	Baseline	Month 6	After Supplementation
Ferritin	61	24	56
Iron	91	61	94
TIBC	336	406	346
Transferrin Sat	28%	16%	27%

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.

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Dr.RaviCardio

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Jan 21, 2025 at 1:03 AM#3

TomTeleRx 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.

Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 90 → 98 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: Jan 21, 2025 at 2:03 AM

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jim_asheville

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Asheville, NC

Jan 21, 2025 at 1:16 AM#4

Dr.RaviCardio said:
Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 90 → 98 fL.

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 69 to 26. Supplementing.
Vitamin D: Was already low (20 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!

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mark_tokyo

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Jan 21, 2025 at 2:23 AM#5

COA_Karl said:
Iron studies on micronutrients — important especially for women: Marker Baseline Month 6 After Supplementation Ferritin 61 24 56 Iron 91 61 94 TIBC…

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Vitamin B12 monitoring — anyone have experience?

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