The Bloods That Never Improve
Every few months the same results come back. B12 low. Ferritin all over the place. Vitamin D low again. Albumin drifting down. You have been taking the tablets. You take them every day. And nothing on the paper moves.
So either you are doing it wrong, or something more basic is going on.
It is the second one. You are pouring water into a bucket with a hole in it, and then being asked why the bucket is not full.
Absorption Happens in Specific Places — and Crohn's Sits in the Worst One
The gut is not one organ that absorbs everything everywhere. Each nutrient has an address.
- Duodenum and upper jejunum: iron, calcium, folate.
- Jejunum: most fats, proteins, carbohydrates, and the fat-soluble vitamins A, D, E and K.
- Terminal ileum: vitamin B12 — and bile salts. Nowhere else. That is it.
- Colon: water, electrolytes, and the butyrate your bacteria make from fibre.
Now note where Crohn's most commonly settles: the terminal ileum. The one segment that does two jobs no other segment can do.
What Goes Wrong, Nutrient by Nutrient
Vitamin B12. Absorbed only at the terminal ileum. Inflame that segment, or remove it surgically, and B12 uptake stops — no matter how much you swallow, because the receptor site is inflamed or gone. Deficiency shows up as fatigue, brain fog, a sore tongue and, if it is left long enough, tingling and numbness in the feet, which is nerve damage and does not always fully recover. If your ileum has been resected, B12 by injection is likely for life. Take it.
Iron — and why "your iron is fine" can be wrong. Three things happen at once. You lose iron through bleeding. You absorb it badly, because the duodenum where iron is taken up may be inflamed. And inflammation itself raises a hormone that both blocks absorption and locks iron away inside your storage cells. So your ferritin — a storage marker that also rises with inflammation — can look normal or high while you are functionally iron deficient and exhausted. Ask for transferrin saturation alongside CRP, not ferritin alone. Oral iron is often poorly absorbed in active disease and can irritate the gut and shift the microbial community unfavourably; this is why intravenous iron is frequently the better conventional option. That is your gastroenterologist's call.
Vitamin D. Fat-soluble, so it needs functioning fat absorption — which is exactly what bile salt loss destroys. Low vitamin D affects bone, and it also has a role in immune regulation, so it is both a consequence and, plausibly, a contributor.
Bile-salt diarrhoea. With ileal disease or resection, bile salts are not reabsorbed and spill into the colon, where they act as a powerful secretory irritant — driving watery diarrhoea that can persist even when the disease looks quiet. It is a distinct, treatable problem, and conventional bile acid sequestrants exist. Ask about it by name; it is under-recognised, and people spend years being told their Crohn's is active when this is what is happening.
Protein-losing enteropathy. This is the one nobody explains. Inflamed intestinal mucosa leaks albumin and other proteins out of you, into the lumen. You are not merely failing to absorb protein — you are actively losing it. That is why albumin falls, ankles swell, wounds heal slowly and muscle disappears despite protein shakes. You cannot drink your way out of a leak.
Zinc and magnesium. Lost in chronic diarrhoea. Zinc deficiency impairs tissue healing — which matters enormously if you have perianal disease or a fistula.
Why Supplements Alone Plug a Leaking Bucket
Keep taking every supplement, injection and infusion your doctor has prescribed. They are necessary — they are simply not sufficient, and they were never designed to be.
Supplementation addresses intake. But intake was never your bottleneck. Your bottleneck is a damaged absorptive surface, an open barrier, inflammation that actively blocks iron uptake, and a mucosa that is leaking protein out as fast as you put it in. Until those change, you are topping up a bucket instead of mending it.
What Actually Changes Absorption
The state of the intestine. Which means the drivers underneath it — and, in Crohn's, that means the gut barrier and immune regulation first, with metabolic, hormonal and stress/cortisol addressed alongside.
- Phase L — Inflammatory Load Reduction (oral, 4–8 weeks). This has to come first, even here. Absorption cannot normalise while inflammatory signalling is high, because inflammation is itself one of the mechanisms blocking iron uptake and driving protein breakdown. Supplementing into a high-inflammation state is fighting the biology.
- Phase I — Internal Correction (oral, 8–16 weeks). This is the phase that changes absorption, because this is the phase that repairs the epithelial barrier, the mucus layer and the microbial environment that feed it. Restore the surface, and the nutrition follows — and the supplements you have been faithfully taking finally start to count.
- Phase F — Functional Clearance (oral, 6–12 weeks), only once L and I are stable. Applied first — as some "cleanse first" programmes do — it mobilises load faster than an already depleted body can clear it, and people get worse. If that happened to you, the timing was wrong, not the whole idea.
- Phase S — Remission Maintenance (tapered oral, 6–12 months).
All oral. There is no procedure and no clinic visit at any stage. Keep your gastroenterologist and keep your bloods — this is one area where objective monitoring tells all of us the truth.
Honest Limits
If your terminal ileum has been resected, B12 absorption does not come back, and some bile-salt-driven diarrhoea and fat malabsorption will remain permanently. Extensive prior resection changes what is physically possible, and no protocol restores bowel that is no longer there. In those situations the realistic goal is better nutritional status, a lower inflammatory burden and a lower medication load — not a return to normal physiology.
Red Flags
Swelling of the legs or abdomen, breathlessness, fainting, rapid weight loss, inability to keep fluids down, or new tingling and numbness in the feet — get medical assessment promptly. Do not self-treat a suspected B12 neuropathy.
Next Step
Book a video or WhatsApp consultation and bring your recent bloods — B12, folate, ferritin, transferrin saturation, vitamin D, albumin, CRP — and your surgical history. Formulations are couriered to you.
