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What is the best magnesium for IBD in the UK?
Magnesium glycinate is the best form for IBD: the one trial in bowel disease found it absorbed where oxide was not, and it does not add to diarrhoea as citrate and oxide can. Tell your IBD team first.
- Glycinatethe form studied in patients with bowel resection
- 300mgelemental per 2 capsules of the worked example
- Diarrhoeawhy citrate and oxide are the wrong forms
- Your IBD teamshould know you are taking it
Worked example: Futuro Labs Magnesium Glycinate on Amazon UK, 300mg elemental per serving, £19.99 for 90 days. Label breakdown. This page is about the form and the label; magnesium status in IBD is a matter for your gastroenterology team.
Why magnesium and IBD are linked
Inflammatory bowel disease attacks the gut lining that absorbs magnesium, and the diarrhoea that comes with a flare carries magnesium out faster than a normal diet replaces it. Gröber's 2015 review lists gastrointestinal losses and malabsorption among the main causes of low magnesium, and people with Crohn's disease, particularly with small bowel involvement or resection, are the textbook example. Low intake shows as fatigue, cramps, twitching and poor sleep, all of which a flare already brings, so it gets missed. That is why the first move is not a supplement but a conversation with your IBD team and a blood test, which they can order.
The trial that answers the form question
Schuette and colleagues in 1994 compared magnesium diglycinate with magnesium oxide in patients with ileal resection, the group with the worst absorption there is. The glycinate form was absorbed; the oxide largely was not. It is a small study, but it is the only one in bowel disease and it points the same way as the general data: chelated glycinate is absorbed further up the gut, is not dependent on stomach acid, and does not pull water into the bowel at useful doses. Citrate and oxide do, which for someone whose problem is diarrhoea makes them the wrong forms even where they might be absorbed.
| Form | Elemental magnesium | Effect on stool | Evidence in bowel disease | Verdict |
|---|---|---|---|---|
| Glycinate (bisglycinate) | about 14% to 20% | Low laxative effect | Absorbed in ileal resection patients (Schuette 1994) | The form to take, once your team knows |
| Citrate | about 16% | Osmotic laxative | General studies only | Wrong form for diarrhoea |
| Oxide | about 60% | Laxative, poorly absorbed | Not absorbed in the resection study | No |
| Sprays and bath flakes | n/a | None | No reliable evidence of skin absorption | No |
| Prescribed magnesium (tablets, injections) | varies | varies | Used by clinicians when levels are genuinely low | Follow your team; do not stack a supplement on top without asking |
Dose, label warnings and the worked example
The worked example, Futuro Labs Magnesium Glycinate, gives 300mg elemental magnesium from 1500mg chelated bisglycinate in 2 capsules, 80% NRV, from a vegan capsule made in the UK under GMP and BRC certification, third-party tested for heavy metals and microbiology, 180 capsules for £19.99, 22p a day. Its label says not to use it if you are taking other medications without checking first, and for IBD that line matters: some IBD medicines and magnesium can affect each other's absorption if taken at the same time, and your pharmacist can tell you how far apart to space them. Start with 1 capsule with a meal to check tolerance, move to 2, and stay under the 400mg a day guidance level unless your team prescribes more.
What this page is not
It is not a treatment for IBD, and magnesium has no authorised claims about the gut. The claims it does carry, normal muscle function, electrolyte balance, reduction of tiredness and fatigue, describe why a low level makes a flare feel worse, not a way to prevent one. If your magnesium is genuinely low on a blood test, your team may prescribe it; if it is normal, a food-first approach plus a modest, well tolerated supplement during and after flares is the sensible middle. The best magnesium for IBD in the UK is the one that gets absorbed without adding to the diarrhoea, and that is chelated glycinate, the 300mg elemental one, taken with your team's knowledge.
What to check on the label
- Glycinate or bisglycinate first; never citrate or oxide for a diarrhoea-prone gut.
- Elemental magnesium printed, so you and your team know the dose.
- A medication warning on the label, and a pharmacist's advice on spacing from your IBD medicines.
- No gut, inflammation or IBD claims; none are authorised.
- Small capsules and no lactose or gluten if those are triggers for you; read the whole ingredients line.
The worked example: Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the worked example because it is the form with evidence in bowel disease at a printed dose: 300mg elemental per 2 capsules (80% NRV) from chelated bisglycinate, low laxative effect, vegan, gluten free, UK made, third-party tested, 22p a day from a £19.99 bottle of 180.
- Elemental magnesium per serving
- 300mg (80% NRV)
- Form
- magnesium bisglycinate 20%
- Serving
- 2 capsules a day
- Bottle
- 180 capsules, 90 days
- Price
- £19.99 (22p a day)
- Capsule
- vegetarian shell, vegan product
Questions people also ask
Is magnesium glycinate safe with Crohn's or colitis?
It is the form least likely to worsen diarrhoea and the one absorbed in the bowel resection trial. Tell your IBD team, and ask a pharmacist about spacing it from your medicines.
Which magnesium does not cause diarrhoea?
Glycinate has the lowest laxative effect of the common forms. Citrate and oxide both pull water into the bowel at useful doses.
Can IBD cause low magnesium?
Yes. Malabsorption and diarrhoea are among the main causes of low magnesium, and people with Crohn's are a recognised at-risk group. A blood test through your team is the right first step.
How much magnesium should someone with IBD take?
300mg elemental a day from a supplement is the usual ceiling without medical advice; your team may prescribe more if a blood test shows a real deficiency.
Does magnesium help IBD symptoms?
No claim is authorised and no trial shows it treats IBD. Correcting a low level can improve the fatigue and cramps that a low level causes, which is a different thing.
Sources
- Futuro Labs Magnesium Glycinate listing, Amazon UK, label and price checked 31 August 2026. https://www.amazon.co.uk/dp/B0BT7Z5VQW
- Schuette SA, Lashner BA, Janghorbani M. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. Journal of Parenteral and Enteral Nutrition 1994;18(5):430-435. PubMed record
- Gröber U, Schmidt J, Kisters K. Magnesium in prevention and therapy. Nutrients 2015;7(9):8199-8226. PubMed record
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnesium Research 2001;14(4):257-262. PubMed record
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to magnesium. EFSA Journal 2010;8(10):1807. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1807
- Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf