Magnesium
200 mg as oxide plus citrate. Magnesium draws water into the bowel, which is why the oxide form is the one that helps constipation.
Written by R. Kessler · About Knurle · Editorial policy
The short answer
Magnesium is a mineral involved in muscle function, nerve signalling and hundreds of enzyme reactions. Magnesium oxide is poorly absorbed and draws water into the intestine, which is why it is the form used when the goal is bowel regularity rather than raising body magnesium.
The form, and why it matters
Oxide is the most concentrated and the least absorbed, and its osmotic effect is the point when constipation is the problem. Citrate is better absorbed and gentler. Glycinate is the best-tolerated and the least likely to loosen stools. Keel uses oxide plus citrate, which covers both jobs.
Typical dose
The adult reference intake is 310 to 420 mg a day depending on age and sex, from food and supplements together, with a supplemental tolerable upper intake of 350 mg for adults. Keel carries 200 mg.
What the research shows
Low magnesium is common in general diets, and whole grains, nuts and greens are the main sources, which are exactly the foods that shrink when appetite does. A 2025 study of combined magnesium and zinc found that correcting low levels of both improved fasting glucose and insulin sensitivity more than either alone, though these were corrections of deficiency rather than super-doses in replete people.
Who should be careful
High doses cause diarrhoea, which is the dose-limiting effect rather than a side effect to worry about. Magnesium supplements interact with several antibiotic classes and with levothyroxine, so separate the doses and ask a pharmacist.
Where it sits in our formulas
| Product | Form on the label | Amount per serving | % Daily Value |
|---|---|---|---|
| Keel | as oxide + citrate | 200 mg | 48% |
Sources
Figures checked against the sources above on 21 September 2026.
Zinc
Zinc citrate in Moat at the everyday nutritional amount, zinc bisglycinate in Keel. The famous cold trials used lozenges at 80 to 207 mg, which is a different thing entirely.
Read itIron
Ferrous bisglycinate at 18 mg, a chelated form that is usually kinder to the stomach than oxide or sulfate at the same elemental amount.
Read itLactoSpore®
Bacillus coagulans at 166 mg, a spore-forming probiotic that survives stomach acid and reaches the gut alive.
Read itMagnesium plus zinc: why the pair matters
Why 200 mg magnesium oxide/citrate with 20 mg zinc bisglycinate behaves differently as a pair than as singles. The blood sugar and steady-energy angle, and why we put them together in Keel.
Read itMagnesium oxide vs citrate vs glycinate: which form
Magnesium oxide is poorly absorbed but draws water into the bowel. Citrate is better absorbed. Glycinate is the gentlest. What each form actually does differently.
Read itHow to fix constipation on Ozempic
Constipation is a common side effect of Ozempic and other GLP-1 medications. Here are evidence-backed steps to ease it safely, from diet adjustments to lifestyle changes.
Read itEvery milligram, printed.
Each amount on the label is the amount in a full daily serving, and it matches what is on this page.
