Magnesium is one of the most popular supplements, but the labels can be confusing: glycinate, citrate, oxide and more. The form matters, because it affects how well magnesium is absorbed and how it treats your stomach. Here is a simple guide.

What Does Magnesium Do?

Magnesium is a mineral involved in hundreds of processes in the body, including muscle and nerve function, energy production, blood sugar control and bone health. Good food sources include leafy green vegetables, beans, groundnuts, nuts, seeds, whole grains and fish. Adults need roughly 310 to 420 mg a day from all sources, depending on age and sex.

Who May Be Low in Magnesium?

  • People whose diet contains few vegetables, beans or whole grains
  • People with long-term diarrhoea or digestive conditions
  • People with type 2 diabetes
  • Heavy alcohol drinkers
  • Older adults
  • People who take some medicines for a long time, such as certain diuretics or stomach acid medicines (proton pump inhibitors)

Magnesium Glycinate

Magnesium glycinate (also called bisglycinate) is magnesium bound to the amino acid glycine. It is well absorbed and is generally gentle on the stomach, with less laxative effect than other forms. It is a popular choice for people who want a daily magnesium supplement and are sensitive to stomach upset, and is often taken in the evening.

Magnesium Citrate

Magnesium citrate is also well absorbed. It draws water into the bowel, so it has a stronger laxative effect, especially at higher doses. This makes it a common choice for people who also have occasional constipation, but less suitable for people with loose stools.

What About Magnesium Oxide?

Magnesium oxide contains a lot of magnesium per tablet but is less well absorbed than glycinate or citrate. It is often used as an antacid or laxative.

Magnesium for Sleep and Muscle Cramps: What the Evidence Says

  • Sleep: A few small studies, mostly in older adults, suggest magnesium may help some people sleep a little better, but the evidence is limited. It is most likely to help people who are actually low in magnesium. Good sleep habits matter more.
  • Muscle cramps: Reviews of trials have found that magnesium is unlikely to help ordinary night-time leg cramps in older adults. Results in pregnancy are mixed. Stretching and staying hydrated can help, and frequent cramps should be checked by a doctor.

Choosing Between Them

  • Want gentle, everyday magnesium: glycinate, for example Carlyle Magnesium Glycinate Plus Ashwagandha. Note that this product also contains ashwagandha, which is not recommended in pregnancy or breastfeeding and should be discussed with your doctor if you have a thyroid condition, autoimmune disease or liver problems.
  • Also have occasional constipation: citrate, for example NOW Magnesium Citrate.
  • Looking for relaxation support without magnesium: some people use L-theanine, an amino acid found in tea. Small studies suggest it may help relaxation, but evidence is limited.

Safety Tips

  • Do not take more than the label says. For adults, supplement doses above 350 mg of magnesium a day are more likely to cause diarrhoea, stomach cramps and nausea.
  • People with kidney disease should not take magnesium supplements unless a doctor advises it, because magnesium can build up in the blood.
  • Magnesium can reduce the absorption of some medicines, including certain antibiotics (such as ciprofloxacin and doxycycline), osteoporosis medicines and thyroid tablets. Take it at least 2 hours apart from these, or as your pharmacist advises.

The Bottom Line

Glycinate is the gentle everyday choice, citrate suits people who also want help with constipation, and food should always come first. If you take regular medicines or have kidney problems, check with our pharmacist before starting magnesium.

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This article is for general information only and does not replace advice from your doctor or pharmacist. If you have questions about your health or a product, message our pharmacist on WhatsApp 0916 577 4708 or call 0809 512 7000.