Is 500 mg of magnesium glycinate too much?
It depends what the 500 milligrams measures. Labels in the US and UK list the magnesium itself, so if yours says 500 milligrams of magnesium, that is above the adult upper limit of 350 milligrams a day from supplements (magnesium in food does not count), and magnesium supplements often cause diarrhoea and stomach cramps. If 500 milligrams is the weight of the magnesium glycinate itself, it holds only about 70 milligrams of magnesium, well within the limit. If it is the full amount of magnesium, check with a doctor or pharmacist before taking that much.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
In the UK
It depends what the 500 milligrams measures. Labels in the US and UK list the magnesium itself, so if yours says 500 milligrams of magnesium, that is above the NHS guidance of 400 milligrams a day from supplements, and magnesium supplements often cause diarrhoea and stomach cramps. If 500 milligrams is the weight of the magnesium glycinate itself, it holds only about 70 milligrams of magnesium, well within the limit. If it is the full amount of magnesium, check with a doctor or pharmacist before taking that much.
The figures
| US (NIH) | UK (NHS) | |
|---|---|---|
| Amount checked | 500 mg | |
| Answer | Above the upper limit | Above NHS guidance |
| Compared with | 350 milligrams a day from supplements (magnesium in food does not count) | 400 milligrams a day from supplements |
| Share of the limit | 143% of the limit | 125% of the limit |
| Adults need | 400 to 420 milligrams for men and 310 to 320 milligrams for women, from food and supplements together | 300 milligrams a day for men and 270 milligrams for women |
Is that the magnesium or the magnesium glycinate?
US and UK labels list the magnesium itself. If 500 mg is the weight of the magnesium glycinate instead, it holds about 70 mg of magnesium, within the upper limit. Magnesium makes up about 14% of magnesium glycinate by weight.
Good to know
- Above the upper limit, magnesium supplements often cause diarrhoea and stomach cramps.
Quick answers
- Is 500 mg of magnesium glycinate too much?
- It depends what the 500 milligrams measures. Labels in the US and UK list the magnesium itself, so if yours says 500 milligrams of magnesium, that is above the adult upper limit of 350 milligrams a day from supplements (magnesium in food does not count), and magnesium supplements often cause diarrhoea and stomach cramps. If 500 milligrams is the weight of the magnesium glycinate itself, it holds only about 70 milligrams of magnesium, well within the limit. If it is the full amount of magnesium, check with a doctor or pharmacist before taking that much.
- What does the NHS say about 500 mg of magnesium?
- It depends what the 500 milligrams measures. Labels in the US and UK list the magnesium itself, so if yours says 500 milligrams of magnesium, that is above the NHS guidance of 400 milligrams a day from supplements, and magnesium supplements often cause diarrhoea and stomach cramps. If 500 milligrams is the weight of the magnesium glycinate itself, it holds only about 70 milligrams of magnesium, well within the limit. If it is the full amount of magnesium, check with a doctor or pharmacist before taking that much.
- What is the upper limit for magnesium?
- US: 350 milligrams a day from supplements (magnesium in food does not count). UK (NHS): 400 milligrams a day from supplements.
Sources
- NIH Office of Dietary Supplements fact sheet
https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/ - NHS vitamins and minerals guidance
https://www.nhs.uk/conditions/vitamins-and-minerals/others/
Ask Supplement Check yourself
Type any amount of a vitamin, mineral or supplement, or a whole routine, and see how it compares with the adult limits. Open Supplement Check, free, no sign-up.
In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/supplementcheck/mcp and ask: “Is 500 mg of magnesium glycinate too much?”
More on magnesium
- Magnesium: what it does and how much you need
- Is 500 mg of magnesium too much?
- Is 400 mg of magnesium too much?