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Vitamins and minerals · Answer
Adults need about 310 to 320 mg (women) or 400 to 420 mg (men) of magnesium a day from all sources, mostly food. Supplements typically add 100 to 350 mg of elemental magnesium. The US upper limit for supplemental magnesium is 350 mg a day and EFSA's is 250 mg. People with kidney disease should not supplement without medical advice.
The NIH recommended dietary allowance (RDA), counting food and supplements together:
| Age | Men | Women |
|---|---|---|
| 19 to 30 | 400 mg | 310 mg |
| 31 and over | 420 mg | 320 mg |
Good food sources are nuts, seeds, legumes, whole grains and leafy greens. Most people closing a gap need a supplement of well under the full RDA.
Typical supplemental doses are 100 to 350 mg of elemental magnesium a day. Elemental magnesium is the magnesium itself, not the weight of the compound it is bound to. Two upper limits apply to supplemental magnesium (not food):
Stay at or below the lower figure unless a doctor directs otherwise. Doses above these limits mainly cause diarrhoea, nausea and cramping; very high doses can cause low blood pressure and irregular heartbeat.
Using label amounts as of October 2026:
| Product | Elemental Mg | Label dose | Daily elemental Mg |
|---|---|---|---|
| Dis-Chem Gold Slow Release Magnesium | 68.4 mg per tablet | 2 to 3 tablets | 137 to 205 mg |
| Dis-Chem Gold Magnesium Chelate | 99 mg per tablet | 1 to 2 tablets | 99 to 198 mg |
| The Real Thing Tri-Mag | about 120 mg per capsule | 2 capsules | about 240 mg |
| Flora Force Magnesium Glycinate | 100 mg per capsule (our reading of the label) | 1 to 2 capsules | 100 to 200 mg |
Tri-Mag's two-capsule dose is just under EFSA's limit, so avoid adding another magnesium product on top. See best magnesium in South Africa for price per 100 mg.
With food, to limit stomach upset. Evening dosing is common for preference; it is not proven to be better. Split larger doses across the day if your gut is sensitive.
In people with adequate intake, there is no good evidence that extra magnesium improves performance, sleep or exercise cramps, and the AIS places it in Group C. Supplements help when intake is low or a deficiency has been diagnosed. For the evidence in detail, see does magnesium help sleep and cramps? and for form differences magnesium glycinate vs citrate.
If you want to know whether you actually are low, a blood test is the starting point, though blood levels are an imperfect guide to body stores. Read also can you take too many vitamins?. Pricing and form comparisons are on our best magnesium page.
| Product | Size | Price (source, date) | Servings | R per serving | Sweeteners |
|---|---|---|---|---|---|
| Dis-Chem Gold Slow Release Magnesium 60 coated tablets | 60 tablets | R134.99-R169.99 (Dis-Chem Living Fit, 2026-10) | 24 | R5.62 | not stated |
| Dis-Chem Gold Magnesium Chelate 90 coated tablets | 90 tablets | R300 (Dis-Chem Living Fit, 2026-10) | 60 | R5.00 | not stated |
| The Real Thing Tri-Mag 90 capsules | 90 capsules | R285 (Faithful to Nature, 2026-10) | 45 | R6.33 | not stated |
| Flora Force Magnesium Glycinate 60 capsules | 60 capsules | R169 (Faithful to Nature, 2026-10) | 30 | R5.63 | not stated |
Educational information, not medical advice. Speak to a doctor, pharmacist or registered dietitian before using supplements if you are pregnant or breastfeeding, under 18, taking medication, or living with kidney, liver or heart disease. Prices were observed in October 2026 and are not offers.