How to Choose a Magnesium Supplement in Canada
Short answer: start with the label, not the form name on the front. Check the amount of elemental magnesium per dose (not the weight of the compound), confirm an 8-digit NPN, and keep your total from supplements and medicines at or below Health Canada's upper limit of 350 mg a day for ages 9 and older, unless a health professional advises otherwise. Choose the form by how it agrees with you; if you are deciding between glycinate and citrate, see our Magnesium Glycinate vs Magnesium Citrate guide. If you have kidney disease or take regular medication, ask your doctor or pharmacist first.
Magnesium forms: what we can say about each
Magnesium in supplements is always bound to another compound, which gives the form its name. Human studies comparing forms are few and small. In one small study in healthy volunteers (Firoz and Graber, 2001), magnesium oxide was absorbed less than magnesium chloride, lactate and aspartate. Treat absorption claims on packaging with caution.
| Form | What it is | What we can verify | Examples we carry (label amounts) |
|---|---|---|---|
| Bisglycinate (glycinate) | Magnesium bound to the amino acid glycine | Several Canadian "bisglycinate" products are blends that also contain magnesium oxide, so read the ingredient line | NFH Magnesium SAP (150 mg from 833 mg magnesium bisglycinate per capsule); CanPrev Magnesium Bis-Glycinate 200 Gentle (200 mg per capsule from a bis-glycinate chelate, magnesium oxide and glycine blend); Designs for Health Magnesium Glycinate Complex (150 mg per capsule from a bisglycinate chelate and magnesium oxide blend); Webber Naturals Magnesium Bisglycinate 200 mg (retailer label copies list bisglycinate and oxide) |
| Citrate | Magnesium bound to citric acid | Compared with glycinate in our glycinate vs citrate guide | NFH Magnesium Citrate SAP (136 mg from 850 mg magnesium citrate, plus 45 mg taurine, per capsule) |
| Oxide | Magnesium bound to oxygen; a concentrated compound | Lower absorption than chloride, lactate and aspartate in the small study above | Found on its own and inside blends; check the label |
| Malate, L-threonate | Magnesium bound to malic acid or L-threonic acid | We have not cited human trials for these forms, so we make no claim about them | See the Magnesium collection |
How to read a Canadian magnesium label
- Elemental amount vs compound weight. The medicinal ingredient line usually reads "Magnesium (from X mg magnesium citrate) Y mg". Y is the elemental magnesium, the number to compare and to add up. For example, NFH Magnesium Citrate SAP lists 136 mg of magnesium from 850 mg of magnesium citrate, and NFH Magnesium SAP lists 150 mg from 833 mg of magnesium bisglycinate.
- Per capsule vs per dose. Multiply by the number of capsules in the label dose. NFH Magnesium SAP is 1 capsule twice daily for adults (300 mg a day); CanPrev 200 Gentle is 1 capsule a day (200 mg).
- The NPN. Natural health products licensed by Health Canada carry an 8-digit Natural Product Number. Magnesium laxatives and antacids are drugs and carry a DIN instead, and their magnesium counts toward your total. Look either number up with our guide How to Check an NPN or DIN.
- Age and cautions. Labels state who the product is for. Designs for Health Magnesium Glycinate Complex is labelled for adults and adolescents 9 and over; NFH Magnesium Citrate SAP for adolescents 14 to 18 and adults. More tips: How to Read a Natural Health Product Label in Canada.
How much magnesium? Health Canada's numbers
The recommended dietary allowance (RDA) covers magnesium from all sources, mostly food. The tolerable upper intake level (UL) for magnesium is different: Health Canada's table notes that it applies to magnesium from pharmacological sources only, such as supplements and medicines, and not to magnesium from food and water.
| Group | RDA per day (all sources) | UL per day (supplements and medicines only) |
|---|---|---|
| Children 1–3 | 80 mg | 65 mg |
| Children 4–8 | 130 mg | 110 mg |
| Children 9–13 | 240 mg | 350 mg |
| Teens 14–18 | Males 410 mg; females 360 mg | 350 mg |
| Adults 19–30 | Men 400 mg; women 310 mg | 350 mg |
| Adults 31 and older | Men 420 mg; women 320 mg | 350 mg |
See Health Canada's DRI reference values for elements for pregnancy, breastfeeding and infants. The UL is not a target. Diarrhea was the effect used to set the limit for supplemental magnesium (see the 2023 review in Sources). Add up every product: a 300 mg daily supplement plus a multivitamin or an antacid that contains magnesium can pass 350 mg.
Who should ask a doctor first
- Kidney disease. The CanPrev, Webber Naturals and Designs for Health product pages all ask you to consult a health professional first if you have kidney disease. The kidneys remove extra magnesium, and ODS notes that the risk of magnesium toxicity rises when kidney function is impaired.
- Regular medication. Magnesium can interact with some medicines, including oral bisphosphonates for osteoporosis and tetracycline or quinolone antibiotics (NIH Office of Dietary Supplements, U.S. background). Your pharmacist can tell you how far apart to take them.
- Pregnancy or breastfeeding. NFH Magnesium Citrate SAP asks you to consult a health-care practitioner first.
- Children. Use only products labelled for your child's age, and keep within the lower ULs above.
Frequently asked questions
Is magnesium glycinate the same as magnesium bisglycinate?
Labels and retailers use both names for magnesium bound to glycine. The name tells you the form; the elemental amount on the label tells you the dose.
Why does my bisglycinate label also list magnesium oxide?
Some products are blends. CanPrev 200 Gentle, Designs for Health Magnesium Glycinate Complex and Webber Naturals Magnesium Bisglycinate all list oxide alongside bisglycinate. The elemental amount on the label covers the whole blend.
How much magnesium can I take from supplements?
Health Canada's upper limit is 350 mg a day from supplements and medicines combined for ages 9 and older, and lower for younger children. Follow the label dose, and ask a health professional before going above it.
Can magnesium affect my medicines?
Yes, it can. Bisphosphonates and some antibiotics are examples. Ask your pharmacist how to space them.
When to see a doctor or pharmacist
- Before starting magnesium if you have kidney disease or take prescription medication.
- If you are pregnant or breastfeeding, or choosing a product for a child.
- If you get ongoing diarrhea, or feel weak, dizzy or unwell after starting a supplement.
- If you are taking magnesium for a symptom such as cramps or poor sleep that does not improve, so the cause can be checked.
Related reading and products
Browse the Magnesium collection, or shop by brand: NFH, CanPrev, Webber Naturals and Designs for Health. Related guides: Magnesium Glycinate vs Magnesium Citrate and Calcium Carbonate vs Calcium Citrate.
Sources
- Health Canada. Dietary Reference Intakes tables: Reference values for elements.
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnesium Research. 2001;14(4):257–262.
- Costello RB, et al. Perspective: Call for re-evaluation of the tolerable upper intake level for magnesium supplementation in adults. Advances in Nutrition. 2023. PMC10509448.
- NIH Office of Dietary Supplements (U.S.; background). Magnesium: Fact Sheet for Health Professionals.
- Product amounts, directions and cautions: Canadian label copy for each product (NFH, CanPrev, Designs for Health and Webber Naturals listings) and the Healthy Hub product pages linked above.
This guide is general information, not medical advice. Ask your pharmacist or doctor about your own situation.
