500 mg of magnesium glycinate is not 500 mg of magnesium. Most of that weight is glycine. The magnesium itself is closer to 70 mg. Here is the label math.
By BoneScience Editorial · Sources checked against PubMed abstracts and the NIH Office of Dietary Supplements on November 8, 2026 · Last reviewed November 8, 2026
Compound weight vs elemental magnesium
Supplements carry magnesium as a salt or a chelate: magnesium joined to another molecule, which makes up most of the weight. The NIH Office of Dietary Supplements says the Supplement Facts panel declares elemental magnesium, not the weight of the entire compound. A front label reading "Magnesium Glycinate 500 mg" may be giving you the compound.
| Form | Formula used | Magnesium by weight | Magnesium in 500 mg of the compound |
|---|---|---|---|
| Magnesium oxide | MgO | About 60% | About 300 mg |
| Magnesium chloride | MgCl2 (hexahydrate to dry) | About 12 to 26% | About 60 to 128 mg |
| Magnesium citrate | Mg3(C6H5O7)2 (nonahydrate to dry) | About 12 to 16% | About 59 to 81 mg |
| Magnesium malate | MgC4H4O5 | About 16% | About 78 mg |
| Magnesium glycinate (bisglycinate) | Mg(C2H4NO2)2 | About 14% | About 70 mg |
Approximate; real ingredients vary with water content and buffering. Calculated from molecular formulas with standard atomic weights.
Real ingredients differ from the bare formula. Albion's TRAACS® magnesium bisglycinate chelate is specified at about 10% magnesium, not 14%. A dimagnesium malate ingredient reviewed by the European Food Safety Authority is specified at not less than 20%. The ingredient's specification beats any table.
The label math, step by step
- Find the magnesium line. The milligrams next to "Magnesium" on the panel are elemental magnesium. The form may appear in parentheses, such as "(as magnesium bisglycinate)."
- If you only see a compound weight, multiply. 500 mg of magnesium glycinate at 14% is about 70 mg of magnesium. With a 10% chelate ingredient, it is about 50 mg.
- Check the serving size. If a serving is three capsules, the magnesium line covers all three.
- Check that the math fits. 300 mg of magnesium from a 10% chelate takes 3,000 mg of ingredient. From magnesium oxide, it takes about 500 mg.
Glycinate, bisglycinate, malate, citrate, oxide: what the names mean
- Glycinate and bisglycinate. Magnesium bound to the amino acid glycine. "Bis" means two glycines per magnesium. Labels use both names for the same idea.
- Malate and dimagnesium malate. Magnesium bound to malic acid. Dimagnesium malate is a named supplier ingredient; its specification lists not less than 20% magnesium.
- Citrate. Magnesium bound to citric acid. In a 1990 lab test, 55% of it dissolved in plain water. Oxide barely dissolved.
- Oxide. The most magnesium per milligram, about 60%. The NIH lists oxide, carbonate, chloride and gluconate as the forms most often reported to cause diarrhea.
One check for every label: if magnesium oxide appears anywhere on the panel or ingredient list, it is part of your dose, whatever form the front of the bottle names. If you see the word "buffered," ask what the buffer is.
How much magnesium a day
Recommended Dietary Allowances (RDAs) from the NIH count food, drinks, supplements and medicines together.
| Age | Male | Female |
|---|---|---|
| 9 to 13 years | 240 mg | 240 mg |
| 14 to 18 years | 410 mg | 360 mg |
| 19 to 30 years | 400 mg | 310 mg |
| 31 to 50 years | 420 mg | 320 mg |
| 51 and older | 420 mg | 320 mg |
During pregnancy the RDA is 400 mg (ages 14 to 18), 350 mg (19 to 30) or 360 mg (31 to 50).
The Tolerable Upper Intake Level (UL) for supplemental magnesium is 350 mg a day for everyone 9 and older, teens and adults alike. It is 65 mg for ages 1 to 3 and 110 mg for ages 4 to 8. The UL covers supplements and medications only, not magnesium in food.
Count magnesium from your multivitamin too. A 300 mg magnesium product plus a multivitamin with 100 mg is 400 mg of supplemental magnesium, above the UL. Some heartburn remedies contain magnesium as well. High doses can cause diarrhea, nausea and cramping. If you take prescription medicine, ask your doctor first.
What absorption studies compared
Researchers measure absorption indirectly, by extra magnesium in urine or blood levels over hours. Less than 1% of the body's magnesium is in blood serum, and the body holds that level tightly.
| Study | Who and how long | Magnesium given | What it found | What it did not find, and limits |
|---|---|---|---|---|
| Lindberg 1990 | Healthy volunteers, single dose | 25 mmol (about 608 mg), citrate or oxide | Urine magnesium rose more after citrate. | One dose. Number of volunteers not in the abstract. |
| Firoz 2001 | Healthy volunteers | About 21 mEq a day (about 255 mg) | Oxide: about 4% absorbed. Chloride, lactate and aspartate: higher, and similar to each other. | Glycinate, citrate and malate not tested. Urine marker only. |
| Walker 2003 | 46 healthy adults, 60 days, randomized, placebo-controlled | 300 mg a day as amino acid chelate, citrate or oxide | Citrate and chelate raised 24-hour urine magnesium more than oxide. | Red blood cell magnesium did not differ. Oxide did not differ from placebo. |
| Schuette 1994 | 12 adults who had part of the small intestine removed | 100 mg, glycinate or oxide | Similar absorption overall (23.5% vs 22.8%). In the 4 who absorbed oxide most poorly, glycinate did better (23.5% vs 11.8%) and was better tolerated. | Very small, not healthy volunteers. |
| Siener 2011 | 13 healthy young men | 450 mg oxide, capsules or effervescent tablets | Urine magnesium rose 40% with the dissolved tablet and 20% with capsules. | Same form in both. It tests format, not form. |
| Werner 2019 | 14 healthy men, single dose | 400 mg, citrate or oxide | Citrate raised 24-hour urine magnesium; oxide did not. | Men only, one dose. |
| Blancquaert 2019 | 15 products in lab models, 2 of them in 30 people | Not in the abstract | Products varied widely. The lab's poor performer also did poorly in people. | Forms not named. |
| Pajuelo 2024 | 40 healthy adults on a low-magnesium diet | Not in the abstract | Blood magnesium rose after oxide and citrate. | Single dose, and blood was followed for only 6 hours. Blood magnesium is held in a tight range, so it is a weak marker. Within that window, bisglycinate showed no significant rise. Funded by the maker of a competing ingredient. |
A 2021 systematic review of 14 studies found inorganic forms appear less bioavailable than organic ones, and that all magnesium supplements can maintain normal levels in healthy people who do not start low.
The short version. In small, short studies, oxide was absorbed less than several other forms. Glycinate has two human comparisons: similar to oxide overall in 12 surgery patients (better in the 4 who absorbed oxide poorly), and no 6-hour blood rise in one sponsor-funded single-dose test. We found no human study comparing glycinate with malate.
Label checks that work on any brand
- Magnesium, not compound. Find the milligrams of magnesium on the panel.
- Each form with its share. A product that combines forms can show how much magnesium each supplies. A "proprietary blend" tells you less.
- Registered names mean a named supplier ingredient. Albion® TRAACS® or DiMag® tells you who made the raw material, so you can look up its specification. It is not, by itself, evidence of better absorption.
- Magnesium oxide, present or not. If listed anywhere, it is part of your dose.
- Capsules per serving. A low-percentage form needs more ingredient weight, so more capsules.
- A lot-matched certificate of analysis, and who ran it. A certificate of analysis (COA) is a lab report for one batch, with measured magnesium per serving (for example by ICP-MS). A manufacturer's COA comes from the company that made the capsules. An independent COA comes from an outside lab, ideally accredited to ISO/IEC 17025. A seller should say which it has. Match the lot number to your bottle.
- Your total. Add every product with magnesium and compare it with the 350 mg UL.
Questions readers ask
- How much elemental magnesium is in magnesium glycinate?
- By formula, magnesium bisglycinate is about 14% magnesium, so 500 mg holds about 70 mg. Albion's TRAACS® chelate is specified at about 10%, or about 50 mg per 500 mg. The Supplement Facts panel should state the magnesium amount.
- Is magnesium bisglycinate the same as magnesium glycinate?
- Usually, yes. Both mean magnesium bound to glycine. What differs is the ingredient specification and whether anything else, such as magnesium oxide, is mixed in.
- Magnesium glycinate vs malate: which is absorbed more?
- We found no human study comparing them directly. Compare products on magnesium per serving, how well you tolerate them, and how clearly the label shows each form.
- Magnesium oxide vs glycinate: what is the difference?
- Oxide is about 60% magnesium and glycinate about 14%, so oxide fits a dose in fewer capsules. One head-to-head study, in 12 adults after intestinal surgery, saw similar absorption overall and better tolerance with glycinate.
- What does TRAACS mean on a magnesium label?
- TRAACS® is a registered trademark of Albion Laboratories for its mineral amino acid chelates. It tells you who made the ingredient so you can check its specification. It is not a dose or an absorption figure.
See Prime Magnesium
The studies above were not conducted on BoneScience products. The certificate of analysis is the manufacturer's own testing, not independent testing; check the lot number on your bottle. Albion®, TRAACS® and DiMag® are registered trademarks of Albion Laboratories, Inc.
Related: Does NMN Work? What 12 Human Studies Actually Found · Black Ginger: What 10 Human Trials Actually Found
Sources
- National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. Updated January 6, 2026. ods.od.nih.gov
- Lindberg JS, et al. J Am Coll Nutr. 1990;9(1):48-55. PubMed · doi
- Firoz M, Graber M. Magnes Res. 2001;14(4):257-62. PubMed
- Walker AF, et al. Magnes Res. 2003;16(3):183-91. PubMed
- Schuette SA, et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PubMed · doi
- Siener R, et al. Urol Res. 2011;39(2):123-7. PubMed · doi
- Werner T, et al. Magnes Res. 2019;32(3):63-71. PubMed · doi
- Blancquaert L, et al. Nutrients. 2019;11(7):1663. PubMed · doi
- Pajuelo D, et al. Nutrients. 2024;16(24):4367. PubMed · doi
- Pardo MR, et al. Nutrition. 2021;89:111294. PubMed · doi
- EFSA Panel on Food Additives and Nutrient Sources added to Food. Evaluation of di-magnesium malate. EFSA J. 2018;16(6):e05292. PubMed · doi
- Magnesium percentages calculated by BoneScience from molecular formulas with standard atomic weights (Mg 24.305, O 15.999, C 12.011, H 1.008, N 14.007, Cl 35.45). Approximate.
- Albion Laboratories, Inc. Ingredient specifications for DiMag® dimagnesium malate and TRAACS® magnesium bisglycinate chelate (supplier documents).
- Manufacturer's Certificate of Analysis, BoneScience Prime Magnesium, lot 508009, magnesium by ICP-MS (manufacturer's testing).
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for general education and is not medical advice.