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Magnesium Citrate Powder — Trimagnesium Citrate Dietary Supplement

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Size: 1 Pound

Dietary supplement · Magnesium citrate powder · At least 110 mg magnesium per gram

About Magnesium Citrate Powder

Greenway Biotech Magnesium Citrate Powder is pure trimagnesium citrate, the hydrated magnesium salt of citric acid, sold as a loose powder with nothing else added: no flavors, sweeteners, fillers, or flow agents. It is a dietary supplement taken by mouth, one level teaspoon stirred into water or juice, to help you meet your daily magnesium needs. Each gram supplies at least 110 mg of elemental magnesium; the current lot measures 12.0%, or about 120 mg per gram.

Magnesium is a cofactor in more than 300 enzyme systems and supports normal muscle and nerve function, energy production, and the structural development of bone, and the citrate form dissolves in liquid, which the NIH Office of Dietary Supplements links to more complete absorption than less soluble forms such as magnesium oxide.* Its most material limitation is the one every magnesium supplement shares: the Tolerable Upper Intake Level for magnesium from supplements is 350 mg per day for adults, and amounts above that can cause loose stools. One level teaspoon is the whole day’s serving; keep it level, take it once, and talk to your healthcare provider first if you have kidney disease or take medication.

  • ≥110 mg / g Elemental magnesium per gram of powder, guaranteed at the specification minimum (11.0%); the current lot tests at 12.0%
  • 1 level tsp The Supplement Facts serving, about 3 g: at least 330 mg of magnesium (79% Daily Value), one serving a day
  • 1, 2 & 5 lb bags About 150, 300, or 750 servings; see Choosing a size

Product facts & composition

Composition and specifications, Greenway Biotech Magnesium Citrate Powder
SpecificationDetail
IngredientMagnesium citrate (trimagnesium dicitrate, hydrated form), CAS 153531-96-5. No other ingredients.
Elemental magnesiumSpecification 11.0–13.5% by weight, measured by ICP-OES. Current lot: 12.0%. Theoretical magnesium content of the nonahydrate is 11.9% (three magnesium atoms, 72.9 g, in a formula weight of 613.3 g).
Magnesium per servingOne level teaspoon (about 3 g) supplies at least 330 mg of magnesium (79% of the 420 mg Daily Value). At the current lot’s 12.0%, that serving supplies about 360 mg.
Form and appearanceWhite to off-white fine powder; the current lot passes 99.6% through a 40-mesh screen and 74% through a 100-mesh screen.
SolubilitySoluble in water, though the hydrated form is less soluble than the anhydrous salt (roughly 2% at room temperature), so a serving needs stirring. A 3 g serving in 8 fl oz (240 mL) is about a 1.25% solution. A 2% solution of the current lot measures pH 5.24.
Bulk density0.663 g/mL for the current lot (loose fill). A level US teaspoon (4.9 mL) of this powder weighs about 3 g, which is the basis of the panel serving; heaping the spoon adds magnesium, so keep it level. See Directions.
Heavy metals (current lot)Tested by ICP-MS (USP <233>): arsenic below 0.01 ppm (limit 1.00), cadmium below 0.01 ppm (limit 1.00), lead below 0.01 ppm (limit 0.10), mercury 0.01 ppm (limit 1.00).
Microbiological (current lot)Total plate count below 10 cfu/g (limit 3,000); yeast and mold below 10 cfu/g (limit 300); coliforms, E. coli, and S. aureus negative in 10 g; Salmonella negative in 25 g.
Loss on drying0.58% (current lot, USP method, 105 °C, 4 hours)
Shelf life48 months from the date of manufacture when stored cool and dry.
Package sizes1 lb (454 g), 2 lb (907 g), and 5 lb (2.27 kg) bags
Packaged byGreenway Biotech, Inc., 17861 Road 24, Madera, California 93638, from magnesium citrate manufactured in the United States

Percentages are by weight of product. A 1 lb bag contains about 50 g of elemental magnesium at the 11.0% minimum (about 54 g at the current lot’s 12.0%). Every serving on this page is stated as product weight, with the magnesium it delivers shown beside it, and the figures marked “current lot” come from the certificate of analysis for the lot on hand; they are lot-specific results, not a standing guarantee.

Best uses & benefits

Choose this product when you want a plain, unflavored magnesium powder you can dose precisely and mix into whatever you already drink. Every statement below about magnesium is about the nutrient, drawn from the NIH Office of Dietary Supplements, and not a trial of this finished product.

Meeting your daily magnesium needs

The Recommended Dietary Allowance is 400–420 mg per day for adult men and 310–320 mg for adult women, and national dietary surveys consistently find that many Americans take in less than recommended amounts. One level teaspoon supplies at least 330 mg of magnesium, 79% of the Daily Value, to add to the magnesium in your food.*

Supporting muscle and nerve function and energy production

Magnesium is a cofactor in more than 300 enzyme systems, including those involved in protein synthesis and muscle and nerve function, and it is required for energy production.*

Supporting bone structure

About half to 60% of the body’s magnesium is held in bone, and magnesium contributes to the structural development of bone. Green leafy vegetables, legumes, nuts, seeds, and whole grains are good food sources; a supplement is one way to add to that intake.*

A soluble form in a one-spoon serving

Magnesium in the citrate form dissolves well in liquid, and the NIH reports that small studies have found citrate to be absorbed more completely and to be more bioavailable than magnesium oxide and magnesium sulfate. Because this is a single-ingredient powder with about 120 mg of magnesium per gram, one level teaspoon is a full day’s serving, and a smaller amount is easy to measure if your provider sets a lower target; see Directions.

Where it is a poor fit

  • As a laxative or bowel preparation. The “magnesium citrate” sold in pharmacies as a saline laxative is an over-the-counter drug in oral-solution form, labeled and dosed for that purpose. This powder is a dietary supplement; it is not labeled for laxative use; do not take more than the serving on the panel. See the FAQ on the pharmacy laxative.
  • If you have kidney disease. The NIH notes that the risk of magnesium toxicity rises with impaired kidney function because the body’s ability to remove excess magnesium is reduced. Do not take this or any magnesium supplement without your physician’s direction.
  • For a bath, foot soak, or topical routine. This product is labeled for oral use. For soaking, Epsom Salt (magnesium sulfate) is labeled for external use, and Magnesium Chloride USP covers both a drink and a soak.
  • As a fertilizer. It is not labeled or registered as a plant nutrient. Greenway sells magnesium for plants separately.
  • If you want the highest magnesium per gram. Magnesium oxide carries far more magnesium per gram (about 60%) and is commonly sold as tablets; the trade-off is solubility and absorption. This hydrated citrate carries about 12%. If package weight matters more than form, citrate is not the most concentrated choice.

*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. The asterisk marks each statement this disclaimer covers, wherever it appears on this page.

Serving size & directions

The directions below reflect the Supplement Facts panel for this product. The serving is one level US teaspoon, about 3 g of powder; level it with the back of a knife, because a heaped spoon holds noticeably more. If you own a scale that reads to 0.1 g you can weigh 3 g instead, and the per-gram row lets you work out a smaller amount for a target your provider sets in milligrams.

Serving directions for adults, Greenway Biotech Magnesium Citrate Powder
DirectionAmountMagnesium suppliedNotes
Serving size 1 level teaspoon (about 3 g) At least 330 mg (79% DV); about 360 mg at the current lot’s 12.0% Stir into 8 fl oz (240 mL) or more of water or juice and drink promptly. Take with a meal.
Servings per day 1 One serving is at or near the 350 mg per day Tolerable Upper Intake Level for supplemental magnesium (a lot at the top of the 11.0–13.5% specification can supply about 400 mg per level teaspoon) Do not take a second serving. The 350 mg limit applies to magnesium from supplements and medications, not from food; count any other magnesium supplement, antacid, or laxative you use toward it.
First few days, if you are new to magnesium ½ level teaspoon (about 1.5 g) At least 165 mg; about 180 mg Greenway’s suggestion, not a panel requirement: half a serving for a few days lets you check tolerance before moving to the full teaspoon.
Per 1 g of powder (for a provider-set target) 1.0 g, about ⅓ level teaspoon At least 110 mg; about 120 mg Use this to work out a smaller serving if your healthcare provider gives you a target in milligrams of magnesium: grams of powder = target mg ÷ 110 (guaranteed) or ÷ 120 (current lot). Weigh amounts under a teaspoon on a 0.1 g scale, or use measuring spoons (¼ tsp is about 0.75 g).

Who it is for. Adults. Not for children unless a pediatrician directs it; the upper limit for supplemental magnesium is lower for young children. If you are pregnant or nursing, have kidney disease, or take any prescription medication, ask your healthcare provider before use. Specific medication timing from the NIH: take magnesium at least 2 hours before or after an oral bisphosphonate, and take tetracycline or quinolone antibiotics at least 2 hours before, or 4 to 6 hours after, a magnesium supplement. Long-term proton pump inhibitor use and some diuretics change magnesium status; your provider can advise whether a supplement is appropriate and at what amount.

If you exceed the serving. Loose stools or diarrhea are the expected sign of too much supplemental magnesium; the NIH attributes them to the osmotic activity of unabsorbed magnesium salts in the intestine. Reduce the amount or stop. Very large intakes, especially with impaired kidney function, can cause more serious effects; seek medical attention for symptoms beyond digestive upset.

Worked example. Your provider suggests about 200 mg of supplemental magnesium a day. 200 ÷ 120 = 1.7 g of powder at the current lot’s analysis (1.8 g if you use the guaranteed 110 mg per gram), which is a little over half a level teaspoon. Measure it, stir it into a glass of water with breakfast, and finish it before it settles.

How to use Magnesium Citrate Powder

  1. Check that it suits you. Read the Supplement Facts panel. If you have kidney disease, are pregnant or nursing, or take medication, ask your healthcare provider first, and space it from antibiotics or bisphosphonates as described under Directions.
  2. Measure a level teaspoon. Fill a US teaspoon and level it off with a knife: about 3 g (half a level teaspoon for your first few days). Do not heap it. Reseal the bag tightly right away.
  3. Stir it in. Add 8 fl oz (240 mL) or more of water or juice and stir until dissolved; the hydrated form is less soluble than the anhydrous salt, so give it time. If a little remains, drink it promptly while stirring.
  4. Take it with food. One serving a day with a meal, at whatever time of day suits your routine.
  5. Notice how you tolerate it. Loose stools mean the amount is too high for you: drop back to half a serving. If you take other magnesium-containing products, count them toward the 350 mg daily supplement limit.

Choosing a size

This product has no calculator: the serving is fixed by the Supplement Facts panel, so the only question is how many servings you want on hand. Servings per bag = bag weight in grams ÷ 3. One person taking one full serving a day uses about 91 g a month.

Servings per package at the one-teaspoon (3 g) serving, Greenway Biotech Magnesium Citrate Powder
PackageServingsOne person, one serving a dayElemental magnesium in the bag
1 lb (454 g)About 150About 5 monthsAbout 50 g at the 11.0% minimum (about 54 g at the current lot’s 12.0%)
2 lb (907 g)About 300About 10 months, or 5 months for two peopleAbout 100 g at the minimum (about 109 g)
5 lb (2.27 kg)About 750About 2 years, or a year for two peopleAbout 250 g at the minimum (about 272 g)

Choose the 1 lb bag if you are trying magnesium citrate for the first time or take it seasonally, the 2 lb bag for most of a year, and the 5 lb bag for a household or a formulating pantry. All three are inside the 48-month shelf life if you keep the bag sealed and dry. Select a size from the options at the top of this page; prices, tax, and shipping are shown at checkout.

How magnesium citrate works

The NIH Office of Dietary Supplements describes magnesium as a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions, including protein synthesis and muscle and nerve function, and as required for energy production, oxidative phosphorylation, and glycolysis; it also contributes to the structural development of bone and plays a role in the active transport of calcium and potassium ions across cell membranes.* An adult body holds roughly 25 g of magnesium, 50–60% of it in bone, and less than 1% in blood serum, which is why a serum test is a poor guide to total body status.

Magnesium citrate is the magnesium salt of citric acid: three magnesium ions bound to two citrate ions, C₁₂H₁₀Mg₃O₁₄, usually supplied as a hydrate. The anhydrous salt is about 16% magnesium. This product is a hydrated form; its assayed magnesium (specification 11.0–13.5%, current lot 12.0%) is consistent with the nonahydrate, whose theoretical content is 11.9%. Citrate is an ordinary organic acid the body metabolizes; it is the same anion found in citrus fruit and in the citric acid cycle. Once dissolved, the magnesium is absorbed as the ion, and the kidneys regulate how much the body retains.

Why the form matters: the NIH states that forms of magnesium that dissolve well in liquid are more completely absorbed in the gut than less soluble forms, and that small studies have found the aspartate, citrate, lactate, and chloride forms to be absorbed more completely and to be more bioavailable than magnesium oxide and magnesium sulfate.* Two studies of this kind are listed under Product documents & sources: a 60-day randomized trial (Walker and colleagues, 2003) that found magnesium citrate more bioavailable than magnesium oxide and an amino-acid chelate at 300 mg of magnesium per day, and a single-dose crossover study (Kappeler and colleagues, 2017) that measured higher urinary magnesium excretion after citrate than after oxide. Both were small, and neither is a trial of this finished product; read them as the reason citrate is a reasonable form to choose, not as a fixed multiple of absorption.

The same solubility is behind the upper limit. Magnesium that is not absorbed stays in the intestine, where the NIH notes its osmotic activity can cause loose stools; that adverse effect is the reason the panel stops at one level teaspoon a day.

Compare your options

Greenway sells magnesium in several forms for different routes. Match the product to the route it is labeled for; an external-use product is not an oral one, whatever its grade.

Greenway Biotech Magnesium Citrate Powder compared with other magnesium forms
OptionMagnesium content and formLabeled routeChoose it whenLimitation
Magnesium Citrate Powder, this product At least 11% magnesium as hydrated trimagnesium citrate; about 12% in the current lot Oral dietary supplement You want an unflavored, single-ingredient magnesium powder in a soluble form, one level teaspoon a day Level the spoon; dissolves slowly; not for external use; not a laxative product
Magnesium Chloride USP About 12% magnesium as magnesium chloride hexahydrate (24.305 ÷ 203.31 = 11.96%) Oral solution as directed on its page, and bath or DIY magnesium oil You want one product for both a drink and a soak, or you want the chloride form Hygroscopic; oral use follows that product’s own label and page
Epsom Salt (Magnesium Sulfate) About 10% magnesium as magnesium sulfate heptahydrate External use: bath and foot soak; garden use as labeled You want a soak, not a supplement Not labeled for oral use
Magnesium Oil Spray Magnesium chloride brine, ready to use Topical You want a skin-applied magnesium chloride routine alongside a supplement A topical product; it is not a substitute for dietary magnesium
Magnesium oxide (not a Greenway product) About 60% magnesium Oral, commonly as tablets You want the most magnesium per gram or per tablet Poorly soluble; the NIH reports it is less completely absorbed than citrate in small studies

For the oral-versus-topical decision in more depth, read our guide to oral and topical magnesium routes.

Handling, storage & limitations

  • Daily limit. Keep supplemental magnesium at or below 350 mg per day for adults unless a healthcare provider directs otherwise, counting every supplement, antacid, and laxative that contains magnesium. Excess causes loose stools first; very high intakes, especially with impaired kidney function, can cause low blood pressure, nausea, muscle weakness, and other serious effects (NIH Office of Dietary Supplements).
  • Who should ask first. People with kidney disease; anyone pregnant or nursing; anyone taking bisphosphonates, tetracycline or quinolone antibiotics, diuretics, or proton pump inhibitors; and children, who should use it only under a pediatrician’s direction.
  • Not a drug. This is a dietary supplement. It is not the over-the-counter magnesium citrate saline laxative, it is not labeled for laxative use or bowel preparation, and it is not for external use, bath use, or plant use.
  • Handling the dry powder. The safety data sheet for this material classifies the concentrated powder as a skin irritant, an eye irritant, and a possible respiratory irritant (as dust), with the signal word Warning. Those classifications describe handling the bulk powder, not a serving stirred into a glass: avoid raising or breathing dust, keep it out of your eyes, wash your hands after handling it, and avoid raising dust when you clean up a spill.
  • Storage. Keep the bag tightly sealed in a cool, dry, well-ventilated place away from strong acids, strong bases, and oxidizing agents (SDS). The material has a 48-month shelf life from manufacture when stored cool and dry; reseal the bag tightly after every serving. Keep out of reach of children.
  • Transport and regulatory. Not regulated as a hazardous material for transport (DOT). The safety data sheet states that the material contains no chemicals listed under California Proposition 65.
  • First aid (from the safety data sheet). Eyes: rinse immediately with plenty of water, including under the eyelids, for at least 15 minutes; remove contact lenses if easy to do; get medical attention if irritation develops and persists. Skin: wash with soap and plenty of water for at least 15 minutes; get medical attention if irritation develops and persists. Dust inhaled: move to fresh air; get medical attention if symptoms occur. Swallowed in a large amount: do not induce vomiting; rinse mouth; call a physician. The safety data sheet gives CHEMTREC, 1-800-424-9300, as the 24-hour emergency number.

Frequently asked questions

What is magnesium citrate powder, and how much magnesium is in it?

It is the magnesium salt of citric acid, trimagnesium dicitrate, in its hydrated form, sold as a white to off-white powder with no other ingredients. It is guaranteed to contain at least 11.0% elemental magnesium by weight; the current lot tests at 12.0%. That is at least 110 mg of magnesium per gram, and at least 330 mg in the one-level-teaspoon serving of about 3 g (79% of the Daily Value). A 1 lb bag holds about 150 servings.

How much magnesium citrate powder should I take each day?

One level teaspoon (about 3 g) a day, stirred into 8 fl oz or more of water or juice and taken with a meal, which supplies at least 330 mg of magnesium. That is at or near the 350 mg per day Tolerable Upper Intake Level for magnesium from supplements and medications, so do not take a second serving, do not heap the spoon, and count any other magnesium supplement, antacid, or laxative toward that limit. If you are new to magnesium, half a level teaspoon for the first few days lets you check tolerance. Your healthcare provider may set a different target; at 110–120 mg of magnesium per gram, a smaller amount is easy to work out.

How do I measure a serving?

With an ordinary US measuring teaspoon, filled and leveled off with the back of a knife: one level teaspoon of this powder is about 3 g. Level matters because a heaped teaspoon holds noticeably more powder, and magnesium is a nutrient with a defined daily upper limit from supplements. If you want more precision, a kitchen scale that reads to 0.1 g lets you weigh 3 g, or a smaller amount if your provider has set a lower target.

Is this the same as the magnesium citrate laxative sold at the pharmacy?

No. The pharmacy product is an over-the-counter saline laxative: a bottled oral solution labeled and dosed for that purpose under FDA drug rules. This powder is a dietary supplement, labeled for a one-teaspoon daily serving of about 330 mg of magnesium, and it is not labeled or intended for laxative use or bowel preparation. The two share a chemical name, not a purpose. If you need a laxative, use a product labeled as one and follow its directions.

Magnesium citrate, magnesium chloride, or magnesium oxide: which form should I choose?

Citrate and chloride both dissolve readily in water; the NIH Office of Dietary Supplements reports that small studies have found citrate, chloride, lactate, and aspartate forms to be absorbed more completely than magnesium oxide and magnesium sulfate. Magnesium oxide carries far more magnesium per gram, about 60%, which suits tablets, but dissolves poorly. Between the two Greenway powders labeled for a drink, citrate is a plain supplement powder, while Magnesium Chloride USP also serves as a bath salt and DIY magnesium oil base. Choose citrate for a plain supplement powder and chloride if you want one bag for both a drink and a soak.

Will it dissolve completely?

It should, with stirring. This is the hydrated form of magnesium citrate, which is less soluble than the anhydrous salt, roughly 2% at room temperature; a 3 g serving in 8 fl oz of water is about a 1.25% solution, and the current lot’s 2% test solution measures pH 5.24, mildly acidic. Stir until dissolved, and if a little remains, drink it promptly while stirring. Water or juice is a matter of preference.

Can I take magnesium citrate with my medications?

Ask your healthcare provider or pharmacist, and follow the timing the NIH gives for the known interactions: take magnesium at least 2 hours before or after an oral bisphosphonate, and take tetracycline or quinolone antibiotics at least 2 hours before, or 4 to 6 hours after, a magnesium supplement. Loop and thiazide diuretics and long-term proton pump inhibitor use affect magnesium status, so your provider may want to check your level before you supplement. If you have kidney disease, do not take magnesium supplements without medical direction, since impaired kidneys clear the excess poorly.

Who should not take this product?

It is labeled for adults. Children should use it only under a pediatrician’s direction; the upper limit for supplemental magnesium is lower for young children. People with kidney disease should not use it without their physician’s direction. If you are pregnant or nursing, ask your provider first; the Recommended Dietary Allowance is somewhat higher in pregnancy, and the serving on this page may or may not fit your plan. Stop and consult a provider if you have persistent digestive upset.

Is it tested for heavy metals and microbial contamination?

Yes. The certificate of analysis for the current lot reports arsenic, cadmium, and lead below 0.01 ppm and mercury at 0.01 ppm by ICP-MS (USP method 233), against limits of 1.00, 1.00, 0.10, and 1.00 ppm, and reports total plate count and yeast and mold below 10 cfu/g with coliforms, E. coli, S. aureus, and Salmonella negative. Those are results for the lot on hand; they are not a claim that this product meets the USP monograph for magnesium citrate, which sets a higher magnesium content calculated on an anhydrous basis. Ask us for the certificate for the lot you receive.

Can I use it in the bath or in the garden?

No. It is labeled for oral use only. For a bath or foot soak, use Epsom Salt or Magnesium Chloride USP, which are labeled for that; for plants, use a magnesium product that is labeled and registered as a fertilizer. Using a supplement powder in the bath wastes it, and using it on plants is not a labeled use.

Related guides & articles

Articles give background. For this product, use the Supplement Facts panel and the directions on this page.

Product documents & sources

  • Supplement Facts label: available on request; the serving size, magnesium per serving, and Daily Value on this page are taken from it.
  • Certificate of analysis for the current lot: available on request; the magnesium assay, heavy-metal, microbiological, and physical results quoted on this page.
  • Safety Data Sheet: available on request; composition, hazard classification of the dry powder, handling, storage, and first aid.
Where the rates and statements on this page come from

The serving and its magnesium content come from this product’s Supplement Facts panel and certificate of analysis; the statements about magnesium’s roles, intake recommendations, upper limit, absorption, interactions, and precautions come from the public sources below. They are listed for shoppers, practitioners, and reviewers who want to check them; none of them evaluates or endorses this product.

Statements and sources reviewed September 15, 2026.

Help choosing & next step

Not sure whether citrate or chloride is the right form for you, or how a serving fits a target your provider gave you in milligrams? Email questions@greenwaybiotech.com or call (562) 351-5168, Monday to Friday, 7 AM to 5 PM Pacific. We can explain the product and its documents; we cannot give medical advice, so bring questions about your own health or medications to your healthcare provider.

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