Magnesium

Magnesium suits most people, and the few situations that need a chat first are easy to spot. These are the same quick questions our naturopaths ask in store every day, in the same order.

A good fit if

• You don't eat many wholegrains, legumes, nuts, seeds or leafy greens, the foods that give you most of your magnesium
• You're an older adult, or your diet is narrow or highly processed, which often means you get less than the RDI
• You're pregnant or breastfeeding, when you need more than usual, and you're working with your midwife or doctor
• You found a magnesium oxide blend hard on your stomach and want a gentler, better-absorbed form
• Your kidneys are healthy and you don't take any medicine that needs to be spaced away from minerals

Check with us first if

• You take a bisphosphonate. Magnesium can bind to it, so take them at least two hours apart.
• You take a tetracycline or quinolone antibiotic. Take magnesium at least two hours before, or four to six hours after, the antibiotic.
• You take loop or thiazide diuretics (water tablets), or long-term reflux medicine (a proton pump inhibitor). These can push your magnesium up or down, so it's worth reviewing with the doctor who prescribed them.
• Your bowels tend to run loose. Magnesium carbonate, chloride, gluconate and oxide are the forms most often linked to diarrhoea, and in Cochrane's cramp trials 11–37% of people taking magnesium had minor stomach or bowel side effects. Changing the form and splitting the dose usually sorts it out.
• You take any prescription medicine. A quick check with your doctor, pharmacist or our naturopaths first is the sensible step.

• Magnesium glycinate (bisglycinate). Best known for: Being gentle on the stomach. The usual pick when a larger dose is wanted without loose bowels. Absorption: Good. Chelated to the amino acid glycine and among the forms least associated with diarrhoea. Typical use: Everyday topping-up of intake, and a popular evening choice.
• Magnesium citrate. Best known for: Being one of the best-absorbed everyday forms; at larger doses it also draws water into the bowel. Absorption: High. Absorbed more completely than oxide or sulfate in human studies. Typical use: General daily use in tablets, capsules and powders.
• Magnesium oxide. Best known for: Carrying the most magnesium per milligram of compound, and costing the least. Absorption: Poor. One review cites absorption as low as about 4% in humans. Typical use: Common as a low-cost bulk ingredient in blends; frequently associated with diarrhoea.
• Magnesium L-threonate. Best known for: Being marketed as the 'brain' form for cognition and sleep. Absorption: Adequate, but the claim that it raises magnesium in the brain specifically rests mainly on animal studies. Typical use: Cognition and sleep positioning. Human trial evidence is small and early. Treat the marketing with caution.
• Magnesium chloride. Best known for: Dual use. Taken orally, and sold as bath flakes and topical oils. Absorption: Good when taken orally. Evidence for meaningful absorption through the skin is lacking. Typical use: Oral supplements, plus flakes and sprays where the benefit is largely the ritual, not proven uptake.
• Magnesium taurate. Best known for: Being paired with taurine and positioned for heart health and calm. Absorption: Presumed good, but head-to-head human absorption data is scarce. Typical use: Often chosen for the taurine as much as the magnesium. Form-specific evidence is thin.
• Magnesium orotate. Best known for: Being paired with orotic acid and positioned for cardiac and athletic use. Absorption: Not well characterised in comparative human studies. Typical use: Niche and comparatively expensive. Human research is limited and mostly in clinical populations.

Reference values. The NHMRC sets recommended daily intakes (RDI unless noted) by age and sex. Babies 0–6 months need 30 mg a day and 7–12 months 75 mg a day (Adequate Intake). Children 1–3 years need 80 mg, 4–8 years 130 mg, and 9–13 years 240 mg. Teenagers 14–18 need 410 mg (boys) or 360 mg (girls). Men need 400 mg at 19–30 years and 420 mg from 31. Women need 310 mg at 19–30 years and 320 mg from 31. In pregnancy it's 350–400 mg depending on age, and when breastfeeding 310–360 mg depending on age.

Typical supplemental range. Australian labels usually give somewhere between about 100 mg and 400 mg of actual (elemental) magnesium per daily dose, often split into two or three doses. Look for the elemental magnesium figure, not the weight of the whole compound: 750 mg of magnesium glycinate is not 750 mg of magnesium.

Upper level. The NHMRC upper limit for magnesium from supplements is 350 mg a day from age 9, 110 mg a day for ages 4–8, and 65 mg a day for ages 1–3. There's no limit set for babies, whose magnesium should come from breast milk, formula and food only. The upper limit covers supplements and medicines only, not the magnesium that's naturally in food and drink.

Worth knowing. These figures are reference values for the whole population, not a dose for you personally. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Pumpkin seeds: about 156 mg per 28 g
• Chia seeds: about 111 mg per 28 g
• Almonds, dry roasted: about 80 mg per 28 g
• Spinach, cooked: about 78 mg per half cup
• Cashews, dry roasted: about 74 mg per 28 g
• Black beans, cooked: about 60 mg per half cup

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• Reduced kidney function or kidney failure. Excess magnesium cannot be cleared and can accumulate; do not supplement without medical supervision.
• Bisphosphonates. Separate the magnesium dose by at least two hours.
• Tetracycline or quinolone antibiotics. Magnesium at least two hours before, or four to six hours after, the antibiotic.
• Loop or thiazide diuretics, or long-term proton pump inhibitors. Magnesium status worth reviewing with the prescriber.
• Tendency to loose bowels. Carbonate, chloride, gluconate and oxide are the forms most often linked to diarrhoea.
• Infants under 12 months. The affected inorganic magnesium salts must not be directed for use under 12 months of age.
• Exceeding the label dose. Extremely high intakes can lead to irregular heartbeat and cardiac arrest.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.