Marine 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 you want a larger dose without loose bowels. Absorption: Good. It is bound to the amino acid glycine and is one of the forms least likely to cause diarrhoea. Typical use: Everyday topping-up, and a popular choice in the evening.
• 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. Human studies show it is absorbed more completely than oxide or sulfate. Typical use: General daily use in tablets, capsules and powders.
• Magnesium oxide. Best known for: Packing the most magnesium into each milligram of compound. Absorption: Poor. One review puts absorption as low as about 4% in humans. Typical use: Common as a bulk ingredient in blends, and often linked to diarrhoea.
• Magnesium L-threonate. Best known for: Being marketed as the 'brain' form, for thinking and sleep. Absorption: Adequate. The idea that it raises magnesium in the brain specifically rests mainly on animal studies. Typical use: Sold for thinking and sleep. Human trial evidence is small and early, so treat the marketing with caution.
• Magnesium chloride. Best known for: Two uses. It is taken by mouth, and also sold as bath flakes and skin oils. Absorption: Good when taken by mouth. There is no good evidence that meaningful amounts get in through the skin. Typical use: Oral supplements, plus flakes and sprays, where the benefit is mostly the ritual rather than proven uptake.
• Magnesium taurate. Best known for: Being paired with taurine and positioned for heart health and calm. Absorption: Assumed to be good, but there is little head-to-head human absorption data. Typical use: Often chosen for the taurine as much as the magnesium. Evidence for this form itself is thin.
• Magnesium orotate. Best known for: Being paired with orotic acid and positioned for heart and athletic use. Absorption: Not well measured in human studies that compare forms. Typical use: A niche form. Human research is limited and mostly in people with medical conditions.

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

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Your kidneys are not working well, or you have kidney failure. Extra magnesium cannot be cleared and can build up, so don't take it without medical supervision.
• You take bisphosphonates. Keep your magnesium at least two hours apart from them.
• You take tetracycline or quinolone antibiotics. 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 medicines called proton pump inhibitors. Ask your prescriber to review your magnesium levels.
• You tend to get loose bowels. Carbonate, chloride, gluconate and oxide are the forms most often linked to diarrhoea.
• Babies under 12 months. The inorganic magnesium salts covered by this rule must not be labelled for use under 12 months of age.
• Going over the label dose. Very high intakes can lead to an irregular heartbeat and cardiac arrest.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.