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food source · 5
Quinoa is high in magnesium for a staple food, clearly above white rice and above brown rice too. Magnesium has to bind ATP before the body's energy currency can be spent.
Mechanism · A staple unusually rich in magnesium
ATP has to bind magnesium before enzymes recognize it, so magnesium is the ion that lets the energy currency be spent. Polishing white rice grinds away the bran and the magnesium with it; quinoa is eaten as the whole seed without that kind of milling, so the magnesium stays in the seed you cook.
In practice · Phytate and rinsing
Quinoa has clearly more magnesium than white rice, and more than brown rice too. Its phytate still locks up part of its minerals; rinsing it well or soaking it before cooking removes some of the phytate and washes off the bitter saponins at the same time.
←Rice
The magnesium in rice sits in the bran layer. Brown rice has about 3.5 times as much magnesium as white rice, because polishing grinds that layer away and the magnesium with it.
Mechanism · The nutrients live in the bran
The bran and germ of a rice grain are its store of nutrients: magnesium, B vitamins, phosphorus and manganese sit in that layer, and the starchy center has almost none. Polishing grinds off the outer layer and carries away these parts the body needs to make energy. So white rice is not simply empty; it is rice without that layer.
In practice · With white rice, find magnesium elsewhere
Brown rice has about 3.5 times as much magnesium as white rice, so the source here is brown rice, not white; people whose staple is white rice need vegetables, beans and nuts for their magnesium. The bran of brown rice also carries phytate, which locks up part of the minerals, so a higher content does not mean proportionally more gets absorbed; soaking removes some of the phytate.
Despite its name, buckwheat is not a grass grain; dry buckwheat has about 230 mg of magnesium per 100 g, among the highest of grain-type staples.
Mechanism · Not wheat, yet rich in magnesium
Despite its name, buckwheat is not a grass grain at all but the fruit of a plant in the knotweed family, cooked as a grain. Magnesium is still the ion that lets enzymes recognize ATP. Buckwheat is naturally gluten-free, which gives people with celiac disease another staple, provided it is not mixed with wheat flour or contaminated with wheat in processing; that is a separate matter from its magnesium.
Numbers · Dry weight and a cooked bowl
Dry buckwheat has about 230 mg of magnesium per 100 g. That figure is by dry weight; cooking adds water and thins it out gram for gram, but a bowl still delivers a useful amount. Buckwheat noodles are often mixed with wheat flour, and the less buckwheat they contain, the less magnesium they carry.
ATP has to bind magnesium before enzymes recognize this energy currency. Almonds are a good source of magnesium, and a handful supplies roughly a fifth of an adult's daily need.
Mechanism · Enzymes recognize magnesium with ATP
ATP has to bind magnesium before enzymes recognize it. Magnesium is not energy itself but the ion that lets the energy currency be spent; without enough of it, energy-producing steps all over the body lose a little strength.
Numbers · A mainstay for E, a helper for magnesium
A handful of almonds supplies 18–24% of an adult's daily magnesium need of 320–420 mg, a helper for magnesium, while for vitamin E it is a mainstay. Phytate locks up part of the minerals, and the portion is limited by the calories in the fat: a handful works, while a meal of almonds sends the calories up.
Black beans carry a share of magnesium: about 70 mg per 100 g cooked, roughly 17–22% of an adult's daily need. Magnesium takes part in energy production and in signaling between nerves and muscles.
Mechanism · ATP depends on magnesium
Magnesium takes part in more than 300 enzyme reactions, including making ATP and passing signals between nerves and muscles. ATP has to bind magnesium before enzymes recognize it. Black beans pack magnesium, plant iron and folate into one seed.
Numbers · The magnesium in a serving
Cooked black beans have about 70 mg of magnesium per 100 g, roughly 17–22% of the adult daily need of 320–420 mg, along with about 149 µg DFE of folate and about 355 mg of potassium. Their protein is still incomplete and is best paired with grains.
synergy · 5
Calcium triggers a muscle contraction; relaxing means pumping the calcium back into storage, and that pump runs on ATP bound to magnesium. So both calcium and magnesium need to be adequate, and a large dose of one does not make up for a shortage of the other.
Potassium and sodium keep up the electrical charge across cell membranes and decide how water is distributed in the body; magnesium helps make and use energy (ATP) and affects how excitable nerves and muscles are. So fatigue and cramps during exercise usually cannot be explained by a shortage of a single mineral.
Magnesium acts as a brake on nerves: it sits in the channel of the excitatory NMDA receptor and also supports inhibitory GABA signaling. The mechanism suggests that low magnesium could make nerves harder to calm; whether magnesium supplements improve insomnia, however, has only limited evidence from human trials.
In Peikert 1996, a double-blind randomized trial, a fairly high daily dose of oral magnesium cut migraine frequency more than placebo did. Possible mechanisms are magnesium's blocking of NMDA receptors and relaxation of the smooth muscle in brain blood vessels. The 2012 guideline of the American Academy of Neurology and American Headache Society rates magnesium probably effective for preventing migraine. The trial dose was above the tolerable upper intake level (UL) for supplemental magnesium, 350 mg a day, so it should be used under medical guidance.
In the methylation cycle that B12 takes part in, the step that turns methionine into the methyl donor SAM uses magnesium. The mechanism predicts that long-term magnesium shortage could make the metabolic effects of low B12 more pronounced; this has not been measured directly in people.
cofactor · 6
Vitamin D has to be processed once in the liver and once in the kidney before it becomes active, and the enzymes for both steps need magnesium. When magnesium is short, supplemented vitamin D may not be converted well; this point comes mainly from mechanism studies and reviews.
In severe magnesium deficiency, the parathyroid glands release less parathyroid hormone and the body responds to it less, so blood calcium falls and calcium supplements alone cannot correct it. In the clinic, magnesium has to be replaced first, and blood calcium then rises with it.
The pump that returns calcium to the sarcoplasmic reticulum uses up one magnesium-bound ATP on every trip; without magnesium, ATP cannot be used and calcium cannot get back to storage. But a sound mechanism does not mean magnesium treats cramps: in the trials pooled by Cochrane, magnesium did essentially nothing for the most common cramps, those with no clear cause.
Every muscle contraction runs on ATP, and most ATP in cells has to be bound to magnesium before it can be used; the extra mitochondria and energy output that endurance training builds all depend on this step. Whether people who train endurance regularly need extra magnesium is a question the research on Zone 2 training does not answer.
→Bone
About 60% of the body's magnesium is stored in bone, some of it on the surface of the hydroxyapatite crystals, where it affects how large they grow. Magnesium is also a cofactor for the enzymes that activate vitamin D, so when magnesium is short, supplemented vitamin D may not be converted well.
Magnesium plays a supporting role in bone health, but it cannot be left out: the US Recommended Dietary Allowance is 320 mg a day for adult women and 420 mg for men. It takes part in forming bone mineral crystals (hydroxyapatite) and is a cofactor in activating vitamin D; without enough of it, both calcium and vitamin D work less well.
antagonism · 1
Nanoscale plastic particles (smaller than 100 nm) can enter cells and even mitochondria, and in experiments they disturb the energy-producing electron transport chain, raising reactive oxygen species and lowering ATP output; in the body, ATP works bound to magnesium. This is inferred from the mechanism, and the human evidence is still very early.
depletes · 1
Long-term acid suppression with proton pump inhibitors (PPIs) and diuretics can both lower magnesium: PPIs are thought to reduce intestinal uptake, and diuretics let more magnesium leave in the urine. The FDA issued a PPI low-magnesium warning in 2011, suggesting that for people expected to stay on the drug long term, doctors consider checking magnesium before starting and during treatment.
contrast · 2
Magnesium threonate does supply magnesium, but whether it is safe depends on the dose, kidney function and any medication you take, not just on the price. The claim that it crosses the blood-brain barrier comes from mouse studies, and in people there is only one small, company-funded randomized trial. Getting enough magnesium in the first place is something any form can do; the extra you pay buys the claim about cognition.
Night-time calf cramps are often blamed on low magnesium, so many people take magnesium for them. A Cochrane systematic review pooling trials mostly in older adults found that for night cramps with no clear cause, magnesium is unlikely to give a clinically meaningful preventive effect.