Magnesium, Mg

Magnesium is a mineral involved in more than 300 enzyme-driven reactions throughout the body, from energy production to muscle contraction to the electrical signaling that keeps the heart beating regularly. About 60% of the body's magnesium is stored in bone, with most of the rest in muscle and soft tissue.

What Is Magnesium

Magnesium acts largely as a cofactor — a helper molecule enzymes need to function — in processes that generate and use cellular energy (ATP), synthesize protein and DNA, and regulate muscle and nerve activity, including the electrical rhythm of the heart. Per Linus Pauling Institute, Micronutrient Information Center, roughly 60% of total body magnesium resides in the skeleton, where it also contributes to bone metabolism. Rich dietary sources include nuts (particularly Brazil nuts, almonds, and cashews), seeds, whole grains, legumes, and leafy greens such as spinach and Swiss chard. In this dataset, the most concentrated measured sources include dried seaweed, dried herbs, wheat bran, and pumpkin seeds, which is consistent with nuts, seeds, and unrefined grains being magnesium's most reliable everyday sources.

Health Benefits of Magnesium

Research summarized by the Linus Pauling Institute associates higher magnesium intake with cardiovascular benefits: meta-analyses of prospective studies found higher magnesium intake linked to an 8–11% reduction in stroke risk and roughly an 8% lower risk of hypertension when comparing higher versus lower dietary intake.

The same source reports that meta-analyses have found a 22% lower risk of developing type 2 diabetes when comparing the highest to the lowest magnesium intake groups, with roughly a 6% reduction in risk for each additional 100 mg/day of magnesium consumed; supplementation studies in magnesium-deficient individuals have also shown improved insulin sensitivity.

For bone health, observational studies cited by the Linus Pauling Institute associate higher magnesium intake with greater bone mineral density, though the Institute notes evidence that supplementation itself prevents osteoporotic fractures remains limited.

Magnesium sulfate given intravenously is, per the Linus Pauling Institute (citing World Health Organization guidance), a first-line treatment for preventing eclampsia in pregnancy, and has been associated with a 32% lower risk of cerebral palsy in premature infants when given to mothers at risk of preterm delivery — a clinical, supervised use rather than something achieved through diet or standard supplementation.

How Much Magnesium You Need

RDA/AI figures (as reported via NIH Office of Dietary Supplements, Magnesium — Health Professional Fact Sheet; this fact sheet blocked direct automated fetch, and its figures were corroborated both by the Linus Pauling Institute's independent citation of the same NIH DRI table and by an independent web search) include: infants 0–6 months, 30 mg/day (AI); children 1–3 years, 80 mg/day; 4–8 years, 130 mg/day; adolescent males 14–18, 410 mg/day; adolescent females 14–18, 360 mg/day; adult men 19–30, 400 mg/day; adult men 31+, 420 mg/day; adult women 19–30, 310 mg/day; adult women 31+, 320 mg/day; pregnancy, 350–400 mg/day depending on age; and lactation, 310–360 mg/day depending on age.

The Tolerable Upper Intake Level (UL) applies only to magnesium from supplements and medications, not from food: 65 mg/day for children 1–3 years, 110 mg/day for children 4–8 years, and 350 mg/day for anyone 9 years and older, per the same sourcing. No UL is set for magnesium from food because the kidneys efficiently excrete excess dietary magnesium in people with normal kidney function.

Signs of Deficiency and Excess

Severe magnesium deficiency (hypomagnesemia) is associated with low blood calcium and low blood potassium despite otherwise adequate intake of those minerals, along with neurological and muscular symptoms such as tremor, muscle spasms, and tetany, plus loss of appetite, nausea, vomiting, and personality changes, per the Linus Pauling Institute. People with gastrointestinal disorders such Crohn's disease or celiac disease, kidney disorders, diabetes, chronic alcohol use, or older adults with low dietary intake are described as being at elevated risk of deficiency.

Excess magnesium from food alone is not a documented concern in people with normal kidney function, since the kidneys excrete the surplus. The Linus Pauling Institute notes that people with impaired kidney function are at higher risk of adverse effects from supplemental magnesium and should avoid more than 350 mg/day of supplemental magnesium without medical guidance.

Warnings & Interactions

Several medication classes interact with magnesium. Per the Linus Pauling Institute, bisphosphonates used for osteoporosis should be taken at least two hours apart from magnesium, since magnesium can reduce their absorption; magnesium can similarly reduce absorption of digoxin, nitrofurantoin, some anti-malarial drugs, and quinolone or tetracycline antibiotics. Conversely, long-term use of furosemide or thiazide diuretics, and proton-pump inhibitors used for three months or longer, can increase magnesium loss and raise the risk of hypomagnesemia.

Intravenous magnesium (a clinical, supervised use) may enhance the muscle-relaxing effects of anesthesia and can cause low blood pressure or muscle weakness when combined with calcium channel blockers.

People with impaired kidney function are the population most clearly flagged for caution: because the kidneys are the primary route for clearing excess magnesium, reduced kidney function raises the risk of magnesium accumulating to harmful levels from supplements, and the Linus Pauling Institute advises this group avoid supplemental magnesium above 350 mg/day without medical consultation.

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