Magnesium

Nutrition
Written By Maladywise
 

References

Storage

  • Primarily in bone

Incidence

  • 12% of patients in hospital

  • 65% of patients in ICU

Causes

  • GIT Loss (Anorexia, IBD, Malabsorption)

  • Renal Loss (Loop diuretics, Thiazides, Nephrotoxic drugs)

  • Alcohol

  • Uncontrolled DM

Clinical effects

  • Neuromuscular

    • Hyper-excitability, Tetany, Seizures, Muscle fasciculations

  • Cardiovascular

    • Widening QRS, Prolonged PR, Extrasystoles

  • Calcium Metabolism

    • Hypocalcaemia, Hypoparathyroidism, Vitamin D Deficiency

  • Hypokalemia

RDI

  • About 400 mg/day

When to think about Magnesium?

TL;DR

  • Should probably just ensure everyone eats a diet rich in Magnesium

  • If not able then could supplement

  • Consider supplements in those at risk (gut, kidney, alcohol, T2DM, poor intake)

  • Consider increasing dietary Mg or supplement in those with the following conditions

Asthma

  • Severe asthma guidelines have IV Magnesium Sulfate as part of the protocol

  • Mg supp 340mg for 6 months showed improvement in QoL in asthma

Calcium metabolism / Rickets / Osteoporosis / Bone / Teeth

  • Higher Mg linked to higher BMD in old white men and women

  • Low Mg and perhaps low Mg to Ca ratio = increased risk periodontal disease

  • Some evidence in small studies of improving favourable bone density markers in post-menopausal women and increased BMD in young girls 8 to 14

Muscle cramping

  • Mixed evidence for leg cramps, more evidence in pregnant women (pregnancy = higher risk of lower Mg)

  • One study in pregnant women given Mg supplementation reduced leg cramps by 50%

  • Two reviews and meta-analyses found that magnesium did not help with leg cramps in the general population, but may have a small effect in pregnant women, although the evidence was considered weak.

Pregnancy

  • Oral Mg supplementation given before the 25th week of gestation compared with placebo, for example, was associated with a lower frequency of preterm births, low birth weight infants, and fewer small for gestational age newborns

  • One study showed that Mg supplementation in pregnancy was associated with lower mean arterial pressure in women along with higher birth weight infants and fewer days spent in the neonatal intensive care unit

  • Mg has long been a treatment for preeclampsia/eclampsia with IV (LOE = A) MgS proving to have superior outcomes compared to diazepam or phenytoin in preventing seizures, reducing vascular resistance, and improving cardiac output

Migraines

  • Correlated to lower Mg levels

  • Oral Mg supplementation has been shown to reduce the frequency, duration, and intensity of migraines by 41% compared to placebo at 15.8%

  • Magnesium sulfate (1 gram IV) may be useful in migraine patients with aura (37% responded with less pain) but not in common migraine

Diabetes

  • Normalising Mg deficiency corrects pancreatic B cell function in a small study

  • Reduction of fasting blood glucose by 8% and insulin by 12%

  • T1DM appear to have higher rates of Mg Deficiency (up to 25%)

  • One study showed Mg supplement decreased the rate of decline in neuropathy

  • In overweight and insulin-resistant people with normal Mg, supplementation of Mg at 365mg for 6 months reduced fasting glucose (6%) and increased insulin sensitivity

  • A double-blind, placebo-controlled clinical trial showed that supplementing with 250 mg magnesium per day (as oxide) for 24 weeks improved glycaemic control, LDL- and total cholesterol, and carotid intima-media thickness, in diabetics receiving haemodialysis.

Blood Pressure

  • Normal BP but low Mg showed lowering of BP of 7% / 4% with Mg supplement

  • Mg supplement for 12 weeks in those with recent diagnosis HTN showed an additional 5% / 3% reduction

  • Two meta-analyses of prospective cohort studies showed that BP was inversely related to magnesium levels and intake.

  • A meta-analysis of 34 double-blind, placebo-controlled trials assessing the effectiveness of magnesium supplementation to lower BP in both subjects with and without hypertension showed a significant benefit of magnesium supplementation and suggested that a dose of 300 mg elemental magnesium for 1 month was sufficient to increase serum magnesium levels and lower BP.

  • A meta-analysis of RCTs including only hypertensive patients with a systolic BP of > 155 mmHg and who had previously used antihypertensive drugs showed a particularly strong effect of magnesium supplementation, with a mean decrease in systolic BP of 18.7 mmHg and in diastolic BP of 10.9 mmHg.

  • A 2017 meta-analysis of 11 RCTs found that magnesium supplementation significantly lowered both systolic and diastolic BP in a subset of patients with prediabetes, insulin resistance or other chronic conditions.

CVD

  • A 2013 meta-analysis of 19 prospective cohort studies concluded that both dietary magnesium intake and serum magnesium levels were inversely related to CVD risk, including coronary heart disease, death from CVD and stroke.

  • Low Mg related to arrhythmias and hypertension

Pain

  • A systematic review and meta-analysis of 27 RCTs support the use of IV magnesium sulphate as an adjunct to anaesthesia in reducing pain scores and analgesia use post-operatively.

ADHD

  • One study of 116 kids showed 95% had Mg deficiency

  • 50 kids had 200mg Mg for 6 months showed decreased hyperactivity scales

  • One study of 910 kids showed Omega-3 augmented Mg supplement showing benefit using SNAP-IV scale

Menstrual

  • One study of 38 women showed a reduction in PMS symptoms

  • A 2001 Cochrane review and meta-analysis based on three RCTs concluded that magnesium was more effective than placebo to provide pain relief in dysmenorrhoea.

Colorectal cancer

  • Study of 60k women for 3 years

  • Women in the highest Quintile (top 20% = >225mg daily) versus the lowest quintile (lowest 20% = <209mg daily) had a significantly reduced risk of colorectal cancer (RR = 0.59)

  • The effect is linked to foods containing Mg not supplements (supps not studied)

Probably not significant

Altitude Sickness

  • Mg not clinically significant in one small study on improving altitude sickness

Sedentary movement

  • Not significant

Sleep

  • Not significant

Depression

  • Not significant

Anxiety

  • Not significant

Stress

  • Some animal evidence

Learning

  • Increased memory in rat studies

Triglycerides

  • No strong evidence

Cholesterol

  • No strong evidence

Testosterone

  • Minimal evidence

Cortisol

  • No significant evidence

Inflammation

  • One study of Mg supp in overweight adult for a month = no highly significant patterns apart from an increase in IL-6

Hearing

  • One study in 19 people of 3 months x Mg supp at 500mg showed a perceived reduction in handicap of moderate to severe tinnitus

Bladder

  • One study showed Mg suppl increased urine pH and reduced calcium-dependent kidney stones

 
 
 
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