magnesium - the role, absorption, and uptake in the body

Magnesium - Blog Post - Always Fit

Recommended Daily Intake (RDI):

  • Woman 19-30yrs 310mg/day; >30yrs 320mg/day

  • Men 19-30yrs 400mg/day; >30yrs 420mg/day

The majority of magnesium in the body occurs in the bones, muscles, and tissues.

Roles

  • Magnesium has many metabolic and structural functions it is required for the mitochondria to carry out oxidative phosphorylation.

  • It is involved in both aerobic & anaerobic energy generation plus glycolysis.

  • Maintenance of bone health & optimal bone growth.

  • Co-factor for more than 300 enzymes.

  • Plays a role in regulating potassium fluxes & the metabolism of calcium

  • Muscle & nervous system function.

Magnesium absorption

Magnesium is absorbed in the intestines by both active and passive processes. Kidneys play a central role in magnesium homeostasis through active reabsorption which is influenced by sodium load and the acid-base balance.

What affects magnesium uptake?

  • High fibre intakes of >40-50g per day lowers magnesium absorption

  • High zinc intakes ≥142mg per day reduces absorption

  • Protein intake <30g per day decreases magnesium absorption.

  • When Protein intake is exceptionally high renal magnesium excretion increases.

  • High dietary calcium intakes (~2600mg per day) combined with high sodium intake contributes to a shift to negative magnesium balance.

Deficiency/excess symptoms

  • Depletion of magnesium maybe observed mainly among athletes in endurance type sports.

  • Deficiency symptoms include muscle weakness, irritability, nausea, and depression.

  • In females: Sub-optimal intake of magnesium may cause or increase pre-menstrual tension and discomfort.

  • Excess: large intakes (3-5g) may have a laxative effect.

  • Individuals with abnormal renal function can be subject to hyper magnesium; symptoms include depression, nausea, vomiting & hypotension.

Supplement intake:

Magnesium in supplement form should be present with calcium in a 1 to 2 ratio of magnesium to calcium.

food sources include: 

Rice Bran - Oat Bran - Wheat Bran – Buckwheat Rye - Pumpkin seeds - Edamame Beans – Dates Kale – Banana – Spirulina – Quinoa - Brown Rice - Brazil Nuts