Magnesium: Interactions

Interactions of magnesium with other agents (micronutrients, foods, drugs):

Vitamin D and calcium

The active form of vitamin D (calcitriol) may increase intestinal absorption, that is, absorption through the intestine, of magnesium to a small extent. On the other hand, magnesium absorption does not appear to be calcitriol-dependent, unlike the absorption of calcium and phosphate.It is known that increased intake of calcium affects magnesium balance. However, magnesium deficiency results in low serum calcium levels, poorer parathyroid hormone (PTH) action, and likewise poorer vitamin D action.

Potassium

Magnesium and potassium are quantitatively the most important elements in the intracellular space, with magnesium being the second most abundant intracellular cation. Because of this, magnesium homeostasis is closely related to potassium homeostasis. Significant cation losses occur with gastrointestinal disorders – malabsorption, vomiting, diarrheadiuretics, alcohol, and antibiotics. Resulting magnesium deficiencies increase renal potassium losses – but their mechanism is unclear.In addition, hypomagnesemia (magnesium deficiency) increases the permeability of potassium through K+ channels, resulting in an unequal ratio between extracellular and intracellular potassium, with negative effects on cardiac muscle action potential. Accordingly, the interactions of potassium and magnesium involve gastrointestinal absorption, renal excretion, and endogenous distribution between extracellular and intracellular compartments, as well as various cellular processes.

Zinc

Supplementation of the diet with high doses of zinc appears to interfere with the absorption of magnesium. Supplemental administration of 142 mg zinc/day decreased magnesium absorption in young men and adversely affected magnesium balance (difference between magnesium uptake and loss).

Proteins

Proteins may potentially affect magnesium absorption.

Food or dietary components

Foods or food components that also inhibit enteral magnesium absorption:

  • Phytic acid (phytates)
  • Oxalate
  • Phosphates
  • Long chain saturated fatty acids
  • Tannic acid in coffee and black tea

These foods or dietary components form a poorly soluble, non-absorbable complex with magnesium when absorbed simultaneously inside the intestine and reduce its bioavailability.

Experimental studies have demonstrated that increased dietary fiber intake reduces magnesium utilization. However, the extent to which fiber affects magnesium status is not clear.

Increased urinary magnesium excretion occurs in:

  • Increased caffeine consumption
  • High intake of table salt
  • Regular alcohol consumption
  • Chronic acidosis

Drugs

Drugsantacids, antibiotics, and tetracyclines – severe diarrhea (diarrhea), and absorption disorders associated with food intolerance or gastrointestinal disease also reduce enteral magnesium absorption. For other drugs, see “Magnesium/drugs” below.