Can intestinal disease or chronic diarrhea reduce magnesium uptake and lead to magnesium depletion?

Intestinal disorders, chronic diarrhea, and malabsorptive states can meaningfully impair magnesium balance—an especially relevant consideration in an older adult with persistent gastrointestinal symptoms, prior bowel resection, or inflammatory/malabsorptive disease.

Clinical evidence

• Celiac disease, inflammatory bowel disease, and short-bowel states are recognized settings for impaired gastrointestinal magnesium absorption and magnesium deficiency.
• In inflammatory bowel disease, reported magnesium-deficiency prevalence ranges from 13% to 88% across heterogeneous studies; this range indicates variable risk rather than a single expected rate.
• In a small retrospective series of severe short-bowel syndrome, 10 of 15 patients (66%) had hypomagnesemia, supporting substantial risk when absorptive surface is markedly reduced.
• Chronic diarrhea contributes both by shortening intestinal transit time and by increasing fecal magnesium losses. Sustained loss or reduced absorption can create negative magnesium balance and eventually depletion.

Mechanistic basis

• Magnesium uptake normally occurs through passive paracellular absorption, especially in the small intestine, and through distal-intestinal transcellular transport involving TRPM6/7 channels.
• Inflammation, mucosal dysfunction, intestinal resection, or other malabsorptive processes can disrupt these pathways.
• With diarrhea and fat malabsorption, unabsorbed fatty acids may bind magnesium in the lumen, reducing the fraction available for absorption; diarrhea also directly increases stool magnesium loss.

Clinical interpretation

• Serum magnesium is readily measured but may underestimate total-body depletion because most body magnesium is intracellular or stored in bone.
• In confirmed hypomagnesemia, low urinary magnesium excretion supports inadequate intake or gastrointestinal loss, whereas inappropriately high urinary excretion suggests renal magnesium wasting.

Bottom line

• The claim is supported: intestinal disease, chronic diarrhea, and malabsorption can reduce magnesium uptake and—along with increased fecal losses—contribute to clinically important magnesium depletion.