Is older age associated with reduced absorption or status of vitamin B12, folate, vitamin B6, and magnesium?

Clinical evidence of age-related decline

• Vitamin B12 deficiency: Affects 10% to 15% of adults over age 60, and up to 30% to 40% of institutionalized cohorts.
• Vitamin B6 and folate: Dietary folate inadequacy exceeds 25% in longitudinal aging cohorts, while vitamin B6 insufficiency (plasma pyridoxal-5′-phosphate <30 nmol/L) impacts 13% to 45% of older adults due to poor dietary intake and systemic inflammation.
• Magnesium depletion: Chronic latent deficiency or clinical hypomagnesemia is documented in approximately 30% to 33% of geriatric and institutionalized populations.

Mechanistic pathways and pharmacological interactions

• Hypochlorhydria and gastric pH: Age-related atrophic gastritis and proton-pump inhibitors (PPIs) elevate gastric pH. This chronic hypochlorhydria prevents gastric acid and pepsin from cleaving food-bound vitamin B12 from dietary proteins, causing food-cobalamin malabsorption.
• Intestinal transporter inhibition: Elevated luminal pH decreases magnesium solubility and downregulates the active transcellular transport mediated by TRPM6 and TRPM7 channels in the intestine, while also compromising passive paracellular pathways.
• Drug-nutrient interactions: Metformin compromises vitamin B12 status by directly interfering with calcium-dependent membrane receptors required for ileal absorption. Concurrently, loop and thiazide diuretics accelerate renal magnesium wasting, compounding the effects of reduced dietary intake.

Bottom line

• Aging significantly compromises the absorption and status of vitamin B12, folate, B6, and magnesium through a distinct combination of elevated gastric pH, downregulated intestinal transporters (TRPM6/7), and highly prevalent drug interactions (including PPIs, metformin, and diuretics).