# item.guide
Side-by-Side Comparison Essential Vitamins & Minerals

Magnesium (Elemental Mg) vs. Vitamin D3 (Cholecalciferol)

Comparing 2 standards across 9 specifications. 9 key differences identified.

Comparing:
Magnesium (Elemental Mg)
Vitamin D3 (Cholecalciferol)

Magnesium is an essential macromineral required as an enzymatic cofactor in over 300 biochemical reactions including ATP synthesis, DNA replication, and neuromuscular transmission. Adult RDA is 400–420mg (men) / 310–320mg (women).

View full Magnesium (Elemental Mg) spec sheet →

Vitamin D3 is a secosteroid prohormone synthesized endogenously in skin via solar UVB irradiation of 7-dehydrocholesterol. Adult RDA is 600–800 IU (15–20µg), with a Tolerable Upper Limit of 4,000 IU (100µg)/day, regulating systemic calcium absorption and immune gene expression.

View full Vitamin D3 (Cholecalciferol) spec sheet →

Specification Comparison Table

9 Parameters
Parameter / Spec
Nutrient Type
Essential Macromineral Fat-Soluble Secosteroid Prohormone
Adult RDA / RDI
400 – 420 mg / day (Men) / 310 – 320 mg / day (Women) 600 – 800 IU / day (15 – 20 µg)
Tolerable Upper Limit (UL)
350 mg / day (From supplemental forms only; no limit on whole foods) 4,000 IU / day (100 µg) (Endocrine Society: up to 10,000 IU safe)
Chemical Forms
Magnesium Glycinate (Chelate), Citrate, Malate, Oxide, L-Threonate Cholecalciferol (D3 - Animal/Lichen), Ergocalciferol (D2 - Fungi)
Primary Biological Function
Mg-ATP complex cofactor (>300 enzymes), NMDA receptor gatekeeper, Protein synthesis, Muscle relaxation Calcitriol receptor (VDR) activation, intestinal calcium/phosphorus absorption, antimicrobial peptide synthesis
Deficiency Condition
Muscle cramps, Tremors, Ventricular arrhythmias, Insulin resistance, Insomnia Rickets (children), Osteomalacia (adults), Immune dysregulation
Top Whole Food Sources
Pumpkin Seeds, Hemp Hearts, Chia Seeds, Almonds, Spinach, Black Beans, Dark Chocolate Sunlight UVB, Atlantic Salmon, Sardines, Egg Yolk, Fortified Milk
Cellular Distribution
99% intracellular (60% bone, 39% skeletal muscle, <1% serum)
Target Serum 25(OH)D Level
30 – 50 ng / mL (75 – 125 nmol / L)