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

Vitamin B12 (Cobalamin) vs. Vitamin E (d-Alpha-Tocopherol)

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

Comparing:
Vitamin B12 (Cobalamin)
Vitamin E (d-Alpha-Tocopherol)
Vitamin B12 (Cobalamin) →

Vitamin B12 is a cobalt-containing water-soluble corrinoid synthesized exclusively by microorganisms. Adult RDA is 2.4µg/day (no Upper Limit established), required for DNA synthesis, methionine synthase homocysteine conversion, and myelin sheath maintenance.

View full Vitamin B12 (Cobalamin) spec sheet →
Vitamin E (d-Alpha-Tocopherol) →

Vitamin E is the principal fat-soluble peroxyl radical-scavenging antioxidant protecting cellular polyunsaturated membrane phospholipids. Adult RDA is 15 mg (22.4 IU) of d-alpha-tocopherol, with a Tolerable Upper Limit of 1,000 mg (1,500 IU)/day.

View full Vitamin E (d-Alpha-Tocopherol) spec sheet →

Specification Comparison Table

9 Parameters
Parameter / Spec
Vitamin B12 (Cobalamin)
Vitamin E (d-Alpha-Tocopherol)
Nutrient Type
Water-Soluble Corrinoid Vitamin Fat-Soluble Chromanol Lipophilic Vitamin
Adult RDA / RDI
2.4 µg / day (2.6µg pregnancy, 2.8µg lactation) 15 mg / day (22.4 IU) of 2R-alpha-tocopherol
Tolerable Upper Limit (UL)
None Established (Extremely low toxicity) 1,000 mg / day (1,500 IU synthetic) (Excess impairs Vitamin K clotting cascade)
Chemical Forms
Methylcobalamin (Active), Adenosylcobalamin (Active), Cyanocobalamin (Stable synthetic) RRR-alpha-Tocopherol (Natural d-alpha), all-rac-alpha-Tocopherol (Synthetic dl-alpha), Gamma/Delta-Tocopherols
Primary Biological Function
Methionine synthase cofactor, Methylmalonyl-CoA mutase cofactor, Myelin integrity, Erythropoiesis Breaks lipid peroxidation chain in PUFA cell membranes, protects LDL from oxidative modification, maintains erythrocyte membrane integrity
Deficiency Condition
Pernicious / Megaloblastic Anemia, Irreversible Neurological Peripheral Neuropathy Hemolytic anemia, Spinocerebellar ataxia, Peripheral neuropathy, Loss of vibratory/proprioceptive sense
Top Whole Food Sources
Oysters, Beef Liver, Sardines, Salmon, Beef, Dairy, Eggs (Absent in unfortified plant foods) Wheat Germ Oil, Sunflower Seeds, Raw Almonds, Hazelnuts, Sunflower Oil, Spinach, Hass Avocado
Absorption Mechanism
Requires Gastric Acid, R-Protein, and Intrinsic Factor (IF) via Ileal Cubam receptors —
Hepatic Alpha-TTP Specificity
— The liver secretes only alpha-tocopherol into VLDL via Alpha-Tocopherol Transfer Protein (alpha-TTP); other tocopherols are degraded in bile

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