Side-by-Side Comparison
Essential Vitamins & Minerals
Selenium (Elemental Se) vs. Vitamin B12 (Cobalamin)
Comparing 2 standards across 9 specifications. 9 key differences identified.
Comparing:
Selenium (Elemental Se)
Vitamin B12 (Cobalamin)
Selenium is an essential trace element incorporated as Selenocysteine (the 21st amino acid) into 25 human selenoproteins including Glutathione Peroxidases (GPx) and Iodothyronine Deiodinases (T4->T3 conversion). Adult RDA is 55 µg, with a Tolerable Upper Limit of 400 µg/day.
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.
Specification Comparison Table
9 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nutrient Type
|
Essential Trace Element | Water-Soluble Corrinoid Vitamin |
|
Adult RDA / RDI
|
55 µg / day (60 µg pregnancy, 70 µg lactation) | 2.4 µg / day (2.6µg pregnancy, 2.8µg lactation) |
|
Tolerable Upper Limit (UL)
|
400 µg / day (Avoid selenosis / garlic breath, hair/nail brittleness) | None Established (Extremely low toxicity) |
|
Chemical Forms
|
Selenomethionine (Plant organic), Selenocysteine (Animal selenoprotein), Sodium Selenite / Selenate (Inorganic) | Methylcobalamin (Active), Adenosylcobalamin (Active), Cyanocobalamin (Stable synthetic) |
|
Primary Biological Function
|
Glutathione Peroxidase (GPx1-4) lipid hydroperoxide neutralization, Iodothyronine Deiodinases (Converts thyroid T4 into active T3), Thioredoxin Reductase (TXNRD) | Methionine synthase cofactor, Methylmalonyl-CoA mutase cofactor, Myelin integrity, Erythropoiesis |
|
Deficiency Condition
|
Keshan Disease (Endemic juvenile cardiomyopathy), Kashin-Beck Disease (Deforming osteoarthropathy), Impaired thyroid metabolism | Pernicious / Megaloblastic Anemia, Irreversible Neurological Peripheral Neuropathy |
|
Top Whole Food Sources
|
Brazil Nuts (1 single nut provides ~70–90µg / 130–160% RDA), Eastern Oysters, Yellowfin Tuna, Halibut, Sardines, Beef Liver, Eggs | Oysters, Beef Liver, Sardines, Salmon, Beef, Dairy, Eggs (Absent in unfortified plant foods) |
|
Soil Selenium Geographical Variability
|
Plant selenium reflects regional soil content; volcanic soils (South America, Great Plains) are rich, while parts of China, Scandinavia, and New Zealand are depleted | — |
|
Absorption Mechanism
|
— | Requires Gastric Acid, R-Protein, and Intrinsic Factor (IF) via Ileal Cubam receptors |
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