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

Selenium (Elemental Se) vs. Vitamin K1 (Phylloquinone)

Comparing 2 standards across 10 specifications. 10 key differences identified.

Comparing:
Selenium (Elemental Se)
Vitamin K1 (Phylloquinone)

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.

View full Selenium (Elemental Se) spec sheet →

Vitamin K1 is a fat-soluble naphthoquinone synthesized by photosynthetic plants. Adequate Intake (AI) is 120µg (men) / 90µg (women), acting as an essential cofactor for gamma-glutamyl carboxylase in blood clotting and osteocalcin bone mineralization.

View full Vitamin K1 (Phylloquinone) spec sheet →

Specification Comparison Table

10 Parameters
Parameter / Spec
Nutrient Type
Essential Trace Element Fat-Soluble Naphthoquinone Vitamin
Tolerable Upper Limit (UL)
400 µg / day (Avoid selenosis / garlic breath, hair/nail brittleness) None Established (No adverse effects reported)
Chemical Forms
Selenomethionine (Plant organic), Selenocysteine (Animal selenoprotein), Sodium Selenite / Selenate (Inorganic) Phylloquinone (K1 - Green Plants), Menaquinones (K2: MK-4, MK-7 - Ferments/Animal)
Primary Biological Function
Glutathione Peroxidase (GPx1-4) lipid hydroperoxide neutralization, Iodothyronine Deiodinases (Converts thyroid T4 into active T3), Thioredoxin Reductase (TXNRD) Gamma-glutamyl carboxylase cofactor (Factors II, VII, IX, X), Osteocalcin carboxylation, Matrix Gla Protein (MGP) vascular calcification inhibitor
Deficiency Condition
Keshan Disease (Endemic juvenile cardiomyopathy), Kashin-Beck Disease (Deforming osteoarthropathy), Impaired thyroid metabolism Coagulopathy, Hemorrhage, Impaired bone density
Top Whole Food Sources
Brazil Nuts (1 single nut provides ~70–90µg / 130–160% RDA), Eastern Oysters, Yellowfin Tuna, Halibut, Sardines, Beef Liver, Eggs Spinach, Kale, Broccoli, Brussels Sprouts, Natto (K2 MK-7), Parsley
Adult RDA / RDI
55 µg / day (60 µg pregnancy, 70 µg lactation)
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
Adult Adequate Intake (AI)
120 µg / day (Men) / 90 µg / day (Women)
Warfarin / Anticoagulant Interaction
Direct competitive antagonist to Coumadin/Warfarin (requires consistent daily intake)