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

Iron (Heme & Non-Heme) vs. Selenium (Elemental Se)

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

Comparing:
Iron (Heme & Non-Heme)
Selenium (Elemental Se)
Iron (Heme & Non-Heme) →

Iron is an essential redox trace element central to hemoglobin oxygen transport, myoglobin storage, and mitochondrial electron transport chain cytochromes. Adult RDA is 8mg (men/post-menopausal women) / 18mg (pre-menopausal women), with a Tolerable Upper Limit of 45mg/day.

View full Iron (Heme & Non-Heme) spec sheet →
Selenium (Elemental Se) →

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 →

Specification Comparison Table

9 Parameters
Parameter / Spec
Iron (Heme & Non-Heme)
Selenium (Elemental Se)
Nutrient Type
Essential Trace Mineral Essential Trace Element
Adult RDA / RDI
8 mg (Men) / 18 mg (Women 19–50) / 27 mg (Pregnancy) 55 µg / day (60 µg pregnancy, 70 µg lactation)
Tolerable Upper Limit (UL)
45 mg / day (Hemochromatosis / Fenton reaction oxidative stress) 400 µg / day (Avoid selenosis / garlic breath, hair/nail brittleness)
Chemical Forms
Heme Iron (Fe2+ Porphyrin - Animal), Non-Heme Iron (Fe3+ Ferric / Fe2+ Ferrous - Plants/Supplements) Selenomethionine (Plant organic), Selenocysteine (Animal selenoprotein), Sodium Selenite / Selenate (Inorganic)
Primary Biological Function
Hemoglobin O2 transport, Myoglobin O2 storage, Cytochrome c electron transport, Catalase Glutathione Peroxidase (GPx1-4) lipid hydroperoxide neutralization, Iodothyronine Deiodinases (Converts thyroid T4 into active T3), Thioredoxin Reductase (TXNRD)
Deficiency Condition
Microcytic Hypochromic Anemia, Severe fatigue, Restless legs syndrome, Pica Keshan Disease (Endemic juvenile cardiomyopathy), Kashin-Beck Disease (Deforming osteoarthropathy), Impaired thyroid metabolism
Top Whole Food Sources
Beef Liver, Oysters, Duck Breast, Beef Ribeye, Lentils, Spinach, Dark Chocolate Brazil Nuts (1 single nut provides ~70–90µg / 130–160% RDA), Eastern Oysters, Yellowfin Tuna, Halibut, Sardines, Beef Liver, Eggs
Bioavailability Difference
Heme: 15–35% absorption (uninhibited); Non-Heme: 2–20% (inhibited by phytates/calcium, boosted by Vitamin C) —
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

Other Alternatives to Compare

Compare Iron (Heme & Non-Heme) vs. Calcium (Elemental Ca) → Compare Iron (Heme & Non-Heme) vs. Iodine (Elemental I) → Compare Iron (Heme & Non-Heme) vs. Magnesium (Elemental Mg) → Compare Iron (Heme & Non-Heme) vs. Potassium (Elemental K) → Compare Iron (Heme & Non-Heme) vs. Sodium (Elemental Na) → Compare Iron (Heme & Non-Heme) vs. Vitamin A (Retinol & Beta-Carotene) → Compare Iron (Heme & Non-Heme) vs. Vitamin B1 (Thiamine) → Compare Iron (Heme & Non-Heme) vs. Vitamin B12 (Cobalamin) → Compare Iron (Heme & Non-Heme) vs. Vitamin B2 (Riboflavin) → Compare Iron (Heme & Non-Heme) vs. Vitamin B3 (Niacin / Nicotinic Acid & Nicotinamide) → Compare Iron (Heme & Non-Heme) vs. Vitamin B5 (Pantothenic Acid) → Compare Iron (Heme & Non-Heme) vs. Vitamin B6 (Pyridoxal 5'-Phosphate / PLP) → Compare Iron (Heme & Non-Heme) vs. Vitamin B7 (Biotin / Vitamin H) → Compare Iron (Heme & Non-Heme) vs. Vitamin B9 (Folate & Folic Acid) → Compare Iron (Heme & Non-Heme) vs. Vitamin C (L-Ascorbic Acid) → Compare Iron (Heme & Non-Heme) vs. Vitamin D3 (Cholecalciferol) → Compare Iron (Heme & Non-Heme) vs. Vitamin E (d-Alpha-Tocopherol) → Compare Iron (Heme & Non-Heme) vs. Vitamin K1 (Phylloquinone) → Compare Iron (Heme & Non-Heme) vs. Zinc (Elemental Zn) →