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

Iron (Heme & Non-Heme) vs. Vitamin A (Retinol & Beta-Carotene)

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

Comparing:
Iron (Heme & Non-Heme)
Vitamin A (Retinol & Beta-Carotene)
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 →
Vitamin A (Retinol & Beta-Carotene) →

Vitamin A is an essential fat-soluble isoprenoid comprising preformed retinol and provitamin A carotenoids. Adult RDA is 900 µg RAE (men) / 700 µg RAE (women), with a Tolerable Upper Limit of 3,000 µg/day preformed retinol, essential for rhodopsin retinal photoreception, epithelial differentiation, and immune cell proliferation.

View full Vitamin A (Retinol & Beta-Carotene) spec sheet →

Specification Comparison Table

9 Parameters
Parameter / Spec
Iron (Heme & Non-Heme)
Vitamin A (Retinol & Beta-Carotene)
Nutrient Type
Essential Trace Mineral Fat-Soluble Isoprenoid Vitamin
Adult RDA / RDI
8 mg (Men) / 18 mg (Women 19–50) / 27 mg (Pregnancy) 900 µg RAE / day (Men) / 700 µg RAE / day (Women)
Tolerable Upper Limit (UL)
45 mg / day (Hemochromatosis / Fenton reaction oxidative stress) 3,000 µg / day (10,000 IU) (Preformed retinol only; no UL for beta-carotene)
Chemical Forms
Heme Iron (Fe2+ Porphyrin - Animal), Non-Heme Iron (Fe3+ Ferric / Fe2+ Ferrous - Plants/Supplements) Retinyl Palmitate (Preformed Animal), All-Trans Retinol, Beta-Carotene (Plant Provitamin)
Primary Biological Function
Hemoglobin O2 transport, Myoglobin O2 storage, Cytochrome c electron transport, Catalase 11-cis-retinal rhodopsin visual cycle, RAR/RXR nuclear receptor gene transcription, Mucosal barrier immunity
Deficiency Condition
Microcytic Hypochromic Anemia, Severe fatigue, Restless legs syndrome, Pica Nyctalopia (Night blindness), Xerophthalmia, Bitot's spots, Keratinization of mucous membranes
Top Whole Food Sources
Beef Liver, Oysters, Duck Breast, Beef Ribeye, Lentils, Spinach, Dark Chocolate Beef Liver, Cod Liver Oil, Sweet Potatoes, Carrots, Spinach, Curly Kale, Butter
Bioavailability Difference
Heme: 15–35% absorption (uninhibited); Non-Heme: 2–20% (inhibited by phytates/calcium, boosted by Vitamin C) —
Hepatic Storage
— 80–90% of total body Vitamin A is stored in hepatic stellate cells as retinyl esters

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. Selenium (Elemental Se) → Compare Iron (Heme & Non-Heme) vs. Sodium (Elemental Na) → 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) →