Iron
| Iron | |
|---|---|
| [[File:|250px]] | |
| Chemical formula | Fe |
| Molar mass | 55.845 g/mol |
| Color | Metallic silver-gray (pure iron)
Rust-red when oxidized (Fe₂O₃) |
| Hardness (Mohs) | 4–5 |
| Density | 7.874 g/cm³ (at 20 °C) |
| Solubility | Essentially insoluble as the metal
Iron ions (Fe²⁺, Fe³⁺) are soluble depending on the salt and pH |
| Bioavailability | Heme iron (from meat): 15–35 % absorbed
Non-heme iron (plants, fortified foods, supplements): 2–20 % absorbed ↑ greatly increased by vitamin C, meat/fish, acidic environment ↓ strongly inhibited by phytates (grains/legumes), polyphenols (tea/coffee), calcium, zinc |
| Dietary sources | Heme (high absorption): liver, red meat, poultry, fish, shellfish (especially oysters, clams, mussels) |
| RDA (adults 19–50 y) | Men: 8 mg/day
Women (pre-menopausal): 18 mg/day Women (post-menopausal): 8 mg/day Pregnant women: 27 mg/day |
| Upper limit | 45 mg/day (for ages ≥14 years)
(Applies to supplemental + fortified iron; does not include iron from natural food sources) |
Introduction
"The medical profession has even coined the term ‘rusty brains’ to describe iron overload’s role in Alzheimer’s… Cleaning out ‘rust’ from the brain could be a way to slow and even prevent degenerative disease." - Georgi Dinkov
"Iron is a potentially toxic heavy metal; an excess can cause cancer, heart disease, and other illnesses. Iron causes cell aging." - Ray Peat
"The harmful effects of iron-produced free radicals are practically indistinguishable from those caused by exposure to X-rays and gamma rays; both accelerate ageing and degeneration." - Ray Peat
“A deficiency of copper causes our tissues to retain an excess of iron, so foods such as shrimp and oysters which contain abundant copper should be used regularly.” - Ray Peat, Iron's Dangers
