Trace Minerals: Iron Functions and Absorption

Trace Minerals

• Trace minerals are essential for various bodily functions, although only needed in small amounts

Iron

• Forms:
  • Ferrous (Fe⁺⁺): Reduced form
  • Ferric (Fe⁺⁺⁺): Oxidized form
• Roles in the Body:
  • Cofactor in oxidation-reduction reactions
  • Component of hemoglobin (oxygen transport in blood)
  • Component of myoglobin (oxygen storage in muscles)
  • Energy utilization in cell metabolism
• Absorption:
  • Excess iron is stored in mucosal ferritin.
  • When needed, iron is released to mucosal transferrin, which transfers it to the bloodstream.
  • If not needed, iron is excreted in shed intestinal cells.
• Forms in Food:
  • Heme iron (animal source): High bioavailability, not affected by dietary factors.
  • Nonheme iron (animal and plant sources): Bioavailability affected by dietary factors.
• Factors Enhancing Nonheme Iron Absorption:
  • MFP factor (meat, fish, poultry digestion)
  • Vitamin C
  • Citric acid
  • Lactic acid
  • HCI from stomach
  • Sugars
• Factors Inhibiting Nonheme Iron Absorption:
  • Phytates
  • Fibers
  • Oxalates
  • Calcium/Phosphorus
  • Tannic acid
  • EDTA
• Iron Absorption (Heme vs. Nonheme):
  • Heme iron accounts for ~10% of total iron intake, but is well absorbed (~25%).
  • Nonheme iron accounts for ~90% of total iron intake, but is less well absorbed (~17%).
• Iron Transport and Recycling:
  • Transferrin transports iron in the blood.
  • Liver/spleen break down old red blood cells.
  • Iron is packaged into transferrin and stored in ferritin/hemosiderin.
  • Bone marrow incorporates iron into hemoglobin in red blood cells.
• Significant Sources: Red meats, fish, poultry, shellfish, eggs, legumes, dried fruits
• Recommended Dietary Allowance (RDA):
  • Men: 8 mg/day
  • Women (19-50 years): 18 mg/day
  • Women (51+ years): 8 mg/day
• High Risk for Iron Deficiency: Women in reproductive years, pregnant women, infants, young children, teenagers

Zinc

• Roles in the Body:
  • Component of metalloenzymes
  • DNA/RNA synthesis
  • Hemoglobin synthesis
  • Fatty acid metabolism
  • Vitamin A release
  • Carbohydrate metabolism
  • Protein synthesis
  • Blood clotting/wound healing
  • Thyroid hormone function
  • Behavior/learning performance
  • Taste perception
  • Sperm development
  • Fetal development
• Zinc Absorption:
  • Rate depends on zinc status
  • Phytates/fiber bind zinc, reducing absorption
• Significant Sources: Protein-containing foods, red meats, shellfish, whole grains
• RDA:
  • Men: 11 mg/day
  • Women: 8 mg/day
• Deficiency Symptoms: Growth retardation, delayed sexual maturation, impaired immune function, hair loss, eye/skin lesions, loss of appetite
• Toxicity Symptoms: Loss of appetite, impaired immunity, copper/iron deficiencies

Iodine

• Roles in the Body: Component of thyroid hormones, regulates growth, development, and metabolic rate.
• Iodine Deficiency:
  • Simple goiter: Enlargement of the thyroid gland
  • Goiter: Malfunction of the gland, iodine deficiency, or goitrogen overconsumption.
  • Cretinism: Congenital disease, mental/physical retardation, caused by maternal iodine deficiency during pregnancy.
• Iodine Toxicity: Symptoms include underactive thyroid gland and goiter.
• RDA: 150 µg/day
• Sources: Iodized salt, seafood, bread & dairy, plants grown in iodine-rich soils, animals that feed on those plants

Copper

• Roles in the Body: Part of several enzymes, some are antioxidants
• Deficiency Symptoms: Anemia, bone abnormalities, Menkes disease
• Toxicity: Wilson's disease
• RDA: 900 µg/day
• Sources: Seafood, nuts, seeds, legumes, whole grains

Fluoride

• Roles in the Body: Formation of teeth and bones, helps teeth resist decay
• Deficiency: Tooth decay
• Toxicity: Tooth damage (fluorosis)
• AI:
  • Men: 4 mg/day
  • Women: 3 mg/day
• Sources: Fluoridated water, seafood, tea

Chromium

• Roles in the Body: Enhances insulin action (glucose tolerance factors)
• AI:
  • Men: 35 µg/day
  • Women: 25 µg/day
• Sources: Meat, liver, whole grains, brewer's yeast

Contaminant Minerals (Heavy Metals)

• Contaminants: Mercury, lead, cadmium
• Sources: Soil, water, air pollution
• Effects: Disrupt bodily processes, impair nutrition
• Lead Toxicity in Children:
  • Learning disabilities, low IQ, behavior problems, slow growth, iron-deficiency anemia, dental caries, sleep disturbances, nervous system disorders, seizures, impaired hearing/coordination
• Lead Toxicity in Adults: Hypertension, reproductive complications, kidney failure

This quiz covers the essential trace mineral iron, detailing its forms, roles in the body, and mechanisms of absorption. Learn about the differences between heme and nonheme iron, and what dietary factors can enhance absorption. Test your knowledge on the importance of iron for overall health.