Biochemistry 1: Minerals

Minerals

• Definition: Inorganic compounds needed as structural components and regulators of body processes.
• Classification:
  • Macrominerals (Bulk elements): Required in amounts > 100 mg/day, including 7 elements: Calcium, Phosphorus, Sodium, Potassium, Chloride, Sulfur, and Magnesium.
  • Microminerals (Trace elements): Required in amounts < 100 mg/day, including 11 elements: Iron, Iodine, Copper, Zinc, Fluoride, Manganese, Molybdenum, Selenium, Chromium, Cobalt, and Silicon.

Calcium

• Sources: Milk and milk products, leafy vegetables, and egg yolk.
• Daily requirements:
  • Child: 1000 mg/d
  • Adults: 800 mg/d
  • Pregnant women: 1500 mg/d
• Absorption: Active process in the upper part of the small intestine, requiring calcium-binding protein.
• Distribution: 99% in bones and teeth, 1% in body fluids and other tissues.
• Plasma calcium: 9-11 mg/dl, present in 2 forms: Diffusible calcium (50% of total serum calcium) and Non-diffusible calcium.
• Functions:
  • Calcification of bones and teeth
  • Regulation of transmission of nerve impulses
  • Regulation of contraction of muscles
  • Blood clotting mechanism
  • Cardiac conduction
  • Acts as a second messenger for hormonal action
• Hypercalcemia and Hypocalcemia:
  • Causes: Primary hyperparathyroidism, ectopic cells, excess intake of vitamin D or calcium, bone diseases
  • Effects: Stone formation, calcification in different tissues
  • Causes: Hypoparathyroidism, alkalosis, kidney diseases, vitamin D inhibition
  • Effects: Tetany, Rickets, Osteomalacia

Phosphorus

• Sources: Milk and milk products, fish, meat, liver, kidney, and leafy vegetables.
• Daily requirements:
  • Adults: 800-1000 mg/d
  • Pregnant women: 1500-2000 mg/d
• Absorption: Active transport mechanism, affected by factors that affect calcium absorption.
• Distribution: 600 gm in skeleton (bones and teeth), 700 gm total body phosphorus.
• Plasma phosphorus: 3-5 mg/dl, present in 2 forms: Inorganic phosphate and Organic phosphate.
• Functions:
  • Formation of bones
  • Plasma buffers (phosphate buffers)
  • Cellular components: Nucleic acids, Phospholipids, Phosphoproteins, Coenzymes, Second messengers

Iron

• Sources: Meat, liver, kidney, nuts, beans, and dates.
• Daily requirements:
  • Adults: 10 mg/day
  • Pregnant and lactating women: 30 mg/day
• Absorption and Transport: 10-20% of dietary iron absorbed in the duodenum and proximal jejunum, via Mucosal block theory.
• Iron Containing proteins:
  • Hemoglobin: carries oxygen
  • Myoglobin: stores oxygen
  • Respiratory enzymes: use oxygen
  • Cytochrome P450: detoxicates drugs and oxygen
  • Other enzymes: catalase, peroxidase, and tryptophan oxygenase
• Clinical abnormalities:
  • Iron deficiency anemia: causes, decreased intake, decreased absorption, increased loss, and increased requirements.
  • Iron overload: causes, repeated blood transfusion, intravenous administration of iron, and hemochromatosis.

Zinc

• Sources: Meat, liver, eggs, seafood, milk, and whole grain cereals.
• Absorption: Occurs mainly in small intestine.
• Functions:
  • Essential for growth and reproduction
  • Plays a role in tissue repair and wound healing
  • Forms a complex with insulin in pancreas, helping storage and release of insulin.

This lecture covers the biochemical classification of minerals, their functions, signs of clinical deficiency and over production, and mechanism of absorption.