Introduction, Chemistry, and Functions of Essential Minerals: Dietary Requirements, Bioavailability, and Deficiency Implications
1. Introduction to Essential Minerals
Essential minerals are inorganic nutrients that the human body requires for numerous biochemical and physiological functions. Unlike vitamins, these elements are not synthesized endogenously and must be acquired through dietary sources. Minerals are integral to maintaining cellular structure, enzyme function, electrolyte balance, nerve transmission, and metabolic regulation. Based on their quantitative necessity, they are classified into:
- Macrominerals: Required in quantities exceeding 100 mg/day (e.g., calcium, magnesium).
- Microminerals (Trace Elements): Required in amounts less than 100 mg/day (e.g., iron, zinc).
Deficiencies, excesses, or imbalances of these minerals can result in a wide array of clinical symptoms and pathophysiological disorders. A comprehensive understanding of their biochemistry and nutritional roles is essential for dietary planning and therapeutic interventions.
2. Chemistry and Functional Roles of Essential Minerals
A. Macrominerals
1. Calcium (Ca)
- Chemical Form: Ca2+, a divalent cation.
- Physiological Roles: Structural component of bones/teeth, regulates muscle contraction, nerve signaling, blood coagulation.
- Recommended Intake: 1000–1300 mg/day.
- Bioavailability: High from dairy; decreased by oxalates/phytates.
- Deficiency Pathologies: Rickets, osteomalacia, osteoporosis, tetany.
2. Phosphorus (P)
- Chemical Form: PO43−.
- Physiological Roles: ATP synthesis, bone mineralization, nucleic acid and phospholipid component.
- Recommended Intake: 700–1250 mg/day.
- Bioavailability: Protein-rich foods; animal sources better absorbed.
- Deficiency Pathologies: Myopathy, osteomalacia, energy deficiency.
3. Magnesium (Mg)
- Chemical Form: Mg2+.
- Physiological Roles: Enzyme cofactor, ATP production, DNA/RNA synthesis, neuromuscular transmission.
- Recommended Intake: 310–420 mg/day.
- Bioavailability: Legumes, grains, green vegetables.
- Deficiency Pathologies: Seizures, arrhythmia, muscle cramps.
4. Sodium (Na)
- Chemical Form: Na+.
- Physiological Roles: Fluid balance, nerve impulse transmission.
- Recommended Intake: <2300 mg/day.
- Bioavailability: High from salt and processed food.
- Deficiency Pathologies: Hyponatremia, confusion, coma.
5. Potassium (K)
- Chemical Form: K+.
- Physiological Roles: Cardiac rhythm, nerve/muscle function.
- Recommended Intake: 2600–3400 mg/day.
- Bioavailability: Fruits, vegetables, legumes.
- Deficiency Pathologies: Arrhythmia, fatigue, weakness.
6. Chloride (Cl)
- Chemical Form: Cl−.
- Physiological Roles: Acid-base balance, gastric acid formation.
- Recommended Intake: ~2300 mg/day.
- Bioavailability: From sodium chloride (table salt).
- Deficiency Pathologies: Alkalosis, hypochloremia.
7. Sulfur (S)
- Chemical Form: Part of amino acids cysteine and methionine.
- Physiological Roles: Protein structure, detoxification, enzyme function.
- Recommended Intake: Not defined; from protein intake.
- Bioavailability: Animal proteins, legumes.
- Deficiency Pathologies: Rare; protein deficiency-related.
B. Microminerals (Trace Elements)
1. Iron (Fe)
- Chemical Forms: Fe2+, Fe3+.
- Physiological Roles: Hemoglobin, electron transport, oxidative metabolism.
- Recommended Intake: 8–18 mg/day.
- Bioavailability: Heme > Non-heme; enhanced by vitamin C.
- Deficiency Pathologies: Anemia, cognitive delay, fatigue.
2. Zinc (Zn)
- Chemical Form: Zn2+.
- Physiological Roles: Enzymatic function, immune response, wound healing.
- Recommended Intake: 8–11 mg/day.
- Bioavailability: High in animal protein; reduced by phytates.
- Deficiency Pathologies: Growth retardation, alopecia, immune dysfunction.
3. Copper (Cu)
- Chemical Forms: Cu+, Cu2+.
- Physiological Roles: Iron metabolism, antioxidant defense, neurotransmitter synthesis.
- Recommended Intake: 900 µg/day.
- Bioavailability: Nuts, liver, shellfish.
- Deficiency Pathologies: Anemia, neurological defects.
4. Iodine (I)
- Chemical Form: I−.
- Physiological Roles: Thyroid hormone synthesis.
- Recommended Intake: 150 µg/day.
- Bioavailability: Seafoods, iodized salt.
- Deficiency Pathologies: Goiter, cretinism, hypothyroidism.
5. Selenium (Se)
- Chemical Form: Selenocysteine form.
- Physiological Roles: Antioxidant enzymes, thyroid regulation.
- Recommended Intake: 55 µg/day.
- Bioavailability: Brazil nuts, cereals, fish.
- Deficiency Pathologies: Keshan disease, immune dysfunction.
6. Fluoride (F)
- Chemical Form: F−.
- Physiological Roles: Enamel mineralization, bone strengthening.
- Recommended Intake: 3–4 mg/day.
- Bioavailability: Fluoridated water, tea.
- Deficiency Pathologies: Dental caries, weakened bones.
7. Manganese (Mn)
- Chemical Form: Mn2+.
- Physiological Roles: Bone formation, antioxidant defense.
- Recommended Intake: 1.8–2.3 mg/day.
- Bioavailability: Grains, leafy vegetables.
- Deficiency Pathologies: Skeletal deformities, reproductive issues.
8. Chromium (Cr)
- Chemical Form: Cr3+.
- Physiological Roles: Enhances insulin function.
- Recommended Intake: 20–35 µg/day.
- Bioavailability: Meat, grains.
- Deficiency Pathologies: Glucose intolerance.
9. Molybdenum (Mo)
- Chemical Form: MoO42−.
- Physiological Roles: Enzyme cofactor in sulfur and purine metabolism.
- Recommended Intake: 45 µg/day.
- Bioavailability: Legumes, grains.
- Deficiency Pathologies: Rare; sulfite sensitivity, neurological symptoms.
Conclusion
Essential minerals are indispensable to human health, serving both structural and regulatory functions in the body. Their interactions, synergistic or antagonistic, underscore the complexity of mineral metabolism. For students and professionals in the field of nutrition or biomedical sciences, a solid grasp of mineral chemistry, bioavailability, and associated deficiency syndromes is foundational to both academic understanding and clinical practice. As dietary patterns shift with modernization, ensuring optimal mineral intake through conscious nutritional strategies is imperative for maintaining physiological homeostasis and preventing disease.