Water and minerals

Water and Minerals in Human Nutrition

Overview

This study guide covers the essential roles of water and minerals in the human body, their regulation, differences from other nutrients, and the impact of deficiencies and excesses. It is structured to help Nutrition students understand the physiological and dietary significance of these nutrients.

Water: The Most Abundant Substance in the Body

Distribution and Composition

Water constitutes the largest proportion of body mass in humans, with its percentage varying by age, sex, and body composition.

• Average healthy adult: About 60% water

• Muscle tissue: 65% water

• Fat tissue: 10–40% water

• Sex differences: Men generally have higher water percentage due to more muscle and less fat compared to women.

• Age differences: Children have higher water percentage; elderly have lower percentage.

Functions of Water in the Body

Water is vital for numerous physiological processes and structural functions.

• Universal solvent and transport medium: Dissolves and carries nutrients, oxygen, and hormones.

• Participates in chemical reactions: Essential for metabolic processes.

• Regulates body temperature: Through sweating and heat distribution.

• Lubricates joints and tissues: Present in mucus, saliva, and synovial fluid.

• Provides cushioning: Protects brain, organs, and fetus.

• Removes waste: Facilitates excretion via urine, feces, sweat, and breath.

Fluid Balance and Regulation

Fluid Compartments and Electrolytes

Water is distributed among intracellular and extracellular compartments, regulated by electrolytes.

• Electrolytes: Minerals such as sodium, potassium, and chloride that carry electrical charges and help maintain fluid balance.

• Selective permeability: Cell membranes control movement of water and electrolytes.

Water Intake and Loss

• Intake: From beverages, food, and metabolic water.

• Loss: Through urine, feces, sweat, and exhaled air.

• Balance equation: $\text{Water Consumed} = \text{Water Lost}$

Dehydration and Overhydration

• Dehydration: Results from insufficient intake or excessive loss (e.g., diarrhea, sweating, diuretics).

• Overhydration (Hyponatremia): Excess water dilutes sodium in blood, causing symptoms like confusion, convulsions, and potentially death.

Regulatory Mechanisms

• Antidiuretic hormone (ADH): Released in response to dehydration, signals kidneys to reabsorb water.

• Thirst mechanism: Triggered by increased blood osmolality.

Major Minerals: Functions, Deficiency Symptoms, and Food Sources

Classification and Bioavailability

• Major minerals (macrominerals): Required in amounts >100 mg/day (e.g., sodium, potassium, calcium, phosphorus, magnesium, chloride, sulfur).

• Bioavailability: Influenced by competition for absorption and presence of binding substances (e.g., phytates, oxalates).

Sodium (Na)

• Main roles: Regulates fluid balance, nerve impulse transmission, muscle contraction, acid-base balance.

• Deficiency symptoms: Rare; can cause hyponatremia (muscle cramps, confusion).

• Food sources: Table salt, processed foods.

• Recommended intake: UL = 2,300 mg/day.

Potassium (K)

• Main roles: Maintains fluid and acid-base balance, supports nerve and muscle function.

• Deficiency symptoms: Hypokalemia (muscle weakness, cramps, irregular heartbeat).

• Food sources: Fruits, vegetables, dairy, legumes.

• Recommended intake: AI = 4,700 mg/day.

Chloride (Cl)

• Main roles: Maintains fluid balance, part of hydrochloric acid in stomach, acid-base balance.

• Deficiency symptoms: Rare.

• Food sources: Table salt, processed foods.

Calcium (Ca)

• Main roles: Bone and teeth structure, muscle contraction, nerve transmission, blood clotting.

• Deficiency symptoms: Osteoporosis, muscle spasms.

• Food sources: Dairy products, leafy greens, fortified foods.

• Recommended intake: 1,000–1,200 mg/day (adults).

Phosphorus (P)

• Main roles: Bone and teeth structure, energy metabolism, component of DNA/RNA.

• Deficiency symptoms: Muscle weakness, bone pain.

• Food sources: Meat, dairy, nuts, legumes.

• Recommended intake: 700 mg/day (adults).

Magnesium (Mg)

• Main roles: Cofactor for enzymes, bone health, muscle and nerve function.

• Deficiency symptoms: Muscle cramps, mental disorders.

• Food sources: Nuts, whole grains, leafy greens.

• Recommended intake: 310–420 mg/day (adults).

Sulfur (S)

• Main roles: Component of amino acids and vitamins, helps protein structure.

• Deficiency symptoms: Rare if protein intake is adequate.

• Food sources: Protein-rich foods.

Trace Minerals: Functions, Deficiency Symptoms, and Food Sources

Classification and Unique Factors

• Trace minerals (microminerals): Required in amounts <20 mg/day (e.g., iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium, molybdenum).

• Key factors: Often act as cofactors for enzymes, have narrow safe intake ranges, and are affected by soil and water composition.

Iron (Fe)

• Main roles: Oxygen transport (hemoglobin, myoglobin), energy metabolism.

• Deficiency symptoms: Anemia, fatigue, impaired cognitive function.

• Food sources: Red meat, legumes, fortified grains.

• Recommended intake: 8 mg/day (men, women >50), 18 mg/day (women 19–50).

Zinc (Zn)

• Main roles: Enzyme function, immune system, wound healing.

• Deficiency symptoms: Impaired growth, immune dysfunction.

• Food sources: Meat, seafood, whole grains.

Iodine (I)

• Main roles: Thyroid hormone synthesis, metabolic regulation.

• Deficiency symptoms: Goiter, hypothyroidism.

• Food sources: Iodized salt, seafood.

Selenium (Se)

• Main roles: Antioxidant defense, thyroid function.

• Deficiency symptoms: Muscle weakness, heart disease.

• Food sources: Seafood, nuts, grains.

Copper (Cu)

• Main roles: Iron metabolism, connective tissue formation.

• Deficiency symptoms: Anemia, bone abnormalities.

• Food sources: Nuts, seeds, whole grains.

Manganese (Mn)

• Main roles: Cofactor for enzymes, bone formation.

• Deficiency symptoms: Rare; impaired growth and metabolism.

• Food sources: Whole grains, nuts, leafy vegetables.

Fluoride (F)

• Main roles: Tooth and bone health, prevents dental caries.

• Deficiency symptoms: Increased risk of cavities.

• Food sources: Fluoridated water, tea, seafood.

Chromium (Cr)

• Main roles: Enhances insulin action, glucose metabolism.

• Deficiency symptoms: Impaired glucose tolerance.

• Food sources: Meat, whole grains, some fruits and vegetables.

Molybdenum (Mo)

• Main roles: Cofactor for enzymes involved in amino acid metabolism.

• Deficiency symptoms: Rare.

• Food sources: Legumes, grains, leafy vegetables.

Contaminant Minerals and Health

Impact on Nutrition and Body Processes

• Contaminant minerals: Lead, mercury, and others can disrupt metabolic processes and displace essential minerals.

• Health effects: Impaired growth, cognitive deficits, organ damage.

• Vulnerable populations: Children with iron deficiency are especially at risk.

Summary Table: Major Minerals at a Glance

Mineral	Main Functions	Deficiency Symptoms	Food Sources
Sodium	Fluid balance, nerve transmission	Hyponatremia	Salt, processed foods
Potassium	Fluid balance, muscle function	Muscle weakness, arrhythmia	Fruits, vegetables
Calcium	Bone/teeth, muscle contraction	Osteoporosis	Dairy, leafy greens
Phosphorus	Bone/teeth, energy metabolism	Muscle weakness	Meat, dairy
Magnesium	Enzyme cofactor, bone health	Muscle cramps	Nuts, grains
Chloride	Fluid balance, stomach acid	Rare	Salt, processed foods
Sulfur	Protein structure	Rare	Protein foods

Additional info:

• Some content was inferred and expanded for academic completeness, including definitions, recommended intakes, and regulatory mechanisms.

• Tables and lists were reconstructed from fragmented notes and slide images.