Water and Minerals: Essential Nutrients for Human Health

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Water is a vital component of the human body, making up 45-75% of an adult's body weight. The percentage varies based on several factors:

Body Composition: Muscle tissue contains about 75% water, while fat tissue contains only 1-20% water.
Age: Elderly individuals have less body water due to decreased muscle mass.
Gender: Males typically have a higher percentage of body water because they have more muscle mass. Females generally have more body fat and less muscle, resulting in a lower percentage of body water.

Universal Solvent: Dissolves and transports nutrients and waste products.
Maintains Body Temperature: Regulates heat through sweating and respiration.
Lubricant: Cushions joints and tissues.
Cushion for Cells: Protects organs and tissues from shock and damage.

Extracellular Fluid: Located outside cells, including blood plasma. Regulated mainly by sodium (Na) and chloride (Cl).
Intracellular Fluid: Located inside cells. Regulated mainly by potassium (K) and phosphate (P).
Most body water is found inside cells (intracellular).

Inorganic: Do not contain carbon; not destroyed by heat or light.
Food Content: Amount in food depends on soil composition.
Functions: Essential for bone and teeth structure, fluid balance, and as cofactors for enzyme activity (not enzymes themselves).
Absorption: Minerals can compete with each other for absorption in the digestive tract.

Distribution: 99% in bones and teeth; 1% in blood and soft tissues.
Association: Phosphorus is usually found with calcium in bones and teeth.
Most Abundant Mineral: Calcium is the most abundant mineral in the body.
Absorption: Enhanced by vitamin D, lactose, and phosphorus.
Functions:
- Provides skeletal strength
- Maintains fluid and electrolyte balance for nerve transmission
- Muscle contraction and prevention of spasms
- Acts as a cofactor in enzyme systems
Bone Mass Density: Peaks at ages 20-30; bone loss accelerates in women after menopause.
Deficiency (Osteoporosis):
- Diagnosed with DXA (dual-energy X-ray absorptiometry)
- Risk factors: inadequate calcium/vitamin D, genetics, lack of weight-bearing exercise, smoking, alcohol abuse, eating disorders
Supplements: Calcium carbonate is most common; maximum absorption per dose is 500 mg. Calcium-fortified orange juice should be shaken well before pouring.
Food Sources:
- 1 cup milk or yogurt ≈ 300 mg calcium
- Bioavailability: milk/yogurt (20-30%), kale (40%), spinach (low due to oxalates and phytates)
- Oxalates and phytates in some foods bind calcium, reducing absorption

Location: Most magnesium is stored in bones and teeth.
Function: Essential for healthy bone metabolism.
Food Sources: Dark green, leafy vegetables.
Supplements: Many adults do not meet recommended intake; doses over 350 mg/day may cause diarrhea.

Location: Primarily found outside cells (extracellular fluid).
Function: Maintains water balance in the body.
Chloride: Usually found with sodium (as NaCl, table salt).
Toxicity: Excess sodium can cause hypertension (high blood pressure) in some individuals.
DASH Diet: Dietary Approach to Stop Hypertension; emphasizes low sodium, high potassium, reduced processed foods, and increased fruit intake.
Other Factors: Weight loss and genetics can influence blood pressure.
Deficiency: Can cause muscle cramps.

Most Abundant Trace Mineral: Iron is primarily found in hemoglobin of red blood cells.
Functions: Transports oxygen to all cells.
Absorption:
- Heme iron (from red meat) is better absorbed than non-heme iron (from plants).
- Absorption increases with greater need for iron and adequate stomach acid (HCl).
Deficiency: Most common nutrient deficiency worldwide. Symptoms include fatigue, increased infections, headaches, pale skin, and intolerance to cold. High-risk groups: pregnant women, women of childbearing age, vegans, children, and those with blood loss.
RDA: Women: 18 mg/day; Men: 8 mg/day.
Toxicity: Hemochromatosis is a genetic disorder causing excessive iron absorption.
Food Sources:
- Best: Red meat (heme iron), e.g., hamburger
- Others: Egg yolk, dark green vegetables, peas, legumes, molasses, dark chicken meat
- Cooking tomato sauces in an iron skillet can increase iron content

Zinc:
- Functions: DNA and RNA synthesis, immune system support
- Sources: Oysters, red meat, whole grains (less in fruits and vegetables)
Selenium:
- Function: Antioxidant
- Sources: Brazil nuts, seafood, grains (content depends on soil concentration)
- Deficiency: May cause heart damage
- Toxicity: Can cause brittle nails and hair
Fluoride:
- Most is found in bones
- Function: Prevents tooth decay, strengthens bones
- Source: Fluoridated water
- Deficiency: Tooth cavities
- Toxicity: May cause joint stiffness and osteoporosis

Mineral	Main Functions	Key Food Sources	Deficiency Symptoms	Toxicity Symptoms
Calcium	Bones/teeth, muscle contraction, nerve function	Milk, yogurt, kale, fortified OJ	Osteoporosis, muscle spasms	Kidney stones (rare)
Magnesium	Bone metabolism, enzyme cofactor	Dark green leafy vegetables	Muscle cramps, irregular heartbeat	Diarrhea (from supplements)
Sodium	Fluid balance, nerve transmission	Table salt, processed foods	Muscle cramps	Hypertension
Iron	Oxygen transport (hemoglobin)	Red meat, legumes, spinach	Anemia, fatigue	Hemochromatosis
Zinc	DNA/RNA synthesis, immunity	Oysters, red meat, whole grains	Impaired immunity, growth retardation	Nausea, vomiting
Selenium	Antioxidant	Brazil nuts, seafood, grains	Heart damage	Brittle nails/hair
Fluoride	Tooth/bone health	Fluoridated water	Tooth decay	Joint stiffness, osteoporosis

Metabolic water is a minor but important source, especially during fasting or in desert environments.
Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body.
Osteoporosis is a condition characterized by decreased bone density and increased fracture risk.
The DASH diet is widely recommended for managing hypertension and overall cardiovascular health.