Chapter 8 — Water & Minerals

Water

• Most indispensable nutrient; survival without water: only a few days
• Body composition: 60\% of adult body weight
  • Present in arteries, veins, capillaries, cells, tissues, organs

Functions of Water

• Transport vehicle for nutrients & wastes
• Universal solvent
• Body’s cleansing agent
• Lubricant/cushion for joints
• Protects sensitive tissues (e.g., eyes, spinal cord, fetus)
• Maintains body temperature via sweat evaporation

Water Balance

• Daily losses require equal intake (Fig. 8{-}2)
• Thirst mechanism:
  • Blood too concentrated / volume or pressure too low → hypothalamus signals brain → thirst
  • Pituitary releases hormone → kidneys re-absorb water → decreased urine
  • Thirst sensation lags behind actual need

Dehydration (Table 8{-}1)

• Progressive symptoms: thirst → weakness → exhaustion → delirium → death

Water Intake Recommendations

• DRI provides \approx 80\% of total need from fluids
  • Males: 13 cups beverages
  • Females: 9 cups beverages
• Remaining \approx 20\% from foods + metabolic water (from nutrient oxidation)
• Requirements vary with diet, activity, temperature, humidity, altitude, etc. (Table 8{-}2)

Water Content of Foods (Table 8{-}3)

• 100\%: plain water, diet soft drinks, plain tea, unflavoured seltzer
• 99{-}95\%: sugar-free gelatin, clear broth, celery, cucumber, lettuce, Chinese cabbage, summer squash, decaf black coffee
• 90{-}94\%: sports drinks (e.g., Gatorade), grapefruit, strawberries, broccoli, tomatoes
• 80{-}89\%: soft drinks, milk, yogurt, egg white, fruit juice, low-fat cottage cheese, carrot, fresh apple

Types of Water

• Hard water: high \text{Ca} & \text{Mg}
  • May protect against hypertension & heart disease
• Soft water: high \text{Na}
  • May aggravate hypertension/heart disease; dissolves contaminants more easily

Water Safety

• Universal solvent ⇒ potential contaminants: bacteria, viruses, heavy metals, organic chemicals, industrial spills
• Public systems: disinfect (often chlorine) & test quality
• Health Canada 🇨🇦 issues boil-water advisories when microbial/cloudiness hazards arise

Household & Commercial Options

• Tap water: must meet federal/provincial standards
• Home filters: remove lead, chlorine, some chemicals; do NOT remove chlorine-resistant microbes
• Bottled water: federally regulated, variable mineral profile

Water Quality & Access — Indigenous Communities

• Long-term advisories (>1 yr) widespread
• Example: Neskantaga First Nation, Ontario — boil-water advisory since Feb 1995
• Federal pledges to end advisories (Fig. 8{-}3); status questioned

Body Fluids & Minerals

• Majority of body water = intracellular; remainder extracellular & in blood
• Major minerals form salts ⇒ water follows salt
• Cells actively pump salts to avoid collapse or swelling

Electrolytes

• Compounds partially dissociate in water → ions
• Unequal ion concentrations across permeable membrane → water shifts toward higher concentration

Fluid & Electrolyte Balance

• Requires energy-dependent transport proteins (Na⁺ pumped out, K⁺ pumped in; Fig. 8{-}4 & 8{-}5)
• Imbalances (vomiting, diarrhea, eating disorders) can be medical emergencies

Overview of Minerals

Major Minerals (≥100 mg/d requirement)

• Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), Sodium (Na), Chloride (Cl), Magnesium (Mg)

Trace Minerals (<100 mg/d)

• Iodine (I), Iron (Fe), Zinc (Zn), Copper (Cu), Selenium (Se), Fluoride (F), Chromium (Cr), Manganese (Mn), Molybdenum (Mo)

General Functions of Minerals

• Electrolytes (Na, K, Cl): water & acid-base balance; muscle & nerve function
• Body structure (Ca, P, Mg, F, Zn): bones & teeth
• DNA/RNA/ATP/phospholipid structure: P
• Protein structure: Fe (hemoglobin), I (thyroxine), Zn, Ca, Se
• Cell signaling: Ca^{2+}, Na^{+}
• Antioxidant enzymes: Zn, Cu, Mn, Se, S

Major Minerals Detail

Calcium

• 1\% in body fluids, 99\% in bones/teeth (Fig. 8{-}6,8{-}7)
• Fluid functions: ion transport, nerve transmission, blood pressure, heartbeat contraction, blood clotting, secretion, enzyme activation
• Bone: structural matrix & Ca reservoir
• DRI: 1,000 mg/d; UL: 2,500 mg/d (higher in youth)
• Sources (Snapshot 8{-}1): milk/yogurt/cheese, sardines & salmon (bones), Ca-set tofu, leafy greens (absorption varies; Fig. 8{-}12)
• Absorption: children 60\%, pregnancy 50\%, adults 25\%; ↑ when blood Ca low
• Deficiency → osteoporosis; importance of achieving peak bone mass by late 20’s/early 30’s (Fig. C8{-}3; example Adults A vs B)

Phosphorus

• Functions: acid-base buffer, DNA/RNA, energy metabolism, activates enzymes & vitamins, phospholipids, protein structure
• DRI 700 mg/d; UL 4,000 mg/d
• Stored mainly in bone & teeth
• Deficiency rare (weakness, bone pain); excess → soft-tissue calcification (kidney)
• Sources: dairy, canned fish, lean beef (Snapshot 8{-}2)

Magnesium

• >50\% in bone; remainder in soft tissues & fluids
• Roles: enzyme cofactor, energy release, metabolizes K/Ca/vit D, protein synthesis, muscle relaxation vs Ca contraction, tooth resistance to decay
• DRI: males 400 mg/d, females 310 mg/d; UL 350 mg from supplements
• Deficiency: weakness, confusion → muscle convulsions, hallucinations, swallowing difficulty, growth failure
• Toxicity (non-food sources): diarrhea, dehydration, pH shift
• Sources (Snapshot 8{-}3): legumes, cooked spinach, bran cereals, oysters, yogurt; processing removes Mg

Sodium

• Principal extracellular cation; maintains fluid volume & acid-base, enables muscle & nerve function
• 1 g salt ⇒ 400 mg Na (table salt 40\% Na by weight)
• DRI 1,500 mg/d; UL 2,300 mg/d (≈5.6 g salt)
• Canadians 6,000{-}8,500 mg/d (ages 19{-}30); males > females
• Major sources (Table 8{-}7 & Fig. 8{-}9): processed meats, breads, pizza, poultry dishes, pasta, processed/non-legume dishes, processed foods
• Excess → hypertension, ↑Ca excretion, heart/kidney stress, stomach cancer risk (Asian descent)
• Reduction strategies: limit saltshaker (1 tsp ≈2,400 mg Na), choose unprocessed foods (higher K), read labels; front-of-package “high in sodium” ≥15\% DV (by 2026)

Potassium

• Main intracellular cation; maintains fluid/elec balance, cell integrity, heartbeat
• Sudden large loss (fasting, diarrhea, eating disorders, kwashiorkor) → heart failure
• DRI 4,700 mg/d; typical Canadians meet ≈50\% (low produce intake)
• Deficiency: muscle weakness, paralysis, confusion, heart failure; worsens hypertension, impairs glucose tolerance, ↑acidity, accelerates bone Ca loss, ↑kidney stones
• Toxicity: weakness, vomiting; large oral dose may stop heart (infants esp. vulnerable); stomach usually triggers emesis
• Best sources (Snapshot 8{-}4): fresh fruits, vegetables, legumes, whole foods

Chloride

• Works with Na for fluid & acid-base balance; part of HCl in stomach → protein digestion
• Sources: salt (added & natural)
• DRI 2,300 mg/d; UL 3,600 mg/d; deficiency rare

Sulfate

• Needed to synthesize sulfur-containing compounds (sulfur AAs) for skin, hair, nails
• No DRI; deficiency not observed; excess (water) → diarrhea, colon damage

Trace Minerals Detail

Iodine

• Constituent of thyroxine → regulates basal metabolic rate
• DRI 150 µg/d; UL 1,100 µg/d
• Sources: seafood, soil-dependent crops, iodized salt, milk (sanitizing iodine), bakery products
• Deficiency: goitre, sluggishness, weight gain, cretinism in infants; major global cause of mental impairment
• Toxicity: enlarged thyroid, poisoning

Iron

• Part of hemoglobin & myoglobin → oxygen transport; energy metabolism
• DRI: males 8 mg/d; females 18 mg/d; pregnancy 27 mg/d; UL 45 mg/d; vegetarians require 1.8\times DRI
• Deficiency → iron-deficiency anemia (microcytic, hypochromic RBC; Fig. 8{-}10)
  • Physical: weakness, headaches, pallor, cold intolerance, pica
  • Mental: attention, learning, memory issues (Table 8{-}10)
• Causes: malnutrition, parasites, chronic blood loss, shed cells/nails/hair; high-risk groups: >6 mo infants, children, teens, menstruating & pregnant individuals
• Toxicity: limited absorption protects; hemochromatosis genetic overload → fatigue, depression, abdominal pain, tissue damage, liver failure; acute poisoning leading accidental death in <6 yr olds
• Sources (Snapshot 8{-}5): meat, eggs, legumes, fortified cereal/bread/pasta, soy, broccoli, peas, dried fruits; cast-iron cookware non-food source
• Absorption: heme \approx23\%; non-heme 2{-}20\%
  • Enhanced by \text{vit C}, MFP factor
  • Inhibited by tannins (tea/coffee), Ca & P (milk), phytates & fibre (whole grains)

Zinc

• Works with every protein; enzyme cofactor for DNA/RNA, heme, pancreatic enzymes, macronutrient metabolism, vit A release
• Regulates gene expression, behaviour, learning; immune, wound healing, sperm, taste, fetal development, visual pigments
• DRI: males 11 mg/d; females 8 mg/d
• Sources (Snapshot 8{-}6): meats, shellfish, poultry, dairy; plant sources (legumes, whole grains) less bioavailable (phytates)
• Deficiency: diarrhea, impaired immunity, growth retardation
• Toxicity: appetite loss, impaired immunity, death; blocks Cu & Fe absorption; pancreatic excretion helps regulate

Selenium

• Antioxidant: part of enzymes preventing free-radical formation & activating thyroid hormone
• Deficiency (rare) → higher risk prostate cancer, certain heart diseases
• Sources: meats, shellfish, veg & grains from Se-rich soil

Fluoride

• Not essential for life but prevents dental caries; strengthens developing & erupted teeth
• Primary source: fluoridated tap water (just <40\% Canadians have access)
• Excess → fluorosis (mottled enamel) via water, toothpaste, supplements

Chromium

• Helps regulate blood glucose; deficiency mimics diabetes (↑blood glucose, impaired insulin/glucagon response)
• Supplements ineffective for muscle building/fat loss/cholesterol lowering
• Safe to 200 µg; recommended intake 50 µg/d; 90\% of adults consume less
• Sources: unrefined foods, whole grains

Copper

• Needed for hemoglobin & collagen synthesis; enzyme oxygen-handling; energy release
• Deficiency: impaired growth/metabolism (infants), immunity & arterial function (adults)
• UL 10,000 µg/d
• Sources: organ meats, seafood, nuts, seeds

Controversy 8 – Osteoporosis

• Definition: reduced bone mass → porous, fragile bones; fractures later in life but begins silently earlier

Bone Types

• Cortical: dense outer shell & shaft
• Trabecular: lattice interior, Ca bank
• Bone loss timeline: trabecular mid-20s; cortical ≈40 yr
• Consequences: vertebral compression & dowager’s hump, height loss, wrist/hip fractures, tooth loss

Diagnosis & Treatment

• Assessment: DEXA X-ray or ultrasound; adults with family history screened ≥50 yr
• Therapies: estrogen (↑ heart & breast cancer risk), meds e.g., Fosamax

Prevention

• Diet: adequate Ca, vit D, other nutrients
• Activity: weight-bearing exercise essential
• Epidemiology (Osteoporosis Society of Canada):
  • >2.3 million Canadians ≥40 y with diagnosis
  • 80\% female
  • >80\% fractures ≥50 y due to osteoporosis
  • Economic burden: \$4.6 billion

Calcium Supplements

• Forms:
  1. Calcium compounds (good absorption): carbonate, citrate, gluconate, hydroxylate, malate, lactate, phosphate, AA chelates
  2. Mixed with other compounds (poor): carbonate + Mg/aluminum (antacids), carbonate + vit D
  3. Powdered Ca-rich materials (poor): bone meal, oyster shell, dolomite
• Elemental Ca varies: carbonate 40\%, glutamate 9\%
• Absorbability test: dissolve in vinegar ≤30 min
• Dosing: ≤500 mg elemental each time; take 2{-}3 smaller doses/day

Case Studies

Case 1

• 50-y male, persistent diarrhea & nausea, dehydrated, flushed, heavy antacid (Mg-containing) use
• Concern: magnesium toxicity (from antacids) → diarrhea, pH imbalance
• Further risks: dehydration, electrolyte imbalance; monitor kidney function

Case 2

• 23-y female lacto-vegetarian, fatigue, weakness, irritability, cold sensitivity, pale skin
• Concern mineral: iron
• Likely condition: iron-deficiency anemia
• Dietary advice:
  • Increase iron-rich foods: legumes, eggs, dark greens, iron-fortified cereals, consider cast-iron cookware
  • Combine with vitamin C sources (citrus, peppers)
  • If ok with supplements, low-dose iron under guidance

Lucky Iron Fish Project

• 2008, Cambodia, Carleton University
• Cast-iron fish ingot symbolizes luck
• Added to boiling water/soup to increase iron content, addressing deficiency