Minerals & Water – Exam Review Notes

Water

• Essential nutrient; ≈60\% adult body weight
• Key roles: temperature regulation (sweat evaporation), solvent, transport, lubrication
• Mild dehydration begins after 1{-}2\% body‐weight loss; thirst is late signal
• Serious dehydration → heat exhaustion/heat stroke (dizziness, hot-dry skin, confusion)
• Water intoxication → hyponatremia (low serum Na⁺); risk in excessive rapid intake
• Monitor status via urine: pale-yellow & voiding every ≈3 h = well-hydrated
• Fluid sources: all beverages (except alcohol net loss) + high-water foods; caffeine mild diuretic but counts
• Higher needs with: high protein, fiber, sodium, alcohol, heat, heavy sweating

Fluid & Electrolyte Balance

• Electrolytes (Na⁺, K⁺, Cl⁻) govern water movement; “water follows electrolytes”
• Body regulates blood volume/pressure via hormones + kidney action (review)

Sodium (Na)

• Vital functions: fluid balance, nerve impulse, muscle contraction
• Numbers to know:
– Physiological need: 115{-}500\,\text{mg}
– AI (19–50 y): 1500\,\text{mg}
– UL: 2300\,\text{mg}
• US average ≈3400\,\text{mg}; sources: 10 % natural, 15 % added salt, 75 % additives/processed foods
• High-Na foods may not taste salty; read labels/menus
• Excess Na → hypertension, possible osteoporosis risk
• Cutback: limit processed/fast foods, cook at home, use herbs/spices

Calcium (Ca)

• 99\% in bones/teeth, 1\% in body fluids
• Fluid Ca functions: nerve transmission, muscle contraction, clotting, enzyme cofactor, activates calmodulin (↓BP)
• AI (19–50 y): 1000\,\text{mg}; UL: 2500\,\text{mg}
• Typical absorption ≈30\% (↑ to 50{-}60\% in growth/pregnancy; ↓ with age, low stomach acid)
• Food equivalents (~300 mg each): 1 c milk, 1 c yogurt, 1.5\,\text{oz} hard cheese, calcium-fortified OJ/soy milk
• Non-dairy: canned sardines/salmon w/bones, greens (e.g., 2 c cooked collards), tofu w/Ca sulfate
• Factors ↓ absorption: low vit D, some meds, tannins (tea), alcohol; high protein/Na/caffeine ↑ urinary loss
• Supplements: use only to meet AI; ≤500{-}600\,\text{mg} per dose; avoid bone meal/dolomite/oyster shell; monitor vit D; don’t pair with Fe or thyroid meds

Osteoporosis

• Multi-factor, chronic loss of bone density; peak bone mass set by late teens/20s
• Risk factors: low Ca/Vit D, inactivity, smoking, excess alcohol/protein/Na/caffeine, low estrogen, age, genetics
• Prevention: adequate Ca & Vit D lifelong, weight-bearing/strength exercise, avoid smoking & excess alcohol, balanced diet rich in vitamins K,C,A & \omega3

Iron (Fe)

• Key terms: ferric/ferrous, hemoglobin, myoglobin, ferritin, hemosiderin, transferrin, heme vs non-heme, MFP factor
• Roles: O₂ transport/storage, energy metabolism; free Fe = pro-oxidant
• Absorption: heme ≈25\% (constant); non-heme 2{-}20\% (↑ by vit C & MFP factor; ↓ by phytates, polyphenols, Ca, vegetable proteins)
• Vegetarians need 1.8\times RDA (no heme/MFP, more inhibitors)
• Deficiency progression: depleted stores → ↓transport Fe → microcytic hypochromic anemia (fatigue, poor focus)
• Overload (hemochromatosis) damages liver, heart, joints; avoid excess supplements unless prescribed

Potassium (K)

• AI: men 3400\,\text{mg}, women 2600\,\text{mg}; typical foods: fruits, veg, dairy, legumes
• One banana ≈450\,\text{mg} → need variety of whole foods to reach AI
• Adequate K⁺ lowers BP, supports nerve/muscle function
• Processed/fast foods low in K⁺

Quick Numbers Reference

• Water loss triggering thirst: 1{-}2\% body wt
• Hydration urine check: pale yellow; void ≈ every 3 h
• Sodium: AI 1500\,\text{mg} | UL 2300\,\text{mg} | US avg 3400\,\text{mg}
• Calcium: AI 1000\,\text{mg} | UL 2500\,\text{mg} | ~30\% absorption
• Iron: Vegetarian factor \times1.8; heme abs 25\%, non-heme 2{-}20\%
• Potassium: AI 4700\,\text{mg} (combined male/female guideline)