Minerals & Water – Exam Review Notes

Essential nutrient: \approx 60\% adult body weight
Key roles: temperature regulation (sweat evaporation), solvent, transport, lubrication
Body fluid compartments: intracellular, extracellular, interstitial
Dehydration
- Thirst begins after 1\text{-}2\% body‐weight loss
- Risks: heat exhaustion, heat stroke (hot, dry skin, confusion → ER)
- Chronic mild dehydration → headaches, fatigue, ↑ risk bladder cancer, kidney stones, asthma
Water intoxication / Hyponatremia
- Excess water dilutes blood sodium → medical emergency
Fluid assessment
- Pale-yellow urine & voiding ~every 3 h = well hydrated
- Any non-alcoholic beverage counts; alcohol = diuretic
Fluid needs vary (climate, sweat rate, diet: ↑protein, ↑fiber, ↑sodium, ↑alcohol)

Functions: fluid balance, nerve impulse, muscle contraction
Numbers
- Physiological need: 115{-}500\text{ mg}
- AI: 1500\text{ mg} (adults ≤50 y)
- UL: 2300\text{ mg}
- US intake: \approx 3400\text{ mg} (can hit 5000{-}8000)
Sources
- Natural in food (~10\% total)
- Added salt (~15\%)
- Food additives (~75\%) → processed, canned, instant, fast foods
Health
- Excess → hypertension; possible osteoporosis risk
- Hyponatremia from losses or water intoxication (not low intake)
Cut-down strategies: limit processed foods, read labels, cook at home, use herbs/spices

Storage: 99\% in bones/teeth (hydroxyapatite), 1\% in fluids
Fluid functions: nerve transmission, muscle contraction, blood clotting, enzyme cofactor, BP regulation
Blood Ca homeostasis: parathyroid hormone ↑Ca, calcitonin ↓Ca; rigor vs tetany from regulatory failure (not diet)
AI (19–50 y): 1000\text{ mg}; UL: 2500\text{ mg}
Absorption
- Avg adult \approx 30\%; ↑ to 50{-}60\% in growth, pregnancy, lactation; ↓ with age (↓ stomach acid)
- ↓ by low stomach acid, some meds, tannins (tea), alcohol; losses ↑ with high protein, Na, caffeine
1-cup milk equivalent (~300\text{ mg} Ca): 1 cup milk/yogurt, 1.5 oz hard cheese, fortified OJ/soy milk, etc.
Non-dairy: canned salmon/sardines w/bones, calcium-rich greens (absorption varies)
Supplements: fill gap only; ≤500{-}600\text{ mg} per dose; avoid bone meal/dolomite/oyster shell; separate from Fe & thyroid meds; need vitamin D

Peak bone mass by ~age 20{-}30; higher peak = lower later fracture risk
Multifactorial; risk ↓ with adequate Ca & Vit D, weight-bearing exercise, no smoking, moderate alcohol, balanced diet

Forms & proteins
- Ferrous \text{Fe}^{2+} / Ferric \text{Fe}^{3+}
- Hemoglobin & myoglobin (O$_2$ transport/storage)
- Ferritin & hemosiderin (storage); Transferrin (transport)
- Heme (animal) vs non-heme (plant & animal)
- MFP factor: peptide in meat / fish / poultry that enhances non-heme absorption
Absorption
- Heme ~25\% (steady); Non-heme 2{-}20\% (modulated)
- ↑ by Vit C, MFP; ↓ by phytates, polyphenols, calcium, vegetable proteins
Vegetarians: need 1.8\times RDA due to non-heme only
Deficiency
- High-risk: women, infants, teens, pregnant
- Progression: ↓ ferritin → ↓ transport iron → microcytic, hypochromic anemia (fatigue from poor O$_2$ delivery)
Excess: iron overload / hemochromatosis → organ damage (pro-oxidant free Fe)

AI: men 3400\text{ mg}, women 2600\text{ mg} (graph off-scale!)
Functions: fluid balance, nerve & muscle function, BP control
Rich in whole foods: fruits, vegetables, dairy, legumes; low in processed/fast foods
Bananas ≠ sole source; variety required to reach \sim 4700\text{ mg} target

Water needs: urine color/frequency; dehydration vs hyponatremia signs
Key Na numbers: 1500 AI, 2300 UL; main source = processed foods
Ca: AI 1000\text{ mg}; absorption %; factors affecting; osteoporosis prevention
Iron: heme vs non-heme, absorption enhancers/inhibitors, high-risk groups, vegetarian adjustment
K: high AI → need multiple whole-food sources daily