1.5 Water and other fluids

WATER AND FLUIDS

STAGE 2 NUTRITION

Learning Intentions

• Water and Other Fluids:

  • Identify sources of water and other fluids in the diet and explain their function in maintaining good health.

  • Describe the benefits derived from consuming fluids other than water.

  • Explain factors affecting hydration levels:

    • Fluid intake

    • Salt intake

    • Exercise

    • Illness

    • Caffeine

    • Alcohol

  • Describe the effects of dehydration.

Importance of Water (H2O)

• Nutritional Role:

  • Water does not provide nutrients but is essential for survival.

  • Human body is composed of 50%-80% water, depending on weight and sex.

  • Survival time without food: days; without water: only a few days.

• Water Loss:

  • Daily activities lead to water loss; continuous replenishment is crucial.

  • Males typically require more water than females.

Daily Water Intake Recommendations

• Adequate Intake (AI):

  • Males: 3.4 Liters, Females: 2.8 Liters (includes ~20% from food).

• Variability Factors:

  • Seasonal conditions (heat, humidity), Activity level, Body size, Diet (veggies/fruits, caffeine, alcohol, and salt), Illness.

• Sodium's Impact:

  • Increases water retention leading to elevated blood volume and pressure.

Functions of Water in the Body

• Temperature Regulation:

  • Regulates body temperature through sweating and respiration.

• Nutrient Transport:

  • Transports nutrients, oxygen, and hormones to cells.

• Waste Removal:

  • Eliminates waste products through urine and sweat.

• Digestion:

  • Assists in food digestion and nutrient absorption in the gastrointestinal tract.

• Joint Lubrication:

  • Lubricates and cushions joints, reducing friction.

• Protection:

  • Cushions vital organs and tissues from injury.

• Cell Structure:

  • Maintains cell shape and fluid balance (intracellular and extracellular).

• Biochemical Reactions:

  • Acts as a solvent and reactant in metabolism.

• Electrolyte Balance:

  • Supports nerve signaling and muscle function.

• Blood Volume Maintenance:

  • Critical for circulation and nutrient delivery.

Sources of Water

• Drinks:

  • All beverages (excluding alcohol/seawater); pure water is preferred due to zero calories.

• Food:

  • Dry biscuits (~5% water), fruits/vegetables (~90% water), ~0.75L/day from an average diet.

• Metabolic Water:

  • Created during digestion; ~0.25L usable by the body.

Water Content in Foods

• High Water Content Foods:

  • 99-90%: Milk, watermelon, strawberries, lettuce, cabbage, celery, spinach.

  • 89-80%: Fruit juices, yogurt, apples, grapes, oranges.

  • 79-70%: Bananas, avocado, corn.

  • 69-60%: Pasta, legumes, salmon.

  • 59-50%: Hot dogs, feta cheese.

• Moderate-to-Low Water Content Foods:

  • 49-40% to 0%: Various baked goods, snacks, and oils.

Water Deficiency and Dehydration

• Causes of Water Loss:

  • Normal bodily functions: blood, sweat, urine, feces, vomiting, tears.

• Dehydration Risk:

  • Common post-exercise, in hot weather, or due to illness (diarrhea, vomiting).

  • Mild Symptoms: Fatigue, headaches.

  • Severe Symptoms: Kidney damage, potentially fatal.

Assessing Hydration Levels

• Urine Color Chart:

  • Urine color indicates hydration status; darker urine typically suggests dehydration.

• Dehydration Pinch Test:

  • Pinch skin; if slow to return to normal, dehydration may be present.

Consequences of Dehydration

• Cognitive Effects:

  • Poor visual vigilance, increased tension, anxiety, fatigue, impaired memory.

• Physical Symptoms:

  • Dry skin, increased heart rate, decreased sweating, headaches.

• Kidney Health:

  • Higher water intake may protect against kidney issues and stone formation.

• Weight Management:

  • Consuming water over high-calorie drinks aids weight loss; increased energy expenditure from water intake confirmed.

Alcohol and Caffeine

• Diuretic Effects:

  • Both increase urine production, risking dehydration.

• Recommendations for Consumption:

  • Under 18: No alcohol.

  • Healthy adults: Maximum 4 standard drinks per day; 10 per week.

  • Pregnant women: Avoid alcohol.

  • Breastfeeding: Avoid for baby’s safety.