24.7 Nutrition and Diet

Food fuels our bodies, providing energy and essential nutrients. Carbs, proteins, and fats each play unique roles in metabolism, while vitamins and minerals support vital functions. Understanding these components helps us make informed dietary choices for optimal health.

Balanced diets combine macronutrients and micronutrients in proper proportions. They emphasize variety, moderation, and adequacy to meet our body's needs. Maintaining energy balance through proper nutrition and metabolism is key to preventing malnutrition and obesity.

Nutrition and Diet

Impact of food on metabolism

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• Carbohydrates
  • Primary energy source for the body
  • Broken down into glucose used for cellular respiration
  • Excess glucose stored as glycogen in liver and muscles (glycogenesis)
  • Examples: bread, pasta, rice, fruits, vegetables
• Proteins
  • Essential for building and repairing tissues (muscles, organs, skin)
  • Broken down into amino acids used for protein synthesis
  • Excess amino acids converted into glucose (gluconeogenesis) or stored as fat
  • Examples: meat, fish, eggs, legumes, dairy products
• Fats
  • Important for cell membrane structure and hormone production (testosterone, estrogen)
  • Provide long-term energy storage (9 kcal/g vs 4 kcal/g for carbs and proteins)
  • Excess dietary fat stored in adipose tissue leading to weight gain
  • Examples: oils, butter, nuts, avocados, fatty fish
• Fiber
  • Aids in digestion and promotes regular bowel movements by adding bulk to stool
  • Helps maintain healthy gut bacteria (prebiotic effect)
  • May help regulate blood sugar levels and reduce risk of heart disease by lowering cholesterol
  • Examples: whole grains, fruits, vegetables, legumes

Components of balanced diets

• Macronutrients
  1. Carbohydrates: 45-65% of total daily calories
  2. Proteins: 10-35% of total daily calories
  3. Fats: 20-35% of total daily calories
• Micronutrients
  • Vitamins and minerals consumed in adequate amounts to prevent deficiencies
  • Examples: vitamin A, vitamin C, calcium, iron
• Variety
  • Consuming wide range of foods from different food groups (fruits, vegetables, grains, proteins, dairy)
  • Ensures balanced intake of essential nutrients and phytochemicals
  • Prevents boredom and promotes adherence to healthy eating habits
• Moderation
  • Limiting intake of added sugars, saturated fats, and sodium to reduce disease risk
  • Controlling portion sizes to maintain healthy weight and prevent overeating
  • Allowing occasional treats and avoiding overly restrictive diets
• Adequacy
  • Consuming enough calories and nutrients to support growth, development, and bodily functions
  • Adjusting intake based on age, sex, height, weight, and physical activity level
  • Ensuring sufficient intake of energy, protein, essential fatty acids, vitamins, and minerals

Essential vitamins and minerals

• Vitamin A
  • Maintains healthy vision (prevents night blindness), skin, and immune function
  • Found in orange and yellow fruits and vegetables (carrots, sweet potatoes), and leafy greens (spinach, kale)
• Vitamin C
  • Supports immune function and collagen synthesis (wound healing, skin health)
  • Found in citrus fruits (oranges, lemons), berries (strawberries, kiwi), and leafy greens (broccoli, brussels sprouts)
• Vitamin D
  • Regulates calcium absorption and bone health (prevents rickets and osteoporosis)
  • Obtained through sun exposure and fortified foods (milk, cereals)
• Vitamin E
  • Acts as antioxidant, protecting cells from oxidative damage and inflammation
  • Found in nuts (almonds, hazelnuts), seeds (sunflower), and vegetable oils (olive, canola)
• Calcium
  • Essential for strong bones and teeth, muscle contraction, and nerve function
  • Found in dairy products (milk, yogurt, cheese), leafy greens (collard greens, bok choy), and fortified foods (soy milk, tofu)
• Iron
  • Necessary for formation of hemoglobin and oxygen transport in red blood cells
  • Found in red meat, poultry, fish (oysters, clams), and leafy greens (spinach, swiss chard)
  • Deficiency leads to anemia and fatigue
• Potassium
  • Regulates fluid balance and supports nerve and muscle function (heart rhythm, blood pressure)
  • Found in fruits (bananas, oranges), vegetables (potatoes, tomatoes), and whole grains (oats, brown rice)

Metabolism and Energy Balance

• Metabolism: The sum of all chemical reactions in the body that convert food into energy
• Calories: Units of energy derived from food, used to fuel bodily functions and physical activity
• Nutrients: Essential compounds obtained from food that support growth, repair, and maintenance of body tissues
• Digestion: The process of breaking down food into smaller molecules that can be absorbed and utilized by the body
• Malnutrition: A condition resulting from inadequate or imbalanced intake of nutrients, affecting growth and health
• Obesity: Excessive accumulation of body fat, often due to prolonged caloric surplus and sedentary lifestyle