Exam Notes - BIOL 203

Introduction to Nutrition

  • Nutrition: The study of how organisms acquire and utilize food to maintain life.

    • Involves:

      • Digestion: Breaking down food.

      • Absorption: Nutrients entering the bloodstream.

      • Storage: Keeping nutrients for later use.

      • Metabolism: Chemical processes that convert nutrients to energy.

    • Integrates fields: Biology, chemistry, health sciences.

  • Food: Composed of essential nutrients and non-nutrients (e.g., fiber, phytochemicals) that provide biological activity and health benefits.

Essential vs. Non-essential Nutrients

  • Essential Nutrients: Must be obtained from diet; deficiency can lead to diseases.

    • Six Classes:

      • Carbohydrates

      • Proteins

      • Lipids

      • Vitamins

      • Minerals

      • Water

  • Non-essential Nutrients: Not critical for survival but beneficial for health (e.g., fiber, phytochemicals).

Six Classes of Nutrients

  1. Carbohydrates: Main energy source.

    • Examples: Glucose, starch, sucrose, fiber.

  2. Proteins: Necessary for growth, repair, and maintenance.

    • Building blocks: Amino Acids (20 total, 9 essential).

  3. Lipids: Provide long-term energy, vital for cell membranes.

    • Includes: Triglycerides, phospholipids, cholesterol.

  4. Vitamins: Organic compounds required in small amounts.

    • Types:

      • Water-soluble (B-complex, Vitamin C)

      • Fat-soluble (Vitamins A, D, E, K)

  5. Minerals: Inorganic elements essential for bodily functions.

    • Categories: Major minerals (e.g., calcium, potassium) and trace elements (e.g., iron, iodine).

  6. Water: Key for biochemical reactions and temperature regulation.

Factors Influencing Food Choices

  • Biological: Hunger, appetite, taste preferences.

  • Cultural and Social: Traditions, family influences, social networks.

  • Economic and Practical: Cost, availability, convenience.

  • Psychological: Emotional comfort, habits, health consciousness.

Review Questions

  1. What are the six classes of essential nutrients, and why are they important?

  2. How do non-essential nutrients differ from essential nutrients?

  3. What factors influence food choices, and how can they impact nutrition?

Nutrient Standards and Guidelines

  • Dietary Reference Intakes (DRIs): Quantitative estimates essential for nutrient intake; used for diet planning and assessment.

  • Goals of DRIs:

    1. Prevent Deficiency Diseases: Outline necessary amounts to prevent deficiencies.

    2. Reduce Risks of Chronic Diseases: Promote health and prevent conditions such as cardiovascular disease.

    3. Ensure Safety: Set upper intake levels to prevent toxicity.

Components of DRIs

  1. Estimated Average Requirement (EAR):

    • Meets nutrient needs of 50% of the population.

    • Based on diagnostic measures of adequacy.

  2. Recommended Dietary Allowance (RDA):

    • Meets needs of 98% of the population.

    • The gold standard for nutrient recommendations.

  3. Adequate Intake (AI):

    • Used when RDAs are unavailable.

    • Based on observed intakes in healthy populations.

  4. Tolerable Upper Intake Level (UL):

    • Maximum safe daily intake level.

    • Prevents adverse effects, particularly from supplements.

Additional DRI Components

  1. Estimated Energy Requirement (EER): Calculated based on age, weight, height, and activity level.

  2. Acceptable Macronutrient Distribution Ranges (AMDR):

    • Specifies optimal macronutrient intake ranges as a percentage of total calories:

      • Carbohydrates: 45-65%

      • Fats: 20-35%

      • Proteins: 10-35%.

Application of DRIs

  • Used by:

    • Health professionals for dietary planning.

    • Policy-makers to establish food guidelines.

  • Nutrient recommendations vary by:

    • Gender

    • Life stage (e.g., pregnancy, childhood).

    • Example: Iron recommendations:

      • Women (ages 14-50): 15 mg/day.

      • Men: 8 mg/day.

Major Food Groups in Nutrient Guidelines

  1. Grains: Rich in carbohydrates, fiber, vitamins (e.g., folate, thiamin).

  2. Milk & Alternatives: Provide calcium, protein, and fortified vitamins.

  3. Meat & Alternatives: Good sources of protein, iron, and zinc.

  4. Fruits & Vegetables: High in fiber, vitamins (A, C), and potassium.

Review Questions

  1. What are the goals of the DRIs, and how do they guide nutrition planning?

  2. Explain the differences between EAR, RDA, and AI.

  3. How do macronutrient distribution ranges (AMDR) impact dietary choices?

Basic Chemistry and Organ Systems

  • Atoms, Molecules, and Compounds:

    • Atoms: Basic building blocks of matter.

    • Molecules: Groups of atoms bonded (e.g., water, glucose).

    • Compounds: Molecules with different elements (e.g., carbon dioxide).

Solubility, Enzymes, and pH

  • Solutions: Homogeneous mixtures of solutes (minor) in solvents (major).

    • Aqueous solutions: Water as a solvent (e.g., blood plasma).

  • Enzymes: Proteins that catalyze biochemical reactions; highly specific.

  • pH Scale: Measures hydrogen ion concentration; crucial for enzyme activation and digestion.

Digestive and Circulatory Systems

  • Digestive System:

    • Functions: Digestion, absorption, elimination.

    • Key organs: Stomach, small intestine, pancreas, liver, gallbladder.

    • Villi aid in nutrient absorption.

  • Circulatory System:

    • Transports nutrients, oxygen to cells.

    • Removes waste via blood and lymph.

Review Questions

  1. What roles do enzymes play in digestion?

  2. How does the pH scale relate to nutrient absorption?

Macronutrients

Carbohydrates

  • Types:

    • Simple: Monosaccharides (e.g., glucose, fructose).

    • Complex: Polysaccharides (e.g., starch, glycogen).

  • Digestion and Absorption:

    • Broken down into glucose for energy.

    • Fiber aids digestive health.

  • DRIs:

    • 45-65% of total calorie intake.

Lipids

  • Types:

    • Triglycerides, phospholipids, cholesterol.

    • Essential fatty acids: Omega-3, Omega-6.

  • Functions: Energy storage, insulation, cell membrane integrity.

  • DRIs:

    • 20-35% of total calorie intake.

Proteins

  • Structure:

    • Composed of amino acids (essential and non-essential).

  • Functions:

    • Growth, repair, enzyme, and hormone production.

  • Nitrogen Balance:

    • Positive: Growth, recovery.

    • Negative: Starvation, illness.

  • DRIs:

    • 10-35% of total calorie intake.

Review Questions

  1. What is the difference between simple and complex carbohydrates?

  2. How do lipids contribute to energy storage and cell function?

  3. Explain the importance of nitrogen balance in protein metabolism.

Micronutrients

Vitamins

  • Classification:

    • Water-soluble: B-complex, Vitamin C.

    • B vitamins crucial for energy metabolism.

    • Deficiency symptoms include weakness, inflamed tongue, and sores.

    • Fat-soluble: Vitamins A, D, E, K.

    • Important for metabolic processes and physiological functions.

Specific Vitamins

  • Vitamin B1 (Thiamin): Important for metabolism; rare deficiencies.

  • Niacin (B3): Can be synthesized from tryptophan; must be obtained from diet.

  • Vitamin B6: Coenzyme for over 100 enzymes; high doses can be toxic.

  • Folate: Crucial for DNA metabolism; deficiency may lead to spina bifida.

  • Vitamin B12: Complex absorption process; absence leads to pernicious anemia.

  • Vitamin C: Essential for collagen synthesis; deficiency known as scurvy.

  • Vitamin A: Plays roles in vision and immune function.

  • Vitamin D: Critical for calcium absorption; lack leads to osteoporosis.

  • Vitamin E: Major fat-soluble antioxidant.

  • Vitamin K: Key for blood clotting factors.

Review Questions

  1. What are the key differences between water-soluble and fat-soluble vitamins?

  2. How do major and trace minerals differ in their roles and requirements?

  3. Describe the role of calcium in bone health.

Minerals

Classification

  • Major Minerals: Calcium, potassium, magnesium, sodium.

  • Trace Minerals: Iron, zinc, iodine, copper.

Major Minerals

  • Calcium: Critical for bones and teeth; helps in nerve communication.

  • Phosphorus: Important for bone structure; found in many foods.

  • Magnesium: Influences bone formation; found in leafy greens and legumes.

  • Sodium: Key for fluid balance, nerve function; excess linked to hypertension.

  • Potassium: Associated with lowering blood pressure; found in real foods.

Trace Minerals

  • Iron: Essential for oxygen transport; deficiency leads to anemia.

  • Iodine: Crucial for thyroid hormone synthesis; deficiency results in goiter.

  • Zinc: Important for enzyme function; deficiency affects growth and development.

Review Questions

  1. How do major and trace minerals differ in their roles and requirements?

Water and Energy

Fluid Balance and Osmosis

  • Water Distribution: Intracellular and extracellular compartments.

  • Osmosis: Movement of water across membranes to balance solute concentrations.

Role of Water

  • Transport nutrients and waste; regulate body temperature; facilitate metabolic reactions.

Metabolism and ATP

  • Metabolism: All chemical reactions in the body.

    • Anabolic: Builds molecules (requires energy).

    • Catabolic: Breaks down molecules (releases energy).

  • ATP: Energy currency of the cell, produced via glucose and fat metabolism.

Review Questions

  1. How does osmosis contribute to fluid balance in the body?

  2. Why is water essential for metabolic reactions?

  3. Explain the process of ATP production and its importance for cellular function.

Food Safety

Foodborne Illnesses and Pathogens

  • Sources: Bacteria, viruses, parasites; Common pathogens include Salmonella, E. coli, Listeria.

  • Prevention: Proper cooking, storage, and hygiene practices.

Food Preservation Techniques

  • Methods: Refrigeration, freezing, pasteurization, irradiation; aim to extend shelf life and reduce contamination.

Risk Management and Regulation

  • Agencies: Health Canada, WHO.

  • Guidelines: Set limits for pesticide residues and food additives.

Review Questions

  1. What are common pathogens responsible for foodborne illnesses, and how can they be prevented?

  2. How do preservation techniques help reduce foodborne risks?

  3. What role do regulatory agencies play in ensuring food safety?

Glossary of Key Terms

  • Amino Acids: Building blocks of proteins, some are essential for nutrition.

  • ATP (Adenosine Triphosphate): Energy storage and transfer molecule in cells.

  • Carbohydrates: Organic compounds for energy, including sugars and starches.

  • Cholesterol: A lipid essential for cell membranes and hormone production.

  • Deficiency Disease: Illness caused by a lack of a specific nutrient.

  • DRIs (Dietary Reference Intakes): Nutrient reference values for diet planning.

  • Enzyme: Proteins that catalyze biochemical reactions.

  • Essential Nutrients: Nutrients that must be obtained through diet.

  • Fat-soluble Vitamins: Vitamins (A, D, E, K) stored in body tissues.

  • Fiber: Carbohydrate aiding digestion, not absorbed by the body.

  • Lipids: Compounds including fats, oils, essential for energy and structure.

  • Macronutrients: Nutrients needed in large amounts: carbohydrates, proteins, fats.

  • Micronutrients: Nutrients required in smaller amounts, such as vitamins and minerals.

  • Minerals: Inorganic elements key for bodily functions.

  • Non-essential Nutrients: Beneficial compounds not required in diet.

  • Phytochemicals: Bioactive compounds in plants promoting health.

  • Protein: Essential nutrient for growth, repair, composed of amino acids.

  • Recommended Dietary Allowance (RDA): Nutrient intake level for nearly all healthy individuals.

  • Solubility: The ability of a substance to dissolve in a solvent.

  • Vitamins: Organic compounds necessary for metabolic processes.