Comprehensive Study Guide: Core Concepts in Nutrition (HNSC 1210)

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Science of Nutrition

Key Terms and Concepts in Nutrition

Understanding nutrition begins with mastering its foundational terminology and concepts. These terms are essential for interpreting scientific literature and making informed dietary choices.

Nutrition: The science of how food nourishes the body and influences health.
Nutrients: Substances in food required for energy, growth, and bodily functions.
Essential Nutrients: Nutrients the body cannot synthesize in sufficient amounts and must be obtained from the diet.
Non-Essential Nutrients: Nutrients the body can produce in adequate amounts.
Conditionally Essential Nutrients: Nutrients normally non-essential but required in certain conditions (e.g., illness).
Calorie: A unit of energy; specifically, the amount of heat needed to raise the temperature of 1 gram of water by 1°C.

Six Classes of Nutrients:

Macronutrients: Carbohydrates, proteins, fats (required in large amounts)
Micronutrients: Vitamins, minerals (required in small amounts)
Water: Essential for life, involved in all body processes

Food Energy Values:

Carbohydrates: 4 kcal/g
Protein: 4 kcal/g
Fat: 9 kcal/g
Alcohol: 7 kcal/g (not a nutrient)

Five Characteristics of a Healthy Diet:

Adequacy
Balance
Calorie Control
Moderation
Variety

Factors Influencing Food Choices: Taste, culture, social trends, convenience, cost, emotions, health concerns.

Nutrient Density: The amount of nutrients per calorie in a food. Foods high in nutrient density provide more vitamins and minerals with fewer calories.

Types of Foods: Whole, processed, fortified, enriched, functional foods.

Research Designs in Nutrition:

Case Studies
Epidemiological Studies
Intervention Studies
Laboratory Studies

Valid Nutrition Information vs. Quackery: Valid information is evidence-based, peer-reviewed, and unbiased. Quackery involves unproven or fraudulent claims.

Tools for Healthful Eating

Dietary Assessment and Guidelines

Nutrition science uses various tools and guidelines to assess and improve dietary intake.

Food Intake Analysis Methods: 24-hour recall, food frequency questionnaire, food diary, weighed food record.
Advantages/Disadvantages: Each method varies in accuracy, cost, and participant burden.

Dietary Reference Intakes (DRIs):

RDA (Recommended Dietary Allowance): Average daily intake sufficient for nearly all healthy individuals.
EAR (Estimated Average Requirement): Intake estimated to meet needs of half the population.
AI (Adequate Intake): Used when RDA cannot be determined.
UL (Tolerable Upper Intake Level): Maximum daily intake unlikely to cause harm.
AMDR (Acceptable Macronutrient Distribution Range): Range of intake for energy-yielding nutrients.

Canada’s Food Guide (CFG): Provides recommendations for healthy eating patterns, including the Eat Well Plate, which emphasizes vegetables/fruits, whole grains, and protein foods.

Key Nutrients by Food Group: Vegetables/fruits (vitamins, fiber), grains (carbohydrates, B vitamins), protein foods (protein, iron, B12).

Food Labelling Standards: Nutrition Facts label, ingredient list, nutrient content claims, diet-related health claims.

Phytochemicals and Functional Foods: Non-nutrient compounds in foods that may have health benefits (e.g., flavonoids in berries, probiotics in yogurt).

The Human Body & Digestion

Organization and Function of the Digestive System

The digestive system breaks down food into absorbable units and transports nutrients throughout the body.

Levels of Organization: Cells → Tissues → Organs → Organ Systems
Nutrient Transport: Blood and lymphatic systems distribute nutrients.
Hormones and Nervous System: Regulate hunger, digestion, and absorption (e.g., insulin, glucagon).
"Fight, Flight, Freeze" Reaction: Stress response affecting digestion and metabolism.
Taste Buds: Detect sweet, sour, salty, bitter, umami.

Digestive Process: Mouth → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum

Mechanical Digestion: Chewing, mixing, peristalsis.
Chemical Digestion: Enzymes, acids, bile.

Common Digestive Problems: Heartburn, gas, diarrhea, constipation. Strategies include dietary changes, hydration, and medical consultation.

Alcohol: Recommendations for moderate consumption, serving sizes, digestion, absorption, metabolism, and health effects (both positive and negative).

Carbohydrates

Types, Functions, and Health Implications

Carbohydrates are a primary energy source and come in various forms with distinct health effects.

Types: Simple (sugars), complex (starches, fiber)
Fibre: Soluble (oats, legumes) and insoluble (wheat bran, vegetables); roles in digestion and disease prevention.
Dietary Recommendations: 45–65% of total energy from carbohydrates.
Refined, Enriched, Whole-Grain: Whole-grain contains all parts of the grain; refined is processed; enriched has some nutrients added back.
Roles in Body: Energy, sparing protein, preventing ketosis.
Digestion: Begins in mouth, completed in small intestine.
Lactose Intolerance vs. Milk Allergy: Intolerance is enzyme deficiency; allergy is immune response.
Hyperglycemia vs. Hypoglycemia: High vs. low blood sugar.
Low-Carbohydrate Diets: May lead to nutrient deficiencies and ketosis.
Glycemic Index: Ranks foods by effect on blood glucose; low-GI foods are preferable for blood sugar control.
Diabetes: Types 1, 2, gestational; risk factors, warning signs, management.
Sugar in Health: Excess linked to dental caries, obesity.
Sugar Alcohols vs. Artificial Sweeteners: Sugar alcohols provide fewer calories; artificial sweeteners are non-caloric.

Lipids

Fats: Types, Functions, and Health Effects

Lipids are essential for energy, cell structure, and hormone production, but their types and amounts affect health outcomes.

Functions: Energy storage, insulation, cell membranes, fat-soluble vitamin absorption.
Dietary Recommendations: 20–35% of total energy from fat.
Fatty Acid Classification: Saturated, monounsaturated, polyunsaturated, trans fats.
Saturated vs. Unsaturated vs. Trans Fats: Saturated (solid, animal sources), unsaturated (liquid, plant sources), trans (processed, harmful to health).
Digestion and Absorption: Begins in small intestine with bile and pancreatic enzymes.
Cardiovascular Disease (CVD): High saturated/trans fat intake increases risk; unsaturated fats are protective.
Cholesterol: Dietary cholesterol has less effect on blood cholesterol than previously thought.
Essential Fatty Acids: Omega-3 (e.g., flaxseed, fish) and omega-6 (e.g., vegetable oils); important for inflammation regulation and cell function.
Mercury in Fish: Some fish (e.g., shark, swordfish) are high in mercury; others (e.g., salmon, sardines) are lower.
Fat Replacers: Used in low-fat foods; may affect taste and digestion.
Low-Fat Diets: May lead to inadequate intake of essential fatty acids and fat-soluble vitamins.

Proteins

Structure, Function, and Dietary Considerations

Proteins are vital for tissue structure, enzyme function, and overall health. Their quality and quantity in the diet are important for optimal health.

Synthesis and Structure: Made of amino acids linked by peptide bonds; sequence determines function.
Digestion/Absorption: Begins in stomach, completed in small intestine.
Functions: Enzymes, hormones, immune function, tissue repair.
Protein Utilization: Preventing protein wasting requires adequate energy and essential amino acids.
Dietary Recommendations: 10–35% of total energy from protein.
Protein Quality: Complete (all essential amino acids, e.g., animal sources), incomplete (plant sources); mutual supplementation combines plant proteins.
Nitrogen Balance: Positive (growth), negative (illness), equilibrium (healthy adults).
Protein-Energy Malnutrition: Marasmus and kwashiorkor.
Excess Protein: May stress kidneys, increase calcium loss.
Vegetarian Diets: Health benefits (lower CVD risk), but may lack B12, iron, zinc if poorly planned.

Vitamins

Classification, Functions, and Supplementation

Vitamins are organic compounds required in small amounts for health. They are classified by solubility and have diverse roles in metabolism and disease prevention.

Classes: Fat-soluble (A, D, E, K), water-soluble (B vitamins, C)
Main Functions: Coenzymes, antioxidants, vision, bone health, blood clotting.
Deficiency/Toxicity: Each vitamin has specific symptoms (e.g., scurvy for vitamin C deficiency).
Supplementation: Valid for deficiencies, certain life stages; invalid for "energy boost" claims.
Regulation: Supplements regulated for safety and efficacy in Canada.

Water and Minerals

Fluid Balance and Mineral Nutrition

Water and minerals are essential for physiological processes, including fluid balance, nerve function, and bone health.

Functions of Water: Solvent, temperature regulation, transport, waste removal.
Water Balance: Intake vs. loss; regulated by thirst and kidney function.
DRI for Fluids: Varies by age, sex, activity, climate.
Electrolytes: Sodium, potassium, chloride; regulate fluid movement.
Minerals: Major (calcium, phosphorus, magnesium, sodium, potassium, chloride, sulfur), trace (iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium, molybdenum).
Iron Forms: Heme (animal), non-heme (plant); absorption enhanced by vitamin C.
Osteoporosis: Low bone mass; risk factors include age, gender, genetics, low calcium/vitamin D intake.
Calcium Supplements: Calcium carbonate, citrate, gluconate; differ in absorption and cost.

Alcohol

Metabolism and Health Effects

Alcohol provides energy but is not a nutrient. Its metabolism and effects on health are complex and dose-dependent.

Recommendations: Moderate intake; defined as up to 1 drink/day for women, 2 for men.
Digestion/Absorption: Rapidly absorbed, metabolized mainly in liver.
Health Effects: Moderate intake may reduce CVD risk; excess increases risk of liver disease, cancer, addiction.

Energy Balance: Body Weight, Obesity, & Eating Disorders

Regulation of Body Weight and Related Disorders

Energy balance is the relationship between energy intake and expenditure. Imbalances can lead to underweight, overweight, or obesity, with associated health risks.

Energy Expenditure Components: Basal metabolic rate (BMR), physical activity, thermic effect of food.
BMR Influences: Age, sex, body composition, genetics.
BMI Calculation:
BMI Categories: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), Obese (≥30)
Limitations of BMI: Does not distinguish fat from muscle, not accurate for all populations.
Body Composition Assessment: Skinfolds, bioelectrical impedance, DEXA.
Hunger/Appetite/Satiety: Regulated by hormones (e.g., leptin, ghrelin).
Weight Bias and Stigma: Negative attitudes toward individuals based on weight; can affect health care and psychological well-being.
Eating Disorders: Anorexia nervosa, bulimia nervosa, binge eating disorder; characterized by abnormal eating behaviors and health risks.

Nutrition & Fitness

Physical Activity and Nutritional Needs

Physical activity increases nutrient and energy requirements. Proper nutrition supports performance and recovery.

Benefits of Physical Activity: Improved cardiovascular health, muscle strength, mental health.
Fuel Use: At rest (fat), early activity (glycogen), prolonged activity (fat and carbohydrate).
Dietary Strategies: Carbohydrate loading, adequate protein, hydration.
Protein for Athletes: Supports muscle repair and growth; needs may be higher than for sedentary individuals.
Vitamin/Mineral Supplements: Usually unnecessary if diet is adequate.
Fluid Intake: Essential to prevent dehydration; water is usually sufficient, sports drinks for endurance events.
Performance Enhancers: Some (e.g., caffeine) may be effective; others (e.g., anabolic steroids) are dangerous and banned.

Food Safety & Regulation

Ensuring a Safe Food Supply

Food safety involves preventing foodborne illness through proper handling, preparation, and regulation.

Food Labelling: Regulated to ensure accurate information for consumers.
Foodborne Illness: Caused by bacteria, viruses, parasites, toxins.
Prevention: Clean, separate, cook, chill foods appropriately.

Food Insecurity in the US and the World

Access to Nutritious Food

Food insecurity is the lack of consistent access to enough food for an active, healthy life. It affects health, development, and well-being.

Causes: Poverty, conflict, climate change, economic instability.
Consequences: Malnutrition, stunted growth, increased disease risk.
Solutions: Policy interventions, food assistance programs, sustainable agriculture.

Nutrition: Pregnancy Through Infancy

Special Nutritional Needs

Pregnancy and infancy are critical periods requiring specific nutrients for growth and development.

Key Nutrients: Folate, iron, calcium, DHA, vitamin D.
Breastfeeding: Recommended for first 6 months; provides ideal nutrition and immune protection.
Infant Feeding: Introduction of solids around 6 months; avoid honey, cow's milk before 1 year.

Nutrition: Toddlers to Late Adulthood

Changing Nutritional Needs Across the Lifespan

Nutritional requirements change with age due to growth, development, and aging processes.

Toddlers/Children: Need energy, protein, calcium, iron for growth.
Adolescents: Increased needs for energy, calcium, iron (especially girls).
Adults: Focus on maintaining health, preventing chronic disease.
Older Adults: Risk of nutrient deficiencies due to decreased appetite, absorption; need for vitamin D, B12, calcium.