Chapter 1: Nutrition – Linking Food and Health

Definition and Evolution of Nutrition

• Nutrition is the science that studies food and how food nourishes our bodies and influences our health.

• It has evolved from focusing on nutrient deficiencies to understanding the role of nutrients in chronic disease prevention and overall wellness.

• Wellness is an overall state of health, including physical, emotional, and spiritual aspects, supported by good nutrition.

Nutrition and Health

• Nutrition supports health by providing essential nutrients for growth, maintenance, and repair of body tissues.

• Poor nutrition is linked to chronic diseases such as heart disease, diabetes, and certain cancers.

Essential Nutrients

• There are six classes of essential nutrients:

  • Carbohydrates

  • Fats (Lipids)

  • Proteins

  • Vitamins

  • Minerals

  • Water

• Macronutrients (carbohydrates, fats, proteins) are needed in large amounts and provide energy.

• Micronutrients (vitamins, minerals) are needed in smaller amounts but are essential for body processes.

Dietary Reference Intakes (DRIs)

• DRIs are a set of nutritional reference values for the United States and Canada.

• Six groups of DRIs include:

  • Estimated Average Requirement (EAR)

  • Recommended Dietary Allowance (RDA)

  • Adequate Intake (AI)

  • Tolerable Upper Intake Level (UL)

  • Acceptable Macronutrient Distribution Range (AMDR)

  • Estimated Energy Requirement (EER)

The Scientific Method in Nutrition

• The scientific method is a systematic approach to research:

  1. Observation

  2. Hypothesis formation

  3. Experimentation

  4. Data collection and analysis

  5. Conclusion

  6. Theory development

• Types of nutrition research:

  • Observational studies (e.g., epidemiological studies, case-control studies)

  • Clinical trials

  • Laboratory-based studies

Evaluating Nutrition Claims

• To discern truth from fallacy, consider:

  • Source credibility (e.g., peer-reviewed journals, government agencies)

  • Scientific evidence and consensus

  • Potential conflicts of interest

• Trustworthy sources include:

  • Registered Dietitians (RDs)

  • Centers for Disease Control and Prevention (CDC)

  • National Institutes of Health (NIH)

  • Professional organizations (e.g., Academy of Nutrition and Dietetics)

Key Terms

• Carbohydrates: Organic compounds that are a major energy source.

• Fats: Provide energy, support cell growth, protect organs.

• Proteins: Build and repair tissues, make enzymes and hormones.

• Vitamins: Organic compounds required for metabolism.

• Minerals: Inorganic elements essential for body functions.

• Water: Vital for all bodily processes.

Additional info:

• Nutrigenomics is an emerging field studying the interaction between nutrition and genes.

Chapter 2: Designing a Healthful Diet

Characteristics of a Healthful Diet

• A healthful diet is:

  • Adequate: Provides enough energy, nutrients, and fiber.

  • Moderate: Not excessive in any nutrient or energy.

  • Balanced: Contains the right proportions of nutrients.

  • Varied: Includes many different foods.

  • Nutrient-dense: High in nutrients relative to energy content.

Influences on Food Choices

• Food choices are influenced by:

  • Sensory data (taste, smell, texture)

  • Sociocultural cues (family, culture, social events)

  • Emotions (comfort, stress eating)

  • Learning (preferences, aversions)

Reading Food Labels

• The Nutrition Facts panel provides information on serving size, calories, and nutrient content.

• Key components include:

  • Serving size and servings per container

  • Calories per serving

  • Macronutrient and micronutrient content

  • Percent Daily Values (%DV)

Dietary Guidelines for Americans (2015-2020)

• Key messages include:

  • Follow a healthy eating pattern across the lifespan

  • Focus on variety, nutrient density, and amount

  • Limit added sugars, saturated fats, and sodium

  • Shift to healthier food and beverage choices

  • Support healthy eating patterns for all

USDA Food Patterns and MyPlate

• The USDA Food Patterns and MyPlate help individuals plan balanced meals.

• Food groups include fruits, vegetables, grains, protein foods, and dairy.

Making Healthful Choices When Eating Out

• Strategies include:

  • Choose grilled over fried foods

  • Request dressings and sauces on the side

  • Watch portion sizes

  • Opt for water or unsweetened beverages

Key Terms

• Appetite: Psychological desire to eat.

• Conditioned taste aversion: Learned avoidance of a food.

• Empty Calories: Foods high in energy but low in nutrients.

• Nutrient density: Ratio of nutrients to energy content.

• Exchange system: Tool for meal planning based on macronutrient content.

Chapter 3: The Human Body – Are We Really What We Eat?

Body Structure and Organization

• Levels of organization:

  • Cell → Tissue → Organ → System → Organism

• Cells are the basic unit of life; organelles perform specialized functions within cells.

Mechanisms of Hunger

• Hunger is regulated by the hypothalamus in the brain.

• Hormones (e.g., ghrelin, leptin) and the enteric nervous system (ENS) play roles in hunger and satiety.

Gastrointestinal (GI) Tract

• Major organs in order:

  • Mouth → Pharynx → Esophagus → Stomach → Small intestine → Large intestine → Rectum

• Accessory organs: Salivary glands, liver, gallbladder, pancreas

• Functions include digestion, absorption, and elimination.

Specialized Features of the GI Tract

• Peristalsis: Muscular contractions that move food.

• Bile: Produced by the liver, stored in the gallbladder, emulsifies fats.

• Enzymes: Aid in chemical digestion (e.g., amylase, protease, lipase).

• Brush border: Microvilli in the small intestine increase surface area for absorption.

Common Digestive Disorders

• Gastroesophageal reflux disease (GERD): Acid reflux causing heartburn.

• Peptic ulcers: Sores in the stomach or duodenum lining.

• Celiac disease: Immune reaction to gluten damaging the small intestine.

• Lactose intolerance: Inability to digest lactose due to low lactase enzyme.

• Irritable bowel syndrome (IBS): Chronic GI symptoms without identifiable cause.

• Constipation and diarrhea: Issues with elimination.

Key Terms

• Absorption: Uptake of nutrients by the GI tract.

• Digestion: Breakdown of food into absorbable units.

• Elimination: Removal of undigested food and waste.

• Food allergy vs. food intolerance: Immune response vs. digestive issue.

Chapter 4: Carbohydrates – Plant-Derived Energy Nutrients

Types of Carbohydrates

• Simple carbohydrates: Monosaccharides (glucose, fructose, galactose) and disaccharides (sucrose, lactose, maltose).

• Complex carbohydrates: Polysaccharides (starch, glycogen, fiber).

• Dietary fiber: Non-digestible carbohydrates; includes soluble and insoluble fibers.

Functions of Carbohydrates

• Primary energy source for the body, especially the brain and red blood cells.

• Spares protein from being used as energy.

• Prevents ketosis by providing adequate glucose.

Digestion, Absorption, and Transport

• Digestion begins in the mouth with salivary amylase.

• Continues in the small intestine with pancreatic amylase and brush border enzymes (maltase, sucrase, lactase).

• Monosaccharides are absorbed into the bloodstream and transported to the liver.

Regulation of Blood Glucose

• Hormones involved:

  • Insulin: Lowers blood glucose by promoting uptake into cells.

  • Glucagon: Raises blood glucose by stimulating glycogen breakdown and gluconeogenesis.

• Normal fasting blood glucose: 70–99 mg/dL.

Dietary Recommendations

• DRI for carbohydrates: 45–65% of total energy intake.

• Limit added sugars to less than 10% of calories.

• AI for fiber: 25 g/day for women, 38 g/day for men.

• Good sources of fiber: whole grains, fruits, vegetables, legumes.

Alternative Sweeteners

• Nutritive sweeteners: Provide energy (e.g., sucrose, high-fructose corn syrup).

• Nonnutritive sweeteners: Little or no energy (e.g., aspartame, sucralose); have Acceptable Daily Intake (ADI) levels.

Carbohydrates and Health

• Excess added sugars are linked to obesity, type 2 diabetes, and dental caries.

• Fiber intake is associated with reduced risk of heart disease, diabetes, and certain cancers.

Key Terms

• Glycemic index: Ranks foods by their effect on blood glucose.

• Glycemic load: Considers both quality and quantity of carbohydrate.

• Diabetes: Chronic disease characterized by impaired glucose regulation (type 1, type 2, prediabetes).

Example Table: Types of Carbohydrates

Key Equations

• Photosynthesis (formation of glucose in plants):

• Gluconeogenesis (formation of glucose from non-carbohydrate sources):