Comprehensive Study Notes: Foundations of Nutrition (Chapters 1–3)

Chapter 1: What Is Nutrition?

Major Factors Influencing Food Choices

Food choices are influenced by a variety of factors that interact to shape dietary habits and preferences.

• Taste and Enjoyment: The sensory appeal of food, including flavor, texture, and aroma, is a primary motivator.

• Cultural and Social Factors: Traditions, family, and social events often dictate what and how we eat.

• Availability and Convenience: Access to certain foods and ease of preparation influence choices.

• Cost: Economic status can limit or expand food options.

• Health and Nutrition Knowledge: Awareness of health impacts can guide choices toward nutrient-dense foods.

• Advertising and Media: Marketing strategies can affect perceptions and consumption patterns.

• Emotional Factors: Stress, boredom, or mood can lead to emotional eating.

• Example: Choosing a salad over fries due to health concerns, or selecting traditional dishes during holidays.

Definitions: Nutrients, Kilocalories, and Metabolism

• Nutrients: Chemical substances in food that provide energy, structural materials, and regulatory agents for growth, maintenance, and repair of tissues.

• Kilocalories (kcal): A unit of energy; the amount of heat required to raise the temperature of 1 kilogram of water by 1°C. Used to quantify energy in food.

• Metabolism: The sum of all chemical reactions in the body that convert food into energy and building blocks for growth and maintenance.

Macronutrients vs. Micronutrients

• Macronutrients: Nutrients required in large amounts: carbohydrates, proteins, and fats. Provide energy and structural components.

• Micronutrients: Nutrients needed in smaller amounts: vitamins and minerals. Essential for regulatory functions and disease prevention.

• Example: Vitamin C (micronutrient) vs. protein (macronutrient).

Organic vs. Inorganic Substances

• Organic: Compounds containing carbon-hydrogen bonds (e.g., carbohydrates, proteins, fats, vitamins).

• Inorganic: Compounds without carbon-hydrogen bonds (e.g., minerals, water).

Enzymes and Phytochemicals

• Enzyme: A protein that acts as a biological catalyst, speeding up chemical reactions in the body without being consumed.

• Phytochemical: Non-nutritive compounds found in plants that may have health benefits (e.g., flavonoids, carotenoids).

Quality of the American Diet

• Many professionals view the current American diet as high in calories, saturated fats, added sugars, and sodium, but low in fruits, vegetables, and whole grains.

Overweight vs. Obese

• Overweight: Having a body weight above a healthy range, typically defined by a Body Mass Index (BMI) of 25–29.9.

• Obese: Excessive body fat accumulation, BMI of 30 or higher.

Current Rates of Obesity in the US

• Obesity rates in the US have risen significantly; recent estimates suggest over 40% of adults are obese.

Poverty, Obesity, and Malnutrition

• Poverty can limit access to healthy foods, leading to diets high in energy but low in nutrients, increasing risk for both obesity and malnutrition.

Healthy People 2030

• A set of health objectives for the nation to achieve over the decade, including goals to improve nutrition and reduce obesity.

Nutrition Experts

• Registered Dietitian Nutritionist (RDN): Credentialed expert with specific education and training.

• Licensed Dietitian Nutritionist (LDN): State-licensed nutrition professional.

• Public Health Nutritionist: May have varying credentials; focuses on community and population health.

Chapter 2: Tools for Healthy Eating

Key Principles of a Healthy Diet

A healthy diet is guided by three main principles:

• Balance: Providing appropriate proportions of nutrients.

• Variety: Including many different foods from all food groups.

• Moderation: Not consuming excess amounts of any food or nutrient.

Dietary Reference Intakes (DRIs)

• DRIs are a set of reference values for nutrient intake to prevent deficiencies and reduce risk of chronic diseases.

• Four Main Types:

  • Recommended Dietary Allowance (RDA): Average daily intake sufficient for most healthy individuals.

  • Adequate Intake (AI): Established when evidence is insufficient for an RDA; a recommended intake based on observed estimates.

  • Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.

  • Estimated Average Requirement (EAR): Intake level estimated to meet needs of half the healthy individuals in a group.

• Additional DRIs:

  • Acceptable Macronutrient Distribution Range (AMDR): Range of intake for energy-yielding nutrients.

  • Estimated Energy Requirement (EER): Average dietary energy intake predicted to maintain energy balance.

Nutrient Density

• Foods high in nutrients but relatively low in calories are considered nutrient-dense (e.g., leafy greens, fruits).

Minimally Processed vs. Ultra-Processed Foods

• Minimally Processed: Foods altered slightly for preservation but retain most of their natural properties (e.g., frozen vegetables).

• Ultra-Processed: Foods with added sugars, fats, and additives, often low in nutritional value (e.g., chips, soda).

Energy Density

• Refers to the amount of energy (calories) per gram of food. High energy density foods provide more calories per gram (e.g., fried foods), while low energy density foods provide fewer (e.g., fruits, vegetables).

Portion Sizes and Control

• Portion sizes have increased over time, contributing to higher calorie intake. Strategies for control include using smaller plates and being mindful of serving sizes.

Timing of Eating and Health

• Meal timing can affect metabolism, energy levels, and risk for chronic diseases. Skipping meals or eating late at night may negatively impact health.

Reading a Food Label

• Key components include serving size, calories, macronutrient content, and % Daily Value (%DV) for nutrients.

Nutrient Content Claims

• Statements about the level of a nutrient in a food (e.g., "low fat," "high fiber"). Regulated by the FDA.

Health Claims vs. Structure/Function Claims

• Health Claim: Describes a relationship between a food and reduced risk of a disease; must be supported by scientific evidence and approved by the FDA.

• Structure/Function Claim: Describes the role of a nutrient or ingredient on normal body structure or function (e.g., "calcium builds strong bones"); not pre-approved by the FDA.

Functional Foods and Zoochemicals

• Functional Food: Foods that provide health benefits beyond basic nutrition (e.g., yogurt with probiotics).

• Zoochemical: Health-promoting compounds found in animal foods (e.g., omega-3 fatty acids in fish).

Chapter 3: The Basics of Digestion

The Digestive (GI) Tract

The gastrointestinal (GI) tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus, responsible for digestion and absorption of nutrients.

• Main organs: mouth, esophagus, stomach, small intestine, large intestine, rectum, anus.

• Accessory organs: salivary glands, liver, gallbladder, pancreas.

Mechanical vs. Chemical Digestion

• Mechanical Digestion: Physical breakdown of food (chewing, mixing, churning).

• Chemical Digestion: Enzymatic breakdown of food into absorbable molecules.

GI Motility: Peristalsis, Segmentation, Pendular Movement

• Peristalsis: Wave-like muscle contractions that move food through the GI tract.

• Segmentation: Rhythmic contractions that mix food and increase contact with digestive juices.

• Pendular Movement: Contractions that move chyme back and forth, enhancing mixing and absorption.

Microbiome

• The collection of microorganisms living in the GI tract; important for digestion, immune function, and overall health.

Prebiotics vs. Probiotics

• Prebiotics: Non-digestible food components (e.g., fiber) that promote growth of beneficial bacteria.

• Probiotics: Live beneficial bacteria found in certain foods and supplements.

Digestion, Absorption, and Elimination

• Digestion: Breakdown of food into smaller components.

• Absorption: Uptake of nutrients into the bloodstream or lymphatic system.

• Elimination: Removal of indigestible substances from the body.

Organs of the Digestive Tract and Their Roles

• Mouth: Begins mechanical and chemical digestion (salivary amylase).

• Esophagus: Transports food to stomach via peristalsis.

• Stomach: Mixes food with gastric juices; protein digestion begins (pepsin, HCl).

• Small Intestine: Main site of digestion and absorption; divided into duodenum, jejunum, ileum.

• Large Intestine: Absorbs water and forms feces.

• Sphincters: Muscular rings that regulate passage of food (e.g., lower esophageal sphincter).

• Accessory Organs: Liver (produces bile), gallbladder (stores bile), pancreas (secretes digestive enzymes and bicarbonate).

Digestive Enzymes and Chemicals: Sites of Production and Actions

Enzyme/Chemical	Site of Production	Primary Action
Amylases	Salivary glands, pancreas	Break down carbohydrates
Pepsin	Stomach (chief cells)	Breaks down proteins
Lipases	Pancreas	Break down fats
Lactase	Small intestine (brush border)	Breaks down lactose
HCl	Stomach (parietal cells)	Denatures proteins, activates pepsin
Bicarbonate	Pancreas	Neutralizes stomach acid in small intestine

Structure of the Intestinal Lining

• Villi: Finger-like projections that increase surface area for absorption.

• Microvilli: Tiny hair-like structures on villi, forming the brush border.

• Circular Folds: Folds in the intestinal wall that further increase surface area.

• Importance: Maximizes nutrient absorption efficiency.

Mechanisms of Nutrient Absorption

• Passive Diffusion: Movement of nutrients from high to low concentration without energy.

• Facilitated Diffusion: Movement via a carrier protein, no energy required.

• Active Transport: Movement against a concentration gradient, requires energy (ATP).

Roles of the Nervous and Endocrine Systems in Digestion

• Nervous System: Regulates GI motility and secretion via the enteric nervous system.

• Endocrine System: Releases hormones (e.g., gastrin, secretin) that control digestive processes.

Lymphatic System and Capillaries in Absorption

• Lymphatic System: Absorbs and transports fat-soluble nutrients.

• Capillaries: Absorb water-soluble nutrients into the bloodstream.

Digestive Disorders

Disorder	Location	Cause/Description
Gingivitis/Periodontal Disease	Mouth/gums	Inflammation due to plaque buildup
GERD	Esophagus	Stomach acid refluxes into esophagus
Gastroenteritis	Stomach/intestines	Inflammation from infection or irritants
Peptic Ulcer	Stomach/duodenum	Erosion of mucosal lining, often by H. pylori
Gallstones	Gallbladder	Solid deposits block bile flow
IBS	Large intestine	Functional disorder causing pain, altered bowel habits
Celiac Disease	Small intestine	Autoimmune reaction to gluten damages villi
Crohn’s Disease	GI tract (often ileum)	Chronic inflammation, can affect any part
Colorectal Cancer	Colon/rectum	Uncontrolled cell growth in colon/rectum

Food Allergy vs. Food Intolerance

• Food Allergy: Immune response to a food protein (e.g., peanut allergy).

• Food Intolerance: Non-immune reaction, often due to enzyme deficiency (e.g., lactose intolerance).

Celiac Disease and Lactose Intolerance

• Celiac Disease: Autoimmune disorder where gluten triggers immune damage to the small intestine lining.

• Lactose Intolerance: Inability to digest lactose due to low levels of lactase enzyme, leading to GI symptoms after dairy consumption.

Additional info: Where details were not explicit in the study guide, standard academic definitions and examples were provided for completeness and clarity.