Nutrition Exam 1 Comprehensive Study Guide

Chapter 1: Introduction to Nutrition and Nutrients

Six Categories of Nutrients

Nutrition science identifies six major categories of nutrients essential for human health. These nutrients are required for energy, growth, and bodily functions.

• Carbohydrates: Primary energy source; found in grains, fruits, and vegetables.

• Proteins: Build and repair tissues; found in meat, legumes, dairy.

• Fats (Lipids): Energy storage, cell structure; found in oils, butter, nuts.

• Vitamins: Organic compounds needed in small amounts for metabolic processes.

• Minerals: Inorganic elements for bone health, fluid balance, etc.

• Water: Vital for hydration, metabolic reactions, and temperature regulation.

Additional info: Organic nutrients contain carbon (carbohydrates, proteins, fats, vitamins); inorganic nutrients do not (minerals, water).

Organic vs. Inorganic Nutrients

• Organic nutrients include carbohydrates, proteins, fats, and vitamins.

• Inorganic nutrients are minerals and water.

Macronutrients vs. Micronutrients

• Macronutrients: Needed in large amounts (carbohydrates, proteins, fats, water).

• Micronutrients: Needed in small amounts (vitamins, minerals).

Caloric Content of Food

Each macronutrient provides a specific amount of energy per gram:

• Carbohydrates: 4 kcal/g

• Proteins: 4 kcal/g

• Fats: 9 kcal/g

Formula:

$\text{Total Calories} = (\text{g Carbohydrate} \times 4) + (\text{g Protein} \times 4) + (\text{g Fat} \times 9)$

Dietary Reference Intakes (DRIs)

• EAR: Estimated Average Requirement

• RDA: Recommended Dietary Allowance

• UL: Tolerable Upper Intake Level

• AI: Adequate Intake

Evaluating Nutrition Information

• Use observational and experimental research to assess food quality.

• Identify credible sources for nutrition information (e.g., peer-reviewed journals, government agencies).

Chapter 2: Healthy Diets and Guidelines

Principles of a Healthy Diet

A healthy diet is characterized by balance, variety, and moderation.

• Balance: Consuming appropriate proportions of nutrients.

• Variety: Eating different foods from all food groups.

• Moderation: Avoiding excess intake of any nutrient.

Undernutrition, Overnutrition, and Malnutrition

• Undernutrition: Insufficient intake of nutrients.

• Overnutrition: Excessive intake of nutrients, often leading to obesity or toxicity.

• Malnutrition: Imbalance of nutrient intake, including both under- and overnutrition.

Energy Density and Nutrient Density

• Energy density: Amount of energy (calories) per gram of food.

• Nutrient density: Amount of nutrients per calorie of food.

• Choose foods high in nutrient density and low in energy density for optimal health.

Dietary Guidelines for Americans

• Follow the principles outlined in the 2020-2025 Dietary Guidelines for Americans.

• Emphasize fruits, vegetables, whole grains, lean proteins, and healthy fats.

Food Labels and Nutrition Facts

• Understand how to read food labels, including serving size, calories, and nutrient content.

• Recognize standards for "Excellent source," "Good source," "Free," and "Low sodium."

Chapter 3: Digestion and Absorption

Overview of Digestion

Digestion is the process by which food is broken down into absorbable components.

• Mouth: Mechanical breakdown and enzymatic action (salivary amylase).

• Stomach: Acidic environment, protein digestion begins.

• Small intestine: Major site of nutrient absorption.

• Large intestine: Water absorption and waste formation.

Functions of Organs and Enzymes

• Gallbladder: Stores and releases bile for fat digestion.

• Liver: Produces bile, processes nutrients.

• Pancreas: Secretes digestive enzymes and bicarbonate.

GI Tract Motility

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

• Segmentation: Mixing movements in the intestine.

Digestive Enzymes

• Carbohydrases: Break down carbohydrates.

• Proteases: Break down proteins.

• Lipases: Break down fats.

Hormonal Regulation

• Gastrin: Stimulates gastric acid secretion.

• Secretin: Stimulates bicarbonate release from pancreas.

• Cholecystokinin (CCK): Stimulates bile and pancreatic enzyme release.

• Ghrelin: Stimulates hunger.

Chapter 4: Carbohydrates

Types and Functions of Carbohydrates

• Monosaccharides: Single sugar units (glucose, fructose, galactose).

• Disaccharides: Two sugar units (sucrose, lactose, maltose).

• Polysaccharides: Many sugar units (starch, glycogen, fiber).

• Function: Provide energy, support digestive health.

Dietary Fiber

• Insoluble fiber: Promotes bowel regularity.

• Soluble fiber: Lowers blood cholesterol, regulates blood glucose.

Carbohydrate Digestion and Absorption

• Begins in the mouth (salivary amylase), continues in the small intestine.

• Enzymes break down polysaccharides to monosaccharides for absorption.

Blood Glucose Regulation

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

• Glucagon: Raises blood glucose by stimulating glycogen breakdown.

Ketosis and Diabetes

• Ketosis: Occurs when carbohydrate intake is very low; body uses fat for energy.

• Type 1 Diabetes: Autoimmune destruction of insulin-producing cells.

• Type 2 Diabetes: Insulin resistance; often associated with obesity.

Alternative Sweeteners

Sweetener	Type	Qualities
Aspartame	Artificial	Low-calorie, not heat stable
Saccharin	Artificial	Zero-calorie, heat stable
Sugar alcohols	Natural/Artificial	Lower calorie, may cause GI upset

Chapter 5: Lipids

Classification of Lipids

• Triglycerides: Main form of fat in food and body.

• Phospholipids: Major component of cell membranes.

• Sterols: Includes cholesterol; important for hormone synthesis.

Hydrophilic vs. Hydrophobic

• Hydrophilic: Water-attracting (e.g., phosphate head of phospholipids).

• Hydrophobic: Water-repelling (e.g., fatty acid tails).

Fatty Acids

• Saturated fatty acids: No double bonds; solid at room temperature.

• Unsaturated fatty acids: One or more double bonds; liquid at room temperature.

• Trans fatty acids: Artificially hydrogenated; increase risk of heart disease.

Lipid Transport in the Body

Lipoprotein	Function
Chylomicrons	Transport dietary fat from intestine
VLDL	Transport triglycerides from liver
LDL	Deliver cholesterol to cells
HDL	Remove excess cholesterol from blood

Dietary Recommendations

• Limit total fat, saturated fat, cholesterol, and trans fat intake.

• Include essential fatty acids (omega-3 and omega-6) in the diet.