CH 1. Science of Nutrition

Introduction to Nutrition

Nutrition is the study of nutrients in food, how the body uses them, and the relationship between diet, health, and disease. Understanding the science of nutrition is essential for making informed dietary choices and promoting overall health.

• Essential Nutrient: A nutrient that must be obtained from the diet because the body cannot make it in sufficient quantities to meet its needs.

• Classes of Food: The six main classes are carbohydrates, proteins, fats (lipids), vitamins, minerals, and water. Macronutrients (carbohydrates, proteins, fats) are needed in large amounts, while micronutrients (vitamins, minerals) are needed in smaller amounts.

• Major vs. Trace Minerals: Major minerals are required in amounts greater than 100 mg/day (e.g., calcium, potassium), while trace minerals are needed in smaller amounts (e.g., iron, zinc).

• Simple vs. Complex Carbohydrates: Simple carbohydrates (sugars) consist of one or two sugar units, while complex carbohydrates (starches, fibers) are made of many sugar units.

• Vitamins: Organic compounds required in small amounts. They are classified as water-soluble (e.g., vitamin C, B vitamins) or fat-soluble (e.g., vitamins A, D, E, K). Toxicity can occur if consumed in excess, especially with fat-soluble vitamins.

• Calorie: A unit of energy. 1 kilocalorie (kcal) is the amount of energy needed to raise the temperature of 1 kg of water by 1°C. Calories in food provide energy for bodily functions.

• Alcohol as a Nutrient: Alcohol provides energy (7 kcal/g) but is not considered an essential nutrient because it is not required for normal body functioning.

• Desirable Nutritional Status: A state in which the body has enough nutrients to support normal metabolic functions and health.

• Undernutrition vs. Overnutrition: Undernutrition is a deficiency of energy or nutrients, while overnutrition is an excess intake, which can lead to health problems.

• Nutritional Status Assessment: Methods include dietary surveys, anthropometric measurements, biochemical tests, and clinical assessments.

CH 2. Tools of a Healthy Diet

Dietary Reference Intakes (DRIs) and Dietary Guidelines

Tools such as DRIs and food guides help individuals plan healthy diets and assess nutrient intake.

• Estimated Average Requirements (EAR): The average daily nutrient intake level estimated to meet the requirements of half the healthy individuals in a particular group.

• Recommended Dietary Allowances (RDA): The average daily intake level sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in a group.

• Tolerable Upper Intake Levels (UL): The maximum daily intake unlikely to cause adverse health effects for most people.

• Adequate Intakes (AI): Established when evidence is insufficient to develop an RDA; set at a level assumed to ensure nutritional adequacy.

• Acceptable Macronutrient Distribution Ranges (AMDR): Ranges of intake for energy-yielding nutrients (carbohydrates, proteins, fats) that are associated with reduced risk of chronic disease.

• Daily Values (DV): Reference values used on food labels to help consumers understand the nutrient content of a serving of food in the context of a total daily diet.

• Serving Size: The standardized amount of food used to quantify recommended amounts and nutrition information.

• Energy Density: The amount of energy (kcal) per gram of food. Foods with high energy density provide more calories per gram.

CH 3. The Food Supply

Food Security, Safety, and Processing

The food supply encompasses the production, distribution, and safety of food. Understanding food security and safety is crucial for public health.

• Hunger and Malnutrition: Hunger is the physical sensation of desiring food, while malnutrition refers to deficiencies, excesses, or imbalances in nutrient intake.

• Nutrition Transition: The shift in dietary consumption and energy expenditure that coincides with economic, demographic, and epidemiological changes.

• Food Insecurity: Limited or uncertain access to adequate food. In the U.S., food insecurity is most prevalent among low-income households.

• Food Deserts: Areas with limited access to affordable and nutritious food.

• Organic Foods: Foods produced without synthetic pesticides, fertilizers, or genetically modified organisms (GMOs). For meat, poultry, eggs, and dairy, animals must not be given antibiotics or growth hormones.

• Food Preservation and Processing: Methods include canning, freezing, drying, and pasteurization. These methods help prevent spoilage and extend shelf life.

• Food Additives: Substances added to food to maintain or improve safety, freshness, taste, texture, or appearance. Some are intentional (e.g., preservatives), while others are unintentional (e.g., contaminants).

• Foodborne Illness: Illness caused by consuming contaminated food. Symptoms can include nausea, vomiting, diarrhea, and abdominal pain.

• Food Safety: Practices include proper cooking, storage, and handling to prevent foodborne illness. Danger zone temperatures (40°F–140°F or 4°C–60°C) promote rapid bacterial growth.

CH 4. Human Digestion and Absorption

Digestive System Structure and Function

The digestive system breaks down food into nutrients, which the body absorbs and uses for energy, growth, and cell repair.

• Smallest Functional Unit: The cell is the smallest functional unit in the body.

• Energy Needs: Cells require energy to perform their functions, which is supplied by nutrients from food.

• Tissues and Organs: Tissues are groups of similar cells that perform a specific function. Organs are structures composed of different tissues working together.

• Digestive System Functions: Includes ingestion, digestion, absorption, and elimination. Major organs: mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus. Accessory organs: liver, pancreas, gallbladder.

• Enzymes: Proteins that speed up chemical reactions, including the breakdown of food.

• Chyme: The semi-liquid mass of partly digested food expelled by the stomach into the duodenum.

• Cardiovascular vs. Lymphatic System: The cardiovascular system transports nutrients via blood, while the lymphatic system transports fats and fat-soluble vitamins.

• Electrolytes: Minerals in body fluids that carry an electric charge (e.g., sodium, potassium, chloride). large intestines absorb electrolyes

• Absorption: The process by which nutrients pass from the digestive tract into the blood or lymph.

• Heartburn: A burning sensation in the chest caused by acid reflux from the stomach into the esophagus.

• Ulcer: An open sore in the lining of the stomach or duodenum, often caused by infection with Helicobacter pylori or use of NSAIDs.

• Non-celiac Gluten Sensitivity vs. Celiac Disease: Celiac disease is an autoimmune disorder triggered by gluten, leading to damage in the small intestine. Non-celiac gluten sensitivity causes symptoms similar to celiac disease but without intestinal damage.

Example Table: Types of Dietary Reference Intakes (DRIs)

Key Equations

• Energy Provided by Macronutrients:

• BMI (Body Mass Index):