Nutrition Class Notes PDF

Part 1: Introduction to Nutrition Overview of Nutrition ​ Definition: Nutrition is the biochemical and physiological process by which organisms use food to sustain life. It provides energy, nutrients, and chemical structures essential for health while affecting overall well-be...

Part 1: Introduction to Nutrition Overview of Nutrition ​ Definition: Nutrition is the biochemical and physiological process by which organisms use food to sustain life. It provides energy, nutrients, and chemical structures essential for health while affecting overall well-being. ​ Integrative Science: Combines disciplines like physiology, biochemistry, and anatomy to understand the impact of food on the human body. The 3 Levels of Nutrition 1.​ Nutrients: ○​ The six essential types are carbohydrates, fats, proteins, vitamins, minerals, and water. ○​ Alcohol is a non-nutrient source of energy. ○​ Energy-Yielding Nutrients: ​ Carbohydrates: 4 calories/gram. ​ Fats: 9 calories/gram (most energy-dense). ​ Proteins: 4 calories/gram. ○​ Non-Energy-Yielding Nutrients: Vitamins, minerals, and water. ○​ Classification: ​ Macronutrients: Needed in large amounts (carbohydrates, fats, proteins, water). ​ Micronutrients: Needed in small amounts (vitamins, minerals). 2.​ Foods and Food Groups: ○​ Build on nutrients to understand the dietary sources of health-promoting compounds. ○​ Healthy eating involves consuming the right amounts from each food group. 3.​ Diet Patterns: ○​ Evaluate entire eating habits to determine their impact on health. ○​ Examples include the Mediterranean, ketogenic, and DASH diets. Evaluating Nutrition ​ Food Assessment: Based on nutrient composition (e.g., energy content, sodium levels, and protein amounts). ​ Diet Assessment: Requires knowledge of nutrients and food groups to evaluate overall patterns. Why Nutrition is Important 1.​ Universal Exposure: ○​ Unlike avoidable exposures (e.g., smoking), nutrition affects everyone since all humans must eat to survive. ○​ Nutrition can either lower or promote health risks depending on dietary habits. 2.​ Health Impact: ○​ Nutrition influences chronic disease risk (e.g., heart disease, cancer, diabetes, and obesity). ○​ Chronic diseases: ​ Long-lasting conditions that develop over time and cannot typically be cured.  ​ Leading causes of death in the U.S.: ​ Heart disease (~700,000 deaths/year) and cancer (~600,000 deaths/year) are directly linked to nutrition. ​ 9 out of 10 leading causes of death are connected to nutrition either directly or indirectly. 3.​ Room for Improvement: ○​ Over 40% of U.S. adults have obesity, with 75% categorized as overweight or obese. ○​ Most adults fail to meet dietary recommendations: ​ Only 10% consume enough fruits and vegetables. ​ Overconsumption of processed foods, sugar, sodium, and unhealthy fats is common. ○​ Deficiency in protective nutrients like fiber, calcium, and unsaturated fats increases disease risk. Key Takeaways from Part 1 ​ Nutrients: Understanding their functions is foundational to evaluating foods and diets. ​ Nutrition’s Importance: Everyone is exposed to nutrition, and it significantly affects health outcomes. ​ Goal: Equip students to evaluate foods and diet patterns based on nutrient composition. Part 2: Nutrition’s Broader Impact and Nutrition Science Importance of Nutrition 1.​ Universal Exposure: ○​ Nutrition is an unavoidable factor in life and directly affects health. ○​ Healthy nutrition reduces the risk of chronic diseases, while unhealthy diets increase it. 2.​ Connection to Chronic Diseases: ○​ Chronic diseases are long-term conditions that develop silently and worsen over time. ○​ Directly Related to Nutrition: ​ Heart disease, cancer, stroke, diabetes, kidney disease, and liver disease. ○​ Indirectly Related (via obesity): ​ Alzheimer’s, COPD, and others. ○​ 9 of the top 10 causes of death in the U.S. are tied to nutrition. 3.​ Room for Improvement: ○​ The U.S. diet is marked by: ​ Overconsumption of unhealthy foods and nutrients (e.g., sugar, saturated fats). ​ Underconsumption of essential foods (e.g., fruits, vegetables) and nutrients (e.g., fiber, calcium). Scientific Approach to Nutrition 1.​ The Scientific Method: ○​ Empirical method used to acquire reliable, observation-based knowledge. ○​ Steps: Forming hypotheses, conducting experiments, analyzing data, and drawing conclusions. 2.​ Types of Research: ○​ Basic Research: Studies on cells or animals (e.g., mice, rats) to test hypotheses. ○​ Clinical Research: Human-based studies, including trials and observational research. ○​ Community-Based Research: Testing interventions in real-world settings. 3.​ Why Nutrition Science is Crucial: ○​ Intense public interest in nutrition but limited understanding of physiology. ○​ Misinformation is widespread due to commercial interests and biased sources. ○​ Nutrition science provides reliable data to counter myths and guide decisions. Goals of the Course 1.​ Develop a foundational understanding of nutrition and physiology. 2.​ Learn to critically evaluate nutrition information and research. 3.​ Use evidence-based knowledge to make informed dietary decisions. Main Takeaways from Part 2 ​ Nutrition Matters: ○​ Universal exposure, strong health connections, and significant room for improvement highlight its importance. ​ Nutrition Science:  ○​ Relies on the scientific method to provide unbiased, reliable information. ○​ Helps navigate the overwhelming and often conflicting information about diets and health. ​ Goal: Equip students to critically analyze nutrition information and make informed decisions based on evidence. Section 2 part 1 Next Topic: Handling of food in the human body. Introduction ​ Focus: Overview of digestion and primary organs. ​ Goals: 1.​ Learn digestion terminology. 2.​ Understand the primary organs of digestion. 3.​ Trace the path food takes through the human body. Key Terminology 1.​ Digestion: ○​ Breaking food into individual molecules small enough to be absorbed. ○​ Includes mechanical (physical breakdown) and chemical (enzymatic breakdown) digestion. 2.​ Absorption: ○​ Movement of nutrients from the gastrointestinal (GI) tract into transport pathways (blood or lymph). 3.​ Transport: ○​ Delivery of absorbed nutrients to cells and tissues. Big Picture Goal of Digestion ​ Goal: Harvest nutrients from food and deliver them to cells and tissues. ​ Two types of nutrients: ○​ Energy-yielding: Carbohydrates, proteins, fats. ○​ Non-energy-yielding: Vitamins, minerals, water. Primary Organs of Digestion 1.​ Mouth: ○​ Mechanical digestion: Chewing breaks food into smaller pieces.  ○​ Chemical digestion: ​ Enzymes in saliva: ​ Amylase: Breaks down carbohydrates. ​ Lipase: Breaks down fats. ○​ Food becomes: Bolus (chewed food + saliva). 2.​ Esophagus: ○​ Transport tube connecting mouth to stomach. ○​ No digestion occurs. ○​ Two sphincters: ​ Upper esophageal sphincter: Controls entry into esophagus. ​ Lower esophageal sphincter: Prevents backflow from the stomach. 3.​ Stomach: ○​ Mechanical digestion: Muscular contractions churn food. ○​ Chemical digestion: ​ Enzymes: Break down proteins and fats. ​ Hydrochloric acid (HCl): Kills pathogens and aids digestion. ○​ Functions: ​ Temporary food storage (can expand to 1 gallon). ​ Prepares food for the small intestine. ○​ Food becomes: Chyme (semi-liquid mass of partially digested food). 4.​ Small Intestine: ○​ Segments: Duodenum, Jejunum, Ileum. ○​ Functions: ​ Mechanical digestion: Muscular contractions move chyme. ​ Chemical digestion: Enzymes from small intestine lining and pancreas break down carbohydrates, proteins, and fats. ​ Absorption: Most nutrients are absorbed here. ○​ Adaptations for absorption: ​ Circular folds: Increase surface area. ​ Villi: Finger-like projections with blood and lymph vessels for nutrient absorption. ​ Microvilli: Tiny projections on villi for further surface area maximization. 5.​ Large Intestine (covered in next lecture). Accessory Organs of Digestion (next lecture) ​ Liver, pancreas, gallbladder, and salivary glands (assist but food doesn’t pass through them). Key Concepts 1.​ Types of Digestion: ○​ Mechanical: Physical breakdown (chewing, stomach churning). ○​ Chemical: Enzymatic breakdown into single units. ​ Carbohydrates → Simple sugars. ​ Proteins → Amino acids. ​ Fats → Fatty acids and glycerol. 2.​ Conditions: ○​ GERD (Gastroesophageal Reflux Disease): ​ Lower esophageal sphincter malfunctions. ​ Stomach acid enters esophagus → “Heartburn.”  ​ Risk factors: Alcohol, smoking, obesity, pregnancy. ○​ Gastroparesis: ​ Delayed or stopped stomach emptying due to vagus nerve damage. ​ Causes: Idiopathic or diabetes complications. ​ Symptoms: Nausea, vomiting, bloating, malnutrition. Summary ​ Digestion involves breaking down food (mechanical + chemical) for absorption. ​ Primary organs (mouth, esophagus, stomach, small intestine, large intestine) handle food at different stages. ​ Most nutrient absorption occurs in the small intestine due to its design for maximum surface area. Key Questions to Review 1.​ What are the primary organs of digestion, and why are they considered "primary"? 2.​ What are the two types of digestion, and where do they occur? 3.​ Which nutrients require digestion before absorption, and which do not? 4.​ What structural adaptations in the small intestine maximize nutrient absorption? 5.​ What causes GERD and gastroparesis, and how do they affect digestion? ChatGPT Organized Lecture Notes: Section 2, Part 2 – Handling Food in the Human Body 1. Wrap-Up of Primary Organs of Digestion ​ Large Intestine: ○​ Anatomy: ​ Length: ~5 feet long. ​ Diameter: 2–3 inches (compared to ~1 inch for the small intestine). ​ Sections: ​ Cecum: Beginning section connected to the appendix. ​ Colon (majority of the large intestine): ​ Ascending colon. ​ Transverse colon. ​ Descending colon. ​ Sigmoid colon. ​ Rectum: Final portion of the large intestine. ○​ Functions: ​ Water absorption: ​ Extracts water from chyme to prevent dehydration. ​ Can reduce 1 liter of fluid to ~200 grams of fecal material. ​ Issues like bacterial infections (e.g., diarrhea) can disrupt this process. ​ Mineral absorption: Some minerals (though most are absorbed in the small intestine).  ​ Gut microbiome: ​ Houses trillions of bacteria (more bacteria in the colon than cells in the body). ​ Bacterial concentration: ​ Increases from the stomach (10¹–10² colony-forming units per mL) to the colon (10¹⁰–10¹² CFU/mL). ​ Role of the gut microbiome: ​ Affects digestion, fiber breakdown, and systemic health. ​ Composition determined by: ​ Diet (long-term and short-term changes). ​ Antibiotics, geography, life stage, delivery method (C-section vs. vaginal), infant feeding (breastfeeding vs. formula), stress, and exercise. ​ Imbalance (dysbiosis): ​ Linked to health issues like heart disease, Parkinson’s, depression, thyroid disorders, diabetes, obesity, and gut conditions (IBS, IBD). ​ NIH research focuses on gut microbiome’s impact on health and potential treatments. ​ Healthy behaviors (balanced diet, physical activity) support a beneficial gut microbiome. 2. Accessory Organs of Digestion ​ Definition: Assist digestion but food does not pass through them. ​ Organs: 1.​ Salivary Glands: ​ Produce saliva, which: ​ Moistens food for swallowing. ​ Contains enzymes: ​ Amylase: Breaks down carbohydrates. ​ Lipase: Breaks down fats. 2.​ Liver: ​ Largest internal organ. ​ Regulates metabolism of carbohydrates, lipids, proteins, and alcohol. ​ Function in digestion: ​ Produces bile, which aids fat digestion. 3.​ Gallbladder: ​ Stores and concentrates bile produced by the liver. ​ Releases bile into the small intestine when fat is present. 4.​ Pancreas: ​ Produces digestive enzymes released into the small intestine to break down nutrients. ​ Produces hormones (e.g., insulin) to regulate blood sugar (covered in the carbohydrate section). 3. Bile and Fat Digestion ​ Nature of Fat: ○​ Hydrophobic: Repels water, clumps together in the body’s watery environment. ○​ This clumping makes fat difficult to digest.  ​ Role of Bile: ○​ Emulsification: ​ Bile has hydrophobic and hydrophilic ends. ​ Breaks large fat globules into smaller droplets, increasing surface area for enzymes. ​ Allows fat-digesting enzymes (lipases) to work more effectively. 4. Chemical Digestion ​ Definition: Breakdown of nutrients through enzymatic reactions. ​ Key Process: Hydrolysis: ○​ Enzymes insert water to break chemical bonds between nutrient units. ○​ Example: ​ Carbohydrates: Polysaccharides → Monosaccharides. ​ Proteins: Polypeptides → Amino acids. ​ Fats: Triglycerides → Fatty acids + Glycerol. ○​ Hydrolysis occurs primarily in the small intestine. ​ Enzymes: ○​ Specific to substrates they act on. ○​ Named with suffix -ase: ​ Lipase: Acts on lipids (fats). ​ Amylase: Acts on carbohydrates (starches). ​ Protease/Peptidase: Acts on proteins/peptides. ○​ Enzymes are produced by: ​ Small intestine lining. ​ Pancreas. ​ Reaction Process: ○​ Enzymes bind to substrates → Hydrolysis reaction → Nutrients broken into absorbable units. 5. Main Takeaways 1.​ Large Intestine: ○​ Primarily absorbs water and some minerals. ○​ Houses gut microbiome, which impacts overall health. ○​ Healthy lifestyle behaviors promote a beneficial microbiome. 2.​ Accessory Organs: ○​ Salivary glands: Produce saliva for initial digestion. ○​ Liver: Produces bile for fat digestion. ○​ Gallbladder: Stores and releases bile. ○​ Pancreas: Produces enzymes for chemical digestion. 3.​ Chemical Digestion: ○​ Enzymatic breakdown of nutrients through hydrolysis. ○​ Enzymes are substrate-specific and named accordingly. Key Questions to Review 1.​ What are the main functions of the large intestine? 2.​ What is the gut microbiome, and how does it impact health? 3.​ What roles do the accessory organs play in digestion? 4.​ What is hydrolysis, and how does it work in chemical digestion? 5.​ Which enzymes are involved in breaking down carbohydrates, proteins, and fats?