Chapter 4: Carbohydrates (CHO)

Primary Functions, AMDRs, and Food Sources of Carbohydrates

• Primary Functions: Carbohydrates are the body's main source of energy, especially for the brain and red blood cells. They also spare protein for tissue building and repair, and help prevent ketosis by providing adequate glucose.

• AMDR (Acceptable Macronutrient Distribution Range): 45–65% of total daily calories should come from carbohydrates.

• Best Food Sources: Whole grains, fruits, vegetables, legumes, and dairy products are rich in carbohydrates.

Classification of Carbohydrates

• Simple Carbohydrates: Include monosaccharides (glucose, fructose, galactose) and disaccharides (sucrose, lactose, maltose). Found in fruits, milk, and table sugar.

• Complex Carbohydrates: Include oligosaccharides and polysaccharides (starch, glycogen, fiber). Found in grains, legumes, and vegetables.

• Starch vs. Fiber: Starch is digestible and provides energy; fiber is indigestible and promotes digestive health.

Digestion and Absorption of Carbohydrates

• Digestion: Begins in the mouth (salivary amylase), continues in the small intestine (pancreatic amylase), and ends with brush border enzymes breaking down disaccharides.

• Absorption: Monosaccharides are absorbed in the small intestine and transported to the liver via the portal vein.

• Blood Glucose Regulation: Maintained by insulin (lowers blood glucose) and glucagon (raises blood glucose).

Role of Dietary Fiber in Health

• Promotes bowel regularity, lowers cholesterol, helps control blood glucose, and may reduce risk of chronic diseases.

Key Terms: Sugars and Grains

• Natural Sugars: Occur naturally in foods (e.g., fruit, milk).

• Added Sugars: Added during processing or preparation (e.g., soda, candy).

• Sugar Substitutes: Non-nutritive sweeteners (e.g., aspartame, sucralose).

• Whole Grains: Contain the entire grain kernel (bran, germ, endosperm).

• Refined Grains: Milled to remove bran and germ, losing nutrients.

• Enriched Grains: Nutrients lost during processing are added back.

Diabetes: Mechanisms and Nutrition Considerations

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

• Type 2 Diabetes: Insulin resistance; managed with diet, exercise, and sometimes medication.

• Nutrition Considerations: Emphasize complex carbohydrates, fiber, and consistent meal timing.

Chapter 5: Lipids (LIP)

Primary Functions, AMDRs, and Food Sources of Lipids

• Primary Functions: Provide energy, support cell structure, aid in absorption of fat-soluble vitamins, and serve as precursors for hormones.

• AMDR: 20–35% of total daily calories from fat.

• Best Food Sources: Oils, nuts, seeds, fatty fish, avocados, and dairy products.

Classification of Lipids

• Triglycerides: Main form of fat in food and body; composed of glycerol and three fatty acids.

• Phospholipids: Major component of cell membranes; found in eggs, soybeans.

• Sterols: Include cholesterol; found in animal products.

• Unsaturated Fats: Monounsaturated (olive oil, avocados), Polyunsaturated (omega-3 and omega-6 fatty acids in fish, walnuts).

• Saturated Fats: Found in animal fats, butter, coconut oil; solid at room temperature.

• Trans Fats: Artificially hydrogenated oils; increase cardiovascular risk.

Digestion, Absorption, and Transport of Lipids

• Digestion: Begins in the mouth (lingual lipase), continues in the stomach (gastric lipase), and mainly occurs in the small intestine (pancreatic lipase, bile emulsification).

• Absorption: Fatty acids and monoglycerides form micelles, absorbed into intestinal cells, reassembled into triglycerides, and packaged into chylomicrons for transport.

Dietary Recommendations for Lipids

• Total Fat: 20–35% of calories.

• Saturated Fat: Less than 10% of calories.

• Trans Fat: As low as possible.

• Essential Fatty Acids: Linoleic (omega-6) and alpha-linolenic (omega-3) acids must be obtained from diet.

• Dietary Cholesterol: Minimize intake; focus on overall dietary pattern.

Cardiovascular Disease: Mechanisms and Nutrition Considerations

• Atherosclerosis: Buildup of plaque in arteries, leading to reduced blood flow.

• Risk Factors: High LDL, low HDL, high blood pressure, smoking, poor diet.

• Lifestyle Factors: Diet low in saturated/trans fats, high in fiber, regular exercise, and not smoking reduce risk.

Optimal Blood Lipid Levels

Chapter 6: Proteins (PRO)

Primary Functions, AMDRs, and Food Sources of Protein

• Primary Functions: Build and repair tissues, enzymes, hormones, immune function, and energy (when necessary).

• AMDR: 10–35% of total daily calories from protein.

• Best Food Sources: Meat, poultry, fish, eggs, dairy, legumes, nuts, and seeds.

Protein Structure and Amino Acid Classification

• Basic Structure: Composed of amino acids linked by peptide bonds; each amino acid contains an amino group, carboxyl group, hydrogen, and unique side chain.

• Essential Amino Acids: Must be obtained from diet (9 total).

• Non-Essential Amino Acids: Can be synthesized by the body (11 total).

• Conditionally Essential: Required in diet only under certain conditions (e.g., illness).

Digestion and Absorption of Protein

• Digestion: Begins in the stomach (pepsin, HCl), continues in the small intestine (pancreatic proteases).

• Absorption: Amino acids absorbed in small intestine, transported to liver via portal vein.

• Storage: Amino acids are not stored; excess is converted to energy or fat.

Key Terms in Protein Metabolism

• Deamination: Removal of amino group from amino acid for energy production.

• Denaturation: Alteration of protein structure by heat, acid, or agitation.

• Nitrogen Balance: Balance between nitrogen intake and loss; positive in growth, negative in illness or malnutrition.

Protein Requirements: RDA and AMDR Calculations

• RDA for Protein: 0.8 g/kg body weight per day for adults.

• Calculation Example: For a 70 kg adult: g protein/day

Health Consequences of Protein Intake

• Excess Protein: May stress kidneys, increase calcium loss, and contribute to dehydration.

• Deficiency: Leads to muscle wasting, weakened immunity, and in severe cases, kwashiorkor or marasmus.

• Vegetarian Diets: Can be healthful if well-planned; may reduce risk of chronic diseases but require attention to nutrients like B12, iron, and zinc.

Chapter 7: Alcohol (ETOH)

Sources and Production of Alcohol

• Sources: Beer, wine, spirits, and other fermented beverages.

• Production: Alcohol is produced by fermentation of sugars by yeast; distillation increases alcohol content.

Alcohol Consumption: Patterns and Guidelines

• Reasons for Drinking: Social, cultural, relaxation, stress relief.

• Standard Drink Size: 14 grams (0.6 oz) of pure alcohol (e.g., 12 oz beer, 5 oz wine, 1.5 oz spirits).

• Moderate Intake: Up to 1 drink/day for women, 2 drinks/day for men.

Absorption, Metabolism, and Circulation of Alcohol

• Absorption: Rapidly absorbed in stomach and small intestine; does not require digestion.

• Metabolism: Primarily in the liver via alcohol dehydrogenase and MEOS pathways.

• Circulation: Alcohol is distributed throughout body water and affects all organs.

Effects of Alcohol Consumption

• Short-Term Effects: Impaired judgment, coordination, and reaction time; risk of accidents and injuries.

• Long-Term Effects: Liver disease (fatty liver, hepatitis, cirrhosis), increased risk of cancer, cardiovascular disease, and addiction.