PH

Nutrition Major Lecture Notes

Previous Lecture Review

  • Recap of concepts from the previous lecture session.

Gastrointestinal (GI) Tract Functionality

  • Sphincters' Role in GI Tract:

    • Regulate motility (A)

    • Catalyze enzyme reactions (B)

    • Speed up absorption (C)

    • Neutralize acidic secretions (D)

Enzymes in Nutrition

  • Identify Enzymes:

    • A. Lipid

    • B. Lipoprotein

    • C. Lipase

    • D. Lipyme

    • Correct answer: C. Lipase

Pancreatic Secretions

  • What does the pancreas secrete?

    • A. Amylase

    • B. Bile

    • C. Bicarbonate

    • D. All the answers listed

    • E. A and C

    • Correct answer: D. All the answers listed

Celiac Disease Implications

  • True or False:

    • People with celiac disease experience poor nutrient absorption due to damaged villi in the small intestine.

    • Answer: A. True

Carbohydrates Overview

Module 2, Lecture 3

Lecture Objectives

  • By the end of this lecture, you will:

    1. Identify primary functions of carbohydrates in the body

    2. Explain the types of carbohydrates

    3. Explain whole, refined, and enriched grains

    4. State the recommended intake of carbohydrates

    5. Discuss the digestion and absorption of carbohydrates

    6. Explain the roles of hormones in the regulation of blood glucose

Carbohydrates - Definition and Composition

  • What are Carbohydrates?

    • Composed of carbon (C), hydrogen (H), and oxygen (O).

    • Functions:

    • Source of fiber

    • Adds sweetness and flavor to food.

    • Composed of one or more sugar (saccharide) units.

    • Contains 4 kcal per gram.

    • Functions in the Body:

    • Primary source of energy for all cells.

    • Indispensable energy source for the brain, red blood cells, and muscles during intense exercise.

    • Important for intestinal health.

    • Reduces the use of protein for energy.

    • Food sources include fruits, vegetables, grains, and dairy products.

Food Sources of Carbohydrates

  • Key Sources:

    • Starches and grains

    • Fruits

    • Dairy products

    • Sweets and desserts

    • Vegetables

Types of Dietary Carbohydrates

  • Categories:

    • Monosaccharides (1 sugar unit)

    • Disaccharides (2 sugar units)

    • Oligosaccharides (3-10 sugar units)

    • Polysaccharides (>10 sugar units)

Monosaccharides

  • Examples:

    • Glucose: Found in fruits, vegetables, and honey; circulates in bloodstream.

    • Formula: C6H{12}O_6

    • Fructose: Found in fruits, vegetables, and honey.

    • Galactose: Component of milk sugar (lactose).

Disaccharides

  • Composed of two sugar units:

    • Maltose: Formed during starch digestion; minimal presence in food.

    • Formula: C{12}H{22}O_{11}

    • Sucrose: Known as table sugar; exists in fruits and vegetables.

    • Lactose: Known as milk sugar; found in dairy products.

Complex Carbohydrates

  • Polysaccharides:

    • Starch, Fiber, Glycogen

    • Composition:

    • Starch composed of long chains of glucose.

      • Types of Starch:

      • Amylose (straight-chain polymer)

      • Amylopectin (branched, with up to 100,000 glucose units)

    • Fiber: Indigestible component, includes cellulose and hemicellulose.

    • Functions in gut health and regulation of bowel movements.

    • Glycogen: Storage form in animals, found in liver and skeletal muscle; highly branched structure.

Indigestible Polysaccharides: Fiber

  • Classifications based on water solubility:

    • Soluble Fiber:

    • Examples: oats, beans, citrus; helps lower blood cholesterol and glucose levels.

    • Insoluble Fiber:

    • Examples: whole wheat, vegetables, nuts; promotes bowel movements.

Digestive Role of Fiber

  • Fiber Functions:

    • Promotes satiety.

    • Decreases obesity risk and cancer risk.

Soluble Fiber Mechanism

  1. Cholesterol Utilization for Bile Production:

    • Liver uses blood cholesterol to make bile.

  2. Bile Storage:

    • Gallbladder stores bile.

  3. Bile Functions in the Intestine:

    • Aids digestion and binds to fiber.

  4. Cholesterol Reabsorption:

    • Some cholesterol in bile is reabsorbed into blood.

  5. Excretion:

    • High soluble fiber diet facilitates bile excretion.

Diverticular Disease

  • Definition:

    • Diverticulosis leads to the formation of diverticula (pouches) along the intestinal wall.

    • Preventive measures include high fiber diet and active lifestyle.

Whole Grains vs. Refined Grains

  • Whole vs. Refined:

    • Whole grains retain bran and germ; refined grains have these parts removed.

  • Fortification vs. Enrichment:

    • Fortified: Nutrients added to foods that were absent to prevent deficiencies.

    • Enriched: Nutrients lost during processing are added back.

Grains Nutritional Comparison

  • Whole Wheat Bread vs. Enriched Wheat Bread:

    • Whole wheat provides higher dietary fiber and fewer added sugars compared to enriched grains (white bread).

Recommended Intake of Carbohydrates

  • Dietary Guidelines for Americans:

    • Consume half of all grains as whole grains.

    • Limit added sugar to less than 10% of total kcal.

  • Dietary Reference Intakes (DRIs):

    • RDA = 130 g/day (for adults).

    • Fiber AI = 14 g per 1,000 kcal/day.

    • Recommended daily fiber intake: 25 g (women), 38 g (men).

    • AMDR = 45-65% of total caloric intake; for a 2,000 kcal diet: 225-325 g of carbs.

Low Carbohydrate Diets

  • Description:

    • Consuming less than 100 g of carbohydrates per day.

    • Focuses on unlimited meats and high-fat foods.

  • Impacts:

    • Short-term: "Keto Flu" symptoms, halitosis.

    • Long-term: Potential weight gain, kidney stones, osteopenia, nutrient deficiencies, heart disease, and constipation.

Carbohydrate Digestion Process

Locations and Steps:

  • Mouth:

    • Salivary α-amylase begins digestion of amylose and amylopectin.

  • Stomach:

    • Salivary amylase is inactivated; mechanical digestion continues without chemical digestion.

  • Small Intestine:

    • Pancreatic α-amylase continues starch digestion.

    • Brush border enzymes digest disaccharides into monosaccharides for absorption.

Monosaccharide Absorption Mechanism

  • Transport Mechanisms:

    • Glucose and Galactose: transported through active transport requiring energy.

    • Fructose: employs facilitated diffusion, moving down concentration gradient.

Impact of Fiber on Digestion

  • Total Functions:

    • Fiber delays gastric emptying and absorption; regulates bowel activity and beneficially affects gut health.

Metabolism of Glucose

  • Possible Fates of Glucose:

    1. Immediate energy source for cells.

    2. Conversion into glycogen (glycogenesis).

    3. Conversion into fat for long-term storage in adipose tissue.

Regulation of Blood Glucose by Hormones

  • Pancreas Function:

    • Insulin: Released in response to high blood glucose; facilitates glucose uptake in tissues.

    • Glucagon: Released when blood glucose is low; promotes glucose release from liver.

Diabetes Overview

  • Type 1 Diabetes: Pancreas fails to produce insulin.

  • Type 2 Diabetes: Cells do not respond adequately to insulin.

Summary of Macronutrients

  • Comparison of Carbs, Lipids, Proteins, Water, and Alcohol regarding their basics, food sources, recommended intake, digestion, absorption, metabolism, and related health conditions.