DeBruyne_7e_PPT_ch04

Chapter Overview

• Title: Nutrition for Health and Health Care, Chapter 4 on Lipids

• Authors: Linda Debruyne, Kathryn Pinna

• Edition: Seventh Edition

• Publisher: Cengage (2020)

Learning Objectives

• Major Roles of Fat in the Body:

  • Identify essential functions of fats.

• Chemical and Physical Properties:

  • Compare saturated, monounsaturated, polyunsaturated fats, phospholipids, and sterols.

• Fat Digestion and Absorption:

  • Understand digestion processes and absorption mechanisms.

• Health Relationships:

  • Discuss the links between different types of fats, cholesterol, and chronic diseases with recommendations.

• Sources and Types of Fats:

  • Identify food sources of solid and unsaturated fats and their health impacts.

Roles of Body Fat

• Health Impact:

  • Both excess and deficiency in dietary fat can affect health.

• Functions of Lipids:

  • Energy Provision:

    • Primary energy storage; body's capacity to store fat is nearly unlimited.

  • Muscle Fuel:

    • Significant energy source for muscular work.

  • Padding:

    • Protects internal organs from shock.

  • Insulation:

    • Maintains body temperature by insulating under the skin.

  • Cell Membranes:

    • Major component of cellular structures.

  • Raw Materials:

    • Converts fats into hormones, bile, and vitamin D as required.

The Chemist’s View of Lipids

• Triglycerides:

  • Main form of fat in foods and body; composed of glycerol and three fatty acids.

  • Formation: Glycerol + 3 Fatty Acids = Triglyceride.

• Fatty Acids:

  • Chains differing in length and saturation.

  • Types:

    • Saturated:

      • Fully hydrogenated, single bond between carbon atoms.

    • Unsaturated:

      • Missing hydrogen, containing points of unsaturation.

      • Monounsaturated: One point of unsaturation (e.g., oleic acid in olive oil).

      • Polyunsaturated: Two or more points of unsaturation (e.g., linoleic, linolenic acids).

• Hard vs. Soft Fats:

  • Degree of saturation influences texture and health.

  • Short-chain or unsaturated fats are softer at room temperature.

• Hydrogenation:

  • Adding hydrogen to unsaturated fats to increase saturation.

  • Produces trans-fatty acids, which affect cholesterol levels negatively.

Essential Fatty Acids

• Requirements:

  • Polyunsaturated fatty acids that must come from the diet.

  • Examples:

    • Linoleic (Omega-6): Found in plant oils.

    • Linolenic (Omega-3): Usually from fish oils, important in health and disease prevention.

Phospholipids & Sterols

• Phospholipids:

  • Compose about 5% of dietary lipids, e.g., lecithins used as emulsifiers.

• Sterols:

  • Complex molecules, e.g., cholesterol, synthesized in the liver.

  • Vital for cell membranes and metabolic functions.

Digestion and Absorption of Lipids

• Goals:

  • Break down triglycerides into absorbable units.

• Process:

  • Begins in the mouth with lingual lipase; continues in the stomach and small intestine.

  • Emulsification by bile; lipases convert fats to monoglycerides and free fatty acids.

Health Effects and Recommended Intakes of Fats

• Heart Health:

  • Role of LDL and HDL in heart disease risk.

  • Recommendations:

    • Replace saturated fats with unsaturated fats.

  • Dietary cholesterol impacts varies among individuals.

• Fats and Health Recommendations:

  • Daily fats from oils, limit to 20-35% of energy intake.

Function of Fats in Foods

• Sensory Appeal:

  • Enhance flavor, aroma, and texture, assist in carrying fat-soluble vitamins (A, D, E, K).

• Nutritional Contributions:

  • Essential fatty acids and energy dense.

  • Fats stimulate appetite and increase feelings of fullness.

• Sources of Fat:

  • Differentiation between healthy and harmful fat sources.

Recommendations for Fat Intake

• Daily Fat Intake:

  • Include preferred oils; limit saturated and trans fats.

  • Monitor labels for fat content.

• Healthier Meat Choices:

  • Opt for lean cuts and control portion sizes; avoid fried and high-fat processed meats.

Conclusion

• Continuous evaluation of dietary fats emphasizes switching to beneficial fats while reducing harmful types. The understanding of fat in nutrition has evolved, focusing on quality rather than quantity.