(34) Lipids Fats Part 1
Overview of Lipids
Definition: Lipids are a broad category of compounds that include fats and oils.
Not synonymous with fats, although commonly used that way.
Fats are solid at room temperature, while oils are liquid.
Key Components of Lipids
Composition: Made up of carbon, hydrogen, and oxygen, similar to carbohydrates.
Triglycerides:
Constitute about 95% of the lipids found in food and the human body.
Structure consists of three fatty acid molecules bound to a glycerol backbone.
Various types of triglycerides depend on the nature of fatty acids (saturated vs. unsaturated).
Fatty Acids
Types:
Saturated Fatty Acids: Filled with hydrogen; e.g., stearic acid (18 carbon atoms).
All carbon atoms are saturated with hydrogen.
Unsaturated Fatty Acids: Do not contain the maximum amount of hydrogen.
Monounsaturated Fat: Contains one double bond (e.g., oleic acid).
Polyunsaturated Fat: Contains two or more double bonds (e.g., omega-3, omega-6).
Essential Fatty Acids: Omega-3 and omega-6 are essential, meaning they must be obtained through diet.
Types of Fats in Foods
Comparison of Oils and Fats:
Coconut Oil: High in saturated fats but has some monounsaturated fats and omega-6.
Soybean Oil: Primarily polyunsaturated omega-6 with less saturated fat.
Important to recognize distribution when discussing the health impacts of these oils.
Phospholipids
Role: Component of all cell membranes; act as emulsifiers.
Structure includes hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.
Essential for transport across cell membranes.
Common Examples: Lecithin found in egg yolks, liver, wheat germ, peanuts, soy, milk.
Less common than triglycerides in foods but present in various dietary sources.
Sterols
Cholesterol: The most well-known sterol found in animal foods.
Not essential in the diet since the body can produce it.
Functions include being a component of cell membranes and aiding fat digestion.
Plant Sterols:
Found in plant foods; can help lower cholesterol levels.
Examples include sterols from nuts and seeds.
Fat Digestion Process
Mouth: Begins with lingual lipase, especially active in infants.
Stomach: Mechanical breakdown occurs, and gastric lipase plays a minor role in digestion.
Small Intestine:
Fat enters, and CCK hormone triggers bile release from the gallbladder.
Bile emulsifies fats allowing for better enzyme action.
Pancreatic Lipase: Works with intestinal lipase to break triglycerides into fatty acids and glycerol.
Hydrolysis is the process that breaks down triglycerides and phospholipids.
Role of Bile in Digestion
Production: Made in the liver and stored in the gallbladder, aiding in fat digestion.
Removal of the gallbladder necessitates diet adjustments as less bile is available for emulsification.
Function: Breaks down fat globules, facilitating enzyme action for digestion; vital for nutrient absorption.
Summary of Emulsification Process
Emulsification allows fats to mix with digestive enzymes in a watery environment, enhancing fat absorption.
Bile is key in this process, ensuring fats are adequately processed for absorption in the small intestine.