Fats

1. Importance of Fats

  • Fats are essential for a healthy diet, contributing to taste and texture in foods.

  • They are a major energy source and critical for cell and tissue structure.

  • Fats aid in the absorption of essential vitamins and can be converted into signaling molecules like prostaglandins  .

2. Structure of Fats

  • Fats consist of a glycerol backbone and fatty acid chains.

  • Fatty acids can be categorized by their carbon chain length:

    • Short-chain: 2-5 carbons

    • Medium-chain: 6-12 carbons

    • Long-chain: 13 or more carbons   .

3. Types of Fatty Acids

  • Saturated Fatty Acids: Contain only single bonds; solid at room temperature.

  • Unsaturated Fatty Acids: Contain one or more double bonds; usually liquid at room temperature.

    • Monounsaturated: One double bond.

    • Polyunsaturated: Two or more double bonds

4. Omega Fatty Acids

  • Omega-3: Found in fish (EPA, DHA) and plants (ALA); important for heart health and brain development.

  • Omega-6: Found in oils (linoleic acid) and animal sources (arachidonic acid); essential fatty acids.

  • Omega-9: Monounsaturated (oleic acid); can be synthesized by the body

5. Trans Fats

  • Result from partial hydrogenation, which alters the configuration of fatty acids.

  • Associated with negative health effects, including coronary heart disease    .

6. Digestion of Fats

  • Fats form large globules in water; enzymes (lipases) break them down into free fatty acids and monoglycerides.

  • Bile salts emulsify fats, increasing surface area for digestion.

  • Fatty acids and monoglycerides form micelles to be absorbed by intestinal cells

7. Health Benefits and Recommendations

  • Polyunsaturated fats can lower blood pressure and cholesterol levels, reducing cardiovascular disease risk.

  • Saturated fat intake should be limited; replacing it with polyunsaturated fats is beneficial     .

  • Recommended fat intake: 20-35% of daily calories, with less than 10% from saturated fats   .

Key Concepts: Lipids

1. Four Major Types of Lipids

  1. Fats (Triglycerides) – Store energy, provide insulation.

  2. Phospholipids – Form the structure of cell membranes.

  3. Steroids – Act as hormones and regulate cell membrane fluidity.

  4. Waxes – Provide waterproofing and protection.

2. Role of Fats in Energy Storage

• Fats (triglycerides) = Glycerol + 3 fatty acids.

• Stored in adipocytes (fat cells) in animals and seeds in plants.

• Provide long-term energy storage (1g = 9 kcal).

• Also insulate the body and protect organs.

3. Saturated vs. Unsaturated Fatty Acids

Cis-unsaturated fats → Bent shape, liquid (e.g., olive oil).

• Trans fats → Artificially hydrogenated, solid (e.g., margarine), increase LDL (“bad” cholesterol).

4. Phospholipids & Their Role in Cells

• Structure: Glycerol + 2 fatty acids + phosphate group.

• Amphipathic:

• Hydrophilic head (water-loving).

• Hydrophobic tails (water-fearing).

• Form the phospholipid bilayer of cell membranes.

• Create micelles in water (self-assemble into spheres).

5. Steroids: Structure & Functions

• Four fused carbon rings.

• Examples:

• Cholesterol – Maintains membrane fluidity.

• Testosterone & Estrogen – Regulate body functions.

• Vitamin D & Bile salts – Help with calcium absorption & fat digestion.

6. Cholesterol & Plasma Membrane Fluidity

• Prevents membranes from becoming too rigid or too fluid.

• Acts as a precursor for steroid hormones, vitamin D, and bile salts.

7. Omega Fatty Acids (Essential Fatty Acids)

• Omega-3 and Omega-6 → Body cannot produce them.

• Found in fish, flaxseeds, and nuts.

• Benefits: Reduce heart disease risk, lower triglycerides, and decrease inflammation.

8. Waxes

• Waterproof coatings for feathers, leaves, fruits, and insects.

• Structure: Long-chain fatty acid + alcohol.

Summary

• Lipids are hydrophobic molecules important for energy storage, membrane structure, and signaling.

• Fats (triglycerides) store energy, while phospholipids form cell membranes.

• Saturated fats are solid; unsaturated fats are liquid and healthier.

• Cholesterol is essential for cell membranes and steroid hormone production.

• Omega-3 fatty acids are crucial for heart health.

• Waxes provide protection and waterproofing.