Lipids

Introduction to Lipids

  • Instructor: Dr. Miriam Clegg

  • Institution: University College Cork, Ireland

Learning Objectives

  • Understand the types of lipids.

  • Grasp the structure of lipids and their biological roles.

  • Learn about dietary guidelines and sources of lipids.

  • Understand how lipids are digested and absorbed by the body.

  • Explore the relationship between lipids and health.

Macronutrients vs. Micronutrients

  • Macronutrients: Proteins, fats (lipids), carbohydrates.

  • Micronutrients: Vitamins, minerals; includes dietary fibre, phytochemicals.

  • Energy Sources: Nutrients provide energy—fats are the most concentrated source.

Dietary Fats: Functions

  • Energy Production: Fats are crucial for energy, providing 9 kcal/g.

  • Insulation: Protects vital organs like heart, liver, and kidneys.

  • Hormone Production: Essential for synthesizing hormones and maintaining cell membrane fluidity.

  • Vitamin Transport: Acts as a carrier for fat-soluble vitamins (A, D, E, K) and essential fatty acids.

  • Intake Recommendations: 20-35% of daily energy from fats, limiting saturated fat to less than 10%.

Types of Fats

Saturated Fats

  • Found mainly in animal products (e.g., meat, dairy).

  • Exceptions include some plant sources like coconut oil.

  • Associated with raising LDL cholesterol, contributing to heart disease.

Unsaturated Fats

  • Include monounsaturated (e.g., olive oil, nuts) and polyunsaturated fats (e.g., fatty fish).

  • Generally liquid at room temperature and linked with heart health benefits.

Trans Fats

  • Sources: Processed foods, partially hydrogenated oils.

  • Health Concerns: Raise LDL cholesterol while lowering HDL cholesterol, increasing CVD risk.

Classification of Lipids

  • Triglycerides: Composed of glycerol and three fatty acids.

  • Phospholipids: Form cell membranes, aiding in emulsification.

  • Steroids: Cholesterol and hormone structure.

  • Lipid Derivatives: Eicosanoids and synthetic lipids.

Fatty Acids

Types and Classification

  • Saturated: No double bonds, solid at room temperature. Sources: butter, fatty meats.

  • Unsaturated: One or more double bonds, liquid at room temperature.

  • Essential Fatty Acids: Omega-3 and omega-6 are necessary for health. Found in various dietary sources.

Omega-3 Fatty Acids

  • Key Types: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid).

  • Functions: Integral to cell membranes; precursors for hormones.

  • Sources: Fatty fish, nuts, flaxseed oil.

Omega-6 Fatty Acids

  • Key Types: LA (linoleic acid), AA (arachidonic acid).

  • Sources: Nuts, seeds, vegetable oils, meat.

Fatty Acid Pathways

  • Both n-6 and n-3 fatty acids utilize similar enzymatic pathways for desaturation and elongation.

  • They play significant roles in health, influencing inflammation and cardiovascular health.

Intake Recommendations

  • EFSA: 250-500mg of EPA+DHA combined daily; additional 100-200mg DHA for pregnant women.

  • AHA: Minimum of two servings of oily fish weekly for cardiovascular health.

Digestion and Absorption of Fats

  • Begins in the mouth and stomach with enzymes acting primarily on dairy fats.

  • Pancreatic lipase: Key enzyme for breaking down triglycerides in the small intestine.

  • Formation of micelles facilitates absorption of fatty acids and monoglycerides in intestinal cells.

  • Bile salts enhance fat emulsification, aiding in digestion.

Conclusion

  • Lipids are vital for many bodily functions, including energy storage, cellular structure, and hormonal regulation. A balanced intake of different types of fats is essential for optimal health.