(34) Lipids Part 2 F2020

Lipids Overview

• Continuation of Lipid Study

• Focus on lipid absorption and transport post-digestion.

Lipid Absorption

• Bile aids in digesting triglycerides, breaking them down for absorption.

• Lipids absorbed into absorptive cells of the small intestine.

• Formation of chylomicrons, lipoproteins rich in triglycerides.

Lipid Transport - Lipoproteins

• Lipoproteins facilitate lipid transport through the bloodstream.

  • Chylomicrons: Highest triglyceride content, transported from the intestine.

  • Very Low-Density Lipoproteins (VLDL): Made in the liver; transports triglycerides.

  • Low-Density Lipoproteins (LDL): Higher in cholesterol, lower in triglycerides; linked to health risks.

    • Often referred to as "bad cholesterol."

  • High-Density Lipoproteins (HDL): Carries cholesterol back to liver; known as "good cholesterol."

    • Helps reduce cholesterol levels in the body, lowering cardiovascular disease risk.

Function of Lipoproteins

• Chylomicrons deliver lipids to body cells (fat and muscle cells).

• Delivery results in smaller lipid remnants sent to the liver.

• Some lipids directly enter liver without forming chylomicrons.

• Liver Functions:

  • Produces HDL and VLDL.

  • HDL scavenges cholesterol and returns it to liver; VLDL transports lipids to cells.

• High levels of LDL can lead to plaque buildup, increasing heart disease risk.

Importance of HDL and LDL Balance

• LDL oxidizes in bloodstream, contributing to plaque formation.

• Adequate levels of HDL may help mitigate LDL dangers.

• Dietary antioxidants can prevent LDL oxidation by sourcing from fruits and vegetables.

Dietary Impact on Cholesterol

• Distinction between dietary cholesterol (from foods) and blood cholesterol (LDL/HDL):

  • Dietary cholesterol doesn't directly translate into blood cholesterol.

• Triglycerides are the most common lipid form, providing energy.

• Energy density of lipids: 9 calories per gram.

  • Bodies excel in storing fat, making consumption moderation important.

Roles of Fats in the Body

• Fats provide insulation, shock absorption, and support organ health.

• Essential fatty acids: omega-3 and omega-6.

  • Omega-6: Found in vegetable oils and meats; more required than omega-3.

  • Omega-3: Important for health; forms include DHA, EPA, and ALA from plants.

• The imbalance of omega-6 and omega-3 in the American diet linked to health issues.

Sources of Essential Fatty Acids

• Omega-6 found in common oils (soybean, corn); excessive intake concerns.

• Omega-3 found in fish, nuts, seeds; control inflammation and promote heart health.

Health Effects of Dietary Fats

• Quality and quantity of dietary fat critical:

  • High saturated fats contribute to negative health outcomes.

  • Promote heart disease by raising LDL and lowering HDL.

• Limit saturated fat to <10% of diet and prioritize healthful fats.

• Consider dietary recommendations for fat intake: 20-35% of daily caloric intake.

  • Common issue: High saturated fat and lower quality omega-6 fats.

Dietary Recommendations

• Focus on heart-healthy fats (monounsaturated and omega-3) and moderate overall fat intake.

• Continuous transition from unhealthy fats (butter, bacon) to healthier options (olive oil, nuts).

Mediterranean Diet

• Widely studied; emphasizes plant-based foods:

  • Fruits, vegetables, whole grains.

• Moderate intake of fish and healthy fats, minimal red meat and sweets.

• Anti-inflammatory; promotes heart health through omega-3 and fiber.

Conclusion

• Understanding lipid metabolism and dietary impacts essential for health maintenance.