ASIN Lecture 4 - Lipids moodle

Page 1: Introduction to Lipids

• Title: A SIN 500 Introduction to Nutrition Lecture 4 Lipids

Page 2: Lecture Objectives

• Outline the four major types of fatty acids.

• Discuss the types of essential fatty acids and their health benefits.

• Explain the benefits of including plant sterols in the diet.

• Discuss the role of lipoproteins in regulating blood lipids.

• Discuss the impact that trans and saturated fats have on our health.

Page 3: Functions of Lipids

• Palatability of food: Enhances sensory qualities such as taste and texture.

• Cell membranes: Essential components of cell membranes and nerve fibers (myelin).

• Energy: Provides unlimited storage capacity for energy.

• Insulation and protection: Offers protective padding.

• Essential fatty acids: Supplies necessary fatty acids for body functions.

• Hormone production: Contributes to synthesis of steroid hormones.

• Absorption of vitamins: Facilitates absorption of fat-soluble vitamins.

Page 4: Fatty Acids

• Basic building blocks of lipids: Fundamental components of fatty acids.

• Chain Lengths: Vary from 4 to 24 carbon atoms.

• Triglycerides: Most dietary fats consist of long-chain fatty acids and are the primary storage form of fat in the body.

Page 5: Types of Fatty Acids

• Saturated Fatty Acids:

  • Sources: Animal fats (e.g., lard, butter).

  • Physical state: Solid at room temperature.

• Monounsaturated Fatty Acids:

  • Sources: Nuts, seeds, avocado, canola, olive oil.

• Polyunsaturated Fatty Acids:

  • Sources: Plant fats, fish, grains, and cereals.

  • Physical state: Liquid at room temperature; includes essential fatty acids.

• Trans Fatty Acids:

  • Formed through hydrogenation of liquid fats (e.g., margarine).

Page 6: Essential Fatty Acids

• Human Body: Cannot synthesize two important fatty acids:

  • Linoleic acid, Arachidonic acid (Omega-6).

  • Linolenic acid, EPA, DHA (Omega-3).

• Health Benefits: Omega-3 fatty acids may reduce risks of:

  • Heart disease, hypertension, arthritis, osteoporosis, type II diabetes.

• Dietary Ratios:

  • Ideal ratio of omega-6 to omega-3: 2:1.

  • Typical Western diet ratio: 10-15:1.

Page 7: Omega-3 Fatty Acids

• Functions:

  • Reduce triglycerides, decrease LDL cholesterol, produce anti-inflammatory prostaglandins.

• Food Sources:

  • Linolenic Acid: Found in walnut, soybean, canola oils, vegetables (soybeans), nuts (flaxseed).

  • EPA and DHA: Found in fish (salmon, mackerel) and shellfish (shrimp, oysters).

Page 8: Omega-6 Fatty Acids

• Functions:

  • Essential for cell membranes and immune response.

  • In excess, can promote inflammation and blood clotting.

• Food Sources:

  • Linoleic Acid: Leafy vegetables, seeds, nuts, grains, vegetable oils (cottonseed, safflower).

  • Arachidonic Acid: Can be synthesized from linoleic acid, found in meats.

Page 9: Phospholipids

• Functions:

  • Key components of cell membranes.

  • Lipid transport via lipoproteins.

  • Act as emulsifiers.

• Food Sources:

  • Egg yolks, liver, soybeans, peanuts.

Page 10: Sterols - Cholesterol

• Functions:

  • Structural component of cell membranes.

  • Precursor for steroid hormones, vitamin D, and bile acids.

  • Synthesized in the liver.

• Food Sources:

  • Found exclusively in animal products.

Page 11: Plant Sterols

• Found naturally in plants and oils, mimicking cholesterol's role in animals.

• Health Benefits: Lower blood cholesterol by reducing dietary cholesterol absorption in the intestine.

• Daily Intake: At least 2 grams required for cholesterol-lowering effects (e.g., in specific dietary products).

Page 12: Lipoproteins

• Types:

  • VLDL (Very-low-density lipoproteins): Deliver triglycerides to cells.

  • LDL (Low-density lipoproteins): Deliver cholesterol to cells.

  • HDL (High-density lipoproteins): Remove excess cholesterol for recycling.

Page 13: Guidelines for Daily Fat Intake

• Low-fat diets recommendations:

  • 30-40g for most women and children.

  • 30-50g for some men.

  • 40-60g for teenagers and active children.

  • 70-100g for larger and very active athletes/workers.

Page 14: Fat Content in Food

• Examples and Fat Content (g):

  • 2 chocolate biscuits: 6g

  • 1 small chocolate bar (40g): 12g

  • 1 Danish pastry: 14g

  • 1 croissant: 23g

  • 1 packet potato chips (50g): 18g

  • 1 regular muesli bar: 6g

  • 1 meat pie: 24g

  • 1 sausage roll: 23g

  • 2 slices cheddar cheese (40g): 14g

  • 1 chicken filled bread roll: 10g

  • 1 McDonald’s hamburger and regular fries: 28g

  • 1 slice pizza: 10g

  • 1 piece battered fish and 1 scoop chips: 63g

  • 2 pieces KFC chicken thighs, regular fries: 80g

Page 15: Lipids and Health

• Impact of High Fat Diets:

  • Likely to promote weight gain and obesity.

• Trans Fat Intake:

  • Raises LDL cholesterol, lipoprotein (a) and triglycerides, increasing risk of atherosclerosis and coronary heart disease (CHD).

Page 16: Lipids and Health Continued

• High trans fatty acids linked to insulin resistance and diabetes.

• The belief that low-fat high-carb diets reduce CHD is not strongly supported by evidence.

• Evidence suggests replacing saturated and trans fats with unsaturated fats may effectively prevent CHD.

Page 17: Optimal Diet for Heart Health

• A heart-healthy diet includes:

  1. Whole grains and minimally processed carbohydrates.

  2. Moderate fat intake (30-40% of total energy), focusing on unsaturated and omega-3 fats.

  3. Lowered refined grains and sugars.

  4. Elimination of trans fatty acid sources.

Page 18: Trans Fats in Our Diet

• Common sources of trans fats include:

  • Margarine, instant noodles, fast food (e.g., fries), baked goods, and snacks (e.g., chips).

Page 19: Summary

• Key Takeaways:

  • Fatty acids categorized as saturated, monounsaturated, polyunsaturated, or trans.

  • Essential omega-3 fatty acids provide significant health benefits; should be balanced with omega-6.

  • Plant sterols can aid in reducing blood cholesterol levels alongside reduced saturated fat intake.

  • Lowering LDL and increasing HDL cholesterol is beneficial for health.

  • Minimizing trans fat intake is crucial in reducing risks for CHD.