Macronutrients: Understanding Fat

Macronutrients: Fat

• Fat is a concentrated source of energy, providing 9kcal/g.
• It plays a crucial role in hormone synthesis and is a precursor for cholesterol.
• Fat is a component of cell membranes and transports fat-soluble vitamins.
• The recommended intake of total fat is 33-35% of total energy.

Learning Outcomes

• Classify different types of fats.
• Identify the chemical structures of fats in food.
• List dietary sources of fat.
• Describe the roles of fat in the body and dietary recommendations.

Function of Fat

• Fat is a concentrated source of energy (9kcal/g).
• It is a precursor for cholesterol and certain hormones.
• It is a component of cell membranes.
• Fat transports fat-soluble vitamins.
• Recommended intake: 33-35% of total energy.

Types of Fat

• Saturated Fat
• Trans Fat
• Monounsaturated Fat
• Polyunsaturated Fat (including Omega 6 and Omega 3)

Intakes of Fatty Acids

• Total Fat: 35% of energy.
• Saturated Fat: <10% of energy, <30g/day for men, <20g/day for women.
• Trans Fats: <2% of energy.
• Monounsaturated Fats: ~13% of energy.
• Polyunsaturated Fats (Omega 3): ~6.5% of energy, >0.2%
• Polyunsaturated Fats (Omega 6): Linoleic acid >1%

Sources of Fat

• Dairy and Alternatives: Some saturated fat.
• Meat: Saturated and monounsaturated fat, oily fish (Omega 3).
• Oils and Spreads: Mostly monounsaturated and polyunsaturated fats.
• Foods High in Fat: Often high in saturated and possibly trans fats.

Triacylglycerides/Triglycerides

• Triglycerides are made of glycerol and fatty acids.
• The process of creating them involves dehydration synthesis, forming an ester linkage.

Match the Structure and Label

• Matching different fatty acid structures (saturated, monounsaturated, polyunsaturated)

Omega 3 - EPA and DHA

• EPA and DHA are essential fatty acids.
• Derived from fish, linked to lowering risk of thrombosis, inflammation, and endothelial damage.
• They're also linked to lower triglyceride and LDL levels.
• Supplementation with EPA and DHA may reduce rates of mortality, heart attack, stroke, and sudden cardiac death.

Cholesterol

• Cholesterol is essential for cell membranes, bile acids, steroid hormones, and vitamin D.
• It's synthesized by the body, so it's not necessary to obtain it from food.
• Sources: shellfish, eggs, liver.

Cholesterol and Health

• Evidence on cholesterol intake and morbidity is mixed.
• Diets high in saturated fat are associated with increased total and LDL cholesterol.
• Recommendations: continue to limit saturated fat intake to reduce LDL cholesterol.

Egg Consumption and Cardiovascular Disease

• Studies suggest that eating up to 2 eggs per day does not affect cardiovascular disease or CHD risk.
• Limitations in the studies mean conclusions cannot be drawn on very high egg consumption.

Summary

• Total fat should be approximately 35% of dietary energy.
• Reduce/eliminate saturated and trans fats, and replace with polyunsaturated or monounsaturated fats.
• Essential fatty acids (linoleic and alpha-linolenic acid) must be obtained from the diet.

Additional Questions/Concepts

• Essential omega-3 fatty acid: Docosahexaenoic acid (DHA), Eicosapentanoic acid (EPA), and alpha-linolenic acid (ALA).

• Best source of polyunsaturated fatty acids: Sunflower oil, oily fish (EPA/DHA).

• Proportion of saturated fat: <10% of total energy.

• Double bonds in oleic acid: 1.

Explore the vital role of fats in our diet through this engaging quiz. Learn about different types of fats, their chemical structures, dietary sources, and the recommended intake for optimal health. Test your knowledge on how fats contribute to energy production and cell function.